本市十二万亩池塘大部分是八十年代开挖建成,经过十多年的高密度养殖,在饲养管理中施放大量有机粪肥,投放许多精饲料和青饲料,加之,养殖鱼类的排泄粪便,池水中死亡的生物体和每年塘埂坍塌冲刷流入塘中泥砂相混合,在鱼塘底部形成一层很厚有机质淤泥层,使鱼塘变得越来越浅。淤泥中包藏 Most of the 12 million mu ponds in the municipality were excavated in the 1980s. After more than a decade of intensive farming, large amounts of organic manure and many fine feed and green fodder were put into management. In addition, fecal excrement of farmed fish , Dead organisms in pond water mix with silt that flows into ponds every year due to collapsing ponds, and a thick layer of organic silt forms at the bottom of ponds to make the pond more and more shallow. Contained in the mud