Total chlorine and bromine in soils of Arctic Coastal Plain, northern Alaska 2018 - 2021

These data were generated using X-ray fluorescence to determine total chlorine and bromine concentrations in soils collected from various locations along the Arctic Coastal Plain. This study used soils collected in 2017-2018 specifically for this purpose, as well as archived soils from previous studies in the region, collected from 2008-2011. These data support a study of biological chlorine cycling in the Arctic and its influence on greenhouse gas production. Microbes that can decompose chlorinated organic compounds were once considered relevant only in areas contaminated with pesticides and organic solvents. However, biological chlorine cycling is proving to be widespread in natural environments. Previous studies of biological chlorine cycling were mostly limited to forested ecosystems. This project was the first to demonstrate the importance of the production and degradation of chlorinated organic compounds in Arctic soils. Furthermore, there was little information about the linkages between chlorine cycling and other important ecosystem processes, such as production of carbon dioxide and methane from soils. Species in the genus Dehalococcoides are highly specialized, using hydrogen, acetate, vitamin B12-like compounds, and organic chlorine produced by the surrounding community. We studied which neighbors might produce these essential resources for Dehalococcoides species. We found that Dehalococcoides species are ubiquitous across the Arctic Coastal Plain and are closely associated with a network of microbes that produce or consume hydrogen or acetate, including the most abundant anaerobic bacteria and methanogenic archaea. We also found organic chlorine and microbes that can produce these compounds throughout the study area. Therefore, Dehalococcoides could control the balance between carbon dioxide and methane (a more potent greenhouse gas) when suitable organic chlorine compounds are available to drive hydrogen and acetate uptake, making them unavailable for methane production.

本数据集通过X射线荧光（X-ray fluorescence）技术测定了北极海岸平原（Arctic Coastal Plain）不同采样点土壤中的总氯与总溴浓度。本次研究使用了2017-2018年为该实验专门采集的土壤样品，以及2008-2011年该区域既往研究留存的归档土壤样品。本数据集服务于北极地区生物氯循环及其对温室气体（greenhouse gas）生成影响的相关研究。此前学界曾认为，能够降解氯化有机物的微生物仅存在于农药与有机溶剂污染的区域。但现有研究表明，生物氯循环在自然环境中广泛存在。既往关于生物氯循环的研究大多局限于森林生态系统。本项目首次证实了北极土壤中氯化有机物的生成与降解过程的重要性。此外，此前鲜有关于氯循环与其他关键生态系统过程（如土壤二氧化碳（carbon dioxide）与甲烷（methane）生成）之间关联的研究。脱卤球菌属（Dehalococcoides）微生物具有高度的代谢特异性，可利用周围菌群产生的氢气、乙酸盐、类维生素B12化合物以及有机氯作为营养物质。本研究探究了可为脱卤球菌属微生物提供上述必需营养物质的共生菌群。研究发现，脱卤球菌属微生物广泛分布于北极海岸平原，并与参与氢气或乙酸盐代谢的菌群网络紧密相关，其中包括丰度最高的厌氧细菌与产甲烷古菌（methanogenic archaea）。同时，本研究在全部采样区域均检测到有机氯以及可合成此类物质的微生物。因此，当存在适宜的有机氯化合物以驱动脱卤球菌属微生物摄取氢气与乙酸盐时，该类微生物可调控二氧化碳与甲烷（一种温室效应更强的气体）之间的平衡，使得产甲烷过程无法利用这些营养物质。