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We report an unusual occurrence of margarite, corundum, gahnite and zincohögbomite from the Raleigh terrane in the Piedmont Province of Virginia. The assemblage occurs in a chlorite-rich blackwall associated with a small metamorphosed ultramafic rock body. The blackwall is dominated by chlorite, but also contains distinctive clusters (1-4 mm across) that typically consist of ragged Zn-rich spinel grains surrounded by masses of randomly oriented margarite. Also spatially associated with spinel are smaller grains of corundum and högbomite. In most cases, spinel and högbomite are sufficiently enriched in Zn to be called gahnite and zincohögbomite, respectively. Some högbomite grains are distinctly banded in back-scattered electron images, primarily reflecting variations in Zncontent. Textures suggest that högbomite formed at the expense of spinel (although locally the reverse relationship holds), and högbomite compositions mimic those of spinel. Margarite appears to be a later phase, and textures imply formation via reactions with spinel, corundum and, possibly, chlorite. This occurrence of Zn-rich spinel and högbomite is clearly related to the bulk composition of the blackwall rock, which contains >2500 ppm Zn. The origin of this Zn-rich composition is unclear, but could be due to a small amount of sphalerite or zincian-staurolite in the protolith. [ABSTRACT FROM AUTHOR]

The environmental occurrence of perchlorate (ClO4-) can be related to either natural or anthropogenic sources. Recent studies highlighted the ubiquitous occurrence of natural ClO4- in the environment including wet deposition in the United States. Limited studies have investigated potential mechanisms responsible for natural ClO4- production in the environment. These studies have neither addressed the influence of relevant reaction conditions nor have they evaluated the rates of ClO4- production. The purpose of this study was to determine the comparative yields and rates of ClO4- production from O3 mediated oxidation of Cl-, OCl-, ClO2-, ClO3-, and ClO2. The influence of reactant (O3 and ClOx-) concentration and pH were evaluated. The comparative rate and efficiency of ClO4- production is generally greater for higher oxidation states of Cl (2.7 to 0.5% for ClO2-/ClO2 and 0.02 to 0.005% for OCl-/HOCl oxidation) with the notable exception of ClO3- which does not react with O3. The very slow rate of ClO4- production from Cl- (∼20 × 10-9 mM min-1) even at elevated O3 and Cl- concentrations implies negligible potential for anthropogenic ClO4- formation in process units of water/wastewater systems that use O3 for treatment. Based on results of ClO4- formation from tested Cl species and available literature, we propose a potential formation pathway for ClO4- from Cl- with emphasis on the role of ClO2 and higher oxy-chlorine radicals/intermediates (e.g., Cl2O6) in its formation. [ABSTRACT FROM AUTHOR]

Declines in Ca and Mg in low ANC lakes recovering from acidic deposition are widespread across the northern hemisphere. We report overall increases between 1984 and 2004 in the concentrations of Ca + Mg and Cl in lakes representing the statistical population of nearly 4000 low ANC lakes in the northeast U.S. Increases in Cl occurred in nearly all lakes in urbanized southern New England, but only 18% of lakes in more remote Maine had Cl increases. This spatial pattern implicates road salt application as the major source of the increased Cl salts. Among the 48% of the lake population classified as salt-affected, the median changes in Cl (+133 μeq/L) and Ca + Mg (+47μeq/L) were large and positive in direction over the 20 years. However, in the unaffected lakes, Cl remained stable and Ca + Mg decreased (-3μeq/L), consistent with reported long-term trends in base cations of acid-sensitive lakes. This discrepancy between the Cl groups suggests that changes in ion exchange processes in salt-affected watersheds have altered the geochemical cycling of Ca and Mg. One policy-relevant implication is that waters influenced by Cl salts complicate regional assessments of surface water recovery from "acid rain" related to the passage of the Clean Air Act. [ABSTRACT FROM AUTHOR]

