Mercury contamination of the fish community of a semi‐arid and arid river system: Spatial variation and the influence of environmental gradients

Abstract

Mercury (Hg) contamination of aquatic ecosystems is a global environmental problem. Data are abundant on Hg contamination and factors that affect its bioaccumulation in lake communities, but comparatively little information on riverine ecosystems exists. The present study examines fish Hg concentrations of the Lower Rio Grande/Rio Bravo del Norte drainage, Texas, USA and several of its major tributaries in order to assess whether spatial variation occurs in fish Hg concentrations in the drainage and if patterns of Hg contamination of fish are related to gradients in environmental factors thought to affect Hg concentrations in fish communities. Fish, invertebrates, sediments, and water quality parameters were sampled at 12 sites along the lower Rio Grande/Rio Bravo del Norte drainage multiple times over a one-year period. Spatial variation was significant in fish Hg concentrations when fish were grouped by literature-defined trophic guilds or as stable isotope-defined trophic levels, with highest concentrations found in the Big Bend region of the drainage. Mercury in fish in most trophic guilds and trophic levels were positively related to environmental factors thought to affect Hg in fish, including water column dissolved organic carbon (DOC) and sediment Hg concentrations. It is likely that fish Hg concentrations in the Big Bend region are relatively high because this section of the river has abundant geologic Hg sources and environmental conditions which may make it sensitive to Hg inputs (i.e., high DOC, variable water levels). Results from the present study indicate that Hg contamination of the Rio Grande/Rio Bravo del Norte has substantial implications for management and protection of native small-bodied obligate riverine fish, many of which are imperiled.

Mobility and contamination assessment of mercury in coal fly ash, atmospheric deposition, and soil collected from Tianjin, China

“…The Hg working solutions were obtained by dilution with 5% (v/v) HNO 3 and prepared daily before use from stock solutions of standard HgCl 2 (GSB 07-1274-2000). Working solutions to generate a standard curve were prepared daily from the stock solutions by stepwise dilution of the Hg standard solution immediately before analysis (0 mg/L, 1.25 mg/L, 2.5 mg/L, 5 mg/L, and 10 mg/L).…”

“…Since the outbreak of Minamata disease in the 1950 s, Hg has been known to represent both a potential and an actual threat to human and animal health [2,3]. Many studies conducted worldwide have shown that Hg is a highly hazardous pollutant, and it has been shown to exert a wide variety of adverse effects on human health and the environment [4,5].…”

Ultrasensitive Quantum Dot Fluorescence quenching Assay for Selective Detection of Mercury Ions in Drinking Water

“…Cell toxicity of mercury has been intensively studied by environmental and biological communities over the years. Its low concentration but high toxicity makes mercury contamination a global environmental problem456. Therefore, ultrasensitive determination of mercury is essential to provide evaluation index of mercury ions in aqueous environment.…”

Spatial variability in the speciation and bioaccumulation of mercury in an arid subtropical reservoir ecosystem

“…The Terlingua district was the third largest mercury mining district in the United States, but the mines have been inactive since 1973 [17]. Although Gray et al [17] concluded that little movement of contaminated sediments occurred from the Terlingua mining district, flash flood events are a common characteristic of arid stream systems [39], and river Hg sediment concentrations in both the Rio Grande and Pecos River watersheds have occasionally surpassed the Texas Commission on Environmental Quality screening level of 100 ng/g (dry wt) [13,40]. Consequently, some movement of Hg may occur in sediments during high pulse flows into the main stem of the Rio Grande.…”

“…Because of their size and location in the landscape, reservoirs can exhibit spatial complexity not seen in natural lakes [12], and it is reasonable to believe that they would exhibit spatial variability approaching that seen in riverine systems [13]. Large reservoirs are common in many regions, and many are heavily utilized by humans.…”