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首页> 外文期刊>Journal of Geophysical Research. Biogeosciences >Disturbance impacts on mercury dynamics in northern Gulf of Mexico sediments
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Disturbance impacts on mercury dynamics in northern Gulf of Mexico sediments

机译：干扰对墨西哥湾北部沉积物中汞动力学的影响

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We evaluated the impacts of physical disturbance on sediment Hg biogeochemistry in the northern Gulf of Mexico by exploring changes in Hg abundance and speciation in cores collected between July 2005 and July 2006, a time period that included the passages of Hurricanes Katrina and Rita in this region. Comparisons across space and time reveal large changes in sediment characteristics, both with respect to Hg biogeochemistry and other measures of sediment composition, that indicate substantial disturbance. While the degree of disturbance varied between stations, at sites that clearly received new surface deposits considerable increases in OC and total Hg were observed, along with shifts in major element composition. At the station closest to Hurricane Katrina's track (station A′2), ~(210)Pb levels are consistent with the episodic deposition of >10 cm of sediments. These surface sediments (0-10 cm) at A′2 had the highest %MeHg of all stations and all dates, suggesting that the disturbance resulted initially in increased net methylation. While the observed disturbances elsewhere could not in all cases be definitively linked to hurricane activities, the substantial thickness of deposits (>10 cm) at multiple sites is consistent with a major event, and the similarity in the deposits' chemical fingerprint across all impacted sites suggests similar sources or processes. We estimate that the two hurricanes redistributed approximately 5 times the annual Hg input from the Mississippi-Atchafalaya River system and atmospheric deposition. These observations highlight the need to consider the effects of major disturbances on the biogeochemical cycling of Hg in coastal systems.
机译：我们通过研究2005年7月至2006年7月收集的岩心中汞的丰度和形态变化，评估了物理干扰对墨西哥湾北部沉积物Hg生物地球化学的影响，这段时间包括飓风卡特里娜和丽塔在该地区的通过。跨时空的比较表明，在汞生物地球化学和其他沉积物组成测量方面，沉积物特征发生了巨大变化，这表明存在重大干扰。尽管不同站点之间的扰动程度各不相同，但在明显接收到新表面沉积物的站点，观察到OC和总Hg显着增加，并且主要元素组成发生了变化。在最接近卡特里娜飓风轨道的站点（站点A'2），〜（210）Pb水平与> 10 cm沉积物的间歇性沉积相一致。在A'2的这些表层沉积物（0-10厘米）在所有站位和所有日期中的％MeHg最高，表明该干扰最初导致净甲基化增加。尽管在所有情况下观察到的扰动都不能完全确定地与飓风活动有关，但在多个地点的沉积物的实质厚度（> 10 cm）与重大事件是一致的，并且所有受影响地点的沉积物化学指纹相似建议类似的来源或过程。我们估计这两个飓风重新分配了密西西比-阿查法拉亚河系统和大气沉积物每年汞输入的约5倍。这些观察结果突出了需要考虑主要干扰因素对沿海系统中汞的生物地球化学循环的影响。

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