Winter indoor air pollution in Alaska: identifying a myth

The benzene and toluene levels inside three homes with attached garages were measured for 12 consecutive weeks during the winter months in Fairbanks, Alaska (Latitude 64.5 degrees N). Results for air samples collected over 12 h for the homes showed indoor benzene mixing ratios ranging from 1.6 to 20.4 parts per billion of mixing ratio volume (ppbv), and toluene air mixing ratios ranging from 7.3 to 41.6 ppbv. A correlation between benzene and toluene levels in each home and similar regression lines suggested the same major emission source, car and small equipment gasoline, present in attached garages. In one home, there was a correlation between indoor benzene mixing ratios and the urinary biomarker, trans,trans-muconic acid. Inside, air mixing ratios of benzene and toluene decreased with decreasing outside temperature in all homes studied, even though homes were relatively tight to prevent heat loss during this period of low winter outdoor temperatures. It is suggested that buildup of these pollutants indoors is prevented by the influence of an increased indoor/outdoor temperature differential and an ensuing increase in home ventilation.     

Minimal transmission of zearalenone to milk of dairy cows

Milk and plasma levels of zearalenone (ZEN), alpha-zearalenol (alpha-ZEL), beta-zearalenol (beta-ZEL) and conjugated metabolites were determined after feeding lactating cows with ZEN. In those instances where ZEN and alpha- and beta-ZEL were detected in milk or plasma, they occurred only as conjugates hydrolysable by treatment with a mixture of beta-glucuronidase and aryl sulfatase. With studies where 50 or 165 mg was fed daily to three cows for 21 day periods, neither dosage showed the presence of ZEN or metabolites in either milk or plasma (detection limits: milk, 0.5 ng/ml, ZEN, alpha-ZEL; 1.5 ng/ml, beta-ZEL; plasma, 2-3 times higher). A dose of 544.5 mg zearalenone per day given to a single cow for 21 days yielded maximum concentrations of only 2.5 ng ZEN/ml and 3.0 ng alpha-ZEL/ml in the milk. In plasma, up to 3 ng ZEN/ml could be detected during the initial 4 days of treatment. At a dose of 1.8 g of zearalenone given over a one day feeding period, maximum milk levels of 4.0 ng ZEN/ml, 1.5 ng alpha-ZEL/ml, and 4.1 ng beta-ZEL/ml were observed during the initial 2 days; corresponding maximum levels after a one day dose of 6.0 g zearalenone were 6.1, 4.0 and 6.6 ng/ml milk on days 2-3. In plasma, peak ZEN concentrations (9 and 13 ng/ml at the lower and higher one-day doses, respectively) occurred 12 hr after initial dosing, and declined to negligible levels by days 5-7. Neither alpha- nor beta-ZEL were detected in plasma. Since measurable levels required very high oral doses of ZEN, milk would not normally pose a human health hazard as a result of feeding rations containing ZEN to lactating dairy cows.     

Humic acid enhanced remediation of an emplaced diesel source in groundwater. 1. Laboratory-based pilot scale test

The enhanced solubility of petroleum-derived compounds in humic acid solutions is the basis for a new groundwater remediation technology. In this unique pilot-scale test, a stationary contaminant source consisting of diesel fuel was placed below the water table in a model sand aquifer (1.2 x 5.5 x 1.8-m deep) and flushed with water at a flow rate of 2 cm/h over 5 years. At 51 days, laboratory grade humic acid was added to the water and maintained at a level of approximately 0.8 g/l. The addition of humic acid had only a small impact on the aqueous transport of the BTEX components, which were rapidly dissolved from the diesel, but had a large effect on the flushing of PAHs, including methylated naphthalenes (MNs). Binding to aqueous humic acid enhanced the solubilization of MNs two- to tenfold. During aqueous transport, biodegradation of the BTEX and PAHs occurred, limiting the lateral and longitudinal extent of the diesel contaminant plume in the model aquifer. It appears that through enhanced solubilization, the overall biodegradation rate of the MNs was increased. As the various MNs were depleted from the diesel source, the MN plume shrank and then disappeared.     

