Arsenic speciation of atmospheric particulate matter (PM10) in an industrialised urban site in southwestern Spain

An arsenic speciation study has been performed in PM10 samples collected on a fortnight basis in the city of Huelva (SW Spain) during 2001 and 2002. The arsenic species were extracted from the PM10 filters using a NH2OH x HCl solution and sonication, and determined by HPLC-HG-AFS. The mean bulk As concentration of the samples analyzed during 2001 and 2002 slightly exceed the mean annual 6 ng m(-3) target value proposed by the European Commission for 2013, arsenate [As(V)] being responsible for the high level of arsenic. The speciation analyses showed that As(V) was the main arsenic species found, followed by arsenite [As(III)] (mean 6.5 and 7.8 ng m(-3) for As(V), mean 1.2 and 2.1 ng m(-3) for As(III), in 2001 and 2002, respectively). The high levels of arsenic species found in PM10 in Huelva have a predominant industrial origin, such as the one from a nearby copper smelter, and do not present a seasonal pattern. The highest daily levels of arsenic species correspond to synoptic conditions in which the winds with S and SW components transport the contaminants from the main emission source. The frequent African dust outbreaks over Huelva may result in an increment of mass levels of PM10, but do not represent a significant input of arsenic in comparison to the anthropogenic source. The rural background levels of arsenic around Huelva are rather high, in comparison to other rural or urban areas in Spain, showing a relatively high atmosphere residence time of arsenic. This work shows the importance of arsenic speciation in studies of aerosol chemistry, due to the presence of arsenic species [As(III) and As(V)] with distinct toxicity.     

Groundwater-surface water interaction and its role on TCE groundwater plume attenuation

A field investigation of a TCE plume in a surficial sand aquifer shows that groundwater-surface water interactions strongly influence apparent plume attenuation. At the site, a former industrial facility in Connecticut, depth-discrete monitoring along three cross-sections (transects) perpendicular to groundwater flow shows a persistent VOC plume extending 700 m from the DNAPL source zone to a mid-size river. Maximum TCE concentrations along a transect 280 m from the source were in the 1000s of microg/L with minimal degradation products. Beyond this, the land surface drops abruptly to a lower terrace where a shallow pond and small streams occur. Two transects along the lower terrace, one midway between the facility and river just downgradient of the pond and one along the edge of the river, give the appearance that the plume has strongly attenuated. At the river, maximum TCE concentrations in the 10s of microg/L and similar levels of its degradation product cis-DCE show direct plume discharge from groundwater to the river is negligible. Although degradation plays a role in the strong plume attenuation, the major attenuation factor is partial groundwater plume discharge to surface water (i.e. the pond and small streams), where some mass loss occurs via water-air exchange. Groundwater and stream mass discharge estimates show that more than half of the plume mass discharge crossing the first transect, before surface water interactions occur, reaches the river directly via streamflow, although river concentrations were below detection due to dilution. This study shows that groundwater and surface water concentration measurements together provide greater confidence in identifying and quantifying natural attenuation processes at this site, rather than groundwater measurements alone.     

Environmental hazard screening of a metal-polluted site using pressurized liquid extraction and two in vitro bioassays

Rapid screening methods can improve the cost effectiveness, throughput, and quality of risk assessments of contaminated sites. In the present case study, the objective was to evaluate a combination of pressurized liquid extraction and 2 in vitro bioassays for the hazard assessment of surface soil sampled from 46 points across a pyrotechnical industrial site. Pressurized liquid extraction was used to rapidly produce soil-water extracts compatible with 2 high-capacity bioassays. Hazard assessment using combined toxicological and chemical screening revealed zones with relatively high potential risks of metal pollution. Multivariate data analysis provided indications that significant inhibition in the bioassays was correlated with levels of metals in the extracts, suggesting an elevated toxic potential from certain metals. Low pH and high concentrations of dissolved organic carbon were associated with increased cytotoxicity of extracts, indicating that these factors influence metal bioavailability. The cytotoxicity observed was more strongly correlated to metal concentrations in the extracts than in the soil, suggesting that measurements of total metal concentrations in soils do not provide good indications of the soil's potential toxicity.     

Cadmium concentrations in tissues of willow ptarmigan (Lagopus lagopus) and rock ptarmigan (Lagopus muta) in Nunavik, Northern Québec

Willow and rock ptarmigan were obtained from Northern Québec. Willow ptarmigan were found to have mean cadmium concentrations of 179.7 microg/g (dw) in the kidneys and 25.8 microg/g (dw) in the liver; these levels were three times higher than those found in the rock ptarmigan. The cadmium levels in the ptarmigan were below the threshold above which adverse effects can be observed in birds. The difference between the two ptarmigan species in cadmium content is explained by the diet. A comparison of their diet showed that willow, which stores cadmium, is an important food resource for willow ptarmigan but not for rock ptarmigan. Because there is limited information available on the consumption of ptarmigan kidneys and liver by the Inuit, and the fact that this is a traditional way of life and provides nutritional benefits to the Inuit population, no consumption guidelines are proposed.     

