三峡库区农业小流域盐基离子排放特征研究  

Characteristics of salt-based ion release from small agricultural watersheds in the Three Gorges Reservoir area

作　　者：窦添元 龙娟[1,2] 廖宇琴 木志坚 慈恩[1,2] 魏世强[1,2] DOU Tian-yuan;LONG Juan;LIAO Yu-qin;MU Zhi-jian;CI En;WEI Shi-qiang(College of Resources and Environment,Southwest University,Chongqing 400716,China;Chongqing Key Laboratory of Agricultural Resources and Environment,Chongqing 400716,China)

机构地区：[1]西南大学资源环境学院,重庆400716 [2]重庆市农业资源与环境研究重点实验室,重庆400716

出　　处：《农业环境科学学报》2020年第6期1321-1331,共11页Journal of Agro-Environment Science

基　　金：国家重点研发计划项目(2018YFD0800606)。

摘　　要：为了解盐基离子的农业面源流失负荷与排放特征,对三峡库区涪陵段两个毗邻的集水域汇出口径流水质进行了持续两年的高频(每日)监测。两集水域气候、地貌和农耕方式相同,但其中一个集水域稻田分布零散,破碎度指数高(记为集水域A),另一集水域的稻田连片分布在集水域底部,破碎度指数低(记为集水域B)。结果表明,集水域A阴、阳离子年均输出通量分别为499 kg·hm^-2·a^-1和218 kg·hm^-2·a^-1,集水域B阴、阳离子年均输出通量分别为265 kg·hm^-2·a^-1和118 kg·hm^-2·a^-1。集水域A的盐基离子年均输出通量是集水域B的2倍左右,这种差异很可能是由两集水域稻田布局差异所导致。流域径流水体优势阴、阳离子分别为Cl-和Ca2+,各占阴、阳离子年均排放总量的58%和67%。不同作物季中,水稻/玉米季和榨菜季均贡献了全年盐基离子排放量的1/2左右;不同时期中,5月和11月的离子排放负荷最高,分别占全年的26%和24%。研究表明,5月和11月是控制该流域盐基离子流失的关键时间节点,稻田连片布设于集水域底部是降低农田盐基离子流失的重要空间布局。In order to understand the agricultural non-point source load loss and discharge characteristics of salt-based ions,high-frequency(daily)monitoring of the runoff water quality of the two adjacent catchments in the Fuling section of the Three Gorges Reservoir area was conducted for 2 a.The climate and geomorphology of the two catchments were the same,but the paddy fields in one catchment were scattered and the fragmentation index was high(recorded as catchment area A).The fragmentation index was low.The results showed that the annual average output fluxes of anions and cations in catchment area A were 499 kg·hm^-2·a^-1 and 218 kg·hm^-2·a^-1,respectively,and the average annual output fluxes of anions and cations in catchment area B were 265 kg·hm^-2·a^-1 and 118 kg·hm^-2·a^-1,respectively.The saltbased ion output flux of catchment area A was approximately twice that of catchment area B.This difference was likely caused by the different distribution patterns of the paddy fields.Placing paddy fields on the bottom of the catchment area can reduce agricultural salt-based ion runoff.The dominant anions and cations in the runoff water body of the basin were Cl-and Ca2+,which accounted for 58%and 67%of the total anion and cation emissions,respectively.In terms of different crop seasons,the rice/maize season and mustard season each contributed approximately 50%of the annual salt-based ion emissions.In terms of different periods,the ion load was highest in May and November,accounting for 26%and 24%of the ion discharge load of the entire year,respectively.Studies have shown that May and November are the key time nodes to control the loss of salt ions in the watershed.The continuous arrangement of paddy fields at the bottom of the catchment is an important spatial layout to reduce the loss of farmland salt ions.

关 键 词：三峡库区 面源污染 农业小流域 盐基离子 

分 类 号：X53[环境科学与工程—环境工程]