不同生态修复措施对滇池沉积物无机氮迁移转化影响

Effects of Different Ecological Restoration Measures on Transferring and Transformation of Inorganic Nitrogen in Dianchi Sediment

通过模拟培养试验比较研究了滇池沉积物用细沙原位覆盖后种植苦草、红土原位覆盖后种植苦草以及直接种植苦草三种生态修复措施对无机氮迁移转化的影响。结果表明,直接种植草桶中,水体中高锰酸盐指数、悬浮物质(SS)、NH4+-N及沉积物中NH4+-N的浓度最高,细沙覆盖后种草桶中次之,红土覆盖后种草桶中最低。另外,细沙和红土覆盖后种草桶中,水体中氨氧化作用和亚硝酸盐氧化作用最先出现,分别在第13天和第19天。红土覆盖后种草桶中,水体及沉积物中氨氧化和亚硝酸盐氧化速率最高,细沙覆盖后种草桶中次之。结果表明,滇池沉积物分别用细沙和红土原位覆盖后种植苦草不仅阻止了沉积物中还原性物质、悬浮颗粒物质和NH4+-N向水体的释放,促进了氨氧化和亚硝酸盐氧化反应的进行,并且能够显著降低水体及沉积物中无机氮的浓度,其中,红土覆盖后种植苦草效果最明显。同时,红土覆盖为苦草的扎根提供了有效的附着基质,促进了苦草的生长和恢复。因此,红土覆盖后种植苦草是污染沉积物生态修复的一种有效方法。

Effects of three ecological restoration measures which are planting Vallisneria spiraslis L.directly in Dianchi sediment,planting Vallisneria spiraslis L.in sediment covered by silver sand and planting Vallisneria spiraslis L.in sediment covered by laterite on transfer and transformation of inorganic nitrogen were studied by indoor incubation experiment.Results showed that the concentrations of CODMn,SS and NH4＋-N in waters and NH4＋-N in sediment were the highest in plastic casks treated with planting Vallisneria spiraslis L.diretly in sediment,and there conentrations in plastic casks treated with planting Vallisneria spiraslis L.in sediment covered by laterite were the lowest.Ammonia and nitrite oxidation in waters firstly appear in the plastic casks treated with planting Vallisneria spiraslis L.in sediment covered by silver sand and laterite,and the date were the 13th and 19th day separately.Rates of ammonia and nitrite oxidation in waters and sediment were the highest in plastic casks treated with planting Vallisneria spiraslis L.in sediment covered by laterite,and followed by rates in plastic casks treated with planting Vallisneria spiraslis L.in sediment covered by silver sand.Results indicated that planting Vallisneria spiraslis L.in Dianchi sediment covered by silver sand and laterite are able to not only hold back the release of reductive material,suspended particulate material and ammonia into water from sediment,but also decrease markedly ammonia concentration in sediment.Planting Vallisneria spiraslis L.in sediment covered by laterite which provided an effective attachment matrix for Vallisneria spiraslis L.to take a root and promoted Vallisneria spiraslis L.grow and recovery has the better result than planting Vallisneria spiraslis L.in sediment covered by silver sand,which indicated that planting Vallisneria spiraslis L.in sediment covered by laterite is the effective way of ecological restoration for contaminative sediment.