Modeling lugworm irrigation behavior effects on sediment nitrogen cycling
Modeling lugworm irrigation behavior effects on sediment nitrogen cycling
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DOI：
10.3354/meps11381
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发表时间：
2015-08
影响因子：
2.5
通讯作者：
T. Dornhoffer;G. Waldbusser;C. Meile
中科院分区：
文献类型：
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作者：
T. Dornhoffer;G. Waldbusser;C. Meile
海洋沉积物中的底栖动物对生物地球化学循环的影响，从个体到生态系统的规模，包括刺激硝化和通过反硝化去除氮，都有充分的记录。然而，挖穴深度和灌溉模式对氮循环的影响还没有得到很好的描述。在这里，我们使用文献和实验室数据参数化的反应-迁移模型来研究沙虫行为对沉积物氮循环的影响。饲养口袋的深度和泵送特性（流量和模式）是不同的，硝化，反硝化和底栖生物交换通量的速率进行了计算。正如预期的那样，更强烈的洞穴灌溉刺激反硝化和耦合硝化-反硝化。在高泵送速率和低沉积物耗氧速率（~10−6 mol m−3 s−1）下，模拟结果表明，由于注入的氧化剂消耗不完全，硝化和反硝化速率随着洞穴深度的减小而降低。模型结果还表明，不连续灌溉导致泥沙氮循环的时间变化，但时间平均速率不依赖于灌溉模式。我们确定（1）注入沉积物中的管腔流体的化学成分限制不严，（2）微生物活性/分布对振荡氧化还原条件的响应是影响沉积物氮去除估计的关键知识缺口。
Benthic infauna in marine sediments have well-documented effects on biogeochemical cycling, from individual to ecosystem scales, including stimulation of nitrification and nitrogen removal via denitrification. However, the effects of burrowing depth and irrigation patterns on nitrogen cycling have not been as well described. Here we examined the effects of lugworm behavior on sediment nitrogen cycling using a reaction-transport model parameterized with literature and laboratory data. Feeding pocket depth and pumping characteristics (flow rate and pattern) were varied, and rates of nitrification, denitrification, and benthic exchange fluxes were computed. As expected, more intense burrow irrigation stimulated denitrification and coupled nitrification−denitrification. At high pumping rates and low sediment oxygen consumption rates (~10−6 mol m−3 s−1), simulation results showed a decrease in rates of nitrification and denitrification with decreasing burrow depth due to incomplete consumption of injected oxidants. Model results also suggest that discontinuous irrigation leads to temporal variability in sediment nitrogen cycling, but that the time-averaged rates do not depend on the irrigation pattern. We identify (1) the poorly constrained chemical composition of lumen fluid injected into sediments and (2) the response of microbial activity/distribution to oscillating redox conditions as critical knowledge gaps affecting estimates of sediment nitrogen removal.