氮输入对闽江河口湿地土壤有机碳矿化的影响

Nitrogen Enrichment Impacts on Carbon Mineralization in Wetlands Soil of the Min River Estuary

以闽江河口湿地高潮滩和中潮滩短叶茳芏(Cyperus malaccensis L.)湿地土壤为研究对象,采用室内模拟实验,探讨不同形态及浓度氮(对照组—CK、氨态氮低氮组—N-1、氨态氮高氮组—N-2、硝态氮低氮组—X-1和硝态氮高氮组—X-2)输入对河口湿地(高、中潮滩)土壤有机碳矿化的影响。结果表明:1)随着培养时间的延长,在不同氮处理下的土壤有机碳矿化速率均表现为先增加后减少的趋势,总体上在培养的第4 d达到最大值,而后逐渐下降,15 d左右以后趋于稳定。2)氮输入对土壤有机碳矿化总体上起了一定的抑制作用,尤其在培养初期(第1 d和4 d),不同氮输入处理有机碳矿化速率均显著低于CK组(P<0.05);培养15 d后,高潮滩各氮输入处理(N-1、N-2、X-1和X-2)土壤有机碳累积矿化量均显著低于CK,而中潮滩土壤累积矿化量表现为CK>N-1>N-2>X-1>X-2。3)不同氮浓度和形态的抑制程度有所不同,总体上随氮输入的增加,对有机碳矿化抑制作用增强,而同一浓度下,硝态氮的抑制作用较强于铵态氮。4)高潮滩土壤的有机碳矿化速率和碳的矿化累积量均显著高于中潮滩土壤(P<0.05)。

It is very important to study the mineralization of estuary wetlands soil organic carbon with different nitrogen inputs, which has vital significance to a better understanding of the estuary in re- sponse to global change. The native Cyperus malaccensis wetlands soils of high and m/ddle f/at in the Min River estuary were selected to discuss the mineralization of soil organic carbon with different nitrogen inputs （control group--CK, low ammonia nitrogen group--N- 1 high ammonia nitrogen group--N -2, low nitrate nitrogen group--X - 1, and high nitrate nitrogen group--X - 2 ） in the Min River estuary wetlands （high, middle flat） soil by laboratory incubation. , The results showed： 1 ） With the extend of training time, rates of organic carbon under different nitrogen treatment showed the first increase after decreasing trend, in the whole, it reaches a maximum in the fourth day of cuhure, then it declines gradually and becomes steady after 15 days. 2） In the whole, nitrogen inputs inhibit the carbon miner- alization of the Min River estuary wetlands soil, especially in the early stage of train （day 1 and day 4）, rates of organic carbon under different nitrogen treatment was significantly lower than CK group （P 〈 0. 05）. After 15 days of training, the cumulative mineralization of organic carbon as affected by different nitrogen treatments （N- 1, N- 2, X- 1 and X- 2） in high flat were significantly lower than CK, while in middle flat, the cumulative mineralization of organic carbon shows that ： CK 〉 N - 1 〉 N - 2 〉 X - 1 〉 X - 2, which further indicates that nitrogen inputs plays certain inhibitory effect to soil or- ganic carbon mineralization of the Min River estuary wetlands soil. 3） Different forms and concentra- tion of nitrogen show different degree inhibition, generally, the carbon mineralization inhibition in- creased with increasing nitrogen inputs, while at the same concentration, the inhibitory effect of nitrate nitrogen is stronger to ammonium nitrogen. 4） Rates of organic carbon and cumulative carbon minerali- zation were significantly higher in high fiat than those in middle fiat （P 〈 0.05）.