Gao Haifeng, Bai Junhong, He Xinhua, Zhao Qingqing, Lu Qiongqiong, Wang Junjing
State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing, China.
NSW Department of Primary Industries, West Pennant Hills, New South Wales, Australia.
PLoS One. 2014 Apr 14;9(4):e95011. doi: 10.1371/journal.pone.0095011. eCollection 2014.
Soil nitrogen (N) mineralization in wetlands is sensitive to various environmental factors. To compare the effects of salinity and temperature on N mineralization, wetland soils from a tidal freshwater marsh locating in the Yellow River Delta was incubated over a 48-d anaerobic incubation period under four salinity concentrations (0, 10, 20 and 35‰) and four temperature levels (10, 20, 30 and 40°C). The results suggested that accumulated ammonium nitrogen (NH4+-N) increased with increasing incubation time under all salinity concentrations. Higher temperatures and salinities significantly enhanced soil N mineralization except for a short-term (≈10 days) inhibiting effect found under 35‰ salinity. The incubation time, temperature, salinity and their interactions exhibited significant effects on N mineralization (P<0.001) except the interactive effect of salinity and temperature (P>0.05), while temperature exhibited the greatest effect (P<0.001). Meanwhile, N mineralization processes were simulated using both an effective accumulated temperature model and a one-pool model. Both models fit well with the simulation of soil N mineralization process in the coastal freshwater wetlands under a range of 30 to 40°C (R2 = 0.88-0.99, P<0.01). Our results indicated that an enhanced NH4+-N release with increasing temperature and salinity deriving from the projected global warming could have profound effects on nutrient cycling in coastal wetland ecosystems.
湿地土壤氮矿化对多种环境因素敏感。为比较盐度和温度对氮矿化的影响，对黄河三角洲一处潮汐淡水沼泽的湿地土壤在48天的厌氧培养期内，于四种盐度浓度（0、10、20和35‰）和四个温度水平（10、20、30和40°C）下进行培养。结果表明，在所有盐度浓度下，累积铵态氮（NH4+-N）随培养时间增加而增加。除在35‰盐度下发现有短期（约10天）抑制作用外，较高的温度和盐度显著增强了土壤氮矿化。培养时间、温度、盐度及其交互作用对氮矿化均有显著影响（P<0.001），但盐度和温度的交互作用除外（P>0.05），其中温度的影响最大（P<0.001）。同时，分别用有效积温模型和单库模型对氮矿化过程进行了模拟。在30至40°C范围内，两个模型对沿海淡水湿地土壤氮矿化过程的模拟效果均较好（R2 = 0.88 - 0.99，P<0.01）。我们的结果表明，预计全球变暖导致温度和盐度升高，从而使NH4+-N释放增加，这可能对沿海湿地生态系统的养分循环产生深远影响。