We sampled seawater and snowpacks in the Canadian high Arctic for methylated species of mercury (Hg). We discovered that, although seawater sampled under the sea ice had very low concentrations of total Hg (THg, all forms of Hg in a sample; on average 0.14-0.24 rig L-1), 30- 45% of the THg was in the monomethyl Hg (MMHg) form (on average 0.057-0.095 ng L-1), making seawater itself a direct source of MMHg for biomagnification through marine food webs. Seawater under the ice also contained high concentrations of gaseous elemental Hg (GEM; 129 ± 36 pg L-1), suggesting that open water regions such as polynyas and ice leads were a net source of ~130 ± 30 ng Hg m-2 day-1 to the atmosphere. We also found 11.1 ± 4.1 pg L-1 of dimethyl Hg (DMHg) in seawater and calculated that there could be a significant flux of DMHg to the atmosphere from open water regions. This flux could then result in MMHg deposition into nearby snowpacks via oxidation of DMHg to MMHg in the atmosphere. In fact, we found high concentrations of MMHg in a few snowpacks near regions of open water. Interestingly, we discovered a significant log-log relationship between Cl-1 concentrations in snowpacks and concentrations of THg. We hypothesize that as Cl-1 concentrations in snowpacks increase, inorganic Hg(II) occurs principally as less reducible chloro complexes and, hence, remains in an oxidized state. As a result, snowpacks that receive both marine aerosol deposition of Cl-1 and deposition of Hg(II) via springtime atmospheric Hg depletion events, for example, may contain significant loads of Hg(II). Overall, though, the median wet/dry loads of Hg in the snowpacks we sampled in the high Arctic (5.2 mg THg ha-1 and 0.03 mg MMHg ha-1) were far below wet-only annual THg loadings throughout southern Canada and most of the U.S. (22-200 mg ha-1). Therefore, most Arctic snowpacks contribute relatively little to marine pools of both Hg(II) and MMHg at snowmelt. [ABSTRACT FROM AUTHOR]

Presents information on a study conducted to help understand total residual chlorine (TRC), dynamics and ambient toxicity in two chlorine-contaminated streams in eastern Tennessee. Methodology based on logistic regression analysis; Information on study sites; Testing of toxicity in streams; Experiments conducted to study the effect of sunlight and periphyton on TRC; What results from these experiments show.

Pollution control in one environmental medium may alter polluters' releases into other media. This paper examines cross-media responses to public policies that restrict toxic air emissions and that increase waste management costs. The EPA's 1987-90 Toxic Release Inventories are used to study the policies' effects on air emissions and waste generation of chlorinated solvents. The results suggest that constraints on air emissions reduce waste generation, perhaps because facilities rely less on these chemicals. Increases in hazardous waste management costs increase air emissions, however, suggesting that facilities substitute between releases into different environmental media. [ABSTRACT FROM AUTHOR]

Describes an approach to dating prehistoric earthquakes based on the buildup of cosmogenic 36 Cl in bedrock scarp exposed during surface faulting and discusses its application to a limestone scarp on the Hegben Lake fault in Montana. How cosmogenic chlorine 36 works in dating ancient earthquakes; Findings.

The article reports on a study which found that air pollution along coastlines could contribute to the formation of ozone. Scientists found a great concentration of nitryl chloride in the coastal areas of major cities and the Gulf of Mexico. The researchers concluded that nitryl chloride is formed through the reaction of chloride salts with pentoxide pollutants. It was found that chloride salts are associated to reactive chlorine atoms which oxidize hydrocarbons that cause ozone formation.

The article provides information on the study concerning the regio- and stereospecific formation of protected allylic alcohols zirconium-mediated SN2' substitution of allylic chlorides in the U.S. To eliminate the possibility of complications resulting from heterogeneity, the researchers prepared zirconium oxo complex, possessing substantially improved solubility, and examined its reaction with allylic chlorides.

The article reports on the detection of a significant quantity of a chlorinated organic chemical by scientists operating at the Integrated Atmospheric Deposition Network in the U.S. Great Lakes. This compound is sold under the name Dechlorane Plus, which is used for coating electrical wires and compounds. Scientists who discovered the chemical suggested that it is persistent, bioaccumulative, and potentially toxic. Environmental chemist Ake Bergaman of Stockholm University commented that the detection new organochlorine in the environment is indeed disturbing.

