Hydrologist
New England Water Science Center
Email:
mlombard@usgs.gov
Office Phone:
603-226-7816
Fax:
603-226-7894
ORCID:
0000-0001-5924-6556
Location
331 Commerce Way
331 Commerce Way
Suite #2
Pembroke
, NH
03275-3718
US
Supervisor:
Joseph D Ayotte
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This data release contains data used to develop models and maps that estimate the probabilities of exceeding various thresholds of arsenic concentrations in private domestic wells throughout the conterminous United States. Three boosted regression tree (BRT) models were developed separately to estimate the probability of private well arsenic concentrations exceeding 1, 5, and 10 micrograms per liter (µg/L). A random forest (RF) model was developed to estimate the most probable arsenic concentration category (≤5, >5 to ≤10, or >10 µg/L). The models use arsenic concentration data from private domestic wells located throughout the conterminous United States and independent variables that are available as geospatial...
Categories: Data;
Tags: Environmental Health,
Geochemistry,
Hydrology,
USGS Science Data Catalog (SDC),
United States, All tags...
Water Quality,
arsenic,
drinking water use,
environment,
environmental health (human),
geoscientificInformation,
groundwater quality,
health,
machine learning models,
private wells, Fewer tags
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Groundwater samples from public and private drinking water wells throughout the state of New Hampshire were analyzed for total Arsenic (As). Samples were collected after pH, specific conductivity, dissolved oxygen, and water temperature had met stabilization criteria as outlined in the USGS National Field Manual (United States Geological Survey 2005). The As analyses were carried out in the geochemistry laboratory in the Department of Earth Sciences at the University of New Hampshire (UNH). Not including replicate analysis, a total of 527 samples were analyzed via a hydride generator-inductively coupled plasma mass spectrometer (HG-ICP-MS) using a Cetac HGX-200 plumbed into a Nu Instruments Attom high-resolution...
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This data release contains a table of measured arsenic concentrations and associated model input variables used to test existing multivariate logistic regression models that predict the probabilities of arsenic concentrations exceeding threshold values of 1, 5, and 10 micrograms per liter in bedrock aquifers of New Hampshire. Location data are censored to the county level.
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This data release contains data used to develop models and maps that estimate the occurrence of lithium in groundwater used as drinking water throughout the conterminous United States. An extreme gradient boosting model was developed to estimate the most probable lithium concentration category (≤4, >4 to ≤10, >10 to ≤30, or >30 µg/L). The model uses lithium concentration data from wells located throughout the conterminous United States and predictor variables that are available as geospatial data. The model is included in this data release in the zipped folder named Model_Archive and was used to produce maps that are also included in this data release. The model input data (predictor variables) that were used to...
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This dataset contains annual flow metrics quantifying drought and low streamflows for USGS GAGES-2 gages in the contiguous U.S. satisfying data completeness checks for the periods 1921-2020, 1951-2020, and 1981-2020. The dataset also contains annual climate variables from the USGS Monthly Water Balance Model (MWBM). The dataset provides trend analysis outputs for annual drought and low flow metrics for the periods 1921-2020, 1951-2020, and 1981-2020. Finally, we include six R language code files that were used to create the values included in this release as summarized in the process step section.
Categories: Data;
Tags: NCCWSC,
USGS Science Data Catalog (SDC),
USGS:618460d9d34ec04fc9c00082,
United States,
biota, All tags...
droughts,
streamflow,
surface water (non-marine),
water supply and demand,
watershed management, Fewer tags
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