Mercury Concentrations In Ambient Air Research Articles

Atmospheric wet deposition of mercury in urban Jinan, eastern China: Speciation, scavenging process and potential sources

Understanding the speciation and related influence factors of Hg in wet deposition is important to predict the fate and transport of mercury in the atmosphere. In this study, event-based samples of rainwater were collected for one year in Jinan, a northern city in eastern China. The volume-weighted mean concentration of total mercury (THg) in rainwater was 34.8 ng L−1, comparable to levels in some inland cities in China and were significantly higher than those in North America, Korea and Japan. Most of the Hg in rainwater was associated with particulates, accounted for 15.2–92.9% of THg with a mean of 66.9%, which might be attributed to the scavenging effects of high particulate-bound mercury concentrations in ambient air in urban Jinan. Dissolved mercury (DHg) accounted for 33.1% of THg, in which Hg(OH)2, HgClOH, HgCl2 and Hg(NH3)22+ are the dominant species based on the chemical equilibrium modeling simulations. THg concentrations in rainwater decreased as the rainfall amount increased owing to the dilution effect and 5 mm rainfall might be a threshold for the full wash-out capability of atmospheric Hg. For a continuous rain event, the proportion of DHg in THg could increase from 7.1% to 84.8% with the rainfall processing, especially for the species of HgClOH and HgCl2 under the influence of rainwater pH. Positive matrix factorization (PMF) analysis suggested that the major sources of Hg in rainwater were combustion emissions, marine sources, industrial emissions, as well as complexation process, which contributed to 51.4%, 24.7%, 12.2%, and 11.7% of the THg, respectively. For the specific species, the main sources varied with different Hg species, in which combustion emissions contributed one third to one half of each species sum to particulate mercury (PHg), HgClOH, HgCl2, HgBrOH and HgBrCl followed by marine sources and industrial emissions. Cluster analysis of backward trajectories revealed that polluted air masses, transported from southeast Shandong, Anhui and Jiangsu Provinces, as well as Beijing-Tianjin-Hebei region, contributed to high Hg concentration in rainwater in Jinan.

Elevated Mercury in Ambient Air and Soils Impacts of Historical Air Emissions (1897-1991) from a Chlor-Alkali Plant (CAP)

Mercury contamination was found to be widespread in soils at a property in Upstate New York. Historical site use suggested that the mercury did not result from prior industrial use of the property. Soil contamination may have resulted from atmospheric deposition of mercury released from properties in close proximity to the contaminated property. The purpose of this forensics investigation was to examine to what extent atmospheric deposition of elemental mercury may have influenced mercury levels found in surficial soils on the contaminated property and further to identify the source(s) of the mercury. Work efforts included an examination of historical records available for a chlor-alkali plant (CAP) upwind of the contaminated property to establish historical use and disposal practices for elemental mercury. Mercury emissions test data from the Upstate New York chlor-alkali facility were modeled (USEPA ISC3) as a means of estimating impacts on ambient air and soils vicinal to the facility. Mercury emissions from the facility were modeled as both a point source and volume source. For example, at a location 305 meters to the east and 30 meters to the north of the modeled source centerline elemental mercury concentrations in ambient air were estimated at 270 ng/m3 (average results based upon 5 years of meteorological data). This value is contrasted to a background concentration of 1.6 ng/m3 (USEPA Report to Congress 1997). As a result of the modeling data in combination with findings related to mercury use and disposal practices at the NY CAP documented from the records review, it was concluded that emissions from the CAP facility during the period of operation (1897-1991) most likely accounted for the concentrations of elemental mercury found in surficial soils at properties situated downwind of the CAP. These findings were further corroborated by information available in the open literature for CAPs world-wide.

