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B. L. Sawhney

Bio: B. L. Sawhney is an academic researcher from Connecticut Agricultural Experiment Station. The author has contributed to research in topics: Compost & Vermiculite. The author has an hindex of 18, co-authored 31 publications receiving 1920 citations.
Topics: Compost, Vermiculite, Sorption, Desorption, Illite

Papers
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Journal ArticleDOI
TL;DR: In this paper, a review of the literature concerning selective sorption and fixation of K and similar cations by clay minerals and soil clays and the mechanisms of these reactions are reviewed.
Abstract: Investigations concerning selective sorption and fixation of K and similar cations by clay minerals and soil clays and the mechanisms of these reactions are reviewed. In particular, recent observations on selective sorption of these ions in dilute solutions by weathered micas and vermiculite in relation to the interlayer structures are discussed in detail. Also, implications of the resistance to weathering of small mica particles to cation selectivity by soils are described. Despite the increased understanding of sorption and fixation reactions, the following aspects remain unclear. First, the mechanism of the collapse of alternate layers in vermiculite on K or Cs sorption has not been unequivocally established. Second, factors that impart stability to the central core of mica particles so that K extraction becomes progressively difficult are not known. Third, inability of Ca or Mg ions to expand interlayers of Cs-saturated vermiculite in contrast to K-saturated vermiculite is not completely understood.

602 citations

Journal ArticleDOI
TL;DR: The residual 1,2-dibromoethane (EDB) was found in agricultural topsoils up to 19 years after its last known application as mentioned in this paper, and the residual EDB was highly resistant to both mobilization (desorption into air and water) and microbial degradation in contrast to freshly added EDB.
Abstract: The soil fumigant 1,2-dibromoethane (EDB) was found in agricultural topsoils up to 19 years after its last known application. This residual EDB was highly resistant to both mobilization (desorption into air and water) and microbial degradation in contrast to freshly added EDB. Release of the residual EDB into aqueous solution was extremely slow at 25/sup 0/C but highly temperature dependent. Treatment of release as a radial diffusion process yielded effective intraparticle diffusivities of (2-8) x 10/sup -7/ cm/sup 2//s and half-equilibration times in a 1:2 soil-water suspension of 2-3 decades at 25/sup 0/C. Aerobic degradation of residual EDB by indigenous microbes was negligible after 38 days compared to rapid removal and mineralization of added (/sup 14/C)EDB. The release of residual EDB was greatly enhanced by pulverization of the soil. The results show that the residual EDB is trapped in soil micropores other than the interlayers of expandable clays where release is influenced by extreme tortuosity or steric restriction. 27 references, 7 figures, 2 tables.

480 citations

Journal ArticleDOI
TL;DR: In this article, the selectivity of a number of vermiculites, montmorillonites and micas for K and Cs ions was determined by sorption of these ions from equilibrium solutions of diverse concentrations.
Abstract: Selectivity of a number of vermiculites, montmorillonites and micas for K and Cs ions was determined by sorption of these ions from equilibrium solutions of diverse concentrations. The selec- tivity coefficients were related to the layer charge density and the area of the frayed edges in layer silicates. Montmorillonites had the smallest selectivity for the two ions, while biotite and illite had the great- est selectivity. Selectivity of biotite and illite was limited to small concentrations of K, however. At greater concentrations the selectivity of vermiculite for K exceeded the selectivity of the micas. The greater selectivity of vermiculites than montmorillonites for K and Cs ions was attributed to the greater layer charge density in vermiculites. The greater selectivity of micas than montmorillonites and vermiculites was attributed to the frayed edges of micas in addition to their larger layer charge density. As the frayed edRes in illite were increased in area by removal of the interlayer K, the selec- tivity of illite for K also increased; thus confirming the selectivity of frayed edges for the K ions.

157 citations

Book ChapterDOI
11 Sep 2018

73 citations


Cited by
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Journal ArticleDOI
TL;DR: The use of equilibrium expressions for sorption to natural particles in fate and transport models is often invalid due to slow kinetics and diffusion limitations appear to play a major role.
Abstract: The use of equilibrium expressions for sorption to natural particles in fate and transport models is often invalid due to slow kinetics. This paper reviews recent research into the causes of slow sorption and desorption rates at the intraparticle level and how this phenomenon relates to contaminant transport, bioavailability, and remediation. Sorption kinetics are complex and poorly predictable at present. Diffusion limitations appear to play a major role. Contending mechanisms include diffusion through natural organic matter matrices and diffusion through intraparticle nanopores. These mechanisms probably operate simultaneously, but the relative importance of each in a given system is indeterminate. Sorption shows anomalous behaviors that are presently not well explained by the simple diffusion models, including concentration dependence of the slow fraction, distributed rate constants, and kinetic hysteresis. Research is needed to determine whether adsorption/desorption bond energies may play a role alon...

