红壤小流域不同土地利用方式坡面下水塘底泥养分含量变化

以我国南方丘陵区红壤小流域为研究对象,对不同土地利用方式坡面下的4个水塘底泥中养分含量作了分层比较研究(0-5 cm,5-10 cm,10-15 cm,15-20 cm,20-25 cm,25-30 cm)．结果表明:4个水塘底泥养分含量差异明显,在0-15 cm泥层有机碳、全氮、速效氮和全磷含量以邻近村庄的水塘(简称C塘)底泥最高,其次为板栗园坡下的水塘(简称B塘),水稻田坡面下水塘(简称S塘)和花生地坡面下水塘(简称H塘)最低;在15-30 cm泥层,有机碳和速效氮含量以B塘最高,而全氮和全磷含量则以C塘最高;有效磷含量除C塘0-15 cm底泥外,其余均为痕量．表明土地利用方式对其坡面下水塘底泥养分含量影响明显．各水塘底泥养分随泥层加深均呈递减趋势,其中全氮和速效氮减幅以C塘最大,分别为36．0％和38．7％,有机碳和全磷减幅则以B塘最大,为29．4％和31．9％;各塘底泥养分含量的最大降幅主要在浅层底泥,水塘养分积累加速表明近年来农村面源污染加剧．传统农业耕作方式的改变是农村水体底泥养分含量增加的主要原因之一．

Variations of the nutrient concentrations in the sediments of ponds under the slopes of different land use patterns in small red soil watershed

Based on the low hill small red soil watershed in the Ecological Experiment Station of Red Soil of China Academy of Sciences, the variations of nutrient concentrations in the sediments(0-5 cm, 5-10 cm,10-15 cm, 15-20 cm, 20-25 cm, 25-30 cm)of 4 ponds under the slopes of different land use patterns were investigated. The 4 ponds were B pond (locateal in the downside slope of Chinese chestnut land) , C pond (locateal in the vicinity of the village) , H pond (locateal in the downside slope of peanut land) and S pond (locateal in the downside slope of paddy field respectively. The results showed that: The nutrient concentrations in sediment of 4 ponds were differed obviously. The highest concentrations of TOC, TN, AN and TP in 0-15 cm sediment were appeared in C pond, and the lowest were in H pond. In 15-30 cm sediment, the highest concentrations of TOC and AN were found in B pond, while TN and TP were found in C pond. The concentrations of AP of the sediment in 4 ponds were trace except the 0-15 cm sediment in C pond with low level. This suggested that the land use patterns had significant effect on the nutrient concentrations in the sediments of the ponds. The nutrient concentrations of the sediments (0-30 cm) in 4 ponds all decreased from surface to bottom. The TN and AN with the maximal descent were found in C pond, and the TOC and TP were both in B pond. The most descents of nutrient concentrations in sediment in each pond appeared in superficial sediment layers. The accelerations of the nutrient accumulating in sediment indicated that the export of nutrient from each land use pattern had increased in recent years obviously, and one of the main causes of the nutrient enhancement in the sediment was the transform of the traditional agricultural cultivation fashions.