State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing, 100875, China.
State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing, 100875, China.
Chemosphere. 2019 Aug;228:174-182. doi: 10.1016/j.chemosphere.2019.04.006. Epub 2019 Apr 8.
The interactive effects of salinity and moisture on the net nitrogen mineralization were seldom studied in coastal wetlands. To reveal the phenomenons and mechanisms of salinity and moisture effects, we conducted a 30-days laboratory experiment with different salt addition levels (0, ppt, 5 ppt and 35 ppt) and moisture levels (10%, 50% and 100% of water holding capacity (WHC)), and the key N transformation rates and enzymes activities were measured. Our results showed that during the incubation, the rates of soil net nitrogen mineralization (R) and nitrification (R) under all treatments, increased during 0-1 day, decreased during 1-3 days, then increased and kept around zero. As incubation time increased, urease activities increased, arylamidase activities decreased and fluorescein diacetate activities increased first and then decreased. Increasing salinity under high moisture (100% WHC) treatments and increasing moisture under high salinity (35 ppt) treatments would promote R and R. Whereas, increasing salinity under low moisture (10% WHC) treatments, and increasing moisture under low salinity (0 ppt) treatments would suppress R and R. The responses of enzyme activities to salinity and moisture gradients almost correspond with R, indicating salinity and moisture could affect N transformation by the regulation of related microbial enzyme activities.
在滨海湿地中，盐分和水分对净氮矿化的交互作用很少被研究。为了揭示盐分和水分效应的现象和机制，我们进行了为期 30 天的实验室实验，设置了不同的盐分添加水平（0、5 ppt 和 35 ppt）和水分水平（持水能力的 10%、50%和 100%），并测量了关键氮转化速率和酶活性。结果表明，在培养过程中，所有处理下土壤净氮矿化速率（R）和硝化速率（R）在 0-1 天内增加，在 1-3 天内减少，然后增加并保持在零左右。随着培养时间的增加，脲酶活性增加，芳基酰胺酶活性降低，荧光二乙酸酯活性先增加后减少。在高水分（100%持水能力）处理下增加盐分，以及在高盐分（35 ppt）处理下增加水分，会促进 R 和 R。然而，在低水分（10%持水能力）处理下增加盐分，以及在低盐分（0 ppt）处理下增加水分，会抑制 R 和 R。酶活性对盐分和水分梯度的响应几乎与 R 相对应，表明盐分和水分可以通过调节相关微生物酶活性来影响氮转化。
