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Abelardo D. Beloso

Publications and source records attributed to Abelardo D. Beloso.

4 recordsLinked to original sources
USGS2011

Applications of selective ion exchange for perchlorate removal, recovery, and environmental forensics

Perchlorate (ClO4-) is a widespread contaminant found in drinking water and groundwater that has caused far-reaching ramifications ranging from public health issues to potential liabilities arising from environmental clean-up requirements. The chapter summarizes recent developments in highly selective and regenerable ion exchange technologies for removing ClO4- from contaminated water. The technologies rely on a unique, highly specific resin to trap ClO4-. The resin is then regenerated and ClO4- is either destroyed or recovered—leading to significant cost reduction and waste minimization. The ability to recover trace quantities of pure ClO4- from contaminated media also allows unambiguous identification of the sources of its contamination through stable isotope ratio analysis of chlorine and oxygen atoms. We provide detailed descriptions of the techniques for extracting, purifying, and crystallizing trade amounts of ClO4- and characterizing its isotopic composition for fingerprinting in the environment.

Book chapter↗
USGS2009

Chlorine-36 as a tracer of perchlorate origin

Perchlorate (ClO 4 − ) is ubiquitous in the environment. It is produced naturally by atmospheric photochemical reactions, and also is synthesized in large quantities for military, aerospace, and industrial applications. Nitrate-enriched salt deposits of the Atacama Desert (Chile) contain high concentrations of natural ClO 4 − , and have been exported worldwide since the mid-1800s for use in agriculture. The widespread introduction of synthetic and agricultural ClO 4 − into the environment has contaminated numerous municipal water supplies. Stable isotope ratio measurements of Cl and O have been applied for discrimination of different ClO 4 − sources in the environment. This study explores the potential of 36 Cl measurements for further improving the discrimination of ClO 4 − sources. Groundwater and desert soil samples from the southwestern United States (U.S.) contain ClO 4 − having high 36 Cl abundances ( 36 Cl/Cl = 3100 × 10 −15 to 28,800 × 10 −15 ), compared with those from the Atacama Desert ( 36 Cl/Cl = 0.9 × 10 −15 to 590 × 10 −15 ) and synthetic ClO 4 − reagents and products ( 36 Cl/Cl = 0.0 × 10 −15 to 40 × 10 −15 ). In conjunction with stable Cl and O isotope ratios, 36 Cl data provide a clear distinction among three principal ClO 4 − source types in the environment of the southwestern U.S.

Environmental Science & Technology↗
USGS2007

Oxygen and chlorine isotopic fractionation during perchlorate biodegradation: Laboratory results and implications for forensics and natural attenuation studies

Perchlorate is a widespread environmental contaminant having both anthropogenic and natural sources. Stable isotope ratios of O and Cl in a given sample of perchlorate may be used to distinguish its source(s). Isotopic ratios may also be useful for identifying the extent of biodegradation of perchlorate, which is critical for assessing natural attenuation of this contaminant in groundwater. For this approach to be useful, however, the kinetic isotopic fractionations of O and Cl during perchlorate biodegradation must first be determined as a function of environmental variables such as temperature and bacterial species. A laboratory study was performed in which the O and Cl isotope ratios of perchlorate were monitored as a function of degradation by two separate bacterial strains ( Azospira suillum JPLRND and Dechlorospirillum sp. FBR2) at both 10 °C and 22 °C with acetate as the electron donor. Perchlorate was completely reduced by both strains within 280 h at 22 °C and 615 h at 10 °C. Measured values of isotopic fractionation factors were ε 18 O = −36.6 to −29.0‰ and ε 37 Cl = −14.5 to −11.5‰, and these showed no apparent systematic variation with either temperature or bacterial strain. An experiment using 18 O-enriched water (δ 18 O = +198‰) gave results indistinguishable from those observed in the isotopically normal water (δ 18 O = −8.1‰) used in the other experiments, indicating negligible isotope exchange between perchlorate and water during biodegradation. The fractionation factor ratio ε 18 O/ε 37 Cl was nearly invariant in all experiments at 2.50 ± 0.04. These data indicate that isotope ratio analysis will be useful for documenting perchlorate biodegradation in soils and groundwater. The establishment of a microbial fractionation factor ratio (ε 18 O/ε 37 Cl) also has significant implications for forensic studies.

Environmental Science & Technology↗