氮、硫输入对河口湿地土壤有机碳矿化的实验研究

通过室内培养实验,研究了氮、硫输入对闽江河口湿地土壤有机碳矿化和土壤理化性质的影响.结果表明:NH_4Cl(N1)、NH_4NO_3(N3)、K_2SO_4(S)和NH_4Cl+K_2SO_4(NS1)处理显著促进了湿地土壤有机碳矿化速率(p0.05),较对照分别提高了76.57%、60.09%、83.20%和52.59%,并且不同处理下土壤有机碳矿化速率均表现为随培养时间的增加而递减.氮、硫输入在不同时间对湿地土壤有机碳矿化的影响不尽一致,在前6 d各处理的促进作用最明显.湿地土壤有机碳累积矿化量在不同处理下均表现为随培养时间逐渐增加,其增长速率在培养初始阶段较快,而后逐渐减慢;不同培养时间有机碳累积矿化量在N1、N3、S和NS1处理下与对照处理间均存在显著差异(p0.05).短期培养结束后,N3、NS1处理显著增加了湿地土壤DOC含量(p0.05);N1、N3、NS1和NH_4NO_3+K_2SO_4(NS3)处理均显著增加了土壤NH_4~+-N含量(p0.05);KNO_3(N2)、N3、NS2和NS3处理均显著增加了土壤NO_3~--N含量(p0.05);S、NS1、NS2和NS3处理均显著增加了土壤SO_4~(2-)含量(p0.05).不同处理下湿地土壤Cl-、pH、EC具有微弱的波动变化特征,但在不同处理组间均不存在显著差异(p0.05).多元回归分析显示,DOC、NH_4~+-N和SO_4~(2-)是氮、硫输入处理下影响闽江河口湿地土壤有机碳矿化速率的主要控制因素.

Effects of nitrogen and sulfate input on soil organic carbon mineralization in the Min River estuarine wetland

Using laboratory incubation experiment techniques, the short-term effects of nitrogen and sulfate input on the mineralization of soil organic carbon from the tidal Cyperus malaccensis wetlands were measured in July 2015. Soil physical and chemical properties controlling the variation of soil organic carbon mineralization in Min River estuary were examined. The results showed that under aerobic conditions, the mineralization rates of soil organic carbon significantly increased by 76.57%, 60.09%, 83.20% and 52.59% in NH₄Cl, NH₄NO₃, K₂SO₄ and NH₄Cl plus K₂SO₄ treatments, respectively (p<0.05). During the incubation period, the daily mineralization rates of soil organic carbon decreased with increasing incubation time in different nitrogen and sulfate treatments. The influences of nitrogen and sulfate addition on the mineralization rates of soil organic carbon were different in different time scales, and the mineralization rates of soil organic carbon under all treatments were promoted obviously at the first six days of incubation. The cumulative mineralization of soil organic carbon increased with increasing incubation time under different nitrogen and sulfate treatments, and the increasing rate gradually declined with increasing incubation time. After the short-term incubation, dissolved organic carbon (DOC) contents of wetland soil significantly increased by NH₄NO₃ and NH₄Cl plus K₂SO₄ treatments (p<0.05); NH₄⁺-N contents significantly increased by NH₄Cl, NH₄NO₃, NH₄Cl plus K₂SO₄, and NH₄NO₃ plus K₂SO₄ treatments (p<0.05); NO₃^--N contents significantly increased by KNO₃, NH₄NO₃, KNO₃ plus K₂SO₄, and NH₄NO₃ plus K₂SO₄ treatments (p<0.05); SO₄^2- contents significantly increased by K₂SO₄, NH₄Cl plus K₂SO₄, KNO₃ plus K₂SO₄ and NH₄NO₃ plus K₂SO₄ treatments (p<0.05). The fluctuation characteristics were found in Cl^-, pH and EC contents under all treatments, but no statistically significant differences were found. Stepwise regression analysis showed that DOC, NH₄⁺-N, and SO₄^2- contents after incubation were the main driving factors affecting soil organic carbon mineralization rates in the Min River estuary tidal wetlands.