湘北丘陵林-稻系统镉的迁移  

Cadmium distribution and cycling in forest-rice agroforestry systems in Northern Hunan

作　　者：陈建国[1,2,3] 闫文德[1,2,3] 项文化[1,2,3] 

机构地区：[1]中南林业科技大学生命科学与技术学院,长沙410004 [2]南方林业生态应用技术国家工程实验室,长沙410004 [3]会同杉木生态系统国家野外科学研究站,会同418307

出　　处：《生态学报》2015年第22期7543-7552,共10页Acta Ecologica Sinica

基　　金：林业公益性行业科研专项(201404316);湖南省高等学校科学研究项目(12C0457)

摘　　要：为了研究中南丘陵区林-稻系统镉的迁移规律,2012年5月下旬至9月上旬(中稻稻季)在湘北汩罗市桃林林场选择两种类型的林-稻复合生态系统针对降水、地表径流、山塘水、稻田水及其中镉含量用收支平衡法进行了原位动态研究。结果表明,(1)以降水形式从区域外输入的镉是湘北地域地表系统主要的外来镉源,镉的输入主要集中在稻季的早期;(2)镉以雨水形式输入丘陵林-稻系统后,53%被林地截留,7.5%累积于山塘,11.6%存留于稻田,其余28.9%以稻田水和稻草、谷粒的形式输出林-稻系统;(3)不同林-稻系统比较,混-稻系统对外源镉的固持功能最强,松-稻系统其次,对照系统最弱,其原因在于各系统间岗地森林郁闭度存在差异,郁闭度大能增强岗地对镉的固持能力;(4)在岗地截留镉能力较弱的情况下,山塘能够减缓系统镉的迁移强度;(5)岗地输入山塘水中的大分子有机物能加强镉在稻田中累积。综上所述,林-稻系统镉的累积与雨水常年输入镉有关,系统内岗地森林郁闭度、与有机物输出相关的森林类型影响镉在系统中的迁移和分配。Cadmium （Cd） and its compounds are highly toxic to living organisms and are an environmental health hazard. Rice plants usually accumulate more Cd than other crops; therefore, serious concerns have been raised about human health risks resulting from food webs through Cd-contaminated rice paddy soils since rice is a staple food source for many Asian countries such as China and India. In hilly regions of southern China, rice plants are often cultivated near forests in a forest- rice agroforestry system, where the forests often occupy the upper parts of the hilly areas and the rice paddy fields are often present in the lower parts and in natural depressions. Although forest-rice agroforestry systems have been a typical agricultural model in southern China for many years, the pattern of Cd distribution and cycling and mechanisms controlling its accumulation and transport are still poorly understood in these systems. In this present study, the distribution and dynamic characteristics of Cd were investigated in two types of forest-rice agroforestry systems and one rice paddy system （without forests, as a control） in Taoling Forest Farm, Human Province, China from late May to early September in 2012. The concentration and fluxes of Cd in rainfall water, runoff water, pond water, and rice paddy-field water were measured.The main objectives of this study were to examine the transport patterns of Cd in different components of hydrological process and to calculate input-output budgets of Cd in the forest-rice systems. The results showed that （ 1 ） Cd mainly entered into the forest-rice agroforestry systems through precipitation in the study area, much of which happened during the early stage of the rice growing season. （2） Of the total amount of Cd input into the systems by precipitation, about 53% was retained in forests, 7.5% in ponds, 11.6% in rice paddy fields, and 27.9% was exported from the systems through rice paddy-field water, rice-straw, and rice-grain harvesting. （3） Because of the difference

关 键 词：镉 林-稻系统 收支平衡 水循环 中国南方 

分 类 号：X171[环境科学与工程—环境科学] S718.5[农业科学—林学]