Study On Heavy Metal Pollution And Safety In Sewage Irrigation Regions Of Suburb In Tianjin

In China, water for agricultural production is great in demand. Especially in north arid regions of China, general water irrigation couldn't meet requirements of production, and sewage irrigation and cultivation are enlarging year by year. Since heavy metal pollution becomes more and more serious, much attention should be paid to the safety of edible agricultural products. In our study, the heavy metal pollution in soil and agricultural products of suburb in Tianjin was investigated. And the distribution and accumulation of heavy metals in fish were also investigated.The results showed that heavy metal contamination of soils in suburbs of Tianjin was serious, and most of heavy metals were on the heavy pollution leval. Among these heavy metals, Cd was the most serious. Crops also suffered from heavy metal contamination to different degree, and different varieties and organs had different accumulating capacity for heavy metal. The vegetables were severely polluted by Pb, As and Se, with higher over-limit rate. Especially, the pollution of Pb in root vegtable was the most evident. Besides, the concentrations of Cu, Zn in fruit of wheat were much higher. All kinds of weeds show a certain accumulation capacity. Polygonum aviculare and amaranth were outstanding in accumulation of Pb and Zn, and they may be served as phytoremediation.Different organs of fish demonstrated different accumulating capacity to Cu, Pb, Zn and Cd . Cu and Pb were accumulating in fish brain, while higher content of Cd was in kidney. In addition, the concentrations of four elements were lower in fish flesh. The concentration of Hg in fish increased with growing weight. And the more content of total mercury, the higher concentration of methyl mercury. The distribution of Hg was different in different parts: the content of Hg was the highest in flesh, and the second was viscous. The results showed that methyl mercury mainly accumulated in edible parts. Morever, in different kind of fish, the concentration of total Hg in crucian was higher than carp. By means of evaluation of health risk in fish flesh, the result indicated that flesh had low risk, but it was necessary for long-term trace monitoring.To sum up the above disscusion, soils and agricultural products were polluted by heavy metal in suburb of Tianjin. Compared with literatures in former years, the concentration of some elements showed an increasing tread. The study on heavy metal pollution of agricultural products and soils can provide available proof to edible safety, cultivation or breeding of agricultural products and phytoremediation. It also has important significance in improving quality of agricultural products and people living, and promoting the development of agriculture and fishery.