GEOLOGIC CONTROL OF MERCURY TRANSPORT IN BIG CYPRESS BAYOU AND CADDO LAKE WATERSHEDS HARRISON COUNTY, TEXAS

We present the first assessment of atmospheric pollution by mercury (Hg) in an industrialized area located in the Ossola Valley (Italian Central Alps), in close proximity to the Toce River. The study area suffers from a level of Hg contamination due to a Hg cell chlor-alkali plant operating from 1915 to the end of 2017. We measured gaseous elemental Hg (GEM) levels by means of a portable Hg analyzer during car surveys between autumn 2018 and summer 2020. Moreover, we assessed the long-term dispersion pattern of atmospheric Hg by analyzing the total Hg concentration in samples of lichens collected in the Ossola Valley. High values of GEM concentrations (1112 ng m−3) up to three orders of magnitude higher than the typical terrestrial background concentration in the northern hemisphere were measured in the proximity of the chlor-alkali plant. Hg concentrations in lichens ranged from 142 ng g−1 at sampling sites located north of the chlor-alkali plant to 624 ng g−1 in lichens collected south of the chlor-alkali plant. A north-south gradient of Hg accumulation in lichens along the Ossola Valley channel was observed, highlighting that the area located south of the chlor-alkali plant is more exposed to the dispersion of Hg emitted into the atmosphere from the industrial site. Long-term studies on Hg emission and dispersion in the Ossola Valley are needed to better assess potential impact on ecosystems and human health.

Download Full-text

Speciated Atmospheric Mercury during Haze and Non-haze Days in an Inland City in China

10.5194/acp-2016-467 ◽

2016 ◽

Author(s):

Qianqian Hong ◽

Zhouqing Xie ◽

Cheng Liu ◽

Feiyue Wang ◽

Pinhua Xie ◽

...

Keyword(s):

Elemental Mercury ◽

Atmospheric Mercury ◽

Central China ◽

Mercury Emissions ◽

Gaseous Elemental Mercury ◽

Enhanced Production ◽

Mercury Transport ◽

Haze Pollution ◽

The Mean ◽

Haze Days

Abstract. Long-term continuous measurements of speciated atmospheric mercury were conducted at Hefei, a mid-latitude inland city in east central China, from July 2013 to June 2014. The mean concentrations (± standard deviation) of gaseous elemental mercury (GEM), reactive gaseous mercury (RGM) and particle-bound mercury (PBM) were 3.95 ± 1.93 ng m−3, 2.49 ± 2.41 pg m−3 and 23.3 ± 90.8 pg m−3, respectively, during non-haze days, and 4.74 ± 1.62 ng m−3, 4.32 ± 8.36 pg m−3 and 60.2 ± 131.4 pg m−3, respectively, during haze days. Potential source contribution function (PSCF) analysis suggested that the atmospheric mercury pollution during haze days was caused primarily by local mercury emissions, instead of via long-range mercury transport. In addition, the disadvantageous diffussion during haze days will also enhance the level of atmospheric mercury. Compared to the GEM and RGM, change in PBM was more sensitive to the haze pollution. The mean PBM concentration during haze days was 2.5 times that during non-haze days due to elevated concentrations of particulate matter. A remarkable seasonal trend in PBM was observed with concentration decreasing in the following order in response to the frequency of haze days: autumn, winter, spring, summer. A distinct diurnal relationship was found between GEM and RGM during haze days, with the peak values of RGM coinciding with the decline in GEM. Using HgOH as an intermediate product during GEM oxidation, our results suggest that NO2 aggregation with HgOH could explain the enhanced production of RGM during the daytime in haze days. Increasing level of NOx will potentially accelerate the oxidation of GEM despite the decrease of solar radiation.

Download Full-text

THE EFFECT OF SELENIUM ON MERCURY TRANSPORT ALONG THE FOOD CHAIN

AGROFOR ◽

10.7251/agreng1603119z ◽

2016 ◽

Vol 1 (3) ◽

Cited By ~ 1

Author(s):

Primož ZIDAR ◽

Špela KRŽIŠNIK ◽

Marta DEBELJAK ◽

Suzana ŽIŽEK ◽

Katarina VOGEL MIKUŠ

Keyword(s):

Food Chain ◽

Contaminated Soil ◽

Local Population ◽

Trophic Levels ◽

Food Chains ◽

Chemical Transformations ◽

Soil Concentration ◽

Preliminary Results ◽

Mercury Transport ◽

Hg Accumulation

More than 500 years of mercury (Hg) production in Idrija (Slovenia) resulted in aconsiderable pollution of Idrija region with Hg. Although the mine is closed formore than 20 years, the total soil concentration of Hg may still reach up to severalhundred mgkg-1dry weightin local gardens and more that thousand inother urbanregions. Hg in soil undergoesdifferent chemical transformations and in someformsit may enterplants and higher trophic levelsin food chains, also withbiomagnification pattern.The local population is, besides air and dust, thus exposedto mercury also via consumption of locally produced food.Several studies showedthat the increased level of selenium in soil may reduce the uptake of mercury inplants but very few include other trophic levels in a food chain as well.In our pilotstudy we followed an impact of Seon Hg transport from soil to plants(Lactucasativa) and further to soil dwelling animals (Porcellioscaber). Lettuce wasplanted in a contaminated soil from Idrija and in soil with added HgCl2. The leavesof half of the plants weresprayed with Sesolution (5μg L-1)threeand five weeksafter planting.After six weeks plants were analyzed for Hg and Se and offered asfood to terrestrial isopods for two weeks. Our preliminary results revealed thatfoliar treatment of plants with Se may affect Hg accumulation in plants andtherefore further transport of Hg across the food chain.

Download Full-text

Multispecies and Watershed Approaches to Freshwater Fish Conservation

Multispecies and Watershed Approaches to Freshwater Fish Conservation ◽

10.47886/9781934874578.ch15 ◽

2019 ◽

Keyword(s):

Ecological Monitoring ◽

Army Corps ◽

Ramsar Convention ◽

Vegetation Monitoring ◽

Flow Restoration ◽

Wetland Complex ◽

Conservation Organizations ◽

Caddo Lake ◽

Giant Salvinia ◽

Natural Ecology

<em>Abstract</em>.—Caddo Lake, along with its swamps and tributary bayous, supports a diversity of aquatic ecosystems and has been designated a wetland of global significance by the Ramsar Convention. The life blood of Caddo Lake is the network of tributary creeks and bayous that drain into the wetland complex of the lake’s upper reaches. The ecology of the main tributary, Big Cypress Bayou, however, has been altered by flow regulation by Lake O’ the Pines dam. Additional threats from giant salvinia <em>Salvinia molesta </em>and other invasive plants, water quality impacts, and land uses have added stress to the ecosystem. Several conservation organizations, led by the Caddo Lake Institute, have formed partnerships to address these threats to the watershed. The Sustainable Rivers Program, a partnership of The Nature Conservancy and the U.S. Army Corps of Engineers (Corps), has managed dam operations to enhance the natural ecology of Big Cypress Bayou and Caddo Lake downstream. The Corps has been releasing recommended flows to allow researchers to gather more information to evaluate the success of restoration efforts. Early monitoring results indicate a potential positive response of the fish community to these flow releases. We present results of flow restoration work and associated ecological monitoring. We also summarize floodplain vegetation monitoring, paddlefish restoration and invasive species management projects in Caddo Lake and the Cypress River basin.

Download Full-text