Environmental Geochemistry of Trace Element in Solid Waste Dumping Area of Wanbei Coalfield
Author:Wang Xu Dong
Supervisor:liu gui jian
The increasing requirement of coal resource is resulted in the increasing exhaust of coal wastes.The large amount of coal wastes piled on the earth’s surface could not only lead to spontaneously combustion,land occupation and structural erosion,but also result in the pollution caused by environmental sentitively trace elements in coal wastes.The trace elements in coal wastes could be released and enterred into soil.water and organism by the biophysico-chemical effect,and finally resulted in potential environmental and health impacts.Therefore,the study on the distribution,assocation and transformation behavior of trace elements in the dumping area of coal waste is of greatly significance for the ecological security and risk management.Various environmental medium samples including coal waste,soil,water,sediment corn,earthworm and fish were collected from 7 coal mines in Wanbei Coalfields.The framework of element geochemistry,soil science,hydrogeology and ecology were conducted to investigate the concentrations and distribution characterizations of trace elements in different environmental mediums,reveal the transformation behavior of trace elements and evaluate the potential environmental and health impacts.The results shown that:(1)The enrichement behavior of trace element was various among different environmental mediums.The concentrations of trace elements were various among different parts of coal waste piles.The distribution characterizations of trace elements in soil could be classified into two type:a.the concentrations of trace elements decreased with the distrance.and b.the concentrations of trace elements climb up and then decline with the distrance.The trace elements were mainly associated with residual in both rhizosphere soil and non-rhizosphere soil,the trace element in ex-changeable fractions in non-rhizosphere soil was lower than that of rhizosphere soil.The distribution characterizations of trace element in water,sediment,corn and fish were varrous among different coalfields and trace elements.The concentrations of trace elements in the stem and bract of the selected corn were higher than that of seed.The concentrations of trace elements in viscus,gill and meat of fish were higher than that of scale and bone.(2)The transformation behavior of trace elements in environmental mediums were determined by their associations and physico-chemical properties of environmental mediums.The assocaitions of trace elements in soil were affected by the pH,EC and orgnaic matter of soil.The concentrations of Co,Cu and Zn in plants were affected by the reducible fractions of these elements in soil,while the concentrations of Cr,Mn,Ni,Pb and V in plants were determined by the ex-changeable fractions of these elements in soil.The enrichement behavior of trace elements in earthworm was affected by the soil property.The enrichment characterizations of trace elements in fish were determined by the disposition-release of trace element in sediment,pH of water and sediment property.(3)The environmental risks of trace elements in different environmental medius were suggested as acceptable.The risks of trace elements in soil,coal waste and water were regarded as light levels.The risks of trace elements in non-rhizospnere soil were higher than that of rhizosphere soil.The health risks of carcinogenic elements in corn and fish were mainly posed bv Cr,and may lead to potential health risks.