2019 Vol. 32, No. 12

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2019, 32(12): .
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Characteristics and Control of Marine Macrolitter in Estuaries of Liaodong Bay
CHEN Xi, GAO Yiyao, LING Wei, LIU Qing, SHEN Qian, AN Lihui, WANG Chen
2019, 32(12): 1959-1965. doi: 10.13198/j.issn.1001-6929.2019.09.27
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Marine litter is of global concern particularly in relation to its potential impacts on aquatic ecosystem and human health. The present study was conducted to identify the characteristics and distribution of marine litter in the Bohai offshore area. Six sampling sections, each with a length of 5-10 km, were sampled along coastal Liaodong Bay. Preliminary results showed that floating litter was present at an average concentration of 67 items/km2, corresponding to the mass density of 741 g/km2; while, marine litter collected from seafloor was present at a concentration of 19 items/km2, corresponding to the mass density of 2544 g/km2. Among these sampling sites, plastic was the dominant composition, accounting for 50.9% of the total litter sampled. Moreover, proportion of plastic in benthic marine litter (62.1%) was higher than that of floating marine litter (37.5%). Morphological characteristic and labeling information on the surface of plastic litter indicated that 84.9% of the waste was of domestic origin, and 15.1% originated from commercial fishing. Results suggest that litter waste in the marine environment might be reduced by strengthening and enforcing the management for fishery wastes, raising awareness of marine environmental protection, and implementation a national marine plastic litter action plan.
Effect of Implementation of the Action Plan on Prevention and Control of Air Pollution and Its Impact on Life Expectancy in China
MA Guoxia, YU Fang, ZHANG Yansheng, PENG Fei
2019, 32(12): 1966-1972. doi: 10.13198/j.issn.1001-6929.2019.07.22
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It is the last year for China to implement the Action Plan on Prevention and Control of Air Pollution in 2017. Through the implementation of a series policy measures, including Industrial Structure Adjustment, Clean Energy Utilization, Industrial Pollution Control, Boiler Retrofit and Treatment, Non-point Source Pollution Control, Motor Vehicle Pollution Control and Supervision Capacity Building, the Action Plan on Prevention and Control of Air Pollution has achieved its goals of environmental quality improvements as well as gaining human health benefits from 2013 to 2017. Based on the atmospheric environmental monitoring data of PM10 and PM2.5 from 2013 to 2017 provided by China National Environmental Monitoring Centre, adopting the Disease Burden Method, the impact of the Action Plan on Prevention and Control of Air Pollution on of life expectancy in China was quantitatively analyzed to provide scientific basis for the formulation of environmental policy in China. The major findings are:(1) Based on the analysis of environmental monitoring data, the air quality has improved significantly, and the concentration of PM10 in 338 prefecture-level cities has dropped by 22.7%, and the concentration of PM2.5 in 74 cities deceased from 72.2 μg/m3 in 2013 to 47.4 μg/m3 in 2017. (2) The results of Disease Burden analysis showed that the loss of human health caused by air pollution has declined significantly, the number of premature deaths in urban areas has dropped from 521, 000 to 439, 000 during 2013-2017. (3) Based on the analysis results of premature deaths caused by air pollution from 2013 to 2017, and using 'the Abridged life table of urban citizens', the life expectancy of city in 2017 has increased 0.16 years compared with 2013 level. (4) The article also finds that the University of Chicago's report on the increased life expectancy of 2.4 years in 2017 compared with 2013 level has overestimated the contribution of the Action Plan on Prevention and Control of Air Pollution on human health. Our analysis shows that the Action Plan on Prevention and Control of Air Pollution has significant environmental benefits and positive effects on life expectancy.
Prospect
Analytical Methods, Environmental Behaviors and Toxicological Effects of 1, 2-Dibromo-4-(1, 2-dibromoethyl)-cyclohexane (TBECH) Stereoisomers
WANG Dan, HUANG Honglin, LÜ Lili, LI Haonan, WEN Bei
2019, 32(12): 1973-1983. doi: 10.13198/j.issn.1001-6929.2019.05.07
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1, 2-dibromo-4-(1, 2-dibromoethyl)-cyclohexane, also known as tetrabromoethylcyclohexane (TBECH), is a novel additive brominated flame retardant (BFR). It has a complex stereochemistry and consists mainly of four diastereomers with each of them having a pair of enantiomers. With the ban on production or the restricted use of legacy BFRs, TBECH, as one of the substitutes, is widely used in construction, textile and electronics industries. Due to its long-range transport, bioaccumulation and potential toxicity, TBECH is considered as a possible persistent organic pollutant. The analytical methods, environmental behaviors and toxicological effects of TBECH are reviewed. TBECH is usually detected by gas chromatography-mass spectrometry (GC-MS), but it only focused on the separation and analysis of TBECH diastereomers in the environmental samples. Detection of TBECH enantiomers will become the future development direction in the analysis of TBECH stereoisomers. TBECH has been successfully detected in various environmental media such as air, water, sediment and soil, and as well as in organisms. In addition, TBECH can cause endocrine-disrupting, reproductive and developmental toxicities and other toxic effects on organisms. The environmental behaviors of TBECH are stereoisomer-specific, and bioaccumulation, transformation and toxicological effects of TBECH are selective. So far, studies on environmental behaviors of TBECH are mainly focused on the aquatic ecosystem, which is still insufficient at the stereoisomer level. Therefore, the environmental processes and biological effects of TBECH should be further studied at the diastereomer and enantiomer levels in the future. Moreover, to fully understand the migration and transformation of TBECH and their environmental fate, more attention should be paid to the occurrence, distribution and environmental behavior of TBECH in the terrestrial ecosystem.
Current Insight on Microbial Ecology of Anaerobic Ammonium Oxidation in Natural Environment
HOU Junqing, ZHAO Ji, LI Jia, ZHAO Ziwen, ZHAO Manping, WU Linhui
2019, 32(12): 1984-1992. doi: 10.13198/j.issn.1001-6929.2019.03.23
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The anaerobic ammonium oxidation (anammox) process occurring in the natural environment is a new pathway for nitrogen loss other than traditional denitrification and aerobic ammonia oxidation. Recent studies demonstrate a widespread presence of phylogenetically distinct anammox in the natural environment, suggesting its great significance to the global nitrogen cycle. In this paper, we reviewed the ecophysiological mechanism of anammox process; summarized the functional diversity of anammox microorganisms in different natural habitats; described the driving forces that might have shaped the heterogeneity of anammox bacteria across different scales. The key finding is that appropriate amount of inorganic nitrogen can promote the occurrence of anammox. It is more suitable for anammox bacteria and its activity under low organic carbon content and low oxygen conditions because of chemical autotrophic metabolic pathways. Since the activity of denitrifying bacteria is temporarily inhibited under low nutrient conditions, which promotes the appearance of anaerobic ammonium oxidation. Meanwhile, the relatively high salinity could likely result in the enhanced activity and the shift of anammox bacteria communities. Scalindua is dominant in relatively high salinity environment, but Brocadia is common in low salinity environment. Anammox bacteria could have great potential for adaption to different temperature in the environment, most anammox bacteria such as Scalindua, Kuenenia and Brocadia have strong adaptability to extreme environments. In addition, the concentration of suspended particles and water volume play an important role in determining the community structure and activity of anammox bacteria. In the future, we can combine genomics and proteomics with transcriptomics to study the physiological ecology mechanisms of anammox bacteria in the natural environment, and find out the biochemical relationship between anammox process and the factors such as Fe3+, Mn4+ and SO42- under anaerobic conditions, in order to apply it to engineering technology and to provide a theoretical basis for ecological environment restoration.
