Arsenicals occurrence

Hering, J.G. and Kneebone, P.E. (2002) Biogeochemical controls on arsenic occurrence and mobility in water supplies, in Environmental Chemistry of Arsenic (ed. W.T. Frankenberger Jr.), Marcel Dekker), New York, pp. 155-81. 

Hering, J.G. and Chiu, V.Q. (2000) Arsenic occurrence and speciation in municipal ground-water-based supply system. Journal of Environmental Engineering, 126(5), 471-74. 

Johnson, D.M. (2001) Arsenic Occurrence in Wisconsin s Groundwater. American Water Resources Association-Wisconsin Section, Conference March 29-30, 2001. 

Thornburg, K. and Sahai, N. (2004) Arsenic occurrence, mobility, and retardation in sandstone and dolomite formations of the Fox River valley, eastern Wisconsin. Environmental Science and Technology, 38(19), 5087-94. 

Following consumption of dissolved O2, the thermodynamically favored electron acceptor is nitrate (N03-). Nitrate reduction can be coupled to anaerobic oxidation of metal sulfides (Appelo and Postma, 1999), which may include arsenic-rich phases. The release of sorbed arsenic may also be coupled to the reduction of Mn(IV) (oxy)(hydr)oxides, such as birnessite CS-MnCb) (Scott and Morgan, 1995). The electrostatic bond between the sorbed arsenic and the host mineral is dramatically weakened by an overall decrease of net positive charge so that surface-complexed arsenic could dissolve. However, arsenic liberated by these redox reactions may reprecipitate as a mixed As(III)-Mn(II) solid phase (Toumassat et al., 2002) or resorb as surface complexes by iron (oxy)(hydr)oxides (McArthur et al., 2004). The most widespread arsenic occurrence in natural waters probably results from reduction of iron (oxy)(hydr)oxides under anoxic conditions, which are commonly associated with rapid sediment accumulation and burial (Smedley and Kinniburgh, 2002). In anoxic alluvial aquifers, iron is commonly the dominant redox-sensitive solute with concentrations as high as 30 mg L-1 (Smedley and Kinniburgh, 2002). However, the reduction of As(V) to As(III) may lag behind Fe(III) reduction (Islam et al., 2004). 

O Shea, B.M., Clark, G. and Jankowski, J. (2006) A comparison of arsenic occurrence and geochemistry in two groundwater environments. Geochimica et Cosmochimica Acta, 70(Supplement 1 18), A-464. 

Peters, S.C., Blum, J.D., Klaue, B. and Karagas, M.R. (1999) Arsenic occurrence in New Hampshire drinking water. Environmental Science and Technology, 33(9), 1328-33. 

Smedley, P. (2005) Arsenic Occurrence in Groundwater in South and East Asia Scale, Causes and Mitigation. Towards a More Effective Operational Response Arsenic Contamination of Groundwater in South and East Asian Countries II. Technical Report, World Bank Report No. 31303, World Bank, Washington, DC. 

Tandukar, N., Bhattacharya, P Neku, A. and Mukherjee, A.B. (2006) Extent and severity of arsenic occurrence in groundwater of Nepal, in Managing Arsenic in the Environment From Soil to Human Health (eds R. Naidu, E. Smith, G. Owens et al.), CSIRO Publishing, Collingwood, pp. 541-52. 

De Figueiredo, B.R., Borba, R.P. and Angdlica, R.S. (2007) Arsenic occurrence in Brazil and human exposure. Environmental Geochemistry and Health, 29(2), 109-18. 

Huntsman-Mapila, P., Mapila, T., Letshwenyo, M. et al. (2006) Characterization of arsenic occurrence in the water and sediments of the Okavango delta, NW Botswana. Applied Geochemistry, 21(8), 1376-91. 

NATIONAL ESTIMATES OF ARSENIC OCCURRENCE IN DRINKING WATER... 

