Adsorption of Mercury(II) by Soil: Effects of pH, Chloride, and Organic Matter

Yin, Yujun; Allen, Herbert E.; Li, Yimin; Huang, Chihpin; Sanders, Paul F.

doi:10.2134/jeq1996.00472425002500040027x

Cited by 234 publications

(167 citation statements)

References 0 publications

Supporting

Mentioning

132

Contrasting

Unclassified

Order By: Relevance

“…The presence of Cl-has a significant effect on the mercury speciation, especially at elevated Eh values. This has been reported by other experimentalists and modelers (reviewed by Andersson 1979, Schuster 1991, Yin et al 1996. Hg2+(aq)is calculated to exist in moderate reducing conditions.…”

Section: Wsrc-tr-2000-oo058supporting

confidence: 77%

Mercury speciation modeling using site specific chemical and redox data from the TNXOD OU

Kaplan¹

2000

View full text Add to dashboard Cite

DISCLAIMERTMs report was prepared as an account of work sponsored by an agency of "theUnited States Government. Neither the United States Government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product or process disclose~or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial produc~processor service by trade name, trademarb manufacturer, or otherwise does not necessarily constitute or imply its endorsemen%-recommendation or favoring by the United States Government or any agency thereof. Executive SummaryPrevious research related to the TNX Outfall Delta Operable Unit indicated that the mercury in the contaminated sediment was strongly sorbed to the sediment (Kaplan and Serklz 2000) and it was not toxic (Specht 1999). These two sets of studies were conducted under oxygenated or mildly reducing conditions. The objective of this study was to evaluate mercury speciation under reducing conditions expected in sediments at the TNX Outfall Delta. These changes in speciation would then be used to infer whether mercury toxicity and mobility would be expected (or predicted?) to be significantly altered under reducing conditions. Because the cost of conducting resorption and toxicity tests under reducing conditions would be expensive and time consuming, it was decided to attempt to evaluate this issue through the use of thermodynamic speciation calculations based on site-specific data. Four sets of calculations were conducted (each set comprising 33 individual calculations), whereby the dominant mercury species were estimated thermodynamically as a fi.mction of the oxidation-reduction potential (ORP or Eh values). Attempts were made to relate the results to experimental results reported in the literature. Additionally, 58 field measurements of Eh were made in sediments at or adjacent to the TNX Outfall Delta waste site. Because no Eh measurements had been made at the study site, the measured Eh values provided an indication of the range of likely values that may exist at the study site. There is some uncertainty in the application of these measurements to site processes due to the fact that they did not capture the anticipated seasonal variation of Eh values.The measured Eh values varied a great deal, likely the result of differences in the microenvironment of the sample. The Eh values were in the range of expected values for acidic environments (pH -5). The speciation calculation indicated that as the redox potential decreased, the availability of mercury tended to decrease presumably due to the formation of HgS, a sparingly soluble precipitate. No abiotic methylated mercury was predicted to be formed within the range of likely redox levels for this mildly acidic site. This is an important finding because methylated mercury species are highly toxic. As the pH of the system was increased, less ...

show abstract

Section: Wsrc-tr-2000-oo058supporting

confidence: 77%

Mercury speciation modeling using site specific chemical and redox data from the TNXOD OU

Kaplan¹

2000

View full text Add to dashboard Cite

show abstract

“…However, the ratio of PAH bioaccessibility in small intestinal condition to that in gastric condition varied extensively (0.8 to 8.5), possibly due to the micelles, which could be formed in the aqueous suspensions by bile constituents. Additionally, the increase of solubility of soil organic matter with an increase in solution pH (Yin et al 1996;Khan et al 2006) may also contribute partly to the enhancement of PAH bioaccessibility in the small intestinal condition as compared with that in gastric condition (Tang et al 2006). The bioaccessibility of individual PAHs in soils decreased with the increasing ring number in both gastric and small intestinal conditions, possibly due to the decrease in the water solubility and increase in K ow of individual PAHs with increasing ring number.…”

Section: Discussionmentioning

confidence: 99%

Concentrations and bioaccessibility of polycyclic aromatic hydrocarbons in wastewater-irrigated soil using in vitro gastrointestinal test