Effects of Chelating Agent Combination Technologies on Soil Contaminated by Heavy Metals
LI Xiaobao, DONG Huanhuan, REN Lixia, ZENG Bo, LIAO Zuwen
2019, 32(12): 1993-2000. doi: 10.13198/j.issn.1001-6929.2019.04.16
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Chelating agents were widely used in soil leaching. However, practical applications revealed that the remediation efficiency was not high and secondary pollution was a problem. To improve the remediation efficiency of chelating agents on soil contaminated by heavy metals, a variety of chelating agent combination technologies have been studied. Compared to a single chelating agent remediation technology, a combined remediation system can significantly improve the remediation efficiency of soils contaminated by heavy metals. Research progresses of combination technologies (chelating agent combined with electric remediation technology, chelating agent combined with phyto remediation technology, and chelating agent combined with eluting agent remediation technology) as well as new combination technologies (chelating agent combined with permeable reactive barrier remediation technology, chelating agent combined with ultrasonic remediation technology, and chelating agent combined with fungus remediation technology) are analyzed, and the mechanisms and influencing factors of remediation technology are elaborated. The results of this study indicate that the combined remediation technologies can effectively mobilize heavy metals in the soil, improve remediation efficiency, and show promise for further development. However, these technologies still face a number of challenges with regard to practical application. First, in the terms of the combined remediation factors, chelating agent addition methods, soil acid, alkalinity, concentration, and leaching time still need to be included. Second, when uniting the technologies with the soil composition and pollutants in a series of physical and chemical reactions, the mobilization of heavy metals, as well as the reaction mechanism between heavy metal forms, further clarification is needed. Third, the addition of chelating agents may increase the deleterious effects on plants and the risk of heavy metal infiltration into the ground, causing secondary pollution. Fourth, new joint repair technology has only been applied in the laboratory. It is recommended to conduct in-depth research on the following aspects:the microcosmic mechanisms of combination technology; analysis of chelating agents and other technologies in order to determine the best coupling points for combination technology; development of biodegradable chelating agents; and search for more economical and effective ways to recover chelating agents.
Ecosystem Value Estimation
Evaluation of Carbon Sequestration of Forest Ecosystem in Xiamen City
GAO Yanni, WANG Wei, LIU Xin, ZHANG Linbo, DEND Fuliang, YANG Chunyan, SUN Qianying
2019, 32(12): 2001-2007. doi: 10.13198/j.issn.1001-6929.2018.12.05
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Carbon sequestration of terrestrial ecosystem is one of the most important indicators in ecosystem service assessment and is crucial to accurate estimation of regional carbon budget, which could support decision-making for the regional carbon management. In the present study, we estimated the forest ecosystem carbon sequestration and analyzed its spatio-temporal variation in Xiamen City in 2015 by using VPM (Vegetation Photosynthesis Model) and ReRSM (Remote Sensing Model for Ecosystem Respiration). The result showed that the carbon sequestration of forest ecosystem in Xiamen City was 31.36×104 t/a (measured on carbon) in 2015, with an average of 644.86 g/(m2·a). In general, the intra-annual dynamic of carbon sequestration exhibited a single peak curve, but fluctuated greatly under the influence of typhoons. The most areas of forest ecosystem in Xiamen City was carbon sink, with higher carbon sequestration at the edge of northwest and relative lower value in other regions, which was similar to the trend of DEM. At district scale, Tong'an District had the largest forest area and highest carbon sequestration, accounting for 52.58% and 57.10% of the total forest area and carbon sequestration in Xiamen, respectively. Tong'an District, coupled with Xiang'an and Jimei Districts made up 88.27% of the carbon sequestration of the whole city. Huli District was almost carbon neutral with an average carbon sequestration of 14.25 g/(m2·a). This research showed that the forest ecosystem in Xiamen City had a good carbon sequestration capacity.
Quantification and Valuation of Water Supply Ecosystem Service in Xiamen City, China
LIU Yin, LI Chunming, SUN Qianying, ZHANG Linbo, GAO Yanni, XIE Wenling
2019, 32(12): 2008-2014. doi: 10.13198/j.issn.1001-6929.2019.02.14
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The water pollution problem has become increasingly prominent, which becomes a major factor restraining ecosystem water supply services. However, the impact of water quality and the valuation of water supply service are often neglected in current research. It is still difficult to link management practices to water quality, water supply service and its value, which limits its application in the decision-making of water resources and water environment management. Therefore, a link was established between water quality and quantity, water supply services, and water supply value based on the water resources and water quality. The quantification and valuation of water supply service, and proposed management suggestions for Xiamen City were conducted accordingly. In this study, the SWAT (Soil and Water Assessment Tool) model was employed to simulate water quantity. The market value method and the environmental restoration cost method were employed to evaluate the value of water supply service. The concepts of major excessive pollutant equivalent and water quality equivalent were proposed to estimate the water quality. The results showed that the water supply quantity of the ecosystem in 2015 was 9.26×108 m3, with a value of 14.82×108 RMB in Xiamen. Compared with 2010, the water supply quantity increased by 1.77×108 m3 and its value increased by 2.60×108 RMB. Deterioration of water quality decreased the value of water supply service by 0.31×108 RMB in 2015 and 0.27×108 RMB in 2010, respectively. The water supply service potential in Xiamen City was large with obvious spatiotemporal variations among different water bodies, and it was affected by overall declining water quality. Further research on the improvement of water conservation capacity and water quality should be conducted to enhance the water supply service. The method and results are understandable for non-technical decision makers and allow easy operation and comparison. While the impact of economic development and the pricing strategy of water quality are not fully considered yet, the local economic development level should be considered, and the wastewater treatment cost should be revised in future research.