1,716 citations

Journal ArticleDOI
TL;DR: This review of mineral nutrients shall not be considering two most important, but frequently reviewed, aspects of the subject, namely biological fixation of N/sub 2/ and its assimilation and mechanisms of membrane transport.
Abstract: Broadly, the approach which researchers have adopted in this review has been to ask the following questions about mineral nutrients: What properties make them essential. How are they obtained. How effectively are they used. We shall not be considering two most important, but frequently reviewed, aspects of the subject, namely biological fixation of N/sub 2/ and its assimilation and mechanisms of membrane transport.

1,072 citations

Journal ArticleDOI
TL;DR: The chemical interactions of hydrophobic organic contaminants (HOCs) with soils and sediments (geosorbents) may result in strong binding and slow subsequent release rates that significantly affect remediation rates and endpoints.
Abstract: The chemical interactions of hydrophobic organic contaminants (HOCs) with soils and sediments (geosorbents) may result in strong binding and slow subsequent release rates that significantly affect remediation rates and endpoints The underlying physical and chemical phenomena potentially responsible for this apparent sequestration of HOCs by geosorbents are not well understood This challenges our concepts for assessing exposure and toxicity and for setting environmental quality criteria Currently there are no direct observational data revealing the molecular-scale locations in which nonpolar organic compounds accumulate when associated with natural soils or sediments Hence macroscopic observations are used to make inferences about sorption mechanisms and the chemical factors affecting the sequestration of HOCs by geosorbents Recent observations suggest that HOC interactions with geosorbents comprise different inorganic and organic surfaces and matrices, and distinctions may be drawn along these lines,

1,033 citations

Journal ArticleDOI
TL;DR: In this paper, a comprehensive overview to the biodeterioration of stone and its practical relevance for the conservation is presented. But, the authors do not consider the effects of the microbial contamination on cleaning procedures, protective treatments as well as biocidal applications.

889 citations

01 Nov 2000
TL;DR: A toxicological profile for PCBs, Draft for Public Comment, was released in December 1998 as discussed by the authors, which supercedes any previously released draft or final profile, but no less than once every three years.
Abstract: DISCLAIMER The use of company or product name(s) is for identification only and does not imply endorsement by the Agency for Toxic Substances and Disease Registry. A toxicological Profile for PCBs, Draft for Public Comment, was released in December 1998. This edition supercedes any previously released draft or final profile. Toxicological profiles are revised and republished as necessary, but no less than once every three years. The toxicological profiles are developed in response to the Superfund Amendments and Reauthorization Act (SARA) of 1986 (Public law 99-499) which amended the Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (CERCLA or Superfund). This public law directed ATSDR to prepared toxicological profiles for hazardous substances most commonly found at facilities on the CERCLA National Priorities List and that pose the most significant potential threat to human health, as determined by ATSDR and the EPA. The availability of the revised priority list of 275 hazardous substances was announced in the Administrator of ATSDR to prepare a toxicological profile for each substance on the list. Toxicological Profiles are a unique compilation of toxicological information on a given hazardous substance. Each profile reflects a comprehensive and extensive evaluation, summary, and interpretation of available toxicologic and epidemiologic information on a substance. Health care providers treating patients potentially exposed to hazardous substances will find the following information helpful for fast answers to often-asked questions. Chapter 1: Public Health Statement: The Public Health Statement can be a useful tool for educating patients about possible exposure to a hazardous substance. It explains a substance's relevant toxicologic properties in a nontechnical, question-and-answer format, and it includes a review of the general health effects observed following exposure. Chapter 3: Health Effects: Specific health effects of a given hazardous compound are reported by type of health effect (death, systemic, immunologic, reproductive), by route of exposure, and by length of exposure (acute, intermediate, and chronic). In addition, both human and animal studies are reported in this section. NOTE: Not all health effects reported in this section are necessarily observed in the clinical setting. Please refer to the Public Health Statement to identify general health effects observed following exposure. The following additional material can be ordered through the ATSDR Information Center: Case Studies in Environmental Medicine: Taking an Exposure History—The importance of taking an exposure history and how to conduct one are described, and an example of a thorough exposure history is provided. Other …

660 citations