Plastic debris in the marine environment has been a growing concern due to its durability in the ocean environment and the potential to have a variety of impacts on marine organisms. Characterization of plastic debris is approached via size as macroplastics (> 5mm), microplastics (5-0.330mm), and nanoplastics (<0.330mm), all of which are located in surface waters, within the water column, on beaches and within seafloor sediments. This is a preliminary study on monitoring plastics debris in marine sediments in Puget Sound with the goal of establish a baseline to determine the concentrations of plastics in marine benthic communities and work to deepen our understanding of the impacts of plastic debris on marine ecosystems throughout the Pacific Northwest. In collaboration with the Washington State Department of Ecology’s, Marine Sediment Monitoring Team (MSMT) and the Puget Sound Ecosystem Monitoring Program (PSEMP), ten samples weighing 200 grams each were processed and analyzed from different stations around Puget Sound. Plastic fibers of various colors and sizes were found throughout the samples as well as white plastic shards; foam and film. After multiple density separations it was determined that Bellingham had the highest concentration of microplastics at 2.48E-03 milligram (mg) of microplastics per gram (g) of sediment. The lowest concentration was found at Sinclair Inlet with 4E-05 (mg/g) of microplastics. Further analysis was performed to determine whether there was a correlation between concentration of microplastics and particle size of sand, silt and clay at each of the ten stations sampled. When comparing percent of sand, silt and clay it was determined that there was no correlation with an R value of 0.04 for sand, 0.01 for silt and 0.1 for clay. Future studies include identifying each plastic fiber using infrared spectroscopy and processing/analyzing samples gathered from past years.

Elevated levels of arsenic have been reported in surface waters of many urban lakes around the Puget Sound as a result of the widespread heavy metal contamination from the late ASARCO smelter in Ruston, Washington. Arsenic is a neurotoxin and carcinogen and a priority Superfund contaminant. However, the mobility and toxicity of arsenic is not fully understood. Physical and biogeochemical processes that lead to elevated arsenic concentrations in the water column and aquatic organisms have been studied well in thermally stratified lakes, but not in periodically mixed (polymictic) oxygenated lakes. This project examines the mobility, bioaccumulation and toxicity of arsenic in four urban lakes in south King County that range from seasonally stratified and oxygen depleted (anoxic) to polymictic and oxygenated (oxic). Specifically, we aim to discover why one of the lakes has elevated levels of arsenic (up to 40 ppb) in surface waters, yet regularly mixes and thus remains oxygenated. Typically, arsenic is only mobilized from sediments when a lake becomes anoxic during stratification. Monthly water quality parameters (temperature, pH, dissolved oxygen, and specific conductivity) were measured and water samples (alkalinity, chlorophyll, sulfide, iron, arsenic, and nutrients) were collected at multiple depths throughout the water column. Plankton samples were also collected using vertical net tows. Water and plankton samples were analyzed for dissolved and total arsenic (after digestion) by ICP-MS. Phytoplankton and zooplankton in polymictic oxic lakes accumulated more arsenic than plankton in thermally stratified lakes, even though aqueous arsenic concentrations were similar between the lakes. This data suggests that arsenic in polymictic urban lakes is not only bioavailable, but has the potential to travel up the food chain. This project aims to create a model for predicting arsenic bioavailability based on physical lake characteristics to better predict possible toxicity and, therefore, has important implications for lake management.