Service Capacity of Negative Air Ions in the Terrestrial Ecosystem of Xiamen City
YANG Chunyan, MA Wensi, ZHANG Linbo, GAO Yanni, JIA Zhenyu, LI Fujie
2019, 32(12): 2015-2021. doi: 10.13198/j.issn.1001-6929.2019.06.02
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To explore the service capacity of negative air ions and the factors affecting it in Xiamen terrestrial ecosystems, this study took the data of air negative ions generated by the ecosystem that are beneficial to human physical and mental health as the indicator, improved the service evaluation method of negative air ions, based on negative air ion monitoring data, calculated their service function, and analyzed their spatiotemporal dynamic variations and influential factors. The results indicate that the service capacity of negative air ions in Xiamen City was 1.37×1025 ions in 2015, and the service capacity distribution of negative air ions was 0.8×1016 ions/m2. Tong'an contributed the largest proportion of negative air ions of any district within Xiamen City, with a rate of 56.5%. Forestland was the main ecosystem contributor of negative air ions in Xiamen City, with a rate of 86.6%. The daily concentration of negative air ions exhibited prominent peaks and valleys, with peaks primarily distributed from 01:00-07:00, and valleys distributed around 12:00. Seasonal change was significant:the summertime concentration of negative air ions was 2437 ions/cm3, which is twice that of the springtime level. The concentrations of negative air ions for different ecosystems were markedly different. Forests displayed higher concentrations than other ecosystems, such as grassland and farmland. The main factors affecting negative air ions were found to be temperature and humidity. Negative air ion concentration decreased with increasing temperature and increased with increasing humidity. This study revealed that the forest ecosystem has the strongest service capacity of negative air ions. In addition, the service capacity of arbor greenbelts is greater than that of shrub and herb greenbelts. In urban centers, the greater the area of forests and arbor greenbelts, the greater the service capacity of negative air ions.
Beijing-Tianjin-Hebei Region
Characteristics of a Multi-Factor Superimposing Haze Episode in '2+26' Cities
YIN Lina, CHU Yangxi, DUAN Jingchun, HU Jingnan, TAN Jihua
2019, 32(12): 2022-2030. doi: 10.13198/j.issn.1001-6929.2019.07.19
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The '2+26' cities in the Beijing-Tianjin-Hebei and surrounding region was hit by a severe haze episode from Nov. 23rd to Dec. 4th, 2018, where multiple factors superimposed. To unveil the comprehensive interaction between those factors, the meteorological data, the air quality monitoring data and the regional air pollution characteristic radar chart were used to analyze the causes and characteristics of the episode. Our results show that the entire episode can be divided into four stages based on the mass concentration ratio of PM2.5 to PM10 (PM2.5/PM10). During Stage 1 (Nov. 23rd-26th), PM2.5/PM10 fluctuated between 0.5 and 1.0. Under stagnant and humid conditions, primarily emitted pollutants accumulated and gaseous precursors (e.g. SO2, NOx and NH3) were converted to secondary PM2.5 components (e.g. sulfate, nitrate and ammonium), leading to the formation and aggravation of the episode. For Stage 2 (Nov. 27th), PM2.5/PM10 dropped to 0.2. The northern part of region was heavily affected by a dust storm originating from Mongolia, resulting in temporarily surged PM10 concentration (up to 818 μg/m3). The mid-southern part of the region was influenced by another dust storm originating from Inner Mongolia Autonomous Region and the regional transport of particulate pollution from upwind area, resulting in elevated PM2.5 and PM10 concentrations and reaching daily heavy or severe air pollution (Grade Ⅴ or Ⅵ according to the GB 3095-2012 Ambient Air Quality Standards and HJ 633-2012 Technical Regulation on Ambient Air Quality Index (on trial). During Stage 3 (Nov. 28th-Dec. 2nd), PM2.5/PM10 gradually increased from 0.3 to 0.8. The accumulation of primary pollutants, secondary conversion of gaseous precursors and the catalyzing effect of residual minerals from Stage 2 on sulfate formation resulted in a rapid increase in PM2.5 concentration. The majority of '2+26' cities reached daily heavy or severe pollution (Grade Ⅴ or Ⅵ). Stage 4 (Dec. 3rd-4th) was similar to Stage 2 with PM2.5/PM10 rapidly decreased to 0.2, when the region was again heavily influenced by dust storm and regional transport of particulate pollution. The northwesterly wind lasted longer in Stage 4 than in Stage 2, which effectively cleaned up the pollutants. This work revealed that the entire episode in '2+26' cities was the result of comprehensive interaction of multiple factors, including meteorology, primary emission, secondary conversion of precursor gases, regional transport and dust storms. Therefore, regulation on the emission of various pollutants in the study region should be strengthened prior to adverse meteorological conditions or dust storm periods to alleviate the severity of air pollution.
Influence of Motor Vehicles on Air Quality in Urban Areas based on the CMAQ Model
ZHOU Cheng, LI Shaoluo, SUN Youmin, ZHANG Guiqin, LI Siyuan, ZHU Li
2019, 32(12): 2031-2039. doi: 10.13198/j.issn.1001-6929.2019.08.07
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The effect of motor vehicle exhaust on urban air quality in Jinan City was studied herein. Based on the on-line monitoring data at Sites 1 and 2, and the projected results from CMAQ (community multi-scale air quality) for four simulated scenarios, the characteristics of air pollutants in Jinan City during the heating season were investigated to evaluate the influence of vehicle types on six air pollutants. The results are as follows:(1) The average monthly ρ(PM2.5), ρ(PM10), ρ(NO2), ρ(CO), ρ(O3) and ρ(SO2) are 435 μg/m3, 702 μg/m3, 84.2 μg/m3, 6.8 mg/m3, 4.5 μg/m3 and 92 μg/m3 during the heating season. (2) On December 24th, 2015 (haze days), ρ(CO), ρ(PM2.5) and ρ(PM10) at Site 1 increased significantly, while ρ(SO2), ρ(O3) and ρ(NO2) concentrations did not change significantly. The occurrence of these peaks coincided with the peak commuting times. Studies have shown that all pollutants except O3 and SO2 exceed the national Level 2 standard specified in Ambient air quality standard (GB 3095-2012), and that the characteristics of air pollution in the Jinan City heating season are those of particulate pollution. Moreover, motor vehicles are significant contributors of NO2 and PM10. (3) The contribution rates of different types of vehicles to the four kinds of conventional air pollutants varies greatly because of differences in quantity and speed. The small car has the largest contribution rate to CO, NO2, PM10 and PM2.5 and these values are 87.5%, 50.1%, 53.4% and 52.8%, respectively. Motor vehicle emission can reduce the mass concentration of air O3 with a total contribution of -25.5%. The contribution rates of large car, medium car and small car to air O3 are -8.8%, -2.7% and -8.9%, respectively. The total contribution rate of the mass concentration of the air pollutants on haze days is higher than that of the heating season. On haze days, the contributions of various vehicle types to different pollutant concentrations in the air increased. The results show that the characteristics of environmental air pollution in Jinan City is particulate pollution, and vehicle emission sources contribute a lot to NO2 and PM2.5 in the air.
