Busy summer so far!

Most of May and June were a blur: between gearing up for the Dragonfly Mercury Project, attending and sampling at the 2016 NPS BioBlitz in Washington DC, and presenting at ASLO in Santa Fe, it was an eventful couple of months. I also managed to visit at least six national parks, plus some BLM national recreation areas, in the southeast and southwest. Highlights below. Phew!


NEAEB 2016

It was great to attend NEAEB 2016 right here in Maine! It is the 40th anniversary of this great group of environmental biologists. I enjoyed talking with colleagues new and established, plus had the opportunity to present a poster regarding the Dragonfly Mercury Project and to give a talk regarding mercury in the US EPA TIME lakes (Little Cedar Pond pictured below).

Little Cedar Pond- Stitch

Hot off the press: Extreme events and water chemistry

I was pleased to co-author this paper with Kristin Strock et al., regarding the effects of extreme weather events on our interpretation of long-term patterns in lake geochemistry.

Strock, K. E., Saros, J. E., Nelson, S. J., Birkel, S. D., Kahl, J. S., & McDowell, W. H. (2016). Extreme weather years drive episodic changes in lake chemistry: implications for recovery from sulfate deposition and long-term trends in dissolved organic carbon. Biogeochemistry, 127(2-3), 353-365.


DMP – New USGS Fact Sheet available

The latest update on the Dragonfly Mercury Project is available here.

Dragonfly Mercury Project—A Citizen Science Driven Approach to Linking Surface-Water Chemistry and Landscape Characteristics to Biosentinels on a National Scale – summarizes our findings in 2014, the first year of collaboration among UMaine, USGS, and the NPS.

National Parks: Resource Condition Assessments/Resource Stewardship Strategy

Looking north from the Canon Brook trail.

Looking north from the Canon Brook trail.

I co-authored the recently-published Resource Condition Assessment for Acadia National Park (Natural Resource Report NPS/NRPC/WRD/NRR-2008/069). I am also co-authoring three other such reports: for CACO (Cape Cod Nat’l Seashore), BOHA (Boston Harbor Islands), and SAIR (Saugus Ironworks). These reports seek to compile data, coordinate research findings, and perform new analyses of existing data to assess the current state of the Park’s resources, and determine threats and stressors to the resources. I am also working on a Resource Stewardship Strategy for BOHA, in which we will identify and prioritize science-based strategies for achieving and maintaining desired future conditions for the Park.

Eastern Lakes Survey resampling

Locations of US EPA's ELS-II lakes, plus 11 VT lakes we added for mercury research.

Locations of US EPA's ELS-II lakes, plus 11 VT lakes we added for mercury research.

Mercury (Hg) contamination of surface waters and biota is widespread in the Northeast.  Although watershed processing of Hg is complex, several research projects have identified landscape factors such as wetland extent and forest type, and chemical co-variates such as dissolved organic carbon (DOC), that are correlated with Hg in surface waters.  We hypothesized that watershed characteristics control Hg concentrations in northeastern lakes.  Specifically, we suggested that low-conductivity, wetland-dominated systems with high DOC concentrations will have higher Hg concentrations than high-conductivity higher trophic-level lakes.  We linked landscape statistics calculated using spatial analysis (GIS) to a regional lake data set that contains total Hg (THg, range=0.1-6.42 ng/L), methyl Hg (MeHg, range=<0.02-0.76 ng/L), and full ion chemistry.  The lake data set was the EPA Eastern Lake Survey II statistical population of lakes in the Northeastern U.S. plus 11 Vermont LTM lakes, all sampled within a single summer index period during 2004.  These same lakes were sampled during 1984 and 1986 by US EPA (though not for Hg). We developed and compared four statistical models predicting THg and MeHg from these sets of variables. 

Funding: Northeastern States Research Cooperative, 2007-2008, Evaluating spatial patterns in mercury and methyl mercury in northeastern lakes: landscape setting, chemical climate, and human influences (S. Nelson, J.S. Kahl, D. Krabbenhoft, N. Kamman)

I also participated in a project that assessed major ion chemistry and pH, plus zooplankton community structure and composition (with funding from US EPA), in the same set of lakes, during the same sampling campaign.

Funding: U.S. Department of Agriculture/Northeastern States Research Cooperative, 2003, Evaluating scope and trends for the base cation decline in surface waters of the northeastern US (J.S. Kahl, J. Stoddard, R. Church, S. Nelson, L. Rustad, K. Webster, I. Fernandez, R. Stemberger)

Report: Rosfjord, C.H., J.S. Kahl, K. Webster, S. Nelson, I. Fernandez, L. Rustad, R. Stemberger, 2006. Final Report: Acidic deposition-relevant changes in lake chemistry in the EPA Eastern Lake Survey, 1984-2004. Submitted to USDA NSRC.