Spacial And Temporal Changes Of Soil Elements In Pearl River Delta During Past Decades

Pearl River Delta is one of the most developed areas in China. Degree of industrialization and urbanization are very high. And pollution in soil, air and water is inevitable accomplishing economic developing. It's also a high representative area to research environmental change of eastern China. So, it's important to research spatial-temporal changes at decades scale through twice regional geochemical mapping data.Regional geochemical mapping conducted respectively in 1991 and 2005 when it covered two 1:200000 standard quadrangle of Guangzhou and Jiangmen provided the data to identify the changes of soil elements in past decades.The results are amazing. S, As, Cu, P's cumulations in soil are very remarkable. The area what relative divergence(RE) of these elements exceed 10%, 20%, 50% and 100% respectively get to 57.48%, 55.56%, 43.23%, 16.98% for As, 43.81%, 36.67%, 18.17%, 6.26% for Cu, 38.60%, 35.01%, 21.08%, 4.09% for P; 68.64%, 67.39%, 56.26%, 18.47% for S. And base on the relation between RE and Cumulative Percentage, Cumulative Percentage can get to 10.53%, 22.22%, 66.67%, 200% when RE get to the values above. In addition, the area of cumulative percentage more than 22.22% in K2O, Mn, Ni, Pb, U, Zn et.al has exceeded 10% of whole area. And the area of cumulative percentage more than 66.67% has exceeded or neared to 10% except Pb. Therefore, great deal of soil in this area has happened serious cumulation. And distributing patten of these elements has changed obviously.Furthermore, this paper compares data of 2001 and 2007 when it finished twice regional soil environmental geochemical monitoring network in Pearl River Delta. And it discusses the characteristic and emendation of accuracy. Then to identify the obvious cumulation of Mo, Bi, Ge, W, P, I, and deletion of S, Hg, and N. Otherwise it shows the cumulation and depletion in spatial scale, degree and cause of formation for some marked changing elements.