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为探讨水分与氧化还原电位之间的内在关系及其对沼泽湿地有机碳分解矿化的影响,采用室内培养(25℃,155 d)实验研究了不同水分条件(24%~232%WHC)下三江平原3类湿地(泥炭沼泽、腐殖质沼泽和沼泽化草甸)沉积物氧化还原电位(Eh)变化以及有机碳的矿化特征.结果表明,不同水分条件对湿地沉积物氧化还原电位的影响有较大差异,在低于100%WHC(最大持水量)水分范围时,氧化还原电位随着水分的增加而降低,>100%WHC(至积水2 cm)时,水分含量变化对泥炭沼泽和腐殖质沼泽沉积物氧化还原电位影响作用降低.泥炭沼泽、腐殖质沼泽和沼泽化草甸沉积物有机碳矿化最适宜水分含量存在较大差异,分别为32%、48%和76%~100%WHC.湿地沉积物有机碳矿化速率与氧化还原电位之间存在二次函数关系(p<0.05),在还原态下(Eh值<300 mV),有机碳矿化速率和矿化量随氧化还原电位的升高而升高,在氧化态(Eh值>300 mV)下则逐渐降低.较低的氧化还原电位是三江平原湿地有机碳得以积累的重要原因.
In order to investigate the intrinsic relationship between water and redox potential and its effect on organic carbon decomposition and mineralization in marsh wetlands, indoor cultivation (25 ℃, 155 d) was used to study the effects of different moisture conditions (24% -232% WHC) The changes of redox potential (Eh) and mineralization of organic carbon in three types of wetlands (peat swamp, humus swamp and marsh meadow) in the Sanjiang Plain show that the effects of different water conditions on the redox potential of wetland sediments are The larger the difference, the redox potential decreases with increasing moisture below 100% WHC (maximum water holding capacity), and> 100% WHC (to 2 cm water) The effect of redox potential of humus swamp sediments decreased.The most suitable moisture content of organic carbon mineralization in the sediments of peat swamp, humus swamp and swamp meadow were 32%, 48% and 76% -100%, respectively (P <0.05). In the reduced state (Eh <300 mV), the rates of mineralization and mineralization of organic carbon increased with the redox potential Elevated potential and increased in the oxidation state ( Eh value> 300 mV), and the lower redox potential is the important reason for the accumulation of organic carbon in wetlands in the Sanjiang Plain.