Plastic-derived contaminants in Aleutian Archipelago seabirds with varied foraging strategies.

Phthalates, plastic-derived contaminants, are of increasing global concern. This study quantified phthalates in seabirds collected across >1700 km of the Aleutian Islands, Alaska, and contributes to a body of knowledge on plastic contaminants in marine wildlife. We measured six phthalate congeners in seabirds representing ten species and four feeding guilds. Phthalates were detected in 100% of specimens (n = 115), but varied among individuals (3.64-539.64 ng/g). DEHP and DBP occurred at an order of magnitude higher than other congeners. Total phthalates did not vary geographically, but differed among feeding guilds, with significantly higher concentrations in diving plankton-feeders compared to others. Plastic particles were detected in 36.5% of randomly subsampled seabird stomachs (n = 74), suggesting plastic ingestion as a potential route of phthalate exposure. Our findings suggest feeding behavior could influence exposure risk for seabirds and lend further evidence to the ubiquity of plastic pollutants in marine ecosystems.

Predicting risk of trace element pollution from municipal roads using site-specific soil samples and remotely sensed data.

Studies of environmental processes exhibit spatial variation within data sets. The ability to derive predictions of risk from field data is a critical path forward in understanding the data and applying the information to land and resource management. Thanks to recent advances in predictive modeling, open source software, and computing, the power to do this is within grasp. This article provides an example of how we predicted relative trace element pollution risk from roads across a region by combining site specific trace element data in soils with regional land cover and planning information in a predictive model framework. In the Kenai Peninsula of Alaska, we sampled 36 sites (191 soil samples) adjacent to roads for trace elements. We then combined this site specific data with freely-available land cover and urban planning data to derive a predictive model of landscape scale environmental risk. We used six different model algorithms to analyze the dataset, comparing these in terms of their predictive abilities and the variables identified as important. Based on comparable predictive abilities (mean R2 from 30 to 35% and mean root mean square error from 65 to 68%), we averaged all six model outputs to predict relative levels of trace element deposition in soils-given the road surface, traffic volume, sample distance from the road, land cover category, and impervious surface percentage. Mapped predictions of environmental risk from toxic trace element pollution can show land managers and transportation planners where to prioritize road renewal or maintenance by each road segment's relative environmental and human health risk.

Tissue Phthalate Levels Correlate With Changes in Immune Gene Expression in a Population of Juvenile Wild Salmon.

Phthalates have detrimental effects on health and have been shown to dysregulate the immune system of mammals, birds, and fish. We recently reported that di(2-ethylhexyl) phthalate exposure reduces the abundance and inhibits the proliferation of rainbow trout (Oncorhynchus mykiss) IgM(+) B lymphocytes and expression of secreted immunoglobulin heavy-chain mu transcripts in an in vitro culture system. We proposed that phthalates act as immunomodulators by modifying the normal B cell-activation pathways by accelerating B cell differentiation while suppressing plasmablast expansion, thus resulting in fewer IgM-secreting plasma cells. This hypothesis was tested here in an in vivo field study of juvenile Dolly Varden (Salvelinus malma) from a plastic-polluted lake in the Gulf of Alaska. Fish tissues were analyzed for both phthalate levels using liquid chromatography-coupled tandem mass spectrometry and for changes in immune gene expression using reverse transcriptase-real time polymerase chain reaction. Results showed that fish with higher tissue levels of di(2-ethylhexyl) phthalate, di(n-butyl) phthalate, and/or dimethyl phthalate expressed significantly fewer secreted and membrane-bound immunoglobulin heavy-chain mu and Blimp1 transcripts in their hematopoietic tissue. This suggests that in vivo uptake of phthalates in fish changes the expression of B cell-specific genes. Chronic exposure to phthalates likely dysregulates normal B-lymphoid development and antibody responses in salmonids and may increase susceptibility to infection. Given the conserved nature of B-lineage cells in vertebrate animals, other marine species may be similarly affected by chronic phthalate exposure.

Benzotriazole Enrichment in Snowmelt Discharge Emanating from Engineered Snow Storage Facilities.

Snowpacks in urban environments can retain a high load of anthropogenic contaminants that, upon melting, can deliver concentrated contaminant pulses into the aquatic environment. In climates with an extended period of snowfall accumulation, such as in Anchorage, Alaska, contaminant amplification within meltwater may affect aquatic ecosystem health. A spatiotemporal study of benzotriazoles on snow, meltwater and soils was performed in association with three urban snow disposal facilities. Benzotriazole elution from engineered snow disposal sites behaved similarly to inorganic salt and dissolved organic carbon (DOC) during the initial melt period, with maximum concentrations between 2.23-7.39 µg/L; similar enrichment was observed in creeks. Assays of disposal site soils revealed the presence of tolytriazole. Furthermore, using fluorescence spectroscopy and PARAFAC analysis, a modeled component representative of benzotriazoles was identified, a possible indicator of anthropogenic input rather than a unique indicator for benzotriazole compounds.

