Influence of Suspended Solids on the Distribution of Copper Metals in Riverine Environment

• Main Authors: Yi-Yin Chueh, 闕亦吟
• Other Authors: Chihhao Fan
• Format: Others
• Language: zh-TW
• Published: 2018
• Online Access: http://ndltd.ncl.edu.tw/handle/rvp69w

碩士 === 國立臺灣大學 === 生物環境系統工程學研究所 === 106 === The distribution of heavy metal depends on the transport phenomenon between surface water and sediment. Due to the transfer and diffusion of pollutants within water bodies, the dissolved heavy metals are adsorbed to suspended solids in aqueous phase thus to form the sorbed heavy metals which might deposit in the sediment subsequently. Resuspension of heavy metals from sediment might easily cause secondary pollution of rivers. Therefore, this study combines the soil hydrological assessment model and water quality model to estimate the distribution of heavy metals in the investigated river system. The Soil and Water Assessment Tool (SWAT) was employed to estimate the soil flux using climatic and topographical data, soil properties, soil utilization categories and vegetation types. The SWAT-CUP was used to calibrate all the required parameters. Furthermore, the copper is selected to be the indicator of concern to represent the heavy metal distribution using Water Quality Analysis Simulation Program Model (WASP). By considering the government heavy metal emission control measures and the factories’ locations, the heavy metal yields and their distribution within aqueous and sediment phases were calculated. Different scenarios were designed, including suspended solids yield in the dry period, more-stringent heavy metal discharge control measures and climate change impacts. These scenarios were used to estimate the heavy metals distribution in this watershed. The water quality simulation result demonstrated that the dissolved copper in the water phase is adsorbed to suspended solids easily, resulting in the high concentration of sobbed copper in in water phase. The adsorbed form of the heavy metal is the main type of heavy metals present in water and sediment phases; moreover, the high concentration of adsorbed heavy metals in water phase might result in high heavy metal concentration in sediment phase. In dry period, less sediment and suspended solids yielded in Erren River watershed because of the less rainfall. Therefore, the heavy metal concentration in water phase increased by 215% compared with baseline concentration; however, there is a 20% decrease in heavy metal concentration in the sediment phase in comparison with baseline concentration. Heavy metal concentration in aqueous phase is diluted by high flow and high flow also reduces the adsorption of heavy metals from water to sediment, which causes the concentration of Cu lower than the baseline in upper and middle part of Erren River. More-stringent heavy metal discharge control measures may significantly improve the quality of aqueous and sediment phases. In the mid-downstream river section, the concentration of heavy metals in water body and sediment decreased by 66%. Based on the results from the present study, suspended solids can be the key role of heavy metals transportation between water and sediment phases. The heavy metal pollution in sediment phase might be alleviated by reducing the heavy metal concentration in the surface water phase. In this study, the transportation of heavy metals in water and sediment should provide a reference for the heavy metal pollution management and water quality assurance standard achievement in the future watershed management strategy.