Soil Quality And Heavy Metals Contamination In Soil-rice System In Jilin Province

Environmental quality of agricultural producing area has a direct and significantimpact on the quality and safety of agricultural products, is the most basic agriculturalproduct quality safety guarantee. In order to better evaluate the soil-rice paddy soilenvironment quality and the estimate of heavy metal pollution,this thesissystematically studies two representative paddy field areas in Jilin province in the soilheavy metal (Pb, Cr, Cu, Ni, Zn, Cd) pollution present situation and the sourceapportionment.Analyses the impact of soil properties and soil heavy metalconcentration on rice absorbs heavy metals,and then explores the model predictions.To evaluate soil environmental quality and characterization of heavy metals on soilecological risk in the study area. By actual field simulation, discusses impact on ricegrowth and absorption of heavy metals of pollution of Pb, Cd and Cu single andcombined pollution under different concentrations condition. It has the importanttheoretical and practical significance to understand irrigation area soil pollutioncondition, the quality and safety of rice in rice irrigation area and to put forward thesafe agricultural base planning, to avoid or repair different pollution degree of soil.The Second Songhua River Basin Irrigation topsoil in Pb,Cr,Cu,Ni,Zn,Cdcontents were85.33%,80.67%,48%,63.33%,76.67%and95.3%more than theproportion of soil Jilin background values,Irrigation in Yanbian topsoil Pb, Cr, Cu, Ni,Zn, Cd content of more than Jilin background values were significantly higher thanthe proportion of the Second Songhua River Irrigation, respectively100%,92.85%,61.14%,77.14%,97.14%and22.85%, implied that the Second Songhua RiverIrrigation and Yanbian Irrigation heavy metals in the topsoil has been impact ofhuman activities, and Yanbian Irrigation affected more severely than the secondSonghua River Irrigation District. Among them, a variety of heavy metals exceededJilin background values in Qianguo Irrigation, Yinma Irrigation, Yitong RiverIrrigation, Antu Irrigation, Hunchun Irrigation and Buerhatong River Irrigation. Principal component analysis of heavy metals in the Second Songhua RiverIrrigation topsoil results indicates that: heavy metal Cr, Cu and Ni are main source ofnatural factors and human activities; Pb and Zn mainly from human activities; Cd isaffected by human agricultural activities significantly. Yanbian paddy soil heavymetals principal component analysis showed that: heavy metal Pb, Cu, Zn and Cdelements mainly from human activities; major source of heavy metal elements Crnatural factors and human activities; heavy metal elements Ni mainly by soil parentmaterial impact.Yanbian irrigation rice Pb, Cr elements have some samples exceed the maximumlimit of national food standards (GB2762-2012). It is cause for concern that Yanbianirrigation rice output may cause harm to humans. Yanbian irrigation rice in soil Pb, Cr,Cu, Ni, Zn and Cd enrichment factor in the order of Zn> Cd> Cu> Ni> Cr> Pb.Yanbian irrigation soil Zn, Cd, Cu and other elements of pollution need priorityattention to prevent soil contamination from heavy metals harmful to humanperspective.Multiple regression analysis can get predictive models of the rice to absorb heavymetals in Yanbian, for rice Pb, Cu, Ni elements of this study are the correspondinglinear model can better predict. Exponential model [5] can better predict rice Crelement content.Single low concentrations of Cd and Pb added conditions have slightly toxiceffect on the growth of the rice plant height, but have a role in promoting on ricetillers and leaf growth. Combined pollution has obviously toxic effects on rice growth.Add different levels of heavy metal pollution has different effects on rice yield, undersingle conditions reduced rice yield8~35.4%; under the combined pollution reducerice yields23.4~62.6%. Exogenous heavy metal pollutants enter the body indifferent organs of rice redistribution, and its heavy metal content and distribution indifferent parts has a strong differentiation features.For rice Pb, Cd and Cu were analyzed and found that all Pb, Cd and Cu singleand composite added level of soil its rice grain Pb, Cd and Cu levels weresignificantly increased. Exogenous Pb, Cd adding significantly increased rice grainsPb, Cd content, and the contents more than the national food safety standards (GB2762-2012) in the maximum allowable limits. Under combined pollution situations,Cu content in rice grain did not exceed the national food hygiene standards.Bioavailability of Cu element is not only related to the Cu element content in soil, at the same time may be affected by soil components and factors such as environmentalconditions. Each part of the different levels of add rice biological concentration factorfollow the order of roots﹥stem leaf﹥grain. Biological concentration factor ofcombined pollution are significantly higher than the single pollution.Second Songhua River Basin Irrigation of heavy metals in soil accumulationphenomenon has emerged. The ratios in clean and light pollution level of single factorindex Yanbian irrigation were higher than that in the Second Songhua River Basinirrigation, except Cd.Yanbian irrigation various heavy metal accumulation in soil ishigher than the Second Songhua River irrigation; it is worth more attention toprevention and control of pollution further.The most part of the Second Songhua River basin irrigation and Yanbian irrigation ofsoil heavy metal content does not exceed the national secondary standard of soilquality, the study area soil quality basically does not cause harm to the crops and theenvironment. But the national soil quality standard is the unified national standards,for Jilin province soil on national soil as evaluation standard, evaluation of possiblepollution not accurate phenomenon; future research should establish targeted soilquality standards.Second Songhua River Basin Irrigation and Yanbian Irrigation soil Nemerowpollution index evaluation results showed on individual samples has been a certaindegree of heavy metal pollution, but the overall situation is still good.In particular,Yongshuyu District, Yinma River District, Yitong River District,Buerhatong river District andAntu District due to high alert level and the proportion of light pollution, are not suitable toestablish green food production. The geo-accumulation index results showed that the twostudy regions have different proportions of light pollution. Compared with the singlefactor pollution index, the geo-accumulation index is more sensitive. Although therewere different heavy metal accumulation phenomenon and achieve the level of lightpollution in the Second Songhua River Basin Irrigation and Yanbian Irrigation soil,the overall study area is mild soil ecological risk levels.