Phytoremediation, a plant-based green technology for cleaning hazardous waste sites, has received increasing attention in recent decades. In the 1980s, early research was successful in identifying hyperaccumulators, plants that are able to take up large quantities of available metal contaminants. Subsequent research has identified plant species as likely candidates for arsenic phytoremediation specifically. The ability of vastly different plant species to successfully take up arsenic suggests that multiple modes for entry into the plant exist. Using a broad approach, this experiment focuses on the possibility for different aquatic plants to take up arsenic from their environments, namely contaminated urban lakes. Identification of plant species with the ability to accumulate higher concentrations of arsenic will lead to possible remediation recommendations. This study focuses on the “zone of deposition” for the former ASARCO smelter, located in Ruston, Washington. We collected emergent, floating, and submergent aquatic plant species from eleven lakes contaminated by aerial emissions from the smelter, which specialized in arsenic extraction from copper ores. After washing, drying and microwave-assisted acid digestion, plant samples were analyzed for total arsenic by ICP-MS. Results revealed floating plant species showed low to moderate arsenic removal with no detection of arsenic removal for nearly all emergent species. On the other hand, our results revealed that the highest concentrations of arsenic were consistently found in the submergent plant species, with concentrations exceeding 300 mg As/kg dry weight in milfoil in one lake. Experimental results indicate that submergent species should be studied further for potential use in phytoremediation of arsenic under field conditions.

Arsenic is a neurotoxin and carcinogen and an important environmental pollutant in the South-Central Puget Sound region. Arsenic emitted by the former ASARCO smelter located in Ruston, Washington, has impacted a large number of lakes in the region via aerial deposition downwind. Previous research has shown that arsenic in some of these lakes is bioavailable, and high concentrations were measured in plankton. In this study we investigate the effect of phosphorus on the uptake of arsenic in Chironomidae larvae, freshwater benthic macro-invertebrates known as “blood worms.” These organisms are commonly found in the low oxygen bottom waters of urban lakes where arsenic concentrations are highest, and they are an important prey species for fish. We created microcosms to mimic two lakes in the region: Lake Killarney (a shallow, eutrophic, high-arsenic lake) and Waughop Lake (a shallow, eutrophic, low-arsenic lake) to examine the impact of phosphorus on arsenic mobility and bioavailability. In previous studies, it was found that a higher concentration of phosphorus, a common component of urban runoff, reduces arsenic uptake by aquatic organisms. Eight replicate experimental microcosms were created for each treatment by half-filling cylinders (5 cm diameter X 10 cm tall) with sediment collected from each lake and then filling the rest with phosphorus-augmented (0, 20, 50 or 100 mg P/L) lake water. After 24 hours of equilibration, five larvae were added to each microcosm. Microcosms were kept in the dark in a cold room at 10°C for approximately one month. Larvae were then removed, rinsed and frozen to euthanize. Samples were split and either dried, digested and analyzed for total arsenic by ICP-MS, or freeze-dried, homogenized and analyzed for metallothionein by HPLC. Our results will be discussed including their implications for arsenic bioavailability in urban lakes impacted by urban runoff.

When Mount St. Helens erupted in May 1980, the landslide and subsequent tsunami deposited about 350,000 acre-feet of pyrolized trees into what was left of Spirit Lake. Today this log mat covers approximately 20% of the lake’s surface. While the ecological importance of large woody debris (LWD) has been well established in streams, there has been little research on the nutrient contributions from LWD to lakes. LWD is often removed from lakes for timber and recreational management. It can contribute nutrients to lakes in several ways: (1) through macroinvertebrate processing of the LWD; (2) through physical abrasion caused by wind; and (3) through the production and shedding of biofilm that establishes on the LWD. The resulting inputs may be a significant source of nutrients for oligotrophic (low nutrient) alpine lakes, leading to greater primary productivity. To measure nutrient inputs to Spirit Lake from the floating log mat, three collection sites, representing areas frequently under the log mat or with no log mat coverage, were instrumented with triplicate sediment traps. Sediment traps were also placed under two ~400 ft2 artificial log mats anchored in place in protected bays in the lake. Total inputs of C, N, and P were measured by CHN analysis or ICP-OES. Results were very location specific. The fixed log mat in Donnybrook Cove produced lower C, N and P than was collected nearby by the traps influenced heavily by the mobile natural log mat. In Duck Bay, a warm, organic-rich area of the lake protected from the natural log mat, C and N were greater under the log mat, while P was greater in open water. By understanding the influence of LWD on nutrient cycling in lakes, this study may influence future management decisions concerning the removal or addition of LWD in aquatic environments.