Srinath Rajagopalan
@ssn.edu.in
Associate Professor in Department of Civil Engineering
Sri Sivasubramaniya Nadar College of Engineering
RESEARCH INTERESTS
Sustainable use of wastes in building materials, contaminant fate and transport, microplastics
Scopus Publications
Scopus Publications
S. V. Sivapriya, S. Rajagopalan, A. Duraimurugan, S. Rakesh, P. Ravikumar, and S. Suryaprakash
Springer Science and Business Media LLC
Srinath Rajagopalan, P. Sreehari, B. Mahalingam, and K. Mohammed Haneefa
Springer Singapore
B. Mahalingam, P. Sreehari, Srinath Rajagopalan, S. Ramana Gopal, and K. Mohammed Haneefa
Springer Singapore
W. Andrew Jackson, J.K. Böhlke, Brian J. Andraski, Lynne Fahlquist, Laura Bexfield, Frank D. Eckardt, John B. Gates, Alfonso F. Davila, Christopher P. McKay, Balaji Rao,et al.
Elsevier BV
Jennie Munster, Gilbert N. Hanson, W. Andrew Jackson, and Srinath Rajagopalan
Springer Science and Business Media LLC
Srinath Rajagopalan, Todd Anderson, Stephen Cox, Greg Harvey, Qiuqiong Cheng, and W. Andrew Jackson
American Chemical Society (ACS)
Natural perchlorate is believed to be of atmospheric origin, yet no systematic study has been conducted to evaluate perchlorate deposition rate and possible seasonal or spatial variations. This study evaluated perchlorate concentrations in weekly composite wet deposition samples acquired through the National Atmospheric Deposition Program from 26 sites across the continental United States, Alaska, and Puerto Rico for a 1-3 year period. Perchlorate concentrations varied from <5 ng/L to a high of 102 ng/L with a mean of 14.1 +/- 13.5 ng/L for the 1578 total samples. The annual perchlorate flux by site ranged from a low of 12.5 (TX) to 157 mg/ha-year (NE) and averaged 65 +/- 30 mg/ha-year for all sites. Perchlorate concentrations and flux in wet deposition were generally highest in May-August declining to lows in December-February. Average annual perchlorate flux was correlated (r > 0.5; p < 0.001) with Ca2+, K+, NH4+, NO3(-), Cl(-), and SO4(-2). Wet deposition rate of ClO4(-) in the conterminous United States (excluding Alaska, Hawaii, and Puerto Rico) while diffuse, represents a potential annual net mass flux of 51,000 kg, a value comparable to the estimated annual environmental releases from other known ClO4(-) sources.
Balaji Rao, Todd A. Anderson, Greta J. Orris, Ken A. Rainwater, Srinath Rajagopalan, Renee M. Sandvig, Bridget R. Scanlon, David A. Stonestrom, Michelle A. Walvoord, and W. Andrew Jackson
American Chemical Society (ACS)
A substantial reservoir (up to 1 kg ha(-1)) of natural perchlorate is present in diverse unsaturated zones of the arid and semi-arid southwestern United States. The perchlorate co-occurs with meteoric chloride that has accumulated in these soils throughout the Holocene [0 to 10-15 ka (thousand years ago)] and possibly longer periods. Previously, natural perchlorate widely believed to be limited to the Atacama Desert, now appears widespread in steppe-to-desert ecoregions. The perchlorate reservoir becomes sufficiently large to affect groundwater when recharge from irrigation or climate change flushes accumulated salts from the unsaturated zone. This new source may help explain increasing reports of perchlorate in dry region agricultural products and should be considered when evaluating overall source contributions.
Priyantha W. Jayawickrama and Srinath Rajagopalan
SAGE Publications
During periods of drought, good-quality water becomes a precious commodity, especially in those parts of the United States that receive little rainfall. One way to reduce the demand for drinking water is to substitute non-drinking-quality water in earthwork construction. If nonpotable water from local sources can be used in construction, then the need for hauling in good-quality water from distant sources and the potential for construction delays because of water rationing can be avoided. A research study investigated the feasibility of using alternative water sources in earthwork construction. As a part of this study, alternative water supplies in Texas were identified and characterized for quality and volume availability. In addition, each proposed water source was evaluated to determine whether there were any adverse environmental impacts from its use in earthwork construction. Potential impact from the use of low-quality water on constructability, material behavior, and performance also were evaluated. Of special interest were the effects on corrosive potential, sulfate heave, and dispersion potential of the soil. Simple predictive models are presented to help when decisions are made regarding acceptance or rejection of water obtained from a specific source.