Yangtze River Economic Zone
Diversity of Glucose Dehydrogenase gcd Gene and Its Relationship with Environmental Factors in Sediment of Sancha Lake
LI Yong, ZHANG Jianqiang, FU Wenli, WU Dongming
2019, 32(12): 2040-2047. doi: 10.13198/j.issn.1001-6929.2019.03.06
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The sediment and overlying water of Sancha Lake were collected in the spring and autumn of 2017 to study the diversity of glucose dehydrogenase gcd gene and its relationship with environmental factors. High-throughput sequencing of gcd gene from the genomic DNA in the sediments was carried out to evaluate the diversity in gcd and associated community characteristics and to analyse the correlations between the gcd gene diversity indices and environmental factors. The results showed that:(1) from the 12 samples, 219, 778 valid sequences were obtained, and the classification annotation suggests 6 Phyla, 9 Classes, 15 Orders, 29 Families, 46 Genera, and 610 operational taxonomic units (OTUs), primarily Proteobacteria (25.10%-98.85%) and Acidobacteria (0-3.99%). (2) The phylogenetic tree of gcd gene sequences exhibits two branches and four sub-branches, and the gene sequences primarily attributed to orders Rhizobiales, Burkholderiales, Oceanospirillales, Pseudomonadales, and Acidobacteriales. (3) The gcd gene diversity were all higher in spring than in autumn, increasing from the lake center to the dam to the lake tail. In terms of the community composition of gcd-harboring bacteria, seasonal variation had a small effect on sampling sites L1, L2, L3, and L5, but had an appreciable impact on the sites L4 and L6. (4) The diversity indices of gcd gene were significantly correlated with ρ(DO), w(TP), w(HCl-P), and ρ(DTP). The OTU composition and distribution of gcd gene were significantly correlated with ρ(DO) and ρ(DTP). Our study indicated that the gcd gene in the sediment of Sancha Lake is highly diverse, with heterogeneous composition and distribution, which had great effect on ρ(DTP).
Coupling of Coal Mining and Ecosystem Service: Evidence from Huaibei in China
NA Ren, LI Kangwei, WAN Lunlai, YANG Jun
2019, 32(12): 2048-2056. doi: 10.13198/j.issn.1001-6929.2019.03.24
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This paper aims to analyze the coupling relationship between the coal mining and the service functions of ecosystem in Huaibei City, China. It also reveals the changing pattern of the coupling between the coal mining and the service functions of ecosystem in Huaibei City from 1990 to 2016, using the correlation degree model and the coupling degree model. The results show that the correlation between coal mining and ecosystem services in Huaibei City is between 0.4475 and 0.5534. Among them, the stress of coal mining on ecosystem services is mainly through the destruction of water resources, while the constraint of ecosystem services on coal mining mainly comes from regulatory services. In addition, the degree of coupling between coal mining and ecosystem services in Huaibei City declined gradually from 1990 to 1999, and then it increased steadily from 2000 to 2008. After that, the degree of coupling experienced a downward trend which indicates that the contradiction between the coal mining and regional ecosystem was alleviated, thereby presenting a prosperous development which is comprehensive and coordinated. The research shows that coal mining and ecosystem services in Huaibei City have a moderate coupling situation overall from 1990 to 2016, the temporal variation of coupling degree between coal mining and ecosystem services is characterized by 'inverted N'. It is necessary to continue to promote the transformation of resource-based cities and the construction of ecological governance in order to maintain a coordinated and development.
Changes in Water Area of Gaoyou Lake (including Shaobo Lake) and the Influencing Factors in the Past 30 Years
GUAN Yuying, YU Gongliang, HAN Ruiming, XU Junli, HUO Da, WANG Qiaojia
2019, 32(12): 2057-2064. doi: 10.13198/j.issn.1001-6929.2019.06.27
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The change of lake water area demonstrates the impact of climate and human activities on the structure and function of the lake ecosystem, which therefore becomes an important ecological indicator for lake health assessment and water restoration. The characteristics of natural water area change under the impact of aquaculture and climate change in the past 30 years in Gaoyou Lake (including Shaobo Lake), a typical shallow lake in East China, as well as various influencing factors were analyzed. Using GIS technology, images of the Landsat TM/ETM+ remote sensing from 1988 to 2015 were set up as the data source. The boundary information of Gaoyou Lake (including Shaobo Lake) and its breeding area was extracted by visual interpretation and ratio threshold methods. The results showed that:(1) In the past 30 years, the natural water area of Gaoyou Lake tended to progressively reduce in the early stage and partially recovered in the following years:the largest area appeared was 716 km2 in 1988, the smallest area was 535 km2 in 2011, and 643 km2 in 2015. From 1988 to 2000, the average natural water area decreased by 4.08 km2/a, whereas from 2000 to 2011 the average decrease rate was 12 km2/a, yet from 2011 to 2015 it increased by 108 km2. (2) From 1988 to 2015, the annual amount of precipitation in the catchment decreased first and then increased. The annual average temperature increased gradually in relation to the change of natural water area in Gaoyou Lake (R2=0.472); There was no significant correlation between precipitation and the change of water area (R2=0.118). (3) The enclosed aquaculture lake area was neglectable before 2000, which was only 45 km2 in 2000, while the largest area of 199 km2 appeared in 2011. The average growth rate of aquaculture area was 15.56 km2/a from 2000 to 2009 and 9.00 km2/a from 2009 to 2015. The aquaculture was concentrated in the northern lake area, where the natural water area consequently shrank most significantly, followed by the eastern and the western lake. Since 1988, temperature and fishery aquaculture have a significant impact on the natural waters of Gaoyou Lake that the shoal in the northern part of the lake has been heavily invaded, and the ecological barrier function of wetlands has greatly declined.
