The Research On The Migration And Transfortation Mechanism Of Naphthalene In Raparian Zones With Groundwater Expliotation In Riverside

With the development of industry and agriculture, the pollution of the river has become more and more serious, and the polycyclic aromatic hydrocarbons(PAHs) have become the main pollution components. The groundwater exploitation near the river was thought as an important mining method of groundwater in northern China. This method made a promotion of the water transformation from river to groundwater. With the adding amount of groundwater recharge, the pollutants in the river would become a threat to water quality for the groundwater source areas near the river. Under natural condition, with the unique physical, chemical and biological properties, the Hyporheic Zone can fix and degrade some pollutant, which makes a self-purification of contaminated surface and underground water. Until now, it is hard to understand the mechanism of migration and transformation of pollutants in the Hyporheic Zone with the changes of the hydrodynamic condition caused by artificial exploitation. For the security of water quality in groundwater source areas near the river, research on the migration and transfortation law of pollutants in Hyporheic Zone with the condition of groundwater expliotation in riverside is of great significance.This paper is based on the National Natural Science Fund Project "Study on the migration and transfortation mechanism of typical PAHs in Hyporheic Zone with groundwater expliotation in riverside”. A reservior in northeast China is chosen as the study area. The research on the migration and transfortation mechanism of naphthalene in Hyporheic Zone with groundwater expliotation in riverside makes a contribution to knowing the geochemical and biological processes, formulating a rational exploitation plan and providing a theory foundation for the security of water quality in water resource areas.The experimental results show that the adsorption rate and the equilibrium adsorption capacity of naphthalene of the media in the riparian zone is sub clay, fine sand, sand, gravel. The specific surface area of the media in the riparian zone is positively correlated with the content of TOC. With the vertical depth increases, the adsorption capacity of naphthalene gradually reduced. The riverbed sediment layer is a relatively rich area of naphthalene; for the desorption rate and desorption equilibrium of naphthalene, the media has the opposite effect coupled with an obvious desorption hysteresis. The hysteresis coefficient and specific surface area of the medium is negatively correlated. Therefore the riverbed sediment polluted by naphthalene will suffer a longtime and secondary pollution compared with other pollutants in the riparian zone; with the vertical depth increases, the microbial degradation capacity of naphthalene gradually reduced. The first-order decay equation can well reflect the degradation process. Bacillus-Methyl, the main bacteria in the naphthalene degradation, belonging to gram negative bacteria. The optical microscope observation demonstrates the Brevibacterium in irregular way. The dynamic adsorption of naphthalene by media in the riparian zone follows the Thomas model. The dynamic adsorption, microbial degradation and the blocking effect change with the concentration of naphthalene, namely when the hydraulic gradient is constant, the effects become significant with the increase of the initial concentration of naphthalene. When the initial concentration of naphthalene is constant, the effects become significant with the increase of the hydraulic gradient.Overview, with the over exploitation of groundwater nearby river and the sharply increase of naphthalene in LiaoRiver, the adsorption of naphthalene by media in the riparian zone and the the microbial degradation of naphthalene will correspondingly reduce. In this condition, the comprehensive blocking effect of naphthalene in the riparian zone will decrease, the breakthrough time of naphthalene in riparian zone shortened accordingly, which makes a threat to water safety of water source site.