Field degradation of aminopyralid and clopyralid and microbial community response to application in Alaskan soils.

High-latitude regions experience unique conditions that affect the degradation rate of agrochemicals in the environment. In the present study, data collected from 2 field sites in Alaska, USA (Palmer and Delta) were used to generate a kinetic model for aminopyralid and clopyralid degradation and to describe the microbial community response to herbicide exposure. Field plots were sprayed with herbicides and sampled over the summer of 2013. Quantification was performed via liquid chromatrography/tandem mass spectrometry, and microbial diversity was assessed via next-generation sequencing of bacterial 16S ribosomal ribonucleic acid (rRNA) genes. Both compounds degraded rapidly via pseudo-first-order degradation kinetics between 0 d and 28 d (t1/2 = 9.1-23.0 d), and then degradation slowed thereafter through 90 d. Aminopyralid concentration was 0.048 µg/g to 0.120 µg/g at 90 d post application, whereas clopyralid degraded rapidly at the Palmer site but was recovered in Delta soil at a concentraction of 0.046 µg/g. Microbial community diversity was moderately impacted by herbicide treatment, with the effect more pronounced at Delta. These data predict reductions in crop yield when sensitive plants (potatoes, tomatoes, marigolds, etc.) are rotated onto treated fields. Agricultural operations in high-latitude regions, both commercial and residential, rely heavily on cultivation of such crops and care must be taken when rotating.

Di(2-ethylhexyl) phthalate inhibits B cell proliferation and reduces the abundance of IgM-secreting cells in cultured immune tissues of the rainbow trout.

Plasticizer di(2-ethylhexyl) phthalate (DEHP) and its active metabolite MEHP have important immunotoxic effects in mammalian species, including inhibition of cell proliferation, inflammation inhibition, lowering of the antibody response, and apoptosis. Virtually nothing is known about the potential detrimental effects of DEHP/MEHP on the teleost immune system, although phthalates are a likely threat to fish health. Here we investigated whether short-term in vitro DEHP exposure would affect B lineage cells in the rainbow trout, using cultured immune tissues. Cell culture conditions, evidence of cellular incorporation of DEHP, and possible effects of DEHP on immune genes were first established using the mouse pre-B cell line PD31 and data confirmed a dose-dependent cellular uptake of DEHP using liquid chromatography-coupled ion trap mass spectrometry. Effects of in vitro DEHP exposure on trout B cell proliferation were tested by flow cytometry. Significant, dose-dependent inhibition was evident in both anterior and posterior kidney cultures after 24 h exposure to ≥4 µM DEHP. DEHP-induced cell death was not significant for the range of DEHP tested. Further, the abundance of IgM-secreting plasmablasts and plasma cells was significantly reduced after in vitro exposure of ≥16 µM DEHP for 2 or 7 days. Finally, in vitro DEHP exposure significantly lowered the levels of secreted HCmu transcripts in a dose-dependent manner. B lineage cells from posterior kidney were more sensitive to effects of in vitro DEHP exposure than those from anterior kidney. Together, the data support a model where DEHP modifies the normal B cell activation pathways in rainbow trout, promoting B cell differentiation while suppressing plasmablast expansion, resulting in fewer IgM-secreting plasma cells. Insufficient production of protective antibody make fish more susceptible to infection, and increases their risk for disease and mortality in polluted waters.

Diversity and potential sources of microbiota associated with snow on western portions of the Greenland Ice Sheet.

Snow overlays the majority of the Greenland Ice Sheet (GrIS). However, there is very little information available on the microbiological assemblages that are associated with this vast and climate-sensitive landscape. In this study, the structure and diversity of snow microbial assemblages from two regions of the western GrIS ice margin were investigated through the sequencing of small subunit ribosomal RNA genes. The origins of the microbiota were investigated by examining correlations to molecular data obtained from marine, soil, freshwater and atmospheric environments and geochemical analytes measured in the snow. Snow was found to contain a diverse assemblage of bacteria (Alphaproteobacteria, Betaproteobacteria and Gammaproteobacteria) and eukarya (Alveolata, Fungi, Stramenopiles and Chloroplastida). Phylotypes related to archaeal Thaumarchaeota and Euryarchaeota phyla were also identified. The snow microbial assemblages were more similar to communities characterized in soil than to those documented in marine ecosystems. Despite this, the chemical composition of snow samples was consistent with a marine contribution, and strong correlations existed between bacterial beta diversity and the concentration of Na(+) and Cl(-) . These results suggest that surface snow from western regions of Greenland contains exogenous microbiota that were likely aerosolized from more distant soil sources, transported in the atmosphere and co-precipitated with the snow.

Molecular and biogeochemical evidence for methane cycling beneath the western margin of the Greenland Ice Sheet.