Belt and Road Initiative
Analysis of Urban Air Quality Characteristics and Influencing Factors in Shaanxi-Gansu-Ningxia Region
LIU Xin, XIN Cunlin
2019, 32(12): 2065-2074. doi: 10.13198/j.issn.1001-6929.2019.05.16
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Exploring the fluctuations of air quality index in a short period by using historical observation data can be helpful to formulate air pollution prevention and control measures, which is of great significance for coordinating development of regional environment and economy. In order to study the air quality characteristics of the Shaanxi Province, Gansu Province and Ningxia Hui Autonomous Region (referred to as 'Shaan-Gan-Ning Area') from 2015 to 2017, the mass concentration characteristics of AQI (air quality index) and six pollutants, including ρ(PM2.5), ρ(PM10), ρ(O3), ρ(NO2), ρ(SO2), ρ(CO) were investigated. The data of 32, 910 samples from 29 cities were sorted by mathematical statistics, while the spatial and temporal variation characteristics of the AQI and six pollutant concentrations were analyzed by Kriging interpolation. The results showed:(1) From the space, the pollution in the Guanzhong Plain in Central Shaanxi Province, the northern part of Ningxia Hui Autonomous Region, and the northwestern part of Gansu Hexi Corridor was relatively serious, but in the southwestern part of the region was relatively light. The higher ρ(O3) mainly distributed in the northwest of the region, while the higher ρ(CO) and ρ(NO2) were located the eastern part of the region. ρ(PM2.5) and ρ(PM10) were similar to those of AQI, and ρ(SO2) was higher in the northern part of the region. (2) From the time, the average value of AQI has been stabilized within the national standard value range (88) for three years. The order of seasonal variation in AQI was winter (108) > spring (88) > autumn (78) > summer (74). (3) The monthly variation characteristics of each pollutant concentration were as following:ρ(O3) was the highest in summer, the peak concentration was 140.3 μg/m3, then followed by spring and autumn, and lowest value was found in winter. The concentration of other pollutants showed the highest in winter, the peak concentration were ρ(PM2.5)(83.7 μg/m3), ρ(PM10)(155.9 μg/m3), ρ(SO2)(72.6 μg/m3), ρ(NO2)(52.1 μg/m3) and ρ(CO)(2.04 mg/m3), respectively. (4) Correlation analysis showed that the correlation coefficients of AQI with the mean temperature, average precipitation and pressure were -0.859, -0.903 and 0.620, respectively. The average temperature, average precipitation and AQI showed a significant negative correlation (P < 0.01), but pressure was significantly and positively related to it (P < 0.05); The DEM terrain relief analysis found that the higher the terrain relief level, the smaller the AQI value. AQI was mainly influenced by the number of the industrial companies, the correlation coefficients was 0.634. The study showed that the natural factors have a stronger impact on AQI than the socio-economic factors, and meteorological conditions play an important role in the spread of air pollution.
Correlation between Atmospheric Ozone and Precursor and Meteorological Factors in Lanzhou City
CHEN Xueping, JU Tianzhen, ZHANG Jiangyu, XIAN Long, WANG Peiyu, ZHANG Shengcai
2019, 32(12): 2075-2083. doi: 10.13198/j.issn.1001-6929.2019.06.01
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Lanzhou City plays a significant strategic fulcrum role in the 'Belt and Road' Initiative. Therefore, based on the ozone monitoring instrument (OMI) data products, this paper studied the correlation between the ozone column concentration, precursor compounds and meteorological factors in Lanzhou City from 2006 to 2015. The results showed that the column concentration of O3 in the troposphere and total column concentration of HCHO increased first and then decreased with time, while the column concentration of NO2 in the troposphere decreased gradually with time. Spatial correlation analysis between the column concentration of O3 and NO2 in the troposphere and total column concentration of HCHO showed that the correlation values of the three substances increased first and then decreased. In the view of sensitive control area, the sensitive control zone of VOCs gradually disappeared, and the scope of the VOCs-NOx coordinated control zone was gradually reduced, while the scope of NOx sensitive control zones gradually expanded. In terms of the meteorological factors, the column concentration of O3 in the troposphere had a significantly positive correlation with air temperature and sunlight intensity, while it had a seriously negative correlation with the atmospheric pressure and rainfall. There was a relatively high column concentration of O3 in the troposphere in Lanzhou City when the wind speed reached 1.7-1.9 m/s and the wind direction was northward. This study shows that the reduction of NOx emissions can reduce the column concentration of O3 in the troposphere significantly in Lanzhou City.
Pollution Characteristics and Risk Assessment of Heavy Metals in Atmospheric Particulates in Urumqi City
YANG Pengyue, PALIDA Yahefu
2019, 32(12): 2084-2090. doi: 10.13198/j.issn.1001-6929.2019.06.08
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In order to study the distribution characteristics and health risk assessment of toxic heavy metals, including Cu, Mn, Zn, Pb, Cr and Cd in atmospheric particulate matter, samples were collected at Xinjiang Agricultural University living area in 2018. The heavy metal contents were quantified by a TAS-990 atomic absorption spectrophotometer. It can be concluded that:(1) The average concentrations of TSP, PM10, PM5 and PM2.5 in each season were 93.17-257.14, 70.57-202.29, 57.58-147.96 and 48.71-147.46 μg/m3 in Xinjiang Agricultural University. (2) The average concentrations of heavy metals in different atmospheric particulates in each season were ρ(Zn) > ρ(Cu) > ρ(Pb) > ρ(Cr) > ρ(Mn) > ρ(Cd). (3) The results of health risk assessment indicated that the non-cancer risks of Cu, Zn, Pb and Mn in different particulates were higher in children than adults, the total non-cancer risk (HI) was less than the limit value (1) and the carcinogen risks of Cd, Cr were 3.07×10-6-2.36×10-5. (4) The results of geo-accumulation index analysis (Igeo) showed that Igeo average of Mn was -2.43 in atmospheric particulate, indicating that is was not contaminated; Cr was 0.78, which indicates no to medium pollution; Cu and Pb were 4.53, 4.33, respectively, which was moderate and severe pollution; Zn and Cd were 5.68, 7.18, respectively, which showed heavy pollution. The study shows that Cd and Cr in atmospheric particles at Xinjiang Agricultural University had no carcinogenic risk to human body, and the pollution of Zn and Cd were relatively severe, so Urumqi City should take corresponding control measures in time.
Research
Characterization of Water-Soluble Inorganic Ions in Particles from Coking Process and the Plant Area
WEI Fenghua, LIU Xiaofeng, WU Hui, WANG Zhilei, MU Ling
2019, 32(12): 2091-2097. doi: 10.13198/j.issn.1001-6929.2019.06.28
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Abstract:
In order to investigate the characteristics of water-soluble inorganic ions in the particles from coking process and in the plant area, the total suspended particulates (TSP) from combustion chamber exhaust chimney, the coke oven top as well as the ambient air surrounding the coke oven were collected using high-volume total suspended particulate samplers (TH-1000F, China). The PM1.4 samples from the coke oven top and the ambient air surrounding the coke oven were also collected using Staplex234 cascade impactor in May 2012. Nine ions (SO42-, NH4+, Ca2+, Cl-, NO3-, F-, Mg2+, K+, Na+) in the samples were analyzed by ICS-90 ion chromatograph. The results showed that SO42- was the characteristic water-soluble ion during coking process. The total concentration of water-soluble inorganic ions in TSP was the highest in the exhaust gas of the combustion chamber, which was (5493±901)μg/m3, followed by TSP on the coke oven top, which was (902±222)μg/m3, and TSP in the ambient air surrounding the coke oven was the lowest, which was (712±288)μg/m3. SO42- was the main common ion in the particles from coke oven combustion chamber exhaust, coal-fired boiler flue gas and coal-fired power plant flue gas. The ratio of SO42- to total inorganic ions from the coke oven combustion chamber exhaust was higher than that from the flue gas of coal-fired boiler, while the opposite was true for F-. NH4+ tended to concentrate in fine particles, while SO42- was concentrated in coarse particles from fugitive emissions on the coke oven top. The study showed that the distribution characteristics of water-soluble inorganic ions in the particles from the coking process and in the ambient air surrounding coke oven were different. SO42- was the water soluble ion with the highest mass concentration in TSP from the exhaust gas chimney of combustion chamber as well as the coke oven top.
