Adsorption effect and risk assessment of heavy metalsin river sediments

• Main Authors: GUO, YI-QING, 郭奕慶
• Other Authors: CHIANG, HANN-CHYUAN
• Format: Others
• Language: zh-TW
• Published: 2017
• Online Access: http://ndltd.ncl.edu.tw/handle/ga4rqb

碩士 === 國立宜蘭大學 === 環境工程學系碩士班 === 105 === The Agongdian River is an important water resource in Kaohsiung, Taiwan. However, industrial waste water, livestock wastewater and domestic sewage discharge, causing various pollutants to accumulate in the river, including heavy metals, organochlorine compound, pesticides and other harmful substances, these pollutants through between water and sediment on the geochemical processes further accumulated in the river sediments. According to the recent investigation by EPA of Taiwan, that total concentration of copper, nickel and zinc were part of exceed upper limit to the sediment quality index in the sediments,which was significantly affected copper, nickel and zinc pollution, in order to understand the content of heavy metals in sediments and its potential hazards, so were determined at four stations to analysed form serious pollution of heavy metals in this study river basin sediments, and to understand the copper, nickel and zinc in this study region of potential risk environment. As refer to the sediment quality management strategy in this region for future. Results showed that grain size distribution primary of sand in the sediments, and the total concentration of copper stations part were exceeded the lower limit (50 mg/kg), the nickel are out of the lower limit (24 mg/kg), and zinc are exceeded the upper limit of the sediment quality index (384 mg/kg). The batch adsorption experiment results showed that the capacity of heavy metals adsorbed by sediments in the order Cu>Zn>Ni. The sequence extraction result indicated that copper and nickel were found mainly residual fractions, but also zinc was found mainly Fe/Mn oxides fractions in the sediments. In addition, binding of heavy metals in the sediments is more affected by the spatial distribution, the more close to the downstream of the sediments bonding capacity of the weak bound to heavy metal more likely to appear. The Sediment Quality Guidelines (SQGs) result showed that Agondian River of heavy matals in the sediments potential harm probability in the order Zn>Ni>Cu, at Old Port Bridge station the concentration of nickel and zinc both exceeding the effect range medium (ERM), Ni (51.6 mg/kg)；Zn (410 mg/kg). The Enrichment Factor (EF) result indicated that average in the order Zn (39.7)>Ni (3.68)>Cu (3.41) all more than 1, meaning the concentration of copper, nickel and zinc exceeds the average background in the sediment, so that copper, nickel and zinc may be derive anthropogenic discharges, especially the zinc was most serious pollutant. The Risk Assessment code (RAC) statistics result showed that average in the order Zn (6.4)>Ni (3.6)>Cu (3.0), that degree of risk index ranging 1 and 10. Overall, the risk of copper, nickel and zinc in the sediments of this study region are low risk level.