摘要
采用高密度网格式布点采样法,对湖南某有色金属矿区用酸性含Cd选矿水、矿坑水和堰塘水混合灌溉25a的污染农田土壤Cd分布特征及其作物污染危害进行了调查评价。结果表明,污灌区土壤Cd的水平分布主要受污水流经路线的影响。镉的垂直分布水田和旱地之间存在显著差异性,常年稻田土壤中的Cd主要富集于耕作层,向犁底层以下迁移很少;而在水田改为旱作之后,耕层土壤Cd向下层迁移加剧,犁底层成为Cd的主要富集层。酸性红壤稻田土壤Cd的生物迁移性强,即使土壤Cd含量低于1mg·kg-1水平,也有产生Cd超标稻米的可能性,而当土壤Cd含量达到5mg·kg-1水平时,已不能生产出符合国家卫生标准的稻米。本污灌区早稻和晚稻糙米Cd最高含量分别为5.33mg·kg-1和9.36mg·kg-1,对应的土壤全Cd浓度分别为18.2mg·kg-1和15.5mg·kg-1。作者强调指出,在对污灌农田Cd污染危害进行评价时,要以产品卫生品质而不是以作物产量为指标,对土壤Cd污染危害作出科学评价。
An investigation and evaluation on the distribution features of Cd in the soil body and its effects on the hygienic properties of crop products in the fields irrigated with pond water with mixture of waste water from ore dressing plant and mining gallery for 25 years was carried out in a nonferrous metal mining area in Hunan Province, by using a high-density and chequer-shaped sampling technique. The results showed that the horizontal distribution of soil Cd was mainly affected by the flow route of the irrigation water in this area, while the vertical distribution features in the perennial submerged rice field were obviously different from that in maize culture field derived from paddy soils. In the paddy field, soil Cd mainly accumulated in topsoil and less Cd moved to deep layers. In the maize field, however, more soil Cd moved down and the plough pan became the major layer of Cd accumulation. Meanwhile, movement of Cd from soil to crop was quite strong in the acidic and reddish soil-like paddy field. There was a possibility of producing rice with Cd concentrations beyond the national hygienic standard for unprocessed rice grains even if the concentration of soil total Cd was less than the level of 1 mg·kg^-1. When the concentration of soil total Cd reached 5mg·kg^-1, rice grains meeting the hygienic standard could not be produced anymore. In this wastewater irrigation area, the highest Cd concentration of brown rice was 5.33 mg·kg^-1 and 9.36 mg·kg^-1 for the early and later season rice, respectively, while, the correspending concentration of soil total Cd in top soil was 18.2 mg·kg^-1 and 15.5mg·kg^-1, respectively. It is suggested that a hygienic property of the products rather than a crop yield should be employed as the parameter when evaluating the pollution endangerment of an area with irrigation of Cd-polluted waste water.
出处
《农业环境科学学报》
CAS
CSCD
北大核心
2007年第2期658-661,共4页
Journal of Agro-Environment Science
基金
农业部农业结构调整重大研究专项(04-01-03B)
关键词
污水灌溉
CD
土壤污染
作物污染
稻米卫生品质
调查评价
wastewater irrigation
cadmium
soil pollution
crop pollution
hyginenic quality of rice grains
investigation and evaluation
