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.