狗牙根与空心莲对水库消落带土壤氮磷释放影响的模拟

通过水库水位涨落室内模拟试验,探究丹江口库区消落带优势物种狗牙根和空心莲2种草本植物对土壤氮磷释放过程影响。结果表明:(1)水淹结束后(32天),空心莲子草土壤TN、TP分别降低11.75%,25.28%,狗牙根分别降低3.62%,25.77%。(2)干湿交替环境主要影响土壤中NH_4~+-N、NO_3~--N和AP的含量的变化,对土壤中的TN、TP含量的影响较小。(3)狗牙根的死亡增加土壤TN、NH_4~+-N、TP量,即不耐淹植被过滤带虽然能净化径流中N、P等污染物,但截留的污染物和植物吸收的养分随着植物体的分解再次进入水体或土壤,无法达到有效防控农业面源污染的目的。该研究为丹江口水库利用植被缓冲带防控水体富营养化提供一定理论依据。

Simulation Study on the Effects of Cynodon dactylon and Alternanthera philoxeroides on Soil Nitrogen and Phosphorus Release in the Reservoir Water-level Fluctuation Zone

In order to determine the effects of herbaceous plants on the release process of soil nitrogen and phosphorus, a simulation experiment of reservoir water level fluctuation was conducted under Cynodon dactylon and Alternanthera philoxeroides. The results showed that:(1) After the end of flooding (32 days), the soil total nitrogen (TN) and total phosphorus (TP) decreased by 11.75% and 25.28%, respectively in Alternanthera philoxeroides, and by 3.62% and 25.77%, respectively in Cynodon dactylon. (2) The dry-wet alternative environment mainly affected the changes of ammonium nitrogen (NH₄⁺-N), nitrate nitrogen (NO₃^--N) and available phosphorus in the soil, and had little effect on TN and TP contents in the soil. (3) The death of Cynodon dactylon increased the amount of soil TN, NH₄⁺-N and TP, indicating that the inundated vegetation filter belt could purify N, P and other pollutants in the runoff. However that part of nutrients absorbed by the plants would in turn release to water system by the decomposition of plant biomass. The decomposition of the plant biomass once again entered into the water system or the soil, and thus the purpose of effectively preventing and controlling agricultural non-point source pollution could not be achieved. This study provides a theoretical basis for the using of vegetation buffer zone to prevent and control the eutrophication of water system in the Danjiangkou Reservoir.