Determination Of The Mercury Content Of Lichens and Comparison To Atmospheric Mercury Levels In The South African Highveld Region

The concentration of mercury vapour in ambient air is routinely determined using specialised instruments.As an economical alternative, actively pumped Hopcalite sorbent tubes can be used to trap atmosphericmercury, which is subsequently analysed by cold vapour atomic absorption spectroscopy. Plant materialsare also readily available in most regions and can be analysed to obtain information on time averagedatmospheric mercury levels.Lichen and tree bark samples were collected in the cities of Pretoria and Witbank, dried and acid digestedwith subsequent cold vapour atomic absorption spectroscopy. Average mercury concentrations rangingfrom 74 to 193 μg.kg-1 were found in lichens from three Pretoria suburbs, whilst average Hg levels of 228μg.kg-1 were determined in lichens collected in Witbank. The average mercury concentration in tree barkwas consistently lower than in lichens, with concentrations between 28 and 72 μg.kg-1 determined insamples from three Pretoria suburbs and 75 μg.kg-1 determined in samples taken in Witbank. This study isthe first in South Africa to determine mercury levels in lichens and tree bark.Average total gaseous mercury concentrations in ambient air at the three Pretoria suburban sites, asdetermined by a semi-continuous spectroscopic method using Hopcalite sampling, ranged between 1.6and 2.5 ng.m-3, while an average of 1.7 ng.m-3 was measured in Witbank over the sampling interval.

Rapid Monitoring of Mercury in Air from an Organic Chemical Factory in China Using a Portable Mercury Analyzer

A chemical factory, using a production technology of acetaldehyde with mercury catalysis, was located southeast of Qingzhen City in Guizhou Province, China. Previous research showed heavy mercury pollution through an extensive downstream area. A current investigation of the mercury distribution in ambient air, soils, and plants suggests that mobile mercury species in soils created elevated mercury concentrations in ambient air and vegetation. Mercury concentrations of up to 600 ng/m3 in air over the contaminated area provided evidence of the mercury transformation to volatile Hg(0). Mercury analysis of soil and plant samples demonstrated that the mercury concentrations in soil with vaporized and plant-absorbable forms were higher in the southern area, which was closer to the factory. Our results suggest that air monitoring using a portable mercury analyzer can be a convenient and useful method for the rapid detection and mapping of mercury pollution in advanced field surveys.

Uncertainty-Weighted Time Averaging of Mercury Vapour Concentrations in Ambient Air: Application to Measurements in the United Kingdom

Uncertainty-weighted time averaging of total gaseous mercury concentrations in ambient air, with associated robust uncertainties, has been performed for concentrations measured by the U.K. Heavy Metals Monitoring Network between 2007 and 2009. The results have been compared with averages produced using standard time-averaging methods with a view to investigating the properties of the new method and whether it represents an improvement over current practice.

Human exposure to mercury in the vicinity of chlor-alkali plant

The main objectives of our study were to estimate the impact of a mercury cell chlor-alkali (MCCA) complex in Rosignano Solvay (Tuscany, Italy) on the local environment and to assess mercury exposure of inhabitants living near the plant. Measurement campaigns of atmospheric Hg near the MCCA plant showed that the impact of the emitted Hg from the industry on the terrestrial environment is restricted to a close surrounding area. Total gaseous mercury concentrations in ambient air of inhabited area around the MCCA plant were in the range of 8.0-8.7 ng/m3 in summer and 2.8-4.2 ng/m3 in winter. Peaks of up to 100 ng/m3 were observed at particular meteorological conditions. Background levels of 2 ng/m3 were reached within a radius of 3 km from the plant. Reactive gaseous mercury emissions from the plant constituted around 4.2% of total gaseous mercury and total particulate mercury emission constituted around 1.0% of total gaseous mercury emitted. Analysis of local vegetables and soil samples showed relatively low concentrations of total mercury (30.1-2919 microgHg/kg DW in the soil; <0.05-111 microgHg/kg DW in vegetables) and methylmercury (0.02-3.88 microgHg/kg DW in the soil; 0.03-1.18 microgHg/kg DW in vegetables). Locally caught marine fish and fresh marine fish from the local market had concentrations of total Hg from 0.049 to 2.48 microgHg/g FW, of which 37-100% were in the form of methylmercury. 19% of analysed fish exceeded 1.0 microgHg/g FW level, which is a limit set by the European Union law on Hg concentrations in edible marine species for tuna, swordfish and shark, while 39% of analysed fish exceeded the limit of 0.5 microgHg/g FW set for all other edible marine species. Risk assessment performed by calculating ratio of probable daily intake (PDI) and provisional tolerable daily intake (PTDI) for mercury species for various exposure pathways showed no risks to human health for elemental and inorganic mercury, except for some individuals with higher number of amalgam fillings, while PDI/PTDI ratio for methylmercury and total mercury exceeded the toxicologically tolerable value due to the potential consumption of contaminated marine fish.