Effects of skin and hydraulic fractures on SVE wells

Soil vapor extraction (SVE) systems are intended to cause substantial volumes of air to flow through the subsurface with the purpose of removing volatile contaminants. The effectiveness of SVE can be influenced by any effect that changes the specific gas capacity (discharge as a function of vacuum) of a well. Skins of low permeability material enveloping a well bore are widely recognized to affect the performance of wells used to recover water, natural gas, or petroleum, and skin can also significantly diminish the performance of an SVE well. Skins a few mm thick consisting of material whose gas phase permeability is 0.01 of the formation can reduce the specific gas capacity of an SVE well by factors of 2 to 10 or more. Hydraulic fractures created in the vicinities of shallow wells commonly resemble sand-filled layers shaped like flat-lying disks or gently dipping saucers. The contrast between the gas-phase permeability of the sand in the fracture and that of the formation is particularly important, with significant effects requiring the ratio to be greater than approximately 50. Shallow hydraulic fractures filled with several tenths of m3 of sand in formations that are several orders of magnitude less permeable than that of the enveloping formation should increase specific gas capacity by factors of 10 or more. Field tests of the effects of hydraulic fractures on the performance of SVE were conducted by creating four wells intersecting fractures and a suite of control wells created using conventional methods in silty saprolite. Specific gas capacities ranged over more than an order of magnitude for 10 wells completed within a small area (2 m2) and at the same depth. Specific capacities correlate to the drilling method that was used to create the bore for the well: lowest values occurred in wells drilled with a machine auger, slightly better results were obtained using a Shelby tube, and the best results were obtained from conventional wells bored with a hand auger. Skin factors determined for wells created with a machine auger could be explained by a layer 1 cm thick that has 0.007 times the permeability of the enveloping material, which could readily have been created during the drilling procedure. Specific capacities of wells intersecting hydraulic fractures were 5 to 100 times more than those of conventional wells. The large difference in performance appears to be due in part to the beneficial effects of the fracture, and in part to the detrimental effects of well skin.     

Threats to Imperiled Freshwater Fauna

Threats to imperiled freshwater fauna in the U.S. were assessed through an experts survey addressing anthropogenic stressors and their sources. Specifically, causes of historic declines and current limits to recovery were identified for 135 imperiled freshwater species of fishes, crayfishes, dragonflies and damselflies, mussels, and amphibians. The survey was designed to identify threats with sufficient specificity to inform resource managers and regulators faced with translating information about predominant biological threats into specific, responsive actions. The findings point to altered sediment loads and nutrient inputs from agricultural nonpoint pollution; interference from exotic species; and altered hydrologic regimes associated with impoundment operations as the three leading threats nationwide, accompanied by many lesser but still significant threats. Variations in threats among regions and among taxa were also evident. Eastern species are most commonly affected by altered sediment loads from agricultural activities, whereas exotic species, habitat removal/damage, and altered hydrologic regimes predominate in the West. Altered sediment loading from agricultural activities and exotic species are dominant problems for both eastern mussels and fishes. However, eastern fishes also appear to be suffering from municipal nonpoint pollution (nutrients and sediments), whereas eastern mussels appear to be more severely affected by altered nutrient impacts from hydroelectric impoundments and agricultural runoff. Our findings suggest that control of nonpoint source pollution associated with agriculture activities should be a very high priority for agricultural producers and governmental support programs. Additonally, the large number of hydropower dams in the U.S. subject to federal re-licensing in coming years suggests a significant opportunity to restore natural hydrologic regimes in the affected rivers.     

