摘要
重金属镉(Cd)通过污染的饲料和化肥而影响农产品进而危害人体健康已经成为食品安全和生态环境关注的焦点。为完善"稻鸭共生"系统的肥料和饲料管理,建立合理的物质产投结构及降低重金属Cd的生态毒理风险,在湖南省长沙市望城区桐林坳社区开展了2年田间试验,以常规稻作为对照,采用投入产出法,研究分析"稻鸭共生"生态系统重金属Cd的转化、迁移及循环特征。结果表明,"稻鸭共生"生态系统Cd输入量为:肥料>饲料>秧苗>雏鸭,其中肥料Cd输入主要是磷肥输入。"稻鸭共生"生态系统Cd输出主要是水稻籽粒Cd和成鸭Cd。"稻鸭共生"生态系统内循环的Cd主要是鸭粪Cd、杂草Cd、害虫Cd及归还给系统的水稻秸秆Cd和根系Cd。鸭所摄食的Cd主要来自鸭饲料,大鸭饲料Cd输入大于小鸭饲料Cd输入。在"稻鸭共生"生态系统中重金属Cd沿食物链的转化、迁移过程以鸭粪Cd形式放大,且鸭粪Cd高于鸭饲料Cd输入。稻田土壤Cd输出来看,"稻鸭共生"和常规稻作相比无显著差异(P>0.05)。无论是常规稻作还是"稻鸭共生",水稻植株Cd含量次序为根>秸秆>籽粒。与常规稻作相比,"稻鸭共生"没有增加水稻植株Cd含量和Cd积累。糙米和鸭肉镉含量分别为0.033 mg·kg-1和0.008 mg·kg-1,短期来看,"稻鸭共生"能够提供安全无Cd污染的农产品(鸭和稻米)。
Heavy metal pollution has been being the subject of attention because it endangers food security and agro-ecological environment. Raising ducks in paddy fields is a Chinese traditional agriculture mode of integrated planting and breeding in paddy fields in subtropical regions. Neither chemical pesticides nor herbicides are applied throughout the growing season in the mutual rice-duck ecosystem and surface water is maintained about 10 cm depth during the period of raising ducks. Field experiments on Cd transformation, migration and cycling in mutual rice-duck ecosystems were conducted in 2014–2015 in double cropping rice regions in Hunan Province and a conventional rice field used as the control. The aim of the experiment was to explore heavy metal pollution risk of products of rice-duck mutual ecosystem, and provide references for adjustment and improvement of management strategies of fertilizer and feed, optimization of food chain, input-output structure rationalization and Cd pollution control of the rice-duck mutualism. In 2014, 17-day-old ducks were introduced into the paddy field（at a holding capacity of 675 ducks per hectare） 23 days after early rice seedling transplanting; in 2015, 20-day-old ducks were introduced into the paddy field（at a holding capacity of 675 ducks per hectare） 21 days after early rice seedling transplanting. The ducks were retrieved at the end of heading stage of early rice in the experiments in both years. Input-Output Analysis method was used to analyze heavy metal Cd cycling in the mutual rice-duck ecosystem using collected data in field experiments. Input included materials embodied in fertilizers, feed, seedling, duckling and irrigation, while output covered seed and duck in the rice-duck mutualism. The return materials consisted of feces, rice straw, rice root, weeds and insects. The results showed that Cd input in the mutual rice-duck ecosystem decreased in the order of fertilizer feed rice seedling duckling. Fertilizer Cd input was mainly from phosphate fertilizer, duck Cd input was mainly from duck feed, and matured duck feed Cd input was greater than duckling feed Cd input. Cd cycling inner the ecosystem was from duck feces, weeds and insects transforming to rice straws and roots. In the mutual rice-duck ecosystem, heavy metal Cd was amplified along food chain transformation. The migration process of duck feces Cd input was higher than that of duck feed Cd input. For both rice-duck mutual ecosystem and conventional rice system, the order Cd contents of rice organs was root straw seed. Compared with conventional rice cultivation, rice-duck mutualism did not increase Cd content and accumulation in rice plants. Cd output of paddy soil under rice-duck mutualism and conventional rice cultivation was not significantly different（P 0.05）. For rice-duck mutual ecosystem, the contents of Cd in brown rice and duck were 0.033 mg·kg-1 and 0.008 mg·kg-1, respectively, lower than the limit standard of food Cd content. In the short-term, mutual rice-duck ecosystems provided a safe and non Cd contaminated mode of agricultural production.
出处
《中国生态农业学报》
CAS
CSCD
北大核心
2016年第9期1206-1213,共8页
Chinese Journal of Eco-Agriculture
基金
国家自然科学基金项目(31300372)
国家科技支撑计划项目(2012BAD14B03)资助~~
