Abstract
Soil heavy metal pollution is one of the main environmental problems in Pearl River Delta Economic Zone of China. Based on multi-purpose regional geochemical survey, regional eco-geochemical assessment, local eco-geochemical assessment and comprehensive appraisal, the eco-geochemical survey and assessment in Pearl River Delta Economic Zone of 41,698 km2 were completed. Samples from soils were collected in accordance with the two-layer grid method. Totally 54 elements and indicators for soils were determined. Compared to deep soils, the sampled surface soils are enriched in OrgC, N, P, Cd, S，Hg, Ag, B, Au, S and poor with As, Ni, I, Co, Cr, V, MgO, Sc, Al2O3, Fe2O3 etc. The characteristics of geochemical reference value of element in soil that inherited soil parent material and regional elements combined features reflected that the elements enriched in the soil was interrelated with acid rock, sandstone and shale. The spatial distribution characteristics of element regional geochemistry were conditional by regional environmental geological conditions，and effected by human activities. The Pearl River Delta plain is a typical geochemical landscape area with regional anomaly of multiple-elements. The north, western and eastern parts of the Pearl River Delta Economic Zone are quite different in geochemical features due to regional geological background, soil parent materials, geomorphic characteristics and human activities. Environment quality evaluation results show that the grade I and grade II soil accounted for 19.9% and 57.3% of the total area. Many samples that widely distributed in the economic developed of Pearl River Delta Plain area reached the third-grade of national soil environment standard. The soil enriched in Cd, Hg, As, and the area ratio accounting for 22.8% of the total area. It is mainly controlled by the geochemical background, the Pearl River Delta formation evolution process, especially the marine transgression process lead to Cd, Cu, Zn and Pb enrichment in Pearl River Delta plain. At the same time, under the influence of higher pressure of human activities, all kinds of exogenous input material carrying heavy metal pollutants on soil environmental quality also could not to ignore.
Highlights
In the last three decades, the sustained and rapid socio-economic development of the Pearl River Delta region of China gained a great success, and paid a heavy price in resources and environment, such as decline in the quantity and quality of natural resources, urban and rural environment pollution, shortage of resources, which seriously restricted the economic development [1]-[7]
The results indicated that the geochemical reference value of soil element was originated from the soil parents’ and regional elements combined features reflected that the elements enriched in the soil was interrelated with acid rock, sandstone and shale
The middle, western and eastern parts of the Pearl River Delta Economic Zone are quite different in geochemical features due to regional geological settings, soil parent materials, geomorphic characteristics and human activities (Figure 2)
Summary
In the last three decades, the sustained and rapid socio-economic development of the Pearl River Delta region of China gained a great success, and paid a heavy price in resources and environment, such as decline in the quantity and quality of natural resources, urban and rural environment pollution, shortage of resources, which seriously restricted the economic development [1]-[7]. In order to provide a scientific basis for socio-economic development and planning to improve the ecological environment of this region, Guangdong Provincial People’s Government and China Geological Survey of the Ministry of Land and Resources signed an cooperation agreement of “Eco-geochemical Survey and Assessment in Pearl River Delta Economic Zone of Guangdong Province” in January 2006. This project is part of the multi-purpose geochemical survey program of China. The middle, western and eastern parts of the Pearl River Delta Economic Zone are quite different in geochemical features due to regional geological settings, soil parent materials, geomorphic characteristics and human activities (Figure 2)
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