三江平原农田排水沟渠铁的输出及形态变化  

The transport and change of iron species in agricultural drainage of Sanjiang Plain

作　　者：王莉霞[1] 阎百兴[1] 潘晓峰[1] 祝惠[1] 

机构地区：[1]中国科学院东北地理与农业生态研究所,中国科学院湿地生态与环境重点实验室,长春130012

出　　处：《地理研究》2011年第10期1818-1824,共7页Geographical Research

基　　金：国家自然科学基金(41001193);中国科学院东北地理与农业生态研究所知识创新工程领域前沿项目(KZCX3-SW-NA09-06)

摘　　要：农田沟渠系统的输出将直接影响水体的生态环境安全。在大面积湿地农田化的三江平原,沟渠排水是铁输入河流的源和主要通道,也是北太平洋西北部okhotsk海铁输入的重要来源。以农田沟渠水体中铁为研究对象,采用切向超滤技术分离铁的形态,研究沟渠系统中可溶态铁的形态和迁移特征,探讨湿地开发后沟渠向河流输出铁的特征。通过对2005年～2008年间沟渠水体中铁赋存形态变化研究发现:沟渠水体中铁多以可溶态铁存在,浓度在0.34～3.99 mg.L-1;络合形态是可溶态铁的主要形态,其次为胶体态,离子态铁含量最少;同一年间,可溶性铁含量平水期要略高于夏汛期,干渠中可溶态铁的含量略低于支渠,可溶态铁在支渠向干渠迁移过程中,络合态铁所占比例由70.12%降至56.53%,沟渠中可溶态铁浓度受田间降雨量的控制,同时pH、阳离子总量(CEC)、HCO3-、PO43-等因素共同影响可溶态铁浓度。沟渠水体中可溶态铁浓度受水体化学性质的影响,与水体中PO43-、CEC和HCO3-浓度呈现不同程度相关关系。据估算三江平原每年通过沟渠输送可溶态铁约在45t～116t,湿地开垦为农田是导致可溶态铁锐减的原因,农田增施有机肥可能会提高可溶态铁的输出。Drainage ditches are the important channels for transporting nutriment in agro-ecosystems,and the character of drainage water will threaten ecosystem safety in nearby water bodies.After the fifty years＇ cultivation of wetlands in Sanjiang Plain,drainage ditch was extensively built and has become an important source and passageway transporting iron into river or even Okhotsk Sea,thus affecting the primary productivity in the North Pacific Ocean.In order to assess the change of iron species from drainage canal to river under long-time cultivation of wetlands and the factors affecting the iron behavior,the samples in main canal and branch canal were collected in wet and dry seasons during 2005 to 2008.The dissolved iron was divided into colloidal iron,complexed iron and ionic iron employing the cross-flow filtrate technique.The results showed that iron often exists in total dissolved iron（TDI） and acid labile iron（ALI） in drainage ditches.The concentration of TDI ranged from 0.34 to 3.99 mg·L-1,and the farming activities including tillage and irrigation contributed to the increase of iron output.The mean concentration of TDI in dry season was higher than that in wet season because of dilution.Generally,iron exists in complexed form（exceeding 60% of TDI）,followed by colloidal form（about 20% of TDI） and ionized form.The concentration of TDI was higher in main canal than that in branch canal by changing complexed iron into colloidal and ionic forms.The chemical parameters including pH,cation concentration,HCO-_3,PO3-_4,NH＋_4-N,NO-_3N and TOC were researched,and correlation analysis was made between the chemical parameters and TDI.The analysis showed that the concentration of TDI was controlled by rainfall,and affected by the factors including pH,cation concentration,HCO-_3,and PO3-_4.So some field management measures would affect the iron output.For example,application of organic fertilizers would increase TDI transportation whereas the chemical fertilizer decreases TDI output.It is estimated that

关 键 词：沟渠 铁形态 水体 三江平原 

分 类 号：S276[农业科学—农业水土工程]