Search Results (2)

Characterizing and enumerating microplastics (MPs) have received considerable attention in recent years. Most attention has focused on major waterways and especially in the water column. However, less is known about MPs in smaller lakes and tributaries, as well as in sediments, under both baseflow and storm flow conditions. This study examines the role of an unnamed tributary in transporting microplastics and 6PPD-quinone from a major state highway into a small, salt-impacted lake in Grand Rapids, Michigan. Water and sediment samples were collected over a one-year period to characterize microplastic types, abundances, and seasonal variability, while environmental conditions were monitored to assess storm event impacts. Results confirmed widespread microplastic presence in both habitats, with abundances ranging from 61 to 16,390 MPs/L. Many microplastics were black fragments, often unidentifiable but suspected to be rubber-derived. Storm events significantly increased microplastic transport, particularly in the tributary, where concentrations peaked at 16,390/L during fall stormflow. Concentrations of 6-PPD-quinone were very low overall (<1 ng/L), with spikes during storm events in the tributary (up to 201 ng/L). Sediment analysis revealed higher microplastic abundances in the tributary compared to the lake, with black fragments dominating in both habitats. These findings underscore the critical role of storm-driven runoff in microplastic and chemical transport, highlighting the need for improved road infrastructure design to mitigate environmental impacts on downstream water bodies. Full article

The coastal waters of Hawaii are extremely important for recreation as well as for the health of the marine environment. Non-point source pollution from storm runoff poses a great threat to surface water quality in Hawaii. The State of Hawaii Department of Transportation (HDOT) includes infiltration trenches as a best management practice (BMP) option to reduce pollution caused by stormwater runoff. HDOT guidelines state that the implementation of BMPs is needed to reduce sediment and pollutant loads to streams and the ocean. In this study, the suitability of soils adjacent to highways on Oahu for the siting of infiltration trenches was examined. In addition to field surveys and in-situ tests, laboratory investigations on soil properties, infiltration experiments on undisturbed soil columns, and mathematical modeling of hydraulic functioning of the infiltration trench were conducted. Dissolved metal concentrations in highway stormwater runoff were observed to exceed the groundwater environmental action levels for all heavy metals tested, but the soils had high sorption capacity for these metals. The results of the simulations indicated that all the sampled Oahu soils, with one exception, would require less than two hours to drain a filled hypothetical trench. Therefore, these soils are suitable for construction of infiltration trenches as a possible BMP, even when clogging of soil is considered in the simulation. Full article