Microbial processes that mineralize organic carbon and enhance solute production at the bed of polar ice sheets could be of a magnitude sufficient to affect global elemental cycles. To investigate the biogeochemistry of a polar subglacial microbial ecosystem, we analyzed water discharged during the summer of 2012 and 2013 from Russell Glacier, a land-terminating outlet glacier at the western margin of the Greenland Ice Sheet. The molecular data implied that the most abundant and active component of the subglacial microbial community at these marginal locations were bacteria within the order Methylococcales (59-100% of reverse transcribed (RT)-rRNA sequences). mRNA transcripts of the particulate methane monooxygenase (pmoA) from these taxa were also detected, confirming that methanotrophic bacteria were functional members of this subglacial ecosystem. Dissolved methane ranged between 2.7 and 83 µM in the subglacial waters analyzed, and the concentration was inversely correlated with dissolved oxygen while positively correlated with electrical conductivity. Subglacial microbial methane production was supported by δ(13)C-CH4 values between -64‰ and -62‰ together with the recovery of RT-rRNA sequences that classified within the Methanosarcinales and Methanomicrobiales. Under aerobic conditions, >98% of the methane in the subglacial water was consumed over ∼30 days incubation at ∼4 °C and rates of methane oxidation were estimated at 0.32 µM per day. Our results support the occurrence of active methane cycling beneath this region of the Greenland Ice Sheet, where microbial communities poised in oxygenated subglacial drainage channels could serve as significant methane sinks.

Perchlorate trophic transfer increases tissue concentrations above ambient water exposure alone in a predatory fish.

This study examined effects of varying concentrations of the environmental contaminant perchlorate in northern pike (Esox lucius) based on exposure in water and/or from prey (threespine stickleback, Gasterosteus aculeatus). Routes of exposure to pike were through contaminated water at 0, 10, or 100 mg/L perchlorate for 49 d and/or through feeding, 1 per day over 14 d, sticklebacks that were previously maintained in water at 0, 10, or 100 mg/L perchlorate. Both water and food significantly contributed to pike tissue concentrations of perchlorate as compared to controls, but, as expected for a water-soluble contaminant, perchlorate did not biomagnify from prey to predatory fish. Pike gastrointestinal tissue retained significantly more perchlorate than other tissues combined. Route of exposure and concentration of perchlorate in various media are important to consider in risk assessment when evaluating uptake and tissue concentration of perchlorate because significantly higher tissue concentrations may result from combined prey and water exposures than from prey or water exposures alone in a concentration-dependent manner.

Arsenic speciation and mobility in surface water at Lucky Shot Gold Mine, Alaska.

Historical mining in Alaska has created a legacy of approximately 6,830 abandoned mine sites which include adits, tailing piles and contaminated land that continue to impact surface and groundwater quality through run-off and leaching of potentially toxic metals, especially arsenic (As). One such site is the Lucky Shot Gold Mine in Hatcher Pass, south-central Alaska, which operated from 1920 until 1942, mining gold-bearing quartz veins hosted in a Cretaceous tonalite intrusion. Arsenopyrite (FeAsS) and pyrite (FeS(2)) present in the quartz veins contribute to elevated As levels in water draining, abandoned mine adits. As future underground mining at Lucky Shot may further adversely impact water quality, baseline geochemical studies were undertaken to assess As mobility in the vicinity of the mine adits. Water samples were collected from streams, adits and boreholes around the mine and analysed for major and minor elements using inductively coupled plasma-mass spectrometry (ICP-MS) and for anions by ion chromatography (IC). Arsenic species separation was performed in the field to determine the ratio of inorganic As(III)/As(V) using anion-exchange chromatography, following established methods. It was determined that water draining the adits had elevated levels of As roughly seventy times the United States Environmental Protection Agency Drinking Water Standard of 10 µg L(-1), although this was rapidly diluted downstream in Craigie Creek to <2 µg L(-1). Adit and surface water pH was circum-neutral and displayed no characteristics of acid mine drainage. Despite being well oxygenated, As(III) is the dominant As species in adit water, accounting for close to 100 % of total As. The proportion of As(V) increases downstream of the adits, as some As(III) is oxidized, but the speciation enhances arsenic mobility at the site. The δ(18)O measurements indicate that the water in the system has a short residence time as it is very similar to meteoric water, supporting the observation that the predominance of As(III) in adit water results from the lack of thermodynamical equilibrium being attained and preferential absorbance of As(V).

Characterization of water dynamics in frozen soils by solid-state deuteron NMR.

The presence of unfrozen water in soils at sub-freezing temperatures is important for biogeochemical processes as well as for the genesis of landscapes and survival of life. While several mechanisms can lead to the existence of liquid water at sub-freezing temperatures, this work focuses on the dynamical (entropic) contribution stemming from motions of water molecules at water-soil or water-ice interfaces. We demonstrate the utility of solid-state (2)H NMR methods for characterization of water dynamics in soils on various time scales. Using a sample from McMurdo Dry Valleys, Antarctica, we show the existence of dynamics spanning a milliseconds to picoseconds time scale range. Computational modeling allows for a quantitative description of the dynamics, which involves models such as an exchange between bound and free water, and changes in effective viscosity of water in the soil matrix.