| 崇明东滩湿地干湿交替过程脲酶活性变化初探 |
| 摘要点击 3105 全文点击 1628 投稿时间：2013-01-03 修订日期：2013-02-04 |
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| 中文关键词 滨海湿地 干湿交替 半月潮 日潮 脲酶 温度敏感性 |
| 英文关键词 coastal wetlands drying and rewetting spring tides semi-diurnal tides urease temperature sensitivity |
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| 中文摘要 |
| 以典型滨海湿地——崇明东滩为原型区域,采集湿地沉积物及海水样品,通过土柱模拟方法(30、35、40℃),研究了半月潮(15d左右为周期的"大潮")与日潮(一个太阴日内出现的涨潮和落潮)水分生态过程沉积物脲酶(Urease)活性及溶解性有机氮(DON)与铵态氮(NH4+-N)含量等的变化,计算了Urease活性的表观温度敏感性系数(Q10'),旨为揭示典型滨海湿地潮汐驱动下周期性干湿交替过程沉积物Urease活性的变化规律. 半月潮过程,干燥沉积物(1%~3%)淹水后,Urease活性迅速增加. 随着沉积物变干,酶活性逐渐下降. Urease活性对沉积物水分变化的敏感性随干湿交替频次的增加而下降. 日潮过程对Urease活性的影响较小. 30、35、40℃下,酶活性分别为(0.067±0.018)、(0.143±0.027)、(0.028±0.011)g·(10 g·h)-1. 相比较而言,半月潮过程Urease活性明显低于日潮过程. 这表明,干湿交替显著降低了沉积物Urease活性(30、35℃). 半月潮过程中,沉积物Urease活性Q10'的最高值出现在35~40℃,而日潮过程中出现在30~35℃. 因此,干湿交替可能增高了Urease活性Q10'的温度响应范围. 此外,半月潮过程中,Urease活性主导着沉积物NH4+-N含量的变化(30、35℃),但其与DON含量之间并无显著相关性. 日潮过程Urease活性与NH4+-N和DON含量之间均不显著相关. |
| 英文摘要 |
| Sediment and sea water samples were taken from Chongming east intertidal flat, a typical coastal wetland in China, to define the responses of urease activity to periodicalternation of drying and rewetting. Sediment cores were incubated under 30, 35 and 40℃ with simulated spring tides (approximately twice a month) and semi-diurnal tides (two almost equal high tides and two low tides in a lunar day). Urease activities in sediments were determined during the incubations as well as dissolved organic nitrogen (DON) and ammonium nitrogen (NH4+-N) contents. The apparent temperature sensitivity index (Q10') of urease activity was calculated based on the observations of urease activities under 30, 35 and 40℃. Urease activities rapidly increased following the rewetting of dried sediments (1%-3%) and dropped with decreasing sediment moisture during simulated spring tides. Repeated drying and rewetting cycles lowered the sensitivity of urease to the changes of moisture. In contrast, semi-diurnal tides slightly affected urease activities, in which the enzyme maintained relatively stable activities with (0.067±0.018), (0.143±0.027) and (0.028±0.011) g·(10 g·h)-1 under 30, 35 and 40℃, respectively. Urease activities during spring tides were found to be much lower than those of semi-diurnal tides under both 30 and 35℃, implying that repeated drying and rewetting cycles possibly lessened urease activities in sediments. In addition, the highest Q10' of urease activity occurred happened between 35℃ and 40℃ during the spring tides, but happened between 30℃ and 35℃ during semi-diurnal tides. This indicated that drying and rewetting events helped to increase the temperature regime, where the Q10' of urease activity achieved to the highest. Moreover, NH4+-N contents depended on the urease activities in sediments during spring tides under 30℃ and 35℃. However, No significant relationship between urease activities and DON contents was found. In contrast, changes in DON and NH4+-N contents hardly affected urease activities during semi-diurnal tides. |
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