Mercury in soil, vegetation, and organisms across Niwot Ridge, Saddle Catchment, and Green Lakes Valley, 2020 - 2023.

This dataset includes soil, vegetation, water, atmospheric
deposition, litterfall, incubation, and organism data from the Niwot
Ridge, Saddle Catchment, and Green Lakes Valley collected during
2020 and 2021 to investigate the storage, transformation, and
mobilization of mercury in the Colorado Rocky Mountains. During Summer 2020, we collected soil cores (10cm x 3cm) across
vegetation plant functional groups in wet meadows, moist meadows,
dry meadows, krummholz, subalpine forest, shrub areas, as well as at
the inlet and outlet of the Green Lakes in Green Lakes Valley. At
each of these sites, we collected leaves from forbs, graminoids, and
shrubs, as well as litter (and moss if present). For organisms, we
sampled pika hairs from nine different pika trapped on the West
Knoll, in addition to caddisfly pupae found in wet meadows in the
Saddle Catchment. We analyzed hairs from weasel specimens at the CU
Boulder Natural History Museum that were trapped either on, or near,
Niwot Ridge. Finally, we analyzed dust samples collected by Dr. Ruth
Heindel in 2018 and 2019 on Niwot Ridge. We analyzed soil samples
for organic matter; pH; water content; percent carbon, nitrogen, and
sulfur; stable carbon, nitrogen, and sulfur isotopes; total mercury;
and methylmercury. We analyzed vegetation samples for percent
carbon, nitrogen, and sulfur; stable carbon, nitrogen, and sulfur
isotopes; total mercury; and methylmercury. We analyzed organism and
dust samples for total mercury and methylmercury. During Spring 2021, we collected composite snow cores from 4 sites
in the Saddle region and 3 sites in the subalpine forest. We
measured snow depth and density to calculate snow water equivalent
and then analyzed these samples for sulfate, nitrate, chloride,
dissolved organic carbon, dissolved organic nitrogen, total mercury,
and methylmercury concentrations. During Summer 2021, we collected soil cores (10cm x 3cm) every other
week from June through September from a solifluction lobe, alpine
wet meadow, shrubby riparian zone, alpine dry meadow, and subalpine
wetland inlet and outlet that we analyzed for the same constituents
as for the Summer 2020 soil samples. We also sampled the overlying
water from the six sites (when standing water was present) which we
measured for dissolved oxygen, conductivity, pH, temperature, total
dissolved solids, and nitrate in situ using a YSI probe, as well as
analyzed for sulfate, nitrate, chloride, dissolved organic carbon,
dissolved organic nitrogen, total mercury, and methylmercury
concentrations. We also collected weekly surface grab samples from
the Saddle Stream and Como Creek June – September which we measured
for the same constituents as the overlying water samples. For the
organism sampling, we collected grasshoppers and caddisfly pupae
from the Saddle region of Niwot Ridge, as well as fish from Green
Lakes 1-3 and Lake Albion in the Green Lakes Valley. We collected a
composite wet atmospheric deposition sample in collaboration with
the National Atmospheric Deposition Network and a composite dry
atmospheric deposition sample in collaboration with Dr Janice
Brahney from the Saddle region at Niwot Ridge which we analyzed for
total mercury and methylmercury concentrations. In addition to the above sampling, we also collected soils and
vegetation from along an elevation gradient in Boulder County during
Summers 2021 and 2022 that included Niwot Ridge as the alpine
location and C1 as the subalpine location, as well as Montane
(Gordon Gulch), Foothills (Betasso), and Plains (Boulder Open
Space). We collected 4 replicate soil cores (10cm x 3cm) at each
site which we analyzed for organic matter; water content; percent
carbon, nitrogen, and sulfur; total mercury; and methylmercury. At
each of these sites, we also collected leaves from forbs,
graminoids, shrubs, deciduous, and coniferous species which we
analyzed for percent carbon, nitrogen, and sulfur, as well as total
mercury. During Summer 2022, we collected litterfall samples from the along
the same Boulder County elevation gradient. Four replicate samples
were collected monthly in 0.44m^2 laundry baskets strapped to trees
from June – October. Litterfall samples were dried, weighed, and
analyzed for total mercury concentrations. We conducted an incubation experiment during Summer 2022 with soils
from alpine solifluction lobes, subalpine wetlands, and alpine dry
meadow regions. Samples were spiked with inorganic mercury isotope
201 and mercury methylation rates were calculated based on the
production of excess methylmercury 201. Base mercury methylation
rates were determined with both pore water and precipitation spiking
solutions, as well as for sulfate additions (50, 100, and 200 uM)
for the subalpine wetland soils.

