Sediment chemistry of urban stormwater ponds and controls on denitrification
Sediment chemistry of urban stormwater ponds and controls on denitrification
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DOI：
10.1002/ecs2.2318
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发表时间：
2018-06-01
期刊：
影响因子：
2.7
通讯作者：
Bernhardt, Emily S.
中科院分区：
文献类型：
--
作者：
Blaszczak, Joanna R.;Steele, Meredith K.;Bernhardt, Emily S.
雨水池和蓄水池是城市景观中无处不在的特征。这些池塘是通过反硝化作用从地表水体中去除氮（N）的潜在重要控制点。然而，有可能权衡这种水质的好处，如果高氮和污染物浓度在雨水池塘沉积物减少一氧化二氮（N2O），一种有效的温室气体，二氮（N-2）在反硝化过程中的完全还原。这可以通过降低能够产生N2O还原酶的发酵剂的丰度或效率而发生。我们预测，池塘排水日益城市化的景观将有更高的N和金属浓度在其沉积物中，从而更大的N2O产量。我们测量了潜在的反硝化速率，N2O还原酶（nosZ）基因频率，以及沉积物和孔隙水化学分布在美国8个城市的64个池塘。我们发现，几乎没有相关性的比例城市土地覆盖周围的池塘和雨水池塘沉积物中的营养物质和污染物的浓度在所有城市内或跨。回归分析表明，在不同的环境控制下，可以解释的潜在N2和N2 O产生比例。我们的调查提出了许多新的问题，为什么N通量和转换在城市环境中和城市环境中变化如此之大，但也减轻了人们的担忧，即城市雨水池塘中金属浓度升高会增加N2O排放。城市雨水池塘不太可能成为大气中N2O的问题来源，无论其反硝化潜力如何。
Stormwater ponds and retention basins are ubiquitous features throughout urban landscapes. These ponds are potentially important control points for nitrogen (N) removal from surface water bodies via denitrification. However, there are possible trade-offs to this water quality benefit if high N and contaminant concentrations in stormwater pond sediments decrease the complete reduction of nitrous oxide (N2O), a potent greenhouse gas, to dinitrogen (N-2) during denitrification. This may occur through decreasing the abundance or efficiency of denitrifiers capable of producing the N2O reductase enzyme. We predicted that ponds draining increasingly urbanized landscapes would have higher N and metal concentrations in their sediments, and thereby greater N2O yields. We measured potential denitrification rates, N2O reductase (nosZ) gene frequencies, as well as sediment and pore water chemistry in 64 ponds distributed across eight U.S. cities. We found almost no correlation between the proportion of urban land cover surrounding ponds and the nutrient and contaminant concentrations in the stormwater pond sediments within or across all cities. Regression analysis revealed that the proportion of potential N-2 and N2O production that could be explained was under different environmental controls. Our survey raises many new questions about why N fluxes and transformations vary so widely both within and across urban environments, but also allays the concern that elevated metal concentrations in urban stormwater ponds will increase N2O emissions. Urban stormwater ponds are unlikely to be a problematic source of N2O to the atmosphere, no matter their denitrification potential.