Self-purification ability of a water-carrying lake
过水性湖泊自净能力的动态变化

By using the 1991 - 2003 monitoring data of water quality at 5 sampling locations distributed nearby the 2 entrances and 3 exits of the luoma Lake river ways, the self-purification ability of the lake was studied. The results showed that on the whole, the water quality near the exits was better and more steady-going than that near the entrances, indicating that the lake still had strong self-purification ability. The coefficients of variation of the water quality indices among the 5 sampling locations decreased gradually, suggesting that the purification rates of total nitrogen, dissolved oxygen, volatile hydroxybenzene, non-ionic ammonia, and arsenic in water body reduced remarkably, and the self-purification ability of the lake was weakened. The coefficients of variation of total nitrogen and dissolved oxygen and some exogenous pollutants among various sampling locations could be used as the reference indices of self-purification ability and health status of wetland ecosystems.