Fate and effects of anthropogenic chemicals in mangrove ecosystems: a review

The scientific literature for fate and effects of non-nutrient contaminant concentrations is skewed for reports describing sediment contamination and bioaccumulation for trace metals. Concentrations for at least 22 trace metals have been reported in mangrove sediments. Some concentrations exceed sediment quality guidelines suggesting adverse effects. Bioaccumulation results are available for at least 11 trace metals, 12 mangrove tissues, 33 mangrove species and 53 species of mangrove-habitat biota. Results are specific to species, tissues, life stage, and season and accumulated concentrations and bioconcentration factors are usually low. Toxicity tests have been conducted with 12 mangrove species and 8 species of mangrove-related fauna. As many as 39 effect parameters, most sublethal, have been monitored during the usual 3 to 6 month test durations. Generalizations and extrapolations for toxicity between species and chemicals are restricted by data scarcity and lack of experimental consistency. This hinders chemical risk assessments and validation of effects-based criteria.     

Genetic ecotoxicology of asbestos pollution in the house mouse <Emphasis Type="Italic">Mus musculus domesticus</Emphasis>

Purpose  

We tested the genetic diversity in wild mice (Mus musculus domesticus) inhabiting the asbestos-polluted area as a model for the long-term mutagenic effect of asbestos. Hazardous effects of deposited asbestos persist in the environment because of low rate of fiber disintegration. The upper layers of the soil in the vicinity of a former asbestos factory are nearly “saturated” with asbestos fibers and dust. Natural populations of mice dwell in this area and are constantly exposed to asbestos fibers.     

Application of a combined measurement and modeling method to quantify windblown dust emissions from the exposed playa at Mono Lake, California

Particulate matter < or =10 microm (PM10) emissions due to wind erosion can vary dramatically with changing surface conditions. Crust formation, mechanical disturbance, soil texture, moisture, and chemical content of the soil can affect the amount of dust emitted during a wind event. A refined method of quantifying windblown dust emissions was applied at Mono Lake, CA, to account for changing surface conditions. This method used a combination of real-time sand flux monitoring, ambient PM10 monitoring, and dispersion modeling to estimate dust emissions and their downwind impact. The method identified periods with high emissions and periods when the surface was stable (no sand flux), even though winds may have been high. A network of 25 Cox sand catchers (CSCs) was used to measure the mass of saltating particles to estimate sand flux rates across a 2-km2 area. Two electronic sensors (Sensits) were used to time-resolve the CSC sand mass to estimate hourly sand flux rates, and a perimeter tapered element oscillating microbalance (TEOM) monitor measured hourly PM10 concentrations. Hourly sand flux rates were related by dispersion modeling to hourly PM10 concentrations to back-calculate the ratio of vertical PM10 flux to horizontal sand flux (K-factors). Geometric mean K-factor values (K(f)) were found to change seasonally, ranging from 1.3 x 10(-5) to 5.1 x 10(-5) for sand flux measured at 15 cm above the surface (q15). Hourly PM10 emissions, F, were calculated by applying seasonal K-factors to sand flux measurements (F = K(f) x q15). The maximum hourly PM10 emission rate from the study area was 76 g/m2 x hr (10-m wind speed = 23.5 m/sec). Maximum daily PM10 emissions were estimated at 450 g/m2 x day, and annual emissions at 1095 g/m2 x yr. Hourly PM10 emissions were used by the U.S. Environmental Protection Agency (EPA) guideline AERMOD dispersion model to estimate downwind ambient impacts. Model predictions compared well with monitor concentrations, with hourly PM10 ranging from 16 to over 60,000 microg/m3 (slope = 0.89, R2 = 0.77).     

Identifying natural and anthropogenic sources of metals in urban and rural soils using GIS-based data,PCA, and spatial interpolation

Determining sources of neurotoxic metals in rural and urban soils is important for mitigating human exposure. Surface soil from four areas with significant clusters of mental retardation and developmental delay (MR/DD) in children, and one control site were analyzed for nine metals and characterized by soil type, climate, ecological region, land use and industrial facilities using readily available GIS-based data. Kriging, principal component analysis (PCA) and cluster analysis (CA) were used to identify commonalities of metal distribution. Three MR/DD areas (one rural and two urban) had similar soil types and significantly higher soil metal concentrations. PCA and CA results suggested that Ba, Be and Mn were consistently from natural sources; Pb and Hg from anthropogenic sources; and As, Cr, Cu, and Ni from both sources. Arsenic had low commonality estimates, was highly associated with a third PCA factor, and had a complex distribution, complicating mitigation strategies to minimize concentrations and exposures.     

