Mercury concentrations and distribution in soil, water, mine waste leachates, and air in and around mercury mines in the Big Bend region, Texas, USA

Abstract

Samples of soil, water, mine waste leachates, soil gas, and air were collected from areas mined for mercury (Hg) and baseline sites in the Big Bend area, Texas, to evaluate potential Hg contamination in the region. Soil samples collected within 300 m of an inactive Hg mine contained elevated Hg concentrations (3.8–11 µg/g), which were considerably higher than Hg in soil collected from baseline sites (0.03–0.05 µg/g) distal (as much as 24 km) from mines. Only three soil samples collected within 300 m of the mine exceeded the probable effect concentration for Hg of 1.06 µg/g, above which harmful effects are likely to be observed in sediment-dwelling organisms. Concentrations of Hg in mine water runoff (7.9–14 ng/L) were generally higher than those found in springs and wells (0.05–3.1 ng/L), baseline streams (1.1–9.7 ng/L), and sources of drinking water (0.63–9.1 ng/L) collected in the Big Bend region. Concentrations of Hg in all water samples collected in this study were considerably below the 2,000 ng/L drinking water Hg guideline and the 770 ng/L guideline recommended by the U.S. Environmental Protection Agency (USEPA) to protect aquatic wildlife from chronic effects of Hg. Concentrations of Hg in water leachates obtained from leaching of mine wastes varied widely from <0.001 to 760 µg of Hg in leachate/g of sample leached, but only one leachate exceeded the USEPA Hg industrial soil screening level of 31 µg/g. Concentrations of Hg in soil gas collected at mined sites (690–82,000 ng/m3) were highly elevated compared to soil gas collected from baseline sites (1.2–77 ng/m3). However, air collected from mined areas at a height of 2 m above the ground surface contained concentrations of Hg (4.9–64 ng/m3) that were considerably lower than Hg in soil gas from the mined areas. Although concentrations of Hg emitted from mine-contaminated soils and mine wastes were elevated, persistent wind in southwest Texas disperses Hg in the air within a few meters of the ground surface.

Potential Ecological Risk and Health Risk Assessment of Heavy Metals and Metalloid in Soil around Xunyang Mining Areas

“…This result might be the fact that Hg vapor permeates the soil through atmospheric deposition, causing serious Hg pollution in the soil near the Hg mine [45]. Additionally, Hg might get into the soils by waste water from the mining district [46].…”

Mercury soil contents and associated ecological and health risks in kindergartens and functional areas of the city of Vanadzor (Armenia)

“…In soil, mercury is most commonly encountered in organic (Hg -C ) and inorganic (Hg 2+ ) forms (Lymberidi 2005;UNEP 2013), the presence of which affects the soil quality characteristics including natural soil profile and soil fertility values (Laker 2005). Since recent years the mercury contamination issue has become increasingly topical in regard to urban soils (Li et al 2010;Szymon Różański 2015;Gray et al 2015;Wan et al 2016;Kumar et al 2017;Moller et al 2018).…”

Identification of Potential Sources of Mercury (Hg) in Farmland Soil Using a Decision Tree Method in China

“…Mercury (Hg) is considered a global pollutant, and the effects of Hg on ecosystems and human health are well documented [1,2,3]. The concentrations of Hg in farmland soil are greatly influenced by parent material and soil properties, including organic matter, soil microbes, and soil pH [4,5,6], as well as human activities, such as non-ferrous mining, petroleum refining and fossil fuel combustion, discharge of wastes from industry production, and applications of fertilizers [7,8,9].…”