Water Quality Index Iron, Manganese Monitoring And Content Variation Law

Taking Biliuhe reservoir as the research object, this paper studied the distribution characteristics of water temperature, pH, and content of dissolved oxygen, iron and manganese in reservoir water; distribution characteristics of iron and manganese in suspended matters and sediments. The ecological risk assessment of sediment was carried out using the method of accumulation index, the results showed that iron had virtually no pollution, and manganese at several points had moderate pollution in wet period; Control of dissolved oxygen, pH, temperature, water power, microorganisms and other conditions to study the impact of the release of the sediment.At last, the cause of pollution in Biliuhe reservoir was analyzed based on the pollution sources, including point source pollution, non-point source pollution and endogenous pollution. The main results are as follows:(1) On the basis of hydrological meteorological, geographical features, social and economic factors, we made reservoir water quality monitoring scheme and planned specific monitoring sections and points for continuous water quality monitoring.(2) Water quality indexes such as Water temperature, pH, and dissolved oxygen, iron and manganese content in reservoir water were analyzed. The results indicated that water pH value was almost normal, which ranged from 6 to 9 and met the III grade water quality standard; water temperature had remarkable seasonal regulartics, and the phenomenon of thermocline existed in summer; in most cases, dissolved oxygen content was better than the Ⅱ grade water quality standard; iron and manganese content met the requirements of water quality, except that in a few months the content exceeded the standard. This was mainly related to the erosion caused by rainfall, as well as the sediment contamination release.(3) Iron and manganese content in suspended solids was basically in the normal range; suspended solids were free from Fe contamination on the whole, but were polluted by manganese in several sampling points. For a few months, manganese contamination level was up to middle level.(4) The release of iron and manganese was inhibited under aerobic conditions, but the phenomenon is obvious under anaerobic conditions;Under acidic conditions, the release of iron and manganese is relatively obvious compared with alkaline conditions.The higher the temperature, the larger the amount of iron and manganese released from sediments. It was mainly because that temperature promoted the activity of microorganism, leading to the decrease of redox potential on sediment-water interface; The release amount of iron and manganese was larger in the case of disturbance in contrast with static state, which could be explained that disturbance stimulated the release of iron and manganese in pore water into overlying water.