Environmental Background Values Of Chemical Elements In Soils,Plants And Waters Of Taibaishan Nature Reserve

Taibaishan Nature Reserve is located in the middle segment of Mountain Qinling. The study of environmental background value is a basic work of environmental science. The environmental background value in Taibaishan Nature Reserve was studied in the 80's of 20th century. After about 20 years, it is necessary to investigate the environmental background values again. In order to find out the environmental background values and the characters of the natural environment, we systematically collected soil, plant and water samples in Taibaishan Nature Reserve. Contents of 13 elements in soils, contents of 12 elements in plant leaves, and contents of 7 elements in natural waters have been determined. The distribution rules, contents of elements and affecting factors were discussed, and the water quality was assessed. The main results were as follows:⒈Contents of 13 chemical elements in soils were determined. Background values of soil as bellow: N0.192×÷0.846%, P0.079±0.038%, K2.39±0.53%, Fe2.92±0.30%, Mn518±120㎎?㎏-1, Zn91.5±21.9㎎?㎏-1, Cu19.8±4.2㎎?㎏-1, Pb27.8±7.0㎎?㎏-1, Cr63.0±14.9㎎?㎏-1, Cd0.103±0.054㎎?㎏-1, Hg0.030±0.020㎎?㎏-1, As8.16±1.96㎎?㎏-1, Se0.133×÷0.692㎎?㎏-1. Compared with the research results of 20th century, there was no obviously difference. The background levels of most elements studied were lower than the world average levels. It was in the range of the primary standard in the national environmental quality standard for soil (GB15618-1995)(.Background levels of chemical elements were presented as mean±standard deviation or geometric mean×÷geometric standard deviation depending on distribution type.)⒉Along the altitude from foot to top of the mountain, the contents of Zn,Cr,Pb increased; the contents of Mn,Cu,Cd decreased; Se content decreased firstly, it was lowest in dark brown earth, then increased; the variation of Fe,As and Hg contents was the lowest.⒊The vertical distribution rules of 8 elements (Cu,Zn,Cr,Cd,Pb,Hg,As and Se) in the soil profiles were different. They were affected by the soil forming process and biological cycle. In cinnamon soil, Pb,Se and Cr mainly accumulated on the upper horizon. In the profiles of brown earth,Zn,Cd and Pb were mainly accumulating below the surface layer. Pb,Cr and Hg of dark brown earth were also accumulating below the surface layer. The vertical variation of Cu,Pb,As in forest meadow soil and Cu,As,Cd,Pb in alpine meadow soil was not significant.⒋The parent material was the key factor controlling the contents of elements in soils. The soil physical-chemical properties (pH value, organic matter), supergenic geochemical nature and human activities were influencing the contents of elements in the surface soils.⒌The contents of chemical elements in plant leaves in Taibaishan Nature Reserve are normal compared with the world terrestrial plant. The difference of chemical elements'content in plant leaves was mainly influenced by the characteristic of plant absorption. Biological absorption coefficient reflects absorption and accumulation characteristics of plant directly. On the basis of sequence classified by A.N.ПерельМаН,the sequences of plants in Taibaishan Nature Reserve absorbed elements were as follows: the grade of strong accumulation includes N and Cd; the grade of weak accumulation includes P,Hg and Se; the grade of weak uptake includes K,Cu and Zn; the grade of the weaker uptake includes Mn,Cr,Fe and As.⒍The content of elements in plants has relation to the plants species and contents of available forms of elements in soil. The ability of bioaccumulation of the same plant was different for kinds of elements, while the ability that different plant absorbed the same element was different.⒎Contents of 7 elements (Cu,Zn,Cr,Cd,Pb,Hg and As) of water in Taibaihshan Nature Reserve were determined. Water quality was assessed by single factor index and comprehensive index. The results showed that the water was acid and the contents of 7 heavy met als were Zn>Pb>Cu>Cr>As>Hg>Cd. The water quality of Taibaishan Nature Reserve is good, it basically accorded with the primary standard in the national environmental quality standard for surface water (GB3838-2002).