The ability to decontaminate a room potentially containing the Ebola virus is important to healthcare facilities in the United States. The Ebola virus remains viable in body fluids, a room that has housed a patient with Ebola virus disease must have all surfaces manually wiped with an approved disinfectant, which increases occupational exposure risk. This study evaluated the efficacy of gaseous chlorine dioxide inactivation of bacterial organisms in blood as the Ebola virus surrogates and as the organisms used by the Nebraska Biocontainment Unit to provide the margin of safety for decontamination.Bacillus anthracis, Escherichia coli, Enterococcus faecalis, and Mycobacterium smegmatisblood suspensions that were exposed to ClO2gas concentrations and exposure limits. The log reduction in Colony Forming Units (CFU) was determined for each bacterial blood suspension. Exposure parameters approximating industry practices for ClO2environmental decontamination (360 ppm concentration to 780 ppm-hr exposure, 65% relative humidity) as well as parameters exceeding current practice (1116 ppm concentration to 1400 ppm-hr exposure; 1342 ppm concentration to 1487 ppm-hr exposure) were evaluated. Complete inactivation was not achieved for any of the bacterial blood suspensions tested. Reductions were observed in concentrations ofB. anthracisspores (1.3–3.76 log) andE. faecalisvegetative cells (1.3 log) whereas significant reductions in vegetative cell concentrations forE. coliandM. smegmatisblood suspensions were not achieved. Our results showed that bacteria in the presence of blood were not inactivated using gaseous ClO2decontamination. ClO2decontamination alone should not be used for the Ebola virus, but decontamination processes should first include manual wiping of potentially contaminated blood; especially for microorganisms as infectious as the Ebola virus. [ABSTRACT FROM PUBLISHER]

Reports on plans for demonstrating in situ bioremediation of chlorinated solvents in the United States' federal facilities. Estimated project costs; Use of intrinsic bioremediation in low-concentration plume areas; Extent of chlorinated contaminants; Diagram of the bioremediation methods; Predictions on the impact of a successful demonstration.

Editorial. Argues against the Environmental Protection Agency's (EPA) plan to ban the production of chlorine and related compounds. Allegations that the EPA makes decisions influenced by Greenpeace and its allies; Natural production of chlorine and related compounds; Organochlorine compounds in smoke of burning wood; Presence of polychlorinated dioxins (PCDDs) in soil of remote areas.

An extensive review of CDC epidemiological responses to human outbreaks of anthrax from occupational settings between the years of 1950 and 2001 documented a variety of approaches to mitigation and decontamination [2]. These approaches included taking no action, burning contaminated materials, chlorinating water supplies, instituting administrative and engineering controls and PPE, vaccinating potentially exposed individuals, and in 2 instances, fumigating with formaldehyde vapor (now considered to be a human carcinogen). Secondary contamination of a worker's home was documented in 1 case, but not felt to be clinically significant to warrant any decontamination efforts. In response to the B. anthracis attacks in 2001, chlorine dioxide fumigation, vaporous hydrogen peroxide fumigation, and a combination of HEPA vacuuming, cleaning, and bleach application were all techniques used successfully to clean B. anthracis spore contamination.

Other workers have clearly shown that most, if not all, drinking water in the U.S. contains chemicals that possess mutagenic and/or carcinogenic activity by using bacterial and in vitro methods. In the present work, increased numbers of tumors were observed with samples of organic material isolated from 5 U.S. cities administered as tumor initiators in mouse skin initiation/promotion studies. Only in one case was the result significantly different from control. In studies designed to test whether disinfection practice contributes significantly to the tumor initiating activity found in drinking water mixed results have been obtained. In one experiment, water disinfected by chlorination, ozonation or combined chlorine resulted in a significantly greater number of papillomas when compared to nondisinfected water. In two subsequent experiments, where water was obtained from the Ohio River at different times of the year, no evidence of increased initiating activity was observed with any disinfectant. Analysis of water obtained at the comparable times of the year for total organic halogen, and trihalomethane formation revealed a substantial variation in the formation of these products. Considering the problems such variability poses for estimating risks associated with disinfection by-products, a model system which makes use of commercially obtained humic acid as a substrate for chlorination was investigated using the Ames test. Humic and fulvic acids obtained from two surface waters as well as the commercially obtained humic acid were without activity in TA 1535, TA 1537, TA 1538, TA 98 or TA 100 strains of S. typhimurium. Following treatment with a 0.8 molar ratio of chlorine (based on carbon) significant mutagenic activity was observed with all humic and fulvic acid samples. Comparisons of the specific mutagenic activity of the chlorinated products suggests that the commercial material might provide a useful model for studying health hazards associated with disinfection reactions by-products.