Effects of nutrient loading on the carbon balance of coastal wetland sediments
Effects of nutrient loading on the carbon balance of coastal wetland sediments
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DOI：
10.4319/lo.1999.44.3.0699
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发表时间：
1999-05
影响因子：
4.5
通讯作者：
J. Morris;P. Bradley
中科院分区：
文献类型：
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作者：
J. Morris;P. Bradley
在贫营养的南卡罗来纳州盐沼进行的一项为期12年的研究结果表明，土壤呼吸增加了795 g C m−2 yr−1，而氮和磷施肥的沉积物中的碳储量减少了。施肥地块成为净碳源的大气中，沉积物呼吸继续在这些地块以加快的步伐。经过12年的处理后，施肥区沉积物顶部5 cm的土壤宏有机质比对照区低475 g C m−2，相当于40 g C m−2 yr−1的恒定损失率。目前尚不清楚施肥地块中的土壤碳是否达到了新的平衡或继续下降。施肥样地土壤呼吸的增加远远大于沉积物有机质的损失，这表明土壤呼吸的增加主要是由于初级生产力的增加。在实验室培养的沉积物呼吸也表现出积极的影响的营养。因此，研究结果表明，营养盐负荷的贫营养湿地可以导致增加的沉积物碳周转率和沉积物的碳净损失。
Results of a 12‐yr study in an oligotrophic South Carolina salt marsh demonstrate that soil respiration increased by 795 g C m−2 yr−1 and that carbon inventories decreased in sediments fertilized with nitrogen and phosphorus. Fertilized plots became net sources of carbon to the atmosphere, and sediment respiration continues in these plots at an accelerated pace. After 12 yr of treatment, soil macroorganic matter in the top 5 cm of sediment was 475 g C m−2 lower in fertilized plots than in controls, which is equivalent to a constant loss rate of 40 g C m−2 yr−1. It is not known whether soil carbon in fertilized plots has reached a new equilibrium or continues to decline. The increase in soil respiration in the fertilized plots was far greater than the loss of sediment organic matter, which indicates that the increase in soil respiration was largely due to an increase in primary production. Sediment respiration in laboratory incubations also demonstrated positive effects of nutrients. Thus, the results indicate that increased nutrient loading of oligotrophic wetlands can lead to an increased rate of sediment carbon turnover and a net loss of carbon from sediments.