Winter 2021 Resources and Publications

Stability of inorganic and methylated arsenic species in laboratory standards, surface water and groundwater under three different preservation regimes
Stetson, S.J., M.L. Erickson, J. Brenner, E.C. Berquist, C. Kanagy, S. Whitcomb, and C. Lawrence
Applied Geochemistry  2020 

A new study finds that typical arsenic speciation sample preservation and laboratory holding times are ineffective at preserving the reduced arsenic species, As(III), if well water has high iron or high sulfate. If a domestic water treatment system is not designed specifically for As(III) removal, then the system can have poor arsenic removal efficiency. Study results illustrate that the proportion of the oxidized arsenic species, As(V), is overestimated if sample preservation is inadequate or inappropriate, or if speciation sample hold time is long. Overestimating As(V) proportion is an error that can lead to selection of an ineffective arsenic removal technology because As(III) removal can require a pre-oxidation step to oxidize As(III) to As(V); common domestic treatment systems effectively remove As(V).

Precipitation Drives Nitrogen Load Variability in Three Iowa Rivers
Wolf, K.A., S.C. Gupta, and C.J. Rosen
Journal of Hydrology: Regional Studies August 2020

The study evaluated the impact of changes in precipitation, land cover (area under soybean production, Sb), and N fertilizer application (Napp) on variations in streamflow (SF), baseflow (BF) and N-load in the Des Moines, the Iowa, and the Raccoon rivers.

Seasonality and physical drivers of deep chlorophyll layers in Lake Superior, with implications for a rapidly warming lake
Reinl, K.L., R.W. Sterner and  J.A. Austin 
Journal of Great Lakes Research  2020

A deep chlorophyll layer (DCL) is a common feature of many deep, oligotrophic lakes including Lake Superior. Mechanisms generating and maintaining DCLs are variable across lakes, and seasonal patterns and relationships of DCL structure to physical variables are not well described

Photolysis of atrazine: Role of triplet dissolved organic matter and limitations of sensitizers and quenchers
Wu, B., W.A. Arnold and L. Ma 
Water Research, 2020

Atrazine, a widely used herbicide, is susceptible to photolysis. The role of triplet excited states of chromophoric dissolved organic matter (3 CDOM*) in the photolysis of atrazine, however, is not well understood. 

Field investigation of the groundwater contribution to baseflow in an urban stream from a Quaternary aquifer with a leaky base
Moore, T.L. ,J.L. Nieber, J.S. Gulliver and J.A. Magner  
Hydrological Processes  2020

Groundwater contributions to baseflow in Minnehaha Creek, a creek located in a highly developed watershed in the Minneapolis‐St. Paul metropolitan area, from the watershed's Quaternary aquifer were quantified as part of an effort to manage low flow conditions in the creek. Considerable uncertainty exists with any single method used to quantify groundwater contributions to baseflow; therefore, a “weight of evidence” approach in which methods spanning multiple spatial scales was utilized.

Precipitation as the Primary Driver of Variability in River Nitrogen Loads in the Midwest United States 
Baeumler, N.W. and S. C. Gupta
Journal of the American Water Resources Association 2020

Nitrogen (N) losses from agricultural lands in the Midwest United States are contributing to the expansion of the hypoxic zone in the Gulf of Mexico. This study evaluated the importance of inter‐annual variability in precipitation, land cover, and N fertilizer use on NO3 + NO2‐N loads in seven United States Midwestern Rivers using the backward stepwise regression analysis.