Temporal and spatial distributions of total gaseous mercury concentrations in ambient air in a mountainous area in southwestern China: Implications for industrial and domestic mercury emissions in remote areas in China

Spatial and temporal distributions of total gaseous mercury (TGM) concentrations in ambient air were investigated in the Mt. Gongga area (Sichuan province, PR China) from April 2006 to June 2007. The annual geometric mean TGM concentration at the Moxi baseline station was 3.90 ± 1.20 ng m − 3 . Geometric mean TGM concentrations at 14 representative sampling sites during the warm season ranged from 1.60 to 20.1 ng m − 3 and varied spatially, with levels decreasing between urbanized areas and more remote regions: urban area (U1–U3: 7.76 ± 4.57 to 20.1 ± 15.1 ng m − 3 ), town (T1: 4.61 ± 1.15 ng m − 3 ) and village (V1–V4: 3.26 ± 0.63 to 8.45 ± 3.06 ng m − 3 ), and remote area (R1–R6: 1.60 ± 0.43 to 3.41 ± 1.26 ng m − 3 ). Our study suggested that industrial activities, especially non-ferrous smelting activities, were an important source of atmospheric Hg and played a vital role in the regional distribution of TGM. In addition, domestic coal and biomass combustion to heat residential homes were important sources of TGM in densely populated areas during the winter months.

Total gaseous mercury concentrations in ambient air in the eastern slope of Mt. Gongga, South-Eastern fringe of the Tibetan plateau, China

During May 2005–June 2006, measurements of total gaseous mercury (TGM) concentrations were carried out by using a set of automatic atmospheric mercury vapor analyzer (Tekran 2537A) at Moxi base station (102°07′E, 29°40′N, 1640 m a.s.l.) of the Gongga alpine ecosystem observation and experiment station of Chinese academy of sciences (CAS) which belongs to the Chinese ecosystem research network (CERN). A seasonal distribution pattern of TGM in ambient air was observed on the descending order of winter, fall, spring, and summer. Geometric mean TGM concentration over the sampling periods was 3.98 ng m −3 with a range from 0.52 to 21.03 ng m −3. The measurements showed a noticeable diurnal TGM distribution pattern with high concentration during daytime compared to nighttime; the maximum and the minimum concentration appeared near solar noon and immediately before sunrise, respectively. TGM concentrations were regulated by the wind directions, and wind from the southeastern direction carried more mercury than any other direction suggesting that anthropogenic sources, such as local zinc smelting activities and fuel combustion, played a predominant role in the elevation of TGM concentrations in this area.

Mercury emission from a cement factory and its influence on the environment

Mercury balance was investigated in a cement factory, measuring the mercury concentration in ingredients, fuels, cement and exhaust gases, etc. Daily mercury emission quantity from the factory was estimated to be 1.5 kg, originating mostly from limestone. Gaseous and particulate mercury concentrations in ambient air were 4.1–8.7 ng m −3 and 0.15–0.68 ng m −3, respectively. Particulate mercury concentrations are remarkably higher than the background ones. The influence of mercury emission estimated from the determined mercury levels in the leaves of indicator plants reaches up to 5 km at least from the source. The sum of the mercury quantity deposited from the atmosphere and that taken by leaves of plants in the area within a 5-km radius from the factory was calculated to be about 4% of the entire mercury emitted. The mercury residue was recognized in humus and surface soil in the forest near the factory.