The in situ treatment of BTEX,MTBE, and TBA in saline groundwater

A pilot‐scale test was conducted in a saline aquifer to determine if a petroleum hydrocarbon (PHC) plume containing benzene (B), toluene (T), ethylbenzene (E), xylenes (X), methyl tert‐butyl ether (MTBE), and tert‐butyl alcohol (TBA) could be treated effectively using a sequential treatment approach that employed in situ chemical oxidation (ISCO) and enhanced bioremediation (EBR). Chemical oxidants, such as persulfate, have been shown to be effective in reducing dissolved concentrations of BTEX (B + T + E + X) and additives such as MTBE and TBA in a variety of geochemical environments including saline aquifers. However, the lifespan of the oxidants in saline environments tends to be short‐lived (i.e., hours to days) with their effectiveness being limited by poor delivery, inefficient consumption by nontargeted species, and back‐diffusion processes. Similarly, the addition of electron acceptors has also been shown to be effective at reducing BTEX and associated additives in saline groundwater through EBR, however EBR can be limited by various factors similar to ISCO. To minimize the limitations of both approaches, a pilot test was carried out in a saline unconfined PHC‐impacted aquifer to evaluate the performance of an engineered, combined remedy that employed both approaches in a sequence. The PHC plume had total BTEX, MTBE, and TBA concentrations of up to 4,584; 55,182; and 1,880 μg/L, respectively. The pilot test involved injecting 13,826 L of unactivated persulfate solution (19.4 weight percent (wt.%) sodium persulfate (Na₂S₂O₈) solution into a series of injection wells installed within the PHC plume. Parameters monitored over a 700‐day period included BTEX, MTBE, TBA, sulfate, and sulfate isotope concentrations in the groundwater, and carbon and hydrogen isotopes in benzene and MTBE in the groundwater. The pilot test data indicated that the BTEX, MTBE, and TBA within the PHC plume were treated over time by both chemical oxidation and sulfate reduction. The injection of the unactivated persulfate resulted in short‐term decreases in the concentrations of the BTEX compounds, MTBE, and TBA. The mean total BTEX concentration from the three monitoring wells within the pilot‐test area decreased by up to 91%, whereas MTBE and TBA mean concentrations decreased by up to 39 and 58%, respectively, over the first 50 days postinjection in which detectable concentrations of persulfate remained in groundwater. Concentrations of the BTEX compounds, MTBE, and TBA rebounded at the Day 61 marker, which corresponded to no persulfate being detected in the groundwater. Subsequent monitoring of the groundwater revealed that the concentrations of BTEX continued to decrease with time suggesting that EBR was occurring within the plume. Between Days 51 and 487, BTEX concentrations decreased an additional 84% from the concentration measured on Day 61. Mean concentrations of MTBE showed a reduction during the EBR phase of remediation of 33% while the TBA concentration appeared to decrease initially but then increased as the sulfate concentration decreased as a result of MTBE degradation. Isotope analyses of dissolved sulfate (³⁴S and ¹⁸O), and compound‐specific isotope analysis (CSIA) of benzene and MTBE (¹³C and ²H) supported the conclusions that ISCO and EBR processes were occurring at different stages and locations within the plume over time.     

Fishing‐gear restrictions and biomass gains for coral reef fishes in marine protected areas

Considerable empirical evidence supports recovery of reef fish populations with fishery closures. In countries where full exclusion of people from fishing may be perceived as inequitable, fishing‐gear restrictions on nonselective and destructive gears may offer socially relevant management alternatives to build recovery of fish biomass. Even so, few researchers have statistically compared the responses of tropical reef fisheries to alternative management strategies. We tested for the effects of fishery closures and fishing gear restrictions on tropical reef fish biomass at the community and family level. We conducted 1,396 underwater surveys at 617 unique sites across a spatial hierarchy within 22 global marine ecoregions that represented 5 realms. We compared total biomass across local fish assemblages and among 20 families of reef fishes inside marine protected areas (MPAs) with different fishing restrictions: no‐take, hook‐and‐line fishing only, several fishing gears allowed, and sites open to all fishing gears. We included a further category representing remote sites, where fishing pressure is low. As expected, full fishery closures, (i.e., no‐take zones) most benefited community‐ and family‐level fish biomass in comparison with restrictions on fishing gears and openly fished sites. Although biomass responses to fishery closures were highly variable across families, some fishery targets (e.g., Carcharhinidae and Lutjanidae) responded positively to multiple restrictions on fishing gears (i.e., where gears other than hook and line were not permitted). Remoteness also positively affected the response of community‐level fish biomass and many fish families. Our findings provide strong support for the role of fishing restrictions in building recovery of fish biomass and indicate important interactions among fishing‐gear types that affect biomass of a diverse set of reef fish families.     

A synoptic survey of select wastewater-tracer compounds and the pesticide imidacloprid in Florida’s ambient freshwaters

Current wastewater treatment technologies do not remove many unregulated hydrophilic compounds, and there is growing interest that low levels of these compounds, referred to as emerging contaminants, may impact human health and the environment. A probabilistic-designed monitoring network was employed to infer the extent of Florida’s ambient freshwaters containing the wastewater (Includes reuse water, septic systems leachate, and wastewater treatment effluent.) indicators sucralose, acetaminophen, carbamazepine, and primidone and those containing the widely used pesticide imidacloprid. Extent estimates with 95% confidence bounds are provided for canals, rivers, streams, small and large lakes, and unconfined aquifers containing ultra-trace concentrations of these compounds as based on analyses of 2015 sample surveys utilizing 528 sites. Sucralose is estimated to occur in greater than 50% of the canal, river, stream, and large lake resource extents. The pharmaceuticals acetaminophen, carbamazepine, and primidone are