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引用本文:李典鹏,姚美思,孙涛,刘隋赟昊,张凯,贾宏涛.水位变化对干涸湖底沉积物有机碳矿化的影响.湖泊科学,2019,31(3):881-890. DOI:10.18307/2019.0326
LI Dianpeng,YAO Meisi,SUN Tao,LIU Suiyunhao,ZHANG Kai,JIA Hongtao.Effect of different water level gradients on the mineralization of sediment organic carbon in a dry lake. J. Lake Sci.2019,31(3):881-890. DOI:10.18307/2019.0326
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水位变化对干涸湖底沉积物有机碳矿化的影响
李典鹏1, 姚美思1, 孙涛1, 刘隋赟昊1, 张凯1,2, 贾宏涛1,2
1.新疆农业大学草业与环境科学学院, 乌鲁木齐 830052;2.新疆土壤与植物生态过程重点实验室, 乌鲁木齐 830052
摘要:
人为干扰和气候变化会改变湖泊水位状态,明确不同水位条件下湖泊沉积物有机碳矿化特征及其影响因素,对了解内陆水生态系统碳循环具有重要意义.为探究干旱区典型盐湖沉积物有机碳矿化速率对水位变化的响应,以巴里坤湖干涸湖底原状沉积物为研究对象,初步探究了0(T1)、-9(T2)、-23(T3)、-34(T4)和-45 cm(T5)水位处理对沉积物有机碳矿化速率的影响.结果表明,T1、T2和T3处理有机碳矿化速率在试验初期较高(0~10 d),10 d后缓慢下降,T4和T5处理有机碳矿化速率呈先增加后降低趋势;T1(1.718 μmol/(m2·s))与T3(1.784 μmol/(m2·s))处理有机碳矿化速率不存在显著差异,T1处理有机碳矿化速率是T2、T4和T5处理的1.09、3.31和3.57倍,不同处理有机碳累积矿化量表现为T3 > T1 > T2 > T4 > T5.有机碳累积矿化量(Ct)占沉积物有机碳(C0)的比例(Ct/C0)介于0.012~0.044之间,沉积物有机碳潜在排放量(Ci)占C0的比例(Ci/C0)介于0.018~0.045之间;水位降低,沉积物有机碳矿化常数(k值)减小,T1处理k值最大(0.137 d),T4处理最小(0.032 d).线性方程Cr=0.008x+0.488能较好地模拟有机碳矿化速率(Cr)与水位(x)的关系;不同水位处理有机碳矿化速率与模拟柱中沉积物5 cm温度呈显著的指数函数关系,T4、T5处理有机碳矿化温度敏感系数(Q10)显著高于T1、T2和T3处理,即水位降低增加了巴里坤湖干涸湖底沉积物Q10.因此,就巴里坤湖干涸湖底沉积物而言,水位从0 cm降至-45 cm时有机碳矿化速率降低,Q10增加;反之水位上升则会促进有机碳矿化分解,Q10降低.水位持续下降抑制有机碳矿化可能是维持干旱区盐湖沉积物碳库稳定的机制之一.
关键词:  干旱区盐湖  水位梯度  碳排放  湖底沉积物  温度敏感系数  巴里坤湖
DOI:10.18307/2019.0326
分类号:
基金项目:国家自然科学基金项目(31560171)和新疆农业大学研究生科研创新项目(XJAUGRI2018011)联合资助.
Effect of different water level gradients on the mineralization of sediment organic carbon in a dry lake
LI Dianpeng1, YAO Meisi1, SUN Tao1, LIU Suiyunhao1, ZHANG Kai1,2, JIA Hongtao1,2
1.College of Grassland and Environmental Science, Xinjiang Agricultural University, Urumqi 830052, P.R.China;2.Xinjiang Key Laboratory of Soil and Plant Ecological Processes, Urumqi 830052, P.R.China
Abstract:
The loss of organic carbon during passage through the continuum of inland waters from soils to the sea is a critical issue for the global carbon cycle. However, the amount of organic carbon mineralized and released to the atmosphere during its transport remains an open question, hampered by the absence of predictors of organic carbon mineralization rates. The lake water level can be affected by human disturbance and climate change, and thus change the mineralization of the sediment organic carbon. The primary objective of this study was to study the influence of different water level gradients on the mineralization of sediment organic carbon in a saline lake in arid region. Sediments at 0-50 cm depth were sampled from Lake Barkol. The mineralization rates of sediment organic carbon were measured by Li-COR 8100A under five underground water level treatments (T1, T2, T3, T4 and T5 represent underground water level 0, -9, -23, -34 and -45 cm) were settled and sediment organic carbon mineralization rates were measured by Li-COR 8100A. Results showed the mineralization rates of sediment organic carbon under T1, T2 and T3 treatments were higher (0-10 d) at the beginning of the experiment, and then decreased slowly. The carbon mineralization rates under T4 and T5 treatments increased firstly and then decreased. The mineralization rate of organic carbon under T1 treatment was 1.09, 3.31 and 3.57 times higher than that under T2, T4 and T5 treatments, respectively. The cumulative mineralization of sediment organic carbon under different treatments is T3 > T1 > T2 > T4 > T5. The ratios of cumulative mineralization of organic carbon (Ct) to total sediment organic carbon (C0) (Ct/C0) are ranged from 1.2% to 4.4%, and the ratios of potential organic carbon emissions (Ci) to C0(Ci/C0) are ranged from 1.8% to 4.5%. The decrease of underground water level reduced the mineralization constant (k value) of sediment organic carbon. The k value under T1 treatment was max (0.137 d), and that under T4 treatment was lowest (0.032 d). The best fitting model explaining the relationship between sediment organic carbon mineralization rate and water level (x, cm) was Cr=0.008x+0.488. There were significant positive relationships between organic carbon mineralization rate and sediment temperature at 5 cm depth. Water level had significant effect on the temperature sensitive of sediment organic carbon mineralization (Q10). The Q10 was highest under T5 treatment (2.92), followed by T4 (2.54), and the T1 treatment had the smallest value (1.92). These results indicated that the decrease of underground water level would reduce the mineralization rate of organic carbon and increas Q10. The continuous decline of underground water level inhibits organic carbon mineralization, which may be a mechanism to maintain the stability of carbon pools of lake sediment in arid regions.
Key words:  Arid region saline lake  water level gradient  carbon emission  lake sediment  temperature sensitivity (Q10)  Lake Barkol
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