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北江流域水化学时空变化特征及化学风化
禤映雪1, 唐常源1, 曹英杰2, 江涛3, 黎坤3, 李锐2
1.中山大学;2.中山大学环境科学与工程学院;3.中山大学地理科学与规划学院
摘要:
为了研究我国南方湿润地区河流水化学时空变化特征及控制因素,本文选择珠江流域第二大水系的北江为研究对象,通过分析2015年6月(汛期)和12月(非汛期)干流和支流河水基本水质参数及主量离子,利用化学计量法及质量守恒法定量评估了自然过程及人类活动共同影响下的流域化学风化特征及其通量。结果表明:①北江河水主量离子浓度非汛期高于汛期。岩石的区域分布和矿山活动也构成了河水离子浓度和水化学类型的空间异质性。其中北江干流和支流连江为Ca-HCO3型,而支流滃江则以Ca-SO4型为主。②岩石对北江流域化学风化贡献率依次为碳酸岩(78.44%)>硅酸岩(14.43%)>降水源(5.42%)>蒸发岩(1.71%)。基于碳酸岩是北江径流水化学的主要控制因素,滃江流域的矿山开采活动加速了碳酸岩的风化,其对北江流域化学风化的贡献为7%。③汛期与非汛期的碳酸岩风化速率分别为7.49和5.29 t/(km2?month),年化学风化速率为87.63 t/(km2?year)。研究显示,由于水热条件,流域面积以及岩性的影响,北江流域年化学风化速率略大于西江,远高于东江以及全球流域化学风化平均值。由此可见,北江对整个珠江流域的风化贡献较大。
关键词:  水化学  化学风化  风化通量  北江流域
DOI:
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基金项目:国家自然科学基金项目(面上项目),广州市科技计划项目
Temporal-spatial Variation of Hydro-chemical Characteristics and Chemical Weathering in the Beijiang River Basin
XUAN YINGXUE,TANG CHANGYUAN,CAO YINGJIE,et al
Sun Yat-sen University
Abstract:
In order to investigate the temporal-spatial variations of hydro-chemical characteristics and controlling factors in river water in the wet region of southern China. In this study, water samples were collected in the main stream and its tributaries in June and December 2015, respectively in the Beijiang River, which is the second largest river in the Pearl River Basin. To analyze the basic water quality parameter and major ions and based on the stoichiometry and mass conservation method to quantitatively evaluate the characteristics of chemical weathering and flux influenced by natural and anthropogenic factors. The result showed that (1) The concentrations of main ions were higher in the non-flood season than that in the flood season. The regional distribution of rock and mine activities also constitute the spatial heterogeneity ions concentration and hydrochemistry type of river water. the hydrochemistry type was Ca-HCO3 in the Beijiang River and Ca-SO4 in the Wengjiang River. (2) The contributions of chemical weathering by rocks as follows: carbonate minerals (78.44%)>silicate minerals (14.43%)> precipitation inputs (5.42%)>evaporite (1.71%). As the carbonatite is the main controlling for the water chemistry in the Beijiang River, mining activities accelerated the weathering of carbonatite and contributed 7% to chemical weathering in the Beijiang River. (3) The weathering rates of carbonate mineral were 7.49 t/(km2?month) in the flood season and 5.29 t/(km2?month) in the non-flood season, and the total was 87.63 t/(km2?year). The study showed that the annual chemical weathering rate in the Beijiang River was slight higher than that in the Xijiang, but much higher than Dongjiang and the global average due to the hydrothermal conditions, catchment area and lithology. Therefore, the weathering rate of the Beijiang River was the highest among the three major tributaries of the Pearl River.
Key words:  aquatic chemistry  chemical weathering  ions flux  Beijiang River Basin