Lead geochemistry of sediments in Galveston Bay, Texas

The geochemical behavior of Pb in terrestrial and coastal water systems significantly influences Pb biogeochemical cycling and pollutant exchange at the land-sea continuum. An ideal case study of Pb environmental geochemistry is Galveston Bay, an anthropogenic estuary exposed to industrial runoff, wastewater and shipping vessel spills but also fed by natural rivers.
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Lead geochemistry of sediments in Galveston Bay, Texas Environmental Advances 4 (2021) 100057 Contents lists available at ScienceDirect Environmental Advances journal homepage: www.elsevier.com/locate/envadvLead geochemistry of sediments in Galveston Bay, TexasAmanda M. Lopez a,∗, Alan D. Brandon a, Frank C. Ramos b, Jessica N. Fitzsimmons c,Timothy M. Dellapenna d, Hannah M. Adams ca 3507 Cullen Boulevard, Room 312 Department of Earth and Atmospheric Sciences, University of Houston, Houston, TX 77004 USAb 1255 N. Horseshoe Drive MSC3AB Department of Geological Sciences, New Mexico State University Las Cruces, NM 88003 USAc 3146 TAMU, O&M 403A Department of Oceanography, Texas A&M University, College Station, TX 77843 USAd 1001 Texas Clipper Rd Bldg 3029, Office 341 Department of Marine Sciences/Department of Oceanography, Texas A&M University at Galveston, Galveston, TX77553 USAa r t i c l e i n f o a b s t r a c tKeywords: The geochemical behavior of Pb in terrestrial and coastal water systems significantly influences Pb biogeochemi-Marine biogeochemistry cal cycling and pollutant exchange at the land-sea continuum. An ideal case study of Pb environmental geochem-Lead isotope fingerprinting istry is Galveston Bay, an anthropogenic estuary exposed to industrial runoff, wastewater and shipping vessel spills but also fed by natural rivers. Here, sediments from Galveston Bay were measured for Pb isotope ratios and abundances to constrain Pb sources and fluxes and understand Pb pollution history in the bay. Lead isotopes have been established as source tracers of environmental pollution and allow Pb sources to be reliably fingerprinted and identified. Sediments were leached to distinguish authigenic sediment coatings from lithogenic residual sedi- ments, in addition to bulk sediment digestions. Total Pb concentrations ranged from 1.76 μg/g–29.19 μg/g in bulk digests, which are below federal toxicity thresholds and aligns well with prior measurements of Pb in Galveston Bay sediments in the 20th century. Lead concentrations are spatially constrained by flocculation in eastern bay ar- eas where the Trinity River enters the bay and positively temporally correlated to freshwater discharge. Sediment 206 Pb/204 Pb, 207 Pb/204 Pb, and 208 Pb/204 Pb ratios range between 18.338–19.777±0.002, 15.557–15.755±0.002 and 37.913–43.340±0.005, respectively, and were used in an advanced Bayesian isotope mixing model to iden- tify Pb sources in the Galveston Bay sediment fractions analyzed. Anthropogenic sources supply approximately 83.8%, 16.6% and 25.5% of Pb to the leachates, residues and bulk sediments, respectively. This study showcases the importance of estuaries in moderating terrestrial and marine Pb distribution and provides insight for future contaminant studies in Galveston Bay and other estuarine systems around the world. MAIN FINDINGS Pb isotope ratio and abundance measurements of Galveston Bay sediments demonstrate significant anthropogenic Pb inputs to the estuary despite low Pb levels.Introduction water column, and the biota (Turner and Millward, 2002). Previous studies demonstrate that aqueous Pb is largely scavenged by particles The biogeochemical cycle of lead (Pb) has been greatly influenced by and removed to sediments (Elbaz-Poulichet et al., 1984; Ip et al., 2007;humans such that up to 95% of Pb in the biosphere is estimated to be an- Marsan et al., 2014). In this way, Pb and other particle-reactive heavythropogenic (Smith and Flegal, 1995). Once emitted, Pb can persist and metals are “naturally filtered” out of water systems before reaching theaccumulate in the natural environment (Wright and Welbourn, 2002). ocean. Lead in sediments accrue; thus, sediment cores become recordsEffects of Pb exposure include a variety of detrimental health issues, of Pb loadings at a given location over time.most notably neurotoxicity (Tchounwou et al., 2012). Lead geochem- Datasets constraining Pb fluxes, abundances, sources and mobilityistry of rivers and coastal environments plays a significant role in the between sources and sinks are necessary to improve the understandingbiogeochemical cycling of Pb and pollutant delivery at the land-sea in- of Pb bioge ...