本数据集包含2020至2021年间于尼沃特岭（Niwot Ridge）、鞍流域（Saddle Catchment）与绿湖谷（Green Lakes Valley）采集的土壤、植被、水体、大气沉降、凋落物、培养实验及生物样品，旨在探究科罗拉多落基山脉地区汞的储存、转化与迁移过程。

2020年夏季，研究团队在湿草甸、湿干草甸、干草甸、矮曲林（krummholz）、亚高山森林、灌丛区域，以及绿湖谷内绿湖的入水口与出水口，按植被功能群采集了规格为10cm×3cm的土壤岩芯。在每个采样点，还采集了非禾本科草本植物（forbs）、禾本科草本植物（graminoids）与灌丛的叶片，以及凋落物（若有苔藓则一并采集）。生物样品方面，除在西诺尔（West Knoll）捕获的9只鼠兔的毛发外，还采集了鞍流域湿草甸中的石蛾蛹。此外，对科罗拉多大学博尔德分校自然历史博物馆馆藏的、于尼沃特岭及其周边捕获的鼬类标本毛发进行了分析。最后，对露丝·海因德尔（Ruth Heindel）博士2018至2019年在尼沃特岭采集的粉尘样品开展了检测。本研究对土壤样品的检测指标包括：有机质、pH值、含水量、碳/氮/硫百分含量、稳定碳/氮/硫同位素、总汞与甲基汞；对植被样品的检测指标包括：碳/氮/硫百分含量、稳定碳/氮/硫同位素、总汞与甲基汞；对生物与粉尘样品的检测指标包括：总汞与甲基汞。

2021年春季，研究团队在鞍区域的4个采样点与亚高山森林的3个采样点采集了复合雪芯。通过测量雪深与雪密度计算雪水当量，随后检测了样品中的硫酸盐、硝酸盐、氯化物、溶解性有机碳、溶解性有机氮、总汞与甲基汞浓度。

2021年夏季，研究团队于6月至9月每隔一周，在冻融泥流舌（solifluction lobe）、高山湿草甸、灌丛河岸带、高山干草甸以及亚高山湿地的入水口与出水口采集规格为10cm×3cm的土壤岩芯，检测指标与2020年夏季土壤样品一致。在存在积水的上述6个采样点，研究团队还采集了上层水体，使用YSI探针原位测定溶解氧、电导率、pH值、温度、总溶解固体与硝酸盐浓度，并检测其中的硫酸盐、硝酸盐、氯化物、溶解性有机碳、溶解性有机氮、总汞与甲基汞浓度。此外，于6月至9月每周从鞍溪与科莫溪采集表层瞬时水样，检测指标与上层水体样品一致。生物采样方面，在尼沃特岭的鞍区域采集了蝗虫与石蛾蛹，同时在绿湖谷的1-3号绿湖与奥尔比恩湖采集了鱼类样品。研究团队与国家大气沉降网络合作采集了复合湿性大气沉降样品，与珍妮丝·布拉尼（Janice Brahney）博士合作在尼沃特岭的鞍区域采集了复合干性大气沉降样品，两类样品均用于检测总汞与甲基汞浓度。

除上述采样外，研究团队还于2021与2022年夏季在博尔德县的海拔梯度样带采集了土壤与植被样品，该样带包含作为高山点位的尼沃特岭、作为亚高山点位的C1，以及山地（戈登峡谷）、山麓（贝塔索）与平原（博尔德开放空间）区域。在每个采样点采集4个重复的10cm×3cm土壤岩芯，检测指标包括有机质、含水量、碳/氮/硫百分含量、总汞与甲基汞。在每个采样点，还采集了非禾本科草本、禾本科草本、灌丛、落叶与针叶树种的叶片，检测指标包括碳/氮/硫百分含量与总汞。

2022年夏季，研究团队在博尔德县同一海拔梯度样带采集凋落物样品。于6月至10月每月使用固定于树干上的0.44m²洗衣篮采集4个重复样品。凋落物样品经干燥、称重后，检测其总汞浓度。

2022年夏季，研究团队使用来自高山冻融泥流舌区、亚高山湿地与高山干草甸区域的土壤开展了培养实验。向样品中添加无机汞同位素201，基于过量甲基汞201的生成量计算汞甲基化速率。通过孔隙水与降水两种添加溶液，以及向亚高山湿地土壤添加50、100与200 μM硫酸盐的方式，分别测定基础汞甲基化速率。