National Arsenic Occurrence Survey (NAOS) sampled raw water from approximately 270 public supply wells in all 50 states, and predicted arsenic concentrations in finished water based on known treatments implemented by the systems (Frey and Edwards, 1997). Frey and Edwards (1997) also provided national estimates based on reexamining the NIRS data and a dataset of finished water from 60 large systems (serving >10,000 people) sampled by the Metropolitan Water District of Southern California (Davis et al, 1994). In 1973 to 1997, the USGS analyzed for arsenic in 18,850 raw-water samples from wells in 49 states (all but Hawaii) and Puerto Rico this dataset included 2,262 samples from public supply wells (Focazio et al., 2000). Several older national surveys of arsenic have been described in documents prepared for the USEPA (ISSI Consulting Group et al., 2000). 

In eastern New England, analysis of arsenic occurrence by aquifer type finds that arsenic concentrations are typically lower in glacial aquifers than in bedrock aquifers (Ayotte et al, 1999). Arsenic concentrations are also generally lower in public supply wells than in domestic wells, and lower in higher-pumpage wells than in smaller systems. However, Ayotte et al. 

Moderate and low arsenic concentrations are found in numerous wells in the FRV, irrespective of the presence of the SCH in the open interval of the well. These levels of arsenic in ground water do not correlate to the intersection of the SCH with the static water level (Fig. 8), indicating that the sulfide oxidation initiated by oxygen introduced at the borehole does not cause all arsenic occurrences. Tfiere is no single stratigraphic unit that controls the low to moderate concentrations wells with open intervals in the Sinnipee Group, the St. Peter Sandstone, the Prairie du Chien Group or the Cambrian sandstones are all affected. 

CSME, 1997, Geology and geochemistry of arsenic occurrences in groundwater of six districts of West Bengal Centre for Study of Man Environment, Calcutta. 

ISSI Consulting Group, The Cadmus Group, and ICE Consulting, 2000, Arsenic occurrence in public drinking water supplies Prepared for the U.S. Environmental Protection Agency under contract nos. 68-C7-0005 and 68-C-99-206., EPA-815-R-00-023, 138 p. 

Jain, C. K., and Ali, I., 2000, Arsenic Occurrence, toxicity and speciation techniques Water... 

Lockwood, J. R., Ill, Schervish, M. J., Gurian, P., and Small, M. J., 2001, Characterization of arsenic occurrence in US drinking water treatment facility source waters Department of Statistics, Carnegie Mellon University, 700, 32 p. 

Serfes, M. R, Spayd, S. E., Herman, G. C., and Monteverde, D. R, 2000, Arsenic occurrence, source and possible mobilization mechanisms in ground water of the Piedmont physiographic province in New Jersey EOS Transactions, AGU Fall Meeting Supplement, v. 81, p. 525. 

This chapter details several experimental and field results regarding arsenic occurrence and speciation that may have important implications for health effects and for arsenic removal during water treatment. 

ARSENIC OCCURRENCE IN THE UNITED STATES COMPARED WITH TAIWAN IMPLICATIONS FOR HEALTH... 

Water samples were taken from three deep wells in the blackfoot disease endemic area in Taiwan. An aliquot of each sample was Altered and speciated in the held to separate parAculate arsenic, arsenate [As(V)] and arsenite [As(III)] (7). Arsenic and co-occurring elements were measured with inductively coupled plasma mass specttometty (ICP-MS) or ICP emission specAoscopy (ICP-ES). These Taiwanese well samples were compared with results from the National Arsenic Occurrence Survey (NAOS), which obtained raw water samples from 428 water supplies in all 50 states of the United States (8,9). 

Figure 1 Highest total arsenic occurrence in Taiwanese deep well waters and U.S. drinking water sources.

This study uncovered several aspects of arsenic occurrence and chemistry that may be important to drinking water utilities trying to meet the newly lowered arsenic MCL. 

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