西江广东鲂产卵场水质营养盐现状与评价

Trophic Status and Assessment in Megalobrama hoffmanni Spawning Grounds of Xijiang River

2003-2006年在西江广东鲂(Megalobrama hoffmanni)主要产卵场-封开青皮塘渔场和郁南罗旁渔场的6个点,进行了4次水质监测,据此分析水域营养现状与污染情况。结果表明,青皮塘和罗旁渔场水域溶解氧充足,化学需氧量较低,受到耗氧有机物的污染较小,无机磷浓度均低于《地表水环境质量标准》(GB 3838-2002)Ⅲ类水质标准;两产卵场无机氮(DIN)含量均较高,近4年单因子指数均大于1,水域DIN浓度均高于《地表水环境质量标准》Ⅲ类水质标准,部份监测点超过Ⅴ类,两产卵场主要受氮污染。采用营养指数法及有机污染指数法进行综合评价,两产卵场的水质均达到了清洁水平。

Four surveys on the Megalobrama hoffmanni main spawning grounds （ including 6 sites） located in Qingpitang and Luopang in Xijiang River were carried our from 2003 to 2006. Current trophic status were analyzed and assessed. The results showed that sufficient DO and low level of COD in both Qingpitang and Luopang spawning grounds, implying low oxygen consumption of the organic pollution. The inorganic phosphorus concentrations in both of the two water areas were lower than grade 3 of Chinese surface water quality standard （ GB 3838-2002）. However, DIN levels in both waters were all above normal level and single factor index exceeded 1 during four years. DIN in water exceeded grade 3 of Chinese surface water quality standard, and even exceeded grade 5 of the quality standard at some sites. The results demonstrated that two spawning grounds are mainly polluted by nitrogen. The comprehensive results of using trophic index method and the organic pollution index method demonstrate that water quality of two spawning grounds reach clean level of standard.