Study On Eco-geochemical Field Of Main Rice Producing Areas Of Northeast China

In this study,Suihua City,Harbin City,Wuchang City in Heilongjiang Province,Shulan City,Yongji County,Dongfeng County,Meihekou City,Qianguoerluosi Mongolian Autonomous County,Shuangliao City,Gongzhuling City,Hunchun City in Jilin Province,Panshan County,Dawa District,Yingkou City in Liaoning Province were selected as the study areas.123 sets of soil and rice seed samples were collected.The concentrations and spatial distribution characteristics of 5 heavy metals,13 rare earth elements and 18 trace elements in soil and rice seed samples in rice producing areas were analyzed by statistical methods.The effective concentration and spatial distribution characteristics of B,As,Co,Cu,Mo,Ni,Pb,Zn in soil were tested and analyzed.The migration and transformation rules and influencing factors of eight elements in soil-rice system were further analyzed with effective coefficient and absorption coefficient as indicators.SPSS was used for principal component analysis to screen out the elements with large principal component coefficients.On the basis of further correlation analysis,the combination of marker elements that distinguish different rice producing areas was screened,and the classification function was constructed to identify the origin of the main rice producing areas in Northeast China.The main research results and conclusions are as follows:(1)The contents of heavy metal elements As,Pb and Zn in surface soil were lower than the national soil background values,Cu contents in Heilongjiang and Jilin samples were lower than the national soil background values,Cu contents in Liaoning samples were higher than the national soil background values,Ni contents in Heilongjiang and Liaoning samples were lower than the national soil background values,Ni contents in Jilin samples were higher than the national soil background values except Shulan and Hunchun samples.The content of rare earth elements in each sample area follows the Ordo-Harkins law.The total content of rare earth elements in the soil samples of Shuangliao-Gongzhuling,Qianguo,Shulan,Hunchun,Panshan,Dawa and Yingkou is lower than the average value of soil in China,and that in other sample areas is higher than the average value of soil in Chinese mainland.The fractionation of light and heavy rare earth elements is obvious,and the element Eu is depleted.The other 18 trace elements in the soil surface were weakly to moderately heterogeneous in most sample areas,and the content difference was small in space.(2)The contents of heavy metals in rice seeds in each sample area were Zn > Cu > Ni >As > Pb.The contents of rare earth elements in seed is low in each sample area.Among 13 kinds of rare earth elements,the highest content is Nd,the lowest content is Ce in Suihua sample area,and the lowest content is Er in other samples.The contents of other 18 trace elements in rice seed were low,and the contents of Rb,Ba and Sr in rice seed in the sample area were relatively high.Ta was the lowest element in rice seed in each sample area.(3)The effective state contents of B,As and Mo have little difference in space;the effective state contents of Co,Cu,Ni,Pb and Zn were significantly different in space.The high content was distributed in the sample area of Liaoning Province,and the content was low in the sample area of Heilongjiang Province.The transformation degree of Mo and Cu elements from total amount to effective amount is the strongest,Co,Ni and Pb elements in each sample area is obviously different.B,As,Pb and Zn elements in each sample area are very weak;the transformation of elements is controlled and affected by soil total amount and soil type.Seeds had the strongest absorption capacity for Zn,and had very weak absorption for B,As,Co,Cu,Mo,Ni and Pb.The absorption of elements by seed is comprehensively affected by soil physical and chemical properties such as total amount of soil elements,effective amount,and soil type.(4)The principal component analysis was performed by SPSS,and 14 elements with large principal component coefficients,such as Li,B,Co,Ge,Rb,Sb,As,Cu,Ni,Pb,Zn,Nd,Sm,Er,were screened out.The analysis of variance was further carried out,and six marker elements were finally determined: B,Rb,Cu,Ni,Ge,Nd.Based on the combination of marker elements,the classification function was constructed by SPSS,and the classification function of 12 regions was obtained.The origin identification was carried out based on the classification function,and the overall accuracy was 78.9%.