Organic content and biomass of abyssal holothuroids (Echinodermata) from the Bay of Biscay

The levels of ash, lipid, carbohydrate, protein and calories in the body walls of 3 abyssal holothuroids of the Bay of Biscay [Benthogone rosea Koehler, Paelopatides gigantea (Verrill) and Psychropotes longicauda Theel] are similar to those found in the body walls of shallow-water holothuroids. The biomass of abyssal holothuroids in terms of calories comprises an important fraction of the total biomass in the deep sea; at 2 000 m depth, the holothuroids correspond to one-sixth of the total biomass. However, the numerical and caloric densities of abyssal holothuroids are 4 orders of magnitude less than those of shallow-water holothuroids, although the sizes and caloric contents of individuals are of similar magnitude.Contribution No. 742 of Centre Océanologique de Bretagne     

Cleanup Options for Navajo Abandoned Uranium Mines

This article summarizes the current status of known contamination arising from abandoned uranium mines (AUMs) within the Navajo Nation and examines the options for addressing the elevated risks to health that AUM waste poses to the people of the Navajo Nation. More specifically, this article provides the following:

1. An overview of past uranium mining conducted on the Navajo Nation, the current status of AUM waste within the Navajo Nation, and the human health risks associated with uranium exposure.
2. A discussion of Navajo Fundamental Law, the Diné (the Navajo People) Uranium Remediation Advisory Commission, and the Navajo Nation Department of Justice's position regarding institutional controls and cleanup of AUMs.
3. A summary of cleanup actions taken to date to address AUM waste and the lessons learned from such actions.
4. Options for cleanup of AUM waste consistent with Diné Fundamental Law, the Diné Natural Resources Protection Act of 2005, and the Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (CERCLA).

The information summarized in this article was previously presented as an “Initial White Paper on Cleanup Options for Navajo Abandoned Uranium Mines,” prepared with participation from multiple stakeholders including the Navajo Nation Environmental Protection Agency (NNEPA), the Navajo Nation Department of Justice (NNDOJ), and the United States Environmental Protection Agency (US EPA). ©2016 Wiley Periodicals, Inc.     

An Air Quality Data Analysis System for Interrelating Effects,Standards, and Needed Source Reductions: Part 11. A Lognormal Model Relating Human Lung Function Decrease to O3 Exposure

Forced expiratory volume in 1 second (FEV1) was measured in 21 men exercising while exposed to four O₃ concentrations (0.0,0.08,0.10, and 0.12 ppm). A lognormal multiple linear regression model was fitted to their mean FEV1 measurements to predict FEV1 percent decrease as a function of O₃ concentration and exposure duration. The exercise level used was probably comparable to heavy manual labor. The longest O₃, exposure studied was 6 h. Extrapolating cautiously to an 8-h workday of heavy manual labor, the model predicts that O3 concentrations of 0.08, 0.10, and 0.12 ppm would decrease FEV1 by 9,15, and 20 percent, respectively.     

Nocturnal NO3 radical chemistry in Houston,TX

Radical chemistry in the nocturnal urban boundary layer is dominated by the nitrate radical, NO₃, which oxidizes hydrocarbons and, through the aerosol uptake of N₂O₅, indirectly influences the nitrogen budget. The impact of NO₃ chemistry on polluted atmospheres and urban air quality is, however, not well understood, due to a lack of observations and the strong impact of vertical stability of the boundary layer, which makes nocturnal chemistry highly altitude dependent.Here we present long-path DOAS observations of the vertical distribution of the key nocturnal species O₃, NO₂, and NO₃ during the TRAMP experiment in Summer 2006 in Houston, TX. Our observations confirm the altitude dependence of nocturnal chemistry, which is reflected in the concentration profiles of all trace gases at night. In contrast to other study locations, NO₃ chemistry in Houston is dominated by industrial emissions of alkenes, in particular of isoprene, isobutene, and sporadically 1,3-butadiene, which are responsible for more than 70% of the nocturnal NO₃ loss. The nocturnally averaged loss of NO_x in the lowest 300 m of the Houston atmosphere is ～0.9 ppb h^?1, with little day-to-day variability. A comparison with the daytime NO_x loss shows that NO₃ chemistry is responsible for 16–50% of the NO_x loss in a 24-h period in the lowest 300 m of the atmosphere. The importance of the NO₃ + isoprene/1,3-butadiene reactions implies the efficient formation of organic nitrates and secondary organic aerosol at night in Houston.