Khan

Cao

Lin

et al. 2008

Environ Sci Pollut Res

View full text Add to dashboard Cite

Background, aim, and scope Polycyclic aromatic hydrocarbons (PAHs) are widespread environmental contaminants and contribute to the pollution of soil environment. Soil ingestion is of increasing concern for assessing health risk from PAH-contaminated soils because soil ingestion is one of the potentially important pathways of exposure to environmental pollutants, particularly relevant for children playing at contaminated sites due to their hand-to-mouth activities. In vitro gastro-intestinal tests imitate the human digestive tract, based on the physiology of humans, generally more simple, less time-consuming, and especially more reproducible than animal tests. This study was conducted to investigate the level of PAH contamination and oral bioaccessibility in surface soils, using physiologically based in vitro gastro-intestinal tests regarding both gastric and small intestinal conditions. Materials and methods Wastewater-irrigated soils were sampled from the metropolitan areas of Beijing and Tianjin, China, which were highly contaminated with PAHs. Reference soil samples were also collected for comparisons. At each site, four soils were sampled in the upper horizon at the depth of 0-20 cm randomly and were bulked together to form one composite sample. PAH concentrations and origin were investigated and a physiologically based in vitro test was conducted using all analytical grade reagents. Linear regression model was used to assess the relationship between total PAH concentrations in soils and soil organic carbon (SOC). Results A wide range of total PAH concentrations ranging from 1,304 to 3,369 μg kg -1 in soils collected from different wastewater-irrigated sites in Tianjin, while ranging from 2,687 to 4,916 μg kg -1 in soils collected from different wastewater-irrigated sites in Beijing, was detected. In general, total PAH concentrations in soils from Beijing sites were significantly higher than those from Tianjin sites, indicating a dominant contribution from both pyrogenic and petrogenic sources. Results indicated that the oral bioaccessibility of PAHs in small intestinal was significantly higher (from P<0.05 to P<0.001) than gastric condition. Similarly, the oral bioaccessibility of PAHs in contaminated sites was significantly higher (from P≤0.05 to P<0.001) than in reference sites. Individual PAH ratios (three to six rings), a more accurate and reliable estimation about the emission sources, were used to distinguish the natural and anthropogenic PAH inputs in the soils. Results indicated that PAHs were both pyrogenic and petrogenic in nature. Discussion The identification of PAH sources and importance of in vitro test for PAH bioaccessibility were emphasized in this study. The oral bioaccessibility of individual PAHs in soils generally decreased with increasing ring numbers of PAHs in both the gastric and small intestinal conditions. However, the ratio of bioaccessibility of individual PAHs in gastric conditions to that in the small intestinal condition generally increased with increasing ring number...

show abstract

“…The ratio of PAHs bioaccessibility in small intestinal condition to that in gastric condition varied from 1.1 to 9.7, possibly due to the micelles, which could be formed in the aqueous suspensions by bile constituents, as demonstrated below. Additionally, the increase of solubility of soil organic matter with increase in solution pH (Yin et al, 1996) may also contribute partly to the enhancement of PAH bioaccessibility in small intestinal condition, compared with that in gastric condition.…”

Section: Oral Bioavailability Of Total Pahs In Soilsmentioning

confidence: 99%

Assessment of the bioaccessibility of polycyclic aromatic hydrocarbons in soils from Beijing using an in vitro test

Tang

Zhu

et al. 2006

Environmental Pollution

105

View full text Add to dashboard Cite

Oral bioaccessibility of soil total PAHs in small intestinal condition was significantly higher than gastric condition. AbstractAs an important human exposure pathway of contaminants, soil ingestion is of increasing concern for assessing health risk from polycyclic aromatic hydrocarbons (PAHs) in soils. A wide range of total PAH concentrations ranging from 0.112 mg g ÿ1 to 27.8 mg g ÿ1 in soils collected from different public sites, including gas stations, roadsides, bus stops, a kindergarten, primary and middle schools, a university and residential area, was detected. In general, total PAHs concentrations in soils from traffic areas were significantly higher than that from the other sites, indicating a dominant contribution from motor vehicles. Physiologically based in vitro tests were used to evaluate the oral bioaccessibility of PAHs in surface soil under different land uses in Beijing regarding both gastric and small intestinal conditions. It was found that the oral bioaccessibility of total PAHs in small intestinal condition, ranging from 9.2% to 60.5% of total PAHs in soil, was significantly higher than gastric condition, ranging from 3.9% to 54.9%. The bioaccessibility of individual PAHs in soils generally decreased with the increasing ring number of PAHs in both gastric and small intestinal conditions. However, the ratio of bioaccessibility of individual PAHs in gastric condition to that in small intestinal condition, generally increased with increasing ring number, indicating the relatively pronounced effect of bile extract on improving bioaccessibility of PAHs with relatively high ring numbers characterized by their high K ow values. The observation that bile extract at a level higher than critical micelle concentration could reduce the surface tension of digestive juice substantially, which may cause PAHs to be available for intestinal absorption, calls for more careful establishment of reliable soil criteria for PAHs, especially concerning the health of children who may ingest a considerable amount of PAH-contaminated soil via outdoor hand-mouth activities.

show abstract

Adsorption of Mercury(II) by Soil: Effects of pH, Chloride, and Organic Matter

Cited by 234 publications

References 0 publications

Mercury speciation modeling using site specific chemical and redox data from the TNXOD OU

Mercury speciation modeling using site specific chemical and redox data from the TNXOD OU

Concentrations and bioaccessibility of polycyclic aromatic hydrocarbons in wastewater-irrigated soil using in vitro gastrointestinal test

Assessment of the bioaccessibility of polycyclic aromatic hydrocarbons in soils from Beijing using an in vitro test

Contact Info

Product

Resources

About