Polychlorinated biphenyl spatial patterns in San Francisco Bay forage fish

Industrialized waterways frequently contain nearshore hotspots of legacy polychlorinated biphenyl (PCB) contamination, with uncertain contribution to aquatic food web contamination. We evaluated the utility of estuarine forage fish as biosentinel indicators of local PCB contamination across multiple nearshore sites in San Francisco Bay. Topsmelt (Atherinops affinis) or Mississippi silverside (Menidia audens) contamination was compared between 12 targeted sites near historically polluted locations and 17 probabilistically chosen sites representative of ambient conditions. The average sum of 209 PCB congeners in fish from targeted stations (441 ± 432 ng g^?1 wet weight, mean ± SD) was significantly higher than probabilistic stations (138 ± 94 ng g^?1). Concentrations in both species were comparable to those of high lipid sport fish in the Bay, strongly correlated with spatial patterns in sediment contamination, and above selected literature thresholds for potential hazard to fish and wildlife. The highest concentrations were from targeted Central Bay locations, including Hunter’s Point Naval Shipyard (1347 ng g^?1; topsmelt) and Stege Marsh (1337 ng g^?1; silverside). Targeted sites exhibited increased abundance of lower chlorinated congeners, suggesting local source contributions, including Aroclor 1248. These findings indicate that current spatial patterns in PCB bioaccumulation correlate with historical sediment contamination due to industrial activity. They also demonstrate the utility of naturally occurring forage fish as biosentinels of localized PCB exposure.     

Evaluation of Vegetation Near Coal-burning Power Plants in Southwestern Pennsylvania. II. Ozone Injury on Foliage of Hybrid Poplar

The objective of this study was to determine if the incidence or severity of foliar injury induced by regional, ambient ozone was influenced by local emissions from a complex of coal-burning power plants in southwestern Pennsylvania. Plantings of an ozonesensitive hybrid poplar clone {Populus maximowizii x trichocarpa, clone NE 388) were established in 1972 at various distances and directions from the power plants. Foliar injury caused by ambient ozone was evaluated annually from 1973 to 1990 in early to mid- August. Data are presented for the 12-year period, 1979 to 1990 inclusive, for which the most complete data sets were available. Injury from ambient ozone varied spatially and temporally, but with little relationship to power plant location. There was an apparent negative relationship between emission trends and ozone-induced symptoms, but only for one power plant. The correlation between annual mean levels of ozone-induced stipple and frequency of days (per year) with a 1-hr ozone maximum exceeding 0.04 ppm was weak, but significant. Ozone-induced bifacial necrosis was not observed on the foliage of the hybrid poplar during the drought year of 1988 in spite of record high levels of ozone; however, ozoneinduced stipple was observed.     

Phytoremediation of a Petroleum‐Hydrocarbon Contaminated Shallow Aquifer in Elizabeth City,North Carolina,USA

A former bulk fuel terminal in North Carolina is a groundwater phytoremediation demonstration site where 3,250 hybrid poplars, willows, and pine trees were planted from 2006 to 2008 over approximately 579,000 L of residual gasoline, diesel, and jet fuel. Since 2011, the groundwater altitude is lower in the area with trees than outside the planted area. Soil‐gas analyses showed a 95 percent mass loss for total petroleum hydrocarbons (TPH) and a 99 percent mass loss for benzene, toluene, ethylbenzene, and xylenes (BTEX). BTEX and methyl tert‐butyl ether concentrations have decreased in groundwater. Interpolations of free‐phase, fuel product gauging data show reduced thicknesses across the site and pooling of fuel product where poplar biomass is greatest. Isolated clusters of tree mortalities have persisted in areas with high TPH and BTEX mass. Toxicity assays showed impaired water use for willows and poplars exposed to the site's fuel product, but Populus survival was higher than the willows or pines on‐site, even in a noncontaminated control area. All four Populus clones survived well at the site. © 2014 Wiley Periodicals, Inc.*     

