东太湖水生植物的促淤效应与磷的沉积

Silting up Effect of Aquatic Plants in Lake East Taihu and Accumulation of Phosphorous in The Sludge.

东太湖水生植物促进淤积效应显著，硬度小于５ｋｇ／ｃｍ２的淤积物平均深度０．９６ｍ，总淤积量１４９３７００００ｔ，东南沿岸茭草分布区淤积尤为严重．生物有机物质只占总淤积量的１．５２％，水生植物并非淤积物的主要来源．但生物有机物质引起的淤积物疏松效应使得全湖淤积深度增加了０．２０ｍ，占总淤积深度的２０．８％．表层沉积物中生物有机物质含量３．７７％，疏松效应占淤积深度的６４％．淤积物中总磷平均含量０．０２３％，总积累量３４９１２ｔ．磷在淤积物中的积累主要经非生物沉积途径，水生植物通过促进湖水中含磷物质的沉降和防止淤积物再悬浮起了促进磷沉积的作用．该湖水生植物收获利用率已达５７％，对减轻生物沉积十分有效，但尚有进一步开发利用的潜力．

Remarkable accelerating effect of aquatic plants on silting up of Lake East Taihu was found. For the whole lake,mean depth of sludge(hardness<5kg/cm 2) was 0.96m, and the total amount(dry weight)149 370 000 t.In the zone along Southeastern shore where emerged plant Zizania latifolia was growing luxuriantly,the sludge was much more deeper. Organic matter only took 1.52% of the sludge which means that aquatic plants was not the main source of the materials in the sludge. But the organic matter made the sludge very loose(loosening effect) which added 0.20 m sludge depth, about 20.8% of the total sludge depth. In the surface layer sludge(0—10 cm),organic matter took 3.77% of the sludge and loosening effect took as much as 64% of sludge depth. Mean content of phosphorous in the sludge was 0.023%, and the total amount of phosphorous 34 912 t.Phosphorous accumulated in the sludge mainly by non biological sedimentation means. But aquatic plants accelerated phosphorous sedimentation primarily by promoting settlement of suspended solid in the lake water and protecting the loose sludge from erosion of windwaves or current. It was very effective for reducing biological sedimentation that about 57% of plant product was harvested from the lake,but there was still large amount of plant matter was left in the lake.