Contribution of Cloud Water and Below-Cloud Scavenging Particulate Matter and Gaseous Pollutants to Sulfate and Nitrate in Wet Precipitation
TAN Yeling, ZOU Changwei, HUANG Hong, WEI Chen
2019, 32(12): 2098-2107. doi: 10.13198/j.issn.1001-6929.2019.05.02
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In order to quantify the contribution of cloud water and rain wash-out below the clouds to SO42- and NO3- in wet precipitation and further to differentiate the contribution of scavenging SO42- and NO3- in particulates and of scavenging SO2 and NO2 in the air below the clouds to SO42- and NO3- in wet precipitation, the segmented wet precipitation were collected by APS-3A precipitation automatic samplers from April 2016 to February 2017. The ρ(SO42-) and ρ(NO3-) in segmented wet precipitation were detected by ion chromatography and then the variations were analyzed. SO42- and NO3- in particulates and SO2 and NO2 in the air before rainfall, during rainfall and after rainfall were synchronously monitored. Then we analyzed variation of ρ(SO42-) and ρ(NO3-) in particulates and ρ(SO2) and ρ(NO2) in the air before rainfall, during rainfall and after rainfall. The results showed:(1) During the same wet precipitation process, the ρ(SO42-) and ρ(NO3-) in segmented precipitation decreased gradually and tended to be steady in the final stage of wet precipitation, which illustrated that the wet precipitation scoured the atmospheric pollutants and kept the air clean gradually and that scour effect of the rain became limited, leading to stable of ρ(SO42-) and ρ(NO3-) in later wet precipitation period. (2) The mass concentrations of SO42- and NO3- in particles, and the mass concentrations of SO2 and NO2 in the air were the highest before rain; they decreased during rain, and increased after rain, illustrating that the wet precipitation could scavenge SO42- and NO3- in particulates and SO2 and NO2 in the air; but the concentrations of those pollutants increased slightly without the effects of rain wash-out after rain. (3) The contributions to SO42- and NO3- in wet precipitation ranged from 22% to 56%, with an average of 35%, and from 9% to 49%, with an average of 29%. The contributions to SO42- and NO3- in wet precipitation of SO42- and NO3- in particulates scavenged below the clouds ranged from 39% to 69%, with an average of 55%, and from 43% to 73%, with an average of 56%. The contributions to SO42- and NO3- in wet precipitation of SO2 and NO2 in the air scavenged below the clouds ranged from 5% to 17%, with an average of 10%, and from 5% to 19%, with an average of 15%, respectively. These results indicated that SO42- and NO3- in wet precipitation were mainly from cloud water and SO42- and NO3- in particulates scavenged below the clouds, and minor from SO2 and NO2 in the air scavenged below the clouds.
Removal of Typical Wastewater-Marking Pharmaceuticals with Emergent Aquatic Plants in Urban Rivers
ZHOU Haidong, LIU Xiaojing, CHEN Xiaomeng, WANGJIN Yadan
2019, 32(12): 2108-2116. doi: 10.13198/j.issn.1001-6929.2019.05.10
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Abstract:
Nine pharmaceuticals including of azithromycin (AZM), sulfathiazole (STZ), ibuprofen (IBU), diclofenac (DCF), paracetamol (PRC), atenolol (ATL), clofibric acid (CLF), carbamazepine (CBM) and caffeine (CAF), were selected as the target compounds in this study. They were analyzed with high-performance liquid chromatography tandem mass spectrometer (HPLC-MS/MS). Variation characteristics of WWMPs in different media (aqueous phases, sedimentary phase and plants) and the removal of conventional indicators (chemical oxygen demand (CODCr), ammonia nitrogen (NH3-N), total phosphorus (TP) and total nitrogen (TN) by the artificial ecosystems in the indoor river simulation system were explored. The artificial ecosystems were constructed with 3 combinations of emergent aquatic plants (C. alternifolius and J. effusus, J. effusus and A. calamus, C. alternifolius and A. calamus). The actual removal efficiencies of the target pharmaceuticals by the ecosystem were also calculated by means of material balance. The results showed that the effects of 3 combined plant ecosystems on the removal of 4 conventional indicators were quite significant. The removal efficiencies were 39.7%-47.8%, 88.2%-99.4%, 39.1%-58.1%, and 49.1%-58.5% for CODCr, NH3-N, TP and TN, respectively. Compared with no-plant ecosystem, the ecosystems with aquatic plants had obvious removal effects on the removal of the pharmaceuticals, especially CBM, IBU, ATL and PRC in the aqueous phases, the largest removal rates were more than 54.0%. The ecosystem constructed by the combination of C. alternifolius and A. calamus. had a better removal effect on CAF, CBM, CLF, DCF, IBU and STZ in aqueous phase than the ecosystem constructed by single plants with 51.6% to 87.7% reduction. In the artificial ecosystem constructed by 3 kinds of combined plants, the removal effects of WWMPs in sediment phase were weakened orderly as J. effusus and A. calamus, C. alternifolius and A. calamus, C. alternifolius, J. effusus. The absorption effects of aquatic plants on WWMPs in the artificial ecosystem were also different and the absorption effects were ranked as CBM > CLF > CAF > IBU > DCF > ATL > PRC > AZM > STZ. In terms of total removal rate, the removal efficiencies of WWMPs in sediment phase in 3 combined ecosystems were the same as those in aqueous phase. This investigation indicated that combined plant artificial ecosystems could effectively remove WWMPs and the conventional indicators in urban rivers, and could be an effective way of improving water quality in urban rivers.
