Environmental Geochemistry Research Of Trace Elements In The Yellow River Delta

Heavy metals are ubiquitous environmental pollutants with high toxicity, invisibility, universality and recalcitrance. Heavy metals can accumulate constantly through food chain, deteriorating the ecological environment quality and threatening human health. Recent studies showed that the toxicity, mobility and biological effectiveness of heavy metals in the environment could not been reflected by their total amount alone. The impacts of chemical forms of the heavy metals are more important. Therefore, study on fractions of heavy metals is essential to evaluate their environmental effect.In this thesis, the temporal and spatial distribution characteristics, chemical forms of heavy metals in the Yellow River Delta region was investigated; the possible pollution sources and environmental risk levels of the heavy metal pollution was analyzed; the migration, enrichment characteristics of the collected samples were also explored. Methods or theories on geochemistry, isotope geochemistry, environmental chemistry, ecological toxicology and ecology statistics were used to evaluate the heavy metal pollution level, contamination characteristics and potential ecological risk in this region. On the basis of above results, heavy metal enrichment characteristics, migration and transformation pattern were established. This research provides a systematical investigation on the heavy metal pollution status in this area.Through analyzing the element geochemical characteristics of the samples, the following results were obtained:(1) Temporal and spatial distribution, occurrence characteristics and the risk level of heavy metals during the period of 1925 to 2012 were identified through analysis of the sedimentary column from the Yellow River estuary. (2) The heavy metal amount in sediment, surface water and soil in the Yellow River Delta was systematically studied, which provides a comprehensive understanding on distribution characteristics, potential environmental risk and possible pollution sources of heavy metals in different environmental media. (3) Analysis of heavy metal content in aquatic organisms revealed the uptake diversity and different enrichment characteristics of heavy metals among organisms. Factors affecting heavy metal accumulation in the aquatic organisms were explored by cluster analysis method. (4) Migration behavior, transformation and enrichment characteristics of heavy metals in the environment were summarized.