W. Andrew Jackson, Todd Anderson, Greg Harvey, Greta Orris, Srinath Rajagopalan, and Namgoo Kang
Kluwer Academic Publishers
Srinath Rajagopalan, Todd A. Anderson, Lynne Fahlquist, Ken A. Rainwater, Moira Ridley, and W. Andrew Jackson
American Chemical Society (ACS)
Perchlorate (CLO4-) occurrence in groundwater has previously been linked to industrial releases and the historic use of Chilean nitrate fertilizers. However, recently a number of occurrences have been identified for which there is no obvious anthropogenic source. Groundwater from an area of 155,000 km2 in 56 counties in northwest Texas and eastern New Mexico is impacted bythe presence of ClO4-. Concentrations were generally low (<4 ppb), although some areas are impacted by concentrations up to 200 ppb. ClO4- distribution is not related to well type (public water system, domestic, agricultural, or water-table monitoring) or aquifer (Ogallala, Edward Trinity High Plains, Edwards Trinity Plateau, Seymour, or Cenozoic). Results from vertically nested wells strongly indicate a surface source. The source of ClO4- appears to most likely be atmospheric deposition. Evidence supporting this hypothesis primarily relates to the presence of ClO4- in tritium-free older water, the lack of relation between land use and concentration distribution, the inability of potential anthropogenic sources to account for the estimated mass of ClO4-, and the positive relationship between conserved anions (e.g., IO3-, Cl-, SO4(-2)) and ClO4-. The ClO4- distribution appears to be mainly related to evaporative concentration and unsaturated transport. This process has led to higher ClO4- and other ion concentrations in groundwater where the water table is relatively shallow, and in areas with lower saturated thickness. Irrigation may have accelerated this process in some areas by increasing the transport of accumulated salts and by increasing the number of evaporative cycles. Results from this study highlight the potential for ClO4- to impact groundwater in arid and semi-arid areas through long-term atmospheric deposition.
Purnendu K. Dasgupta, P. Kalyani Martinelango, W. Andrew Jackson, Todd A. Anderson, Kang Tian, Richard W. Tock, and Srinath Rajagopalan
American Chemical Society (ACS)
Perchlorate, an iodide uptake inhibitor, is increasingly being detected in new places and new matrices. Perchlorate contamination has been attributed largelyto the manufacture and use of ammonium perchlorate (the oxidizer in solid fuel rockets) and/or the earlier use of Chilean nitrate as fertilizer (approximately 0.1% perchlorate). However, there are regions such as the southern high plains (Texas Panhandle) where there is no clear historical or current evidence of the extensive presence of rocket fuel or Chilean fertilizer sources. The occurrence of easily measurable concentrations of perchlorate in such places is difficult to understand. In the southern high plains groundwater, perchlorate is better correlated with iodate, known to be of atmospheric origin, compared to any other species. We show that perchlorate is readily formed by a variety of simulated atmospheric processes. For example, it is formed from chloride aerosol by electrical discharge and by exposing aqueous chloride to high concentrations of ozone. We report that perchlorate is present in many rain and snow samples. This strongly suggests that some perchlorate is formed in the atmosphere and a natural perchlorate background of atmospheric origin should exist.
W. Andrew Jackson, Srinivasa Kumar Anandam, Todd Anderson, Tom Lehman, Ken Rainwater, Srinath Rajagopalan, Moira Ridley, and Richard Tock
Wiley
In the spring of 2002, the Texas Commission on Environmental Quality determined that perchlorate (ClO4−) was present in ground water from the McMillan and Paul Davis well fields that supply potable water for the city of Midland. Researchers began a large‐scale sampling program to determine the source(s) and distribution of perchlorate in the area's ground water. This document summarizes the findings of a large‐scale investigation in nine counties carried out from July to December 2002. This program included public water system (PWS) wells and private wells in Andrews, Borden, Dawson, Ector, Gaines, Glasscock, Howard, Martin, and Midland counties, which occupy a total area of 23,960 km2. Water samples were tested for perchlorate and a suite of common ions. From a total of 254 wells sampled in the nine counties, 179 wells (70%) had detectable perchlorate concentrations (>0.5 ppb) and 88 wells (35%) had perchlorate concentrations equal to or above 4 ppb. The highest perchlorate concentration found at a private well was 58.8 ppb in Dawson County, while the highest concentration detected for a well in PWS was 45.6 ppb in city of Midland, Midland County. Perchlorate positively correlated (α < 0.0001) with Cl−, F−, Br−, SO42−, Mg2+, and K+ but not with NO2−, NO3−, Na+, or Ca2+. Research to date has identified the most likely sources to be (1) a natural mineralogical impurity; (2) agricultural fertilizers containing perchlorate; (3) in situ generation of perchlorate by electrochemical reactions; or (4) some combination of the three. This study suggests that there may be significant sources other than the traditional industrial processing of perchlorate, and the distribution of perchlorate in ground water is likely more widespread than previously suspected.