Adsorption Characteristics of Low-Concentration Phosphorus in Simulated Urban Rainstorm Runoff by Surface Modified Non-Sintered Eco-Brick
TANG Haiyan, MENG Xianlin, GAO Dawen
2019, 32(12): 2117-2123. doi: 10.13198/j.issn.1001-6929.2019.04.09
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In order to find out the removal method of low concentration phosphorus in surface runoff after urban heavy rain, The adsorption characteristics of fly ash, activated carbon, zeolite and other materials on low-concentration phosphorus were investigated, and the surface of the bank slope protection brick was modified by the selected adsorption materials to make non-sintered ecological brick materials. The effects of adsorption amount, phosphate concentration and reaction time on the adsorption efficiency of phosphate bricks were studied systematically. The absorption capacity of alfalfa on the surface of eco-bricks was also investigated. The results showed that:(1) Among 3 adsorbent materials, fly ash has the best adsorption effect on phosphate. In 3 hours, the removal rate of phosphate is 54% higher than that of zeolite and 67% higher than that of activated carbon. (2) When the ecological brick surface was loaded with 36 mg/cm2 fly ash, the eco-brick material showed the best phosphate adsorption performance, and the phosphate removal rate was increased by 14% compared with the ecological brick material without the fly ash. (3) The adsorption of phosphate by ecological brick material accords with the Freundlich adsorption isotherm equation and the intraparticle diffusion equation. The adsorption mechanism of phosphate is the physical adsorption dominated by intraparticle diffusion. (4) Under the condition of phosphorus deficiency stress, alfalfa secreted citric acid to dissolve the calcium phosphate crystal on the surface of ecological brick, and then absorbed it into the plant. The desorption ratio of phosphorus on the surface of ecological brick was 38.40%±0.37% in 15 d. Studies have shown that fly ash-modified non-sintered ecological brick materials have a good adsorption effect on phosphate, and the adsorbed phosphate can be absorbed by plants to achieve natural regeneration of ecological brick materials.
Ecological Safety Evaluation of the Polycyclic Aromatic Hydrocarbons (PAHs) in Surface Soil of Farmland around a Municipal Solid Waste Incineration Power Plant
ZHANG Han, LU Shaoyou, LIU Kai, ZOU Tiansen, LÜ Zhanlu, WANG Manxiang, ZHANG Jinliang
2019, 32(12): 2124-2131. doi: 10.13198/j.issn.1001-6929.2019.03.13
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In order to understand and evaluate the pollution status and ecological safety of PAHs in soil of farmland around a municipal solid waste (MSW) incineration power plant, per the sector placement principle sample points were placed in the range of 2 km around the MSW incineration power plant that was operated for a year. The comparison points were set at 10 km from upwind of the perennial dominant wind direction. A total of 21 samples were collected according to Technical Specification of Soil Environmental Monitoring (HJ/T 166-2004). Treated sample was extracted and concentrated by acetonitrile ultrasound, and the content of 15 PAHs was determined by HPLC method. Finally, we analyzed the spatial distribution and component characteristics of measurement. The results showed that the mean level of BaP in the soil around the plant was 9.40 μg/kg (range:0.663-96.2 μg/kg), the level of total PAHs and TEQ(BaP)15 was 174 μg/kg (range:37.5-1382 μg/kg) and 14.6 μg/kg (1.92-135 μg/kg) respectively, which was significantly higher than those in the control area. In the downwind of dominant wind direction throughout the year, the levels of BaP, total PAHs and TEQ (BaP) were higher than those in the upwind direction and in control area. The maximum value was observed at a distance of 1 km on the downwind of dominant wind direction away from the plant. The proportion of PAHs with four or more aromatic rings was 52.5% in the samples around the plant, which was higher than that (35.3%) in the control area. The proportion of carcinogenic PAHs was 43.0% in the farmland around the plant, which was much higher than that (22.2%) in control area. There were sites with highly polluted PAHs around the plant. The levels of w(BaP), ∑15PAHs and TEQ(BaP)15 were higher and increased more rapidly than those reported around the thermal power plant. All these suggested that compared with the control area, there was a rapidly increase in the contents of PAHs, especially the contents of PAHs with four or more aromatic rings, in the surface soil of farmland around a MSW incineration power plant. Therefore, we should strength the monitoring of the PAHs emissions and the environmental impact of MSW incineration power plant. Meanwhile, the risk of PAHs emissions should be fully considered in the environmental impact assessment.
Protective Effect of Foliar Application of Sulfur on Rice under the Stress of Cd
LIU Jiahao, ZHAO Long, SUN Zaijin, HOU Hong, LI Hua
2019, 32(12): 2132-2138. doi: 10.13198/j.issn.1001-6929.2019.10.07
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Cadmium (Cd)-contaminated paddy soil has become a global agricultural safety issue. Paddy soils contaminated by Cd jeopardize the rice cultivation and the health of people with rice as their staple food. Foliage application to alleviate Cd toxicity in rice might offer a cost-effective and practical strategy for safe food production. Field experiments in two consecutive rice seasons and hydroponic experiment were performed to investigate the effectiveness and mechanisms of foliage dressing. Foliar spray of S was effective to reduce the Cd concentration in rice grain (28%-50%) and increase the grain yield (6%-30%). The reduction of Cd concentration in rice decreased the direct damage to the photosynthetic system (with the net photosynthetic rate increased to 2%-25%; stomatal conductance increased to 7%-25%; intercellular CO2 concentration increased to 2%-10%; transpiration rate increased to 1%-11%; and actual PSⅡ photochemical efficiency increased to 3%-21%), and then increased the rice growth. Fourier transform infrared spectra showed that the foliar treatment stimulated the syntheses of aliphatic acid, polysaccharides, carboxylate and proteins, which likely reduced mobility of Cd in cell wall or vacuole. This study provided preliminary evidence that the effect of foliar application of S likely retained the structure of plant cells and effectively regulated protein expression by alleviating Cd stress without sacrificing yield, which has great potential for the remediation of vast agricultural fields.
Effects of Heavy Metals in Soils on Microorganisms and Enzyme Activities in Different Functional Areas of Tongling Mining Area in Anhui Province
ZHAO Xingqing, ZHU Xuyan, HUANG Xing, SUN Yu, HOU Ying
2019, 32(12): 2139-2147. doi: 10.13198/j.issn.1001-6929.2019.02.16
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In order to reveal the intrinsic relationship among soil microbial, enzyme activities and heavy metal contents in polluted soil, and to establish a characterization system between enzyme activities and biological parameters corresponding to different heavy metal pollution levels in soil, five different functional areas (mining area, concentrating area, heap area, tailings area and vegetable garden) in Tongling mining area of Anhui Province were studied. The heavy metal contents (Cu, Zn, Cd, Pb), microbial biomass carbon (MBC), basic respiration, metabolic quotient (qCO2) and six soil enzyme activities (catalase, urease, alkaline phosphatase, neutral phosphatase, cellulase and sucrase) were measured. The results showed that the Nemerow comprehensive pollution index (PN) of soil in different functional areas of the mining area was in the order of heap mining area (10.77) > mineral processing area (4.38) > mining area (4.06) > tailings area (2.55) > vegetable garden (1.35). The single factor pollution index (Pi) of the heavy metals (Cu, Zn, Cd and Pb) was Cd > Cu > Zn > Pb. In addition, the activities of selected soil enzymes were significantly different in different functional areas, and the soil enzymes in the vegetable garden area were the most active. Catalase, neutral phosphatase and invertase activities could effectively characterize the levels of the heavy metal contents (Cu, Zn, Cd, Pb). Metabolic entropy is a better indicator of soil environmental pollution than soil basic respiration or microbial biomass carbon. Soil enzyme activities and metabolic entropy were significantly correlated with the contents of four heavy metals. Therefore, the biological parameters such as soil enzyme activities and metabolic quotient can provide a reference basis for environmental quality assessment and ecological restoration in mining areas.