How can public–private partnerships contribute to security and human rights policy and practice in the extractive industries? A case study of The Democratic Republic of Congo (DRC)

Across sub-Saharan Africa, the presence of foreign large-scale mining companies is increasing. This is in part a result of depleting resources in countries such as Canada, United States and Australia, and in part from a more favorable national mine investment climate in several mineral-rich African countries. Their increased presence raises important questions around the potential role and function of Corporate Social Responsibility (CSR) in the sector. In post-conflict and/or fragile states, CSR has further implications for conflict and risk mitigation strategies to ensure the protection of human rights. One CSR approach increasingly being considered is the public–private partnership, whereby companies, public donors, and development agencies leverage their relationships for mutual benefit. There is merit in exploring its function in post-conflict fragile states, where socio-economic needs are high and the capacity of the state to respond to a variety of mine governance challenges is limited. Two case studies from the Democratic Republic of Congo (DRC) are presented, and their policy implications, discussed.     

Radon emissions from natural gas power plants at The Pennsylvania State University

Burning natural gas in power plants may emit radon (²²²Rn) into the atmosphere. On the University Park campus of The Pennsylvania State University, atmospheric radon enhancements were measured and modeled in the vicinity of their two power plants. The three-part study first involved measuring ambient outdoor radon concentrations from August 2014 through January 2015 at four sites upwind and downwind of the power plants at distances ranging from 80 m to 310 m. For each plant, one site served as a background site, while three other sites measured radon concentration enhancements downwind. Second, the radon content of natural gas flowing into the power plant was measured, and third, a plume dispersion model was used to predict the radon concentrations downwind of the power plants. These predictions are compared to the measured downwind enhancements in radon to determine whether the observed radon concentration enhancements could be attributed to the power plants’ emissions. Atmospheric radon concentrations were consistently low as compared to the EPA action level of 148 Bq m^?3, averaging 34.5 ± 2.7 Bq m^?3 around the East Campus Steam Plant (ECSP) and 31.6 ± 2.7 Bq m^?3 around the West Campus Steam Plant (WCSP). Significant concentrations of radon, ranging from 516 to 1,240 Bq m^?3, were detected in the natural gas. The measured enhancements downwind of the ECSP averaged 6.2 Bq m^?3 compared to modeled enhancements of 0.08 Bq m^?3. Measured enhancements around the WCSP averaged ?0.2 Bq m^?3 compared to the modeled enhancements of 0.05 Bq m^?3, which were not significant compared to observational error. The comparison of the measured to modeled downwind radon enhancements shows no correlation over time. The measurements of radon levels in the vicinity of the power plants appear to be unaffected by the emissions from the power plants.

Implications: Radon measurements at sites surrounding power plants that utilize natural gas did not indicate that the radon concentrations originated from the plants’ emissions. There were elevated radon concentrations in the natural gas supply flowing into the power plants, but combustion dilution puts the concentration below EPA action levels coming out of the stack, so no hazardous levels were expected downwind. Power plant combustion of natural gas is not likely to pose a radiation health hazard unless very different gas radon concentrations or combustion dilution ratios are encountered.     

Blowing Smoke in Yellowstone: Air Quality Impacts of Oversnow Motorized Recreation in the Park

Snowmobile use in Yellowstone National Park has been shown to impact air quality, with implications for the safety and welfare of Park staff and other Park resource values. Localized impacts have been documented at several high-use sites in the Park, but the broader spatial variability of snowmobile emissions and air quality was not understood. Measurements of 87 volatile organic compounds (VOCs) were made for ambient air sampled across the Park and West Yellowstone, Montana, during 2 days of the 2002–2003 winter use season, 1 year before the implementation of a new snowmobile policy. The data were compared with similar data from pristine West Coast sites at similar latitudes. Backward trajectories of local air masses, alkyl nitrate-parent alkane ratios, and atmospheric soundings were used to identify the VOC sources and assess their impact. Different oversnow vehicle types used in the Park were sampled to determine their relative influence on air mass pollutant composition. VOCs were of local origin and demonstrated strong spatiotemporal variability that is primarily influenced by levels of snowmobile traffic on given road segments at different times of day. High levels of snowmobile traffic in and around West Yellowstone produced consistently high levels of benzene, toluene, and carbon monoxide.