Field demonstration of visible opacity photographic systems

The Digital Opacity Compliance System (DOCS) is an innovative method that uses digital imaging technology to quantify visible opacity of stationary sources. DOCS, which has been demonstrated at pilot and full scale as a technically defensible and economically attractive alternative to U.S. Environmental Protection Agency (EPA) Reference Method 9 (Method 9), uses commercial-off-the-shelf (COTS) digital cameras in combination with a user-friendly computer software package to determine opacity. To date, all DOCS field testing has been conducted using two models of digital cameras, notably, Kodak Models DC265 and DC290, both of which are no longer commercially available. To ensure that field-validated digital cameras will be available to future DOCS users, a suite of new digital cameras was evaluated with the opacity determination software including the following: (1) Sony Model Cybershot Model DSC-WI, (2) Nikon Model Coolpix 5200, (3) Fuji Finepix Model E500, and (4) Kodak Model DX6490. Within the opacity range of regulatory interest, that is, 0-40%, the Sony Cybershot Model DSC-WI and Nikon Coolpix Model 5200 digital cameras were found to generate plume photographs of which the DOCS opacity analysis yielded results that were statistically equivalent to the previously field-validated Kodak Model DC290. In contrast, the Fuji Finepix Model E500 generated plume photographs of which the DOCS opacity analysis were, on average, 2.2% less than those generated by the Kodak Model DC290 photographs, a difference that was determined to be statistically significant. Over the same opacity range, photographs taken by the Kodak Model DX6490 yielded DOCS opacity readings that were found to be statistically equivalent to a Method 9-certified transmissometer. Based on the results from the current digital camera validation testing approach, EPA has developed a new camera-based visible opacity measurement method titled "Determination of Visible Emission Opacity from Stationary Sources Using Computer-Based Photographic Analysis Systems." The proposed method is expected to be promulgated after closure of the public comment period.     

Resource frontiers and agglomeration economies: The varied logics of transnational land-based investing in Southern and Eastern Africa

Actor-level data on large-scale commercial agriculture in Sub-Saharan Africa are scarce. The peculiar choice of transnational investing in African land has, therefore, been subject to conjecture. Addressing this gap, we reconstructed the underlying logics of investment location choices in a Bayesian network, using firm- and actor-level interview and spatial data from 37 transnational agriculture and forestry investments across 121 sites in Mozambique, Zambia, Tanzania, and Ethiopia. We distinguish four investment locations across gradients of resource frontiers and agglomeration economies to derive the preferred locations of different investors with varied skillsets and market reach (i.e., track record). In contrast to newcomers, investors with extensive track records are more likely to expand the land use frontier, but they are also likely to survive the high transaction costs of the pre-commercial frontier. We highlight key comparative advantages of Southern and Eastern African frontiers and map the most probable categories of investment locations.Supplementary informationThe online version contains supplementary material available at 10.1007/s13280-021-01682-z.     

GROUNDWATER DISCHARGE AND ITS IMPACT ON SURFACE WATER QUALITY IN A CHESAPEAKE BAY INLET1

ABSTRACT: Surface water, groundwater, and groundwater discharge quality surveys were conducted in Cherrystone Inlet, on Virginia's Eastern Shore. Shallow groundwater below agricultural fields had nitrate concentrations significantly higher than inlet surface waters and shallow groundwater underlying forested land. This elevated nitrate groundwater discharged to adjacent surface waters. Nearshore discharge rates of water across the sediment-water interface ranged from 0.02 to 3.69 liters·m^?2·hr^?1 during the surveys. The discharge was greatest nearshore at low tide periods, and decreased markedly with increasing distance offshore. Vertical hydraulic heads, E_h, and inorganic nitrogen flux in the sediments followed similar patterns. Nitrate was the predominant nitrogen species discharged nearshore adjacent to agricultural land use, changing to ammonium farther offshore. Sediment nitrogen fluxes were sufficient to cause observable impacts on surface water quality; nitrate concentrations were up to 20 times greater in areas of groundwater discharge than in the main stem inlet water. Based on DIN:DIP ratios, nitrogen contributions from direct groundwater discharge and tidal creek inputs appear to be of significant ecological importance. This groundwater discharge links land use activity and the quality of surface water, and therefore must be considered in selection of best management practices and water quality management strategies.     

Shifts in foraging behavior by a Battus philenor population: field evidence for switching by individual butterflies

Summary A bivoltine east Texas population of the pipevine swallowtail butterfly (Battus philenor) exhibits a seasonal shift in the shapes of non-host leaves upon which ovipositing females land. Field mark-recapture studies and analysis of the behavior of wild females of different ages were used to distinguish between two alternative mechanisms for the shift in the populations's predominant leaf-shape search mode: seasonal differences in the outcome of learning for successively emerging naive foragers which exhibit one preference for most of their lives vs. synchronous switching by experienced foragers from one learned preference to another. Results supported each hypothesis: (1) Since wild butterflies are short-lived, the seasonal shift in searching behavior must reflect at least partly the successive emergence of naive females that learn to prefer host species with different leaf shapes. The leaf-shape preferences of older females were, in fact, stronger and less variable than those of younger individuals. About 80% of 51 marked individuals maintained stable leaf-shape search modes over recapture events, exhibiting slightly stronger preferences in later observation periods. (2) Almost 16% of marked females switched search modes across recapture events. Unmarked females sometimes switched search modes within an observation period; switching occurred only after the discovery of the host species with a leaf shape differing from that originally preferred. Switching by individual butterflies was generally more frequent at the time an adult brood shifted from one dominant search mode to another. Individual switching within an adult brood was more common in those years in which the population's shift in predominant search mode occurred during that brood.The evolution of rapid learning by naive females and conservative switching by experienced females is discussed in relation to a quantitative model of switching dynamics.