Mercury is a toxic element that is dispersed globally through the atmosphere. Accurately measuring airborne mercury concentrations aids understanding of the pollutant’s sources, distribution, cycling, and trends. We deployed MerPAS^® passive air samplers (PAS) for ~4 weeks during each season, from spring 2019 to winter 2020, to determine gaseous elemental mercury (GEM) levels at six locations along the northern Gulf of Mexico, where the pollutant is of particular concern due to high mercury wet deposition rates and high concentrations in local seafood. The objective was to (1) evaluate spatial and seasonal trends along the Mississippi and Alabama coast, and (2) compare active and passive sampling methods for GEM at Grand Bay National Estuarine Research Reserve, an Atmospheric Mercury Network site. We observed higher GEM levels (p < 0.05) in the winter (1.53 ± 0.03 ng m⁻³) compared to other seasons at all sites; with the general pattern being: winter > spring > summer ≈ fall. Average GEM levels (all deployment combined) were highest at Bay St. Louis (1.36 ± 0.05 ng m⁻³), the western-most site nearest the New Orleans metropolitan area, and lowest at Cedar Point (1.07 ± 0.09 ng m⁻³), a coastal marsh with extensive vegetation that can uptake GEM. The MerPAS units compared reasonably well with the established active monitoring system, but gave slightly lower concentrations, except in the winter when the two methods were statistically similar. Both the passive and active sampling methods showed the same seasonal trends and the difference between them for each season was <15%, acceptable for evaluating larger spatial and temporal trends. Overall, this work demonstrates that PASs can provide insight into GEM levels and the factors affecting them along coastal regions.

中文翻译：

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墨西哥北部湾沿线气态元素浓度的被动空气采样与主动采样比较

汞是一种有毒元素，它通过大气散布在全球各地。准确测量空气中汞的浓度有助于了解污染物的来源，分布，循环和趋势。我们部署MerPAS ^®从2019年春季到2020年冬季，每个季节都要进行约4周的被动空气采样器（PAS），以确定墨西哥湾北部沿线六个地点的气态元素汞（GEM）含量，由于污染物的浓度很高，因此特别令人关注汞湿沉降率高，且本地海鲜含量高。目的是（1）评估密西西比州和阿拉巴马州沿岸的空间和季节趋势，以及（2）比较大气汞网络站点Grand Bay National Estuarine Research Reserve的GEM主动和被动采样方法。我们在冬季（1.53±0.03 ng m ^-3）观察到较高的GEM水平（p <0.05））与所有站点的其他季节相比；通常的模式是：冬天>春天>夏天≈秋天。平均创业板水平（所有部署加在一起）在圣路易斯湾最高（1.36±0.05 ng m ^-3），最接近新奥尔良大都市区的最西端，在锡达角最低（1.07±0.09 ng m ^-3）），这片沿海沼泽地植被茂盛，可以吸收GEM。MerPAS装置与已建立的主动监测系统相比相当不错，但浓度略低，除非在冬季这两种方法在统计上相似。被动和主动采样方法都显示出相同的季节趋势，并且每个季节之间的差异小于15％，对于评估较大的时空趋势是可以接受的。总体而言，这项工作表明，PAS可以提供​​对GEM水平及其影响沿海地区的因素的洞察力。