Ecol Appl. 2014 Jun;24(4):633-49. doi: 10.1890/13-0594.1.
Marshes in the urban Jamaica Bay Estuary, New York, USA are disappearing at an average rate of 13 ha/yr, and multiple stressors (e.g., wastewater inputs, dredging activities, groundwater removal, and global warming) may be contributing to marsh losses. Among these stressors, wastewater nutrients are suspected to be an important contributing cause of marsh deterioration. We used census data, radiometric dating, stable nitrogen isotopes, and soil surveys to examine the temporal relationships between human population growth and soil nitrogen; and we evaluated soil structure with computer-aided tomography, surface elevation and sediment accretion trends, carbon dioxide emissions, and soil shear strength to examine differences among disappearing (Black Bank and Big Egg) and stable marshes (JoCo). Radiometric dating and nitrogen isotope analyses suggested a rapid increase in human wastewater nutrients beginning in the late 1840s, and a tapering off beginning in the 1930s when wastewater treatment plants (WWTPs) were first installed. Current WWTPs nutrient loads to Jamaica Bay are approximately 13 995 kg N/d and 2767 kg P/d. At Black Bank, the biomass and abundance of roots and rhizomes and percentage of organic matter on soil were significantly lower, rhizomes larger in diameter, carbon dioxide emission rates and peat particle density significantly greater, and soil strength significantly lower compared to the stable JoCo Marsh, suggesting Black Bank has elevated decomposition rates, more decomposed peat, and highly waterlogged peat. Despite these differences, the rates of accretion and surface elevation change were similar for both marshes, and the rates of elevation change approximated the long-term relative rate of sea level rise estimated from tide gauge data at nearby Sandy Hook, New Jersey. We hypothesize that Black Bank marsh kept pace with sea level rise by the accretion of material on the marsh surface, and the maintenance of soil volume through production of larger diameter rhizomes and swelling (dilation) of waterlogged peat. JoCo Marsh kept pace with sea-level rise through surface accretion and soil organic matter accumulation. Understanding the effects of multiple stressors, including nutrient enrichment, on soil structure, organic matter accumulation, and elevation change will better inform management decisions aimed at maintaining and restoring coastal marshes.
美国纽约州杰梅卡湾河口的沼泽地正以平均每年 13 公顷的速度消失，而多种胁迫因素（如废水输入、疏浚活动、地下水抽取和全球变暖）可能是导致沼泽地丧失的原因。在这些胁迫因素中，废水养分被怀疑是导致沼泽恶化的一个重要原因。我们使用普查数据、放射性测年、稳定氮同位素和土壤调查来研究人口增长与土壤氮之间的时间关系；我们还使用计算机辅助断层扫描、地表高程和沉积物淤积趋势、二氧化碳排放和土壤剪切强度来评估土壤结构，以研究消失（黑银行和大蛋）和稳定（乔科）沼泽之间的差异。放射性测年和氮同位素分析表明，人类废水养分在 19 世纪 40 年代末迅速增加，并在 20 世纪 30 年代开始减少，当时首次安装了废水处理厂（WWTP）。目前，杰梅卡湾的 WWTP 向海湾输入的氮负荷约为 13995 千克/天，磷负荷为 2767 千克/天。在黑银行，根和根茎的生物量和丰度以及土壤中有机质的百分比明显较低，根茎直径较大，二氧化碳排放量和泥炭颗粒密度显著增大，土壤强度显著降低，与稳定的乔科沼泽相比，这表明黑银行的分解速率较高，分解的泥炭较多，泥炭高度积水。尽管存在这些差异，但两个沼泽的淤积和地表高程变化速率相似，且高程变化速率接近新泽西州桑迪胡克附近潮汐计数据估计的长期海平面上升速率。我们假设黑银行沼泽通过在沼泽表面堆积物质以及通过产生更大直径的根茎和积水泥炭的膨胀（扩张）来维持土壤体积，从而与海平面上升保持同步。乔科沼泽通过表面淤积和土壤有机质积累与海平面上升保持同步。了解包括富营养化在内的多种胁迫因素对土壤结构、有机质积累和高程变化的影响，将更好地为旨在维持和恢复沿海沼泽的管理决策提供信息。
