title: Small plastic debris changes water movement and heat transfer through beach sediments.
abstract: We investigated the physical properties of beaches contaminated with plastic fragments. We compared sediment cores from Hawai'i Island's Kamilo Beach, notable for plastic accumulation, to cores from a nearby beach. Compared to the nearby beach, Kamilo sediments contained more plastics (up to 30.2% by weight), were coarser-grained, and were more permeable (t-test, p<0.0001). 85% of the fragments were polyethylene, and 95% were concentrated in the top 15 cm of the cores. We constructed artificial cores of standardized grain size and varying plastic-to-sediment ratios. Adding plastic significantly increased the permeability (ANOVA, p=0.002), which was partially attributed to the fragments increasing the mean grain size. Sediments with plastic warmed more slowly (16% maximum decrease in thermal diffusivity), and reached lower maximum temperatures (21% maximum increase in heat capacity). These changes have a variety of potential effects on beach organisms, including those with temperature-dependent sex-determination such as sea turtle eggs.
authors.affiliation: Marine Science Department, University of Hawai'i at Hilo, 200 W. Kawili St., Hilo, HI 96720, United States. hcarson@hawaii.edu
authors.forename: Henry S
authors.initials: HS
authors.lastname: Carson
authors.forename: Steven L
authors.initials: SL
authors.lastname: Colbert
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Kaylor
authors.forename: Karla J
authors.initials: KJ
authors.lastname: McDermid
mesh_terms: D001493:Bathing Beaches; D004784:Environmental Monitoring; D004785:Environmental Pollutants / Q000032:analysis*; D019015:Geologic Sediments / Q000032:analysis*; D006254:Hawaii; D006358:Hot Temperature; D009792:Oceans and Seas; D010316:Particle Size; D010539:Permeability; D010969:Plastics / Q000032:analysis*; D016062:Porosity; D014866:Waste Products / Q000032:analysis; D014872:Water Movements
chemical_list: D004785:Environmental Pollutants; D010969:Plastics; D014866:Waste Products