Distribution Characteristics and Risk Assessment of Per-and Polyfluoroalkyl Substances in Water Environment in Typical Karst Region
QIAO Xiaocui, ZHAO Xingru, GUO Rui, WANG Xing, HAO Shuran, LI Xue, LIU Yan
2019, 32(12): 2148-2156. doi: 10.13198/j.issn.1001-6929.2019.03.05
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To explore the distribution characteristics, the ecological environment and the health risks, water samples were collected from three types of water bodies (groundwater, surface water, and source of pollution) in Du'an County for analysis of PFASs (per-and polyfluoroalkyl) by ultra-high phase liquid chromatography tandem mass spectrometry. The results indicated that PFPeA (perluorpentanoic acid) had the highest detection rate (100%) among PFASs pollutants in this region, with the concentration range varied from 0.067 to 1.021 ng/L. The average concentration of the detected PFASs satisfied the rule of source of pollution (2.592 ng/L) > surface water (0.737 ng/L) > groundwater (0.340 ng/L), and the average value of the pollutants detected meets the source of pollution (7.1) > surface water (4.4) > groundwater (2.9). Human activities contribute largely to the pollution of PFASs. The concentration of PFASs at sampling points (G2, S9, S13, P3) may be affected by potential point sources and the distribution of PFASs in the study areas, which was not affected much by atmospheric deposition. The points of high PFASs concentration in surface and groundwater were basically in the area of high human activities. Due to the influence of karstification, the concentration of PFASs in the groundwater in the southeast is relatively low. According to the principal component analysis results, one source of the PFASs may come from agricultural plastic film and other plastic industries. Other sources may be electroplating, firefighting, mining, plastics, textiles, and electronics. The ecological and health risk assessment of PFOS (perfluorooctane sulfonate) and PFOA (perfluorooctanoic acid) had been investigated, respectively. The results showed that PFOS and PFOA in groundwater was lower than the level of risk to the ecological environment and human health on the basis of existing research. The study shows that PFASs in the water environment of Du'an County have not yet reached the level that is risky to the environment and human health. However, in view of the special hydrogeological conditions in the karst region, it is still necessary to strengthen the control of PFASs production industry and mining enterprises.
Efficiency and Mechanisms of Aqueous Cd Removal by Sepiolite Modified by Heat and Acidification
ZHANG Yue, WANG Xin, LIN Zhijia, PENG Bo, TAN Changyin, ZHANG Xinping
2019, 32(12): 2157-2167. doi: 10.13198/j.issn.1001-6929.2018.11.28
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This study investigated the efficiency and mechanisms of Cd removal with sepiolite(SP) modified by heat and acidification(HHSP). The optimal acid concentration, reaction time and temperature was firstly explored. On this basis, the dynamics and isotherms of Cd adsorption by SP and HHSP were compared and the adsorption mechanisms were further investigated with SEM-EDS, XRD and XPS. The results show that the HHSP prepared with 0.9 mol/L HCl for 24 h and heating at 500℃ for 1h exhibited the highest Cd sorption capacity. The Cd sorption by both SP and HHSP followed the pseudo-second order kinetics, and 73.13% and 85.96% of adsorption occurred in the first 2 h, respectively. The adsorption reached equilibrium after 24 h when the initial Cd concentration was 50 mg/L. The maximum Cd adsorption capacity of HHSP was estimated to be 22.147 mg/g based on Langmuir model, which was 4.23 times as high as that of SP (4.200 mg/g). The pH and pHpzc of SP apparently decreased with acidification, indicating an increase in the adsorption sites for cations on the modified SP. SEM-EDS showed that the acidifying and heating treatment had little effect on the fibrous structure of SP, and the mass ratio of the adsorbed Cd increased from 1.57% for SP to 2.13% for HHSP. XPS analysis indicated that both Cd complexation by the surface hydroxyl (-OH) and precipitation of CdCO3, CdCl2, CdO and Cd (OH)2 contributed to the Cd removal by SP and HHSP. XRD analysis demonstrated that the specific surface area of SP was increased by acid activation due to the removal of CaCO3. The results of this study highlighted that the pre-treatment with acidification and heat can improve the effectiveness of HHSP for Cd immobilization, and provide a useful way to apply HHSP in mitigation of Cd bioavailability in paddy soil.
Efficiency of Ammonia Nitrogen Removal and Microbial Community in Landfill Leachate by Modified Soil Rapid Infiltration System
SU Chengyuan, ZHU Xiaowen, NONG Zhiwen, HUANG Zhi, FANG Yitao, XIE Ying, GUO Yuanyuan
2019, 32(12): 2168-2176. doi: 10.13198/j.issn.1001-6929.2019.03.04
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Aiming at the problems of high concentration of ammonia nitrogen, low biodegradability and difficult treatment in landfill leachate, using aged landfill leachate as model, the removal efficiency and the maximum processing load of ammonia nitrogen in the modified soil rapid infiltration system (SRIS) were investigated. Meanwhile, the concentration of ammonia nitrogen at different depths of the system was monitored. In addition, the microbial community distribution in the system before and after the treatment were analyzed by high-throughput sequencing technology. The results showed that when the influent concentration of ammonia nitrogen was about 125 mg/L, the hydraulic load was 0.11 m3/(m2·d), and the inflow frequency was once a day, the average concentration of ammonia nitrogen in the effluent was about 3 mg/L and the total removal rate was higher than 97.5% after treatment with primary and secondary percolation columns in the modified SRIS. When the hydraulic load increased to 0.22 m3/(m2·d), the total removal rate was 87.27%. When the frequency of inflow was changed to twice a day, the total removal rate was 96.17%. The maximum ammonia nitrogen removal of after treatment with primary and secondary percolation columns in the modified SRIS reached to 200 and 110 mg/L, respectively, and the degradation mainly occurred in the lower and bottom layers. The lower layer of the modified SRIS had the most diverse bacterial community. Proteobacteria was dominated at phylum level, and the relative abundance of Exiguobacterium was the highest at genus level, as well as the presence of a variety of nitrifying, denitrifying bacteria and planctomycetes, which make the main contribution to the removal of ammonia nitrogen in the system. This research demonstrated that the modified SRIS could effectively remove ammonia nitrogen from the landfill leachate, which provides a reference for the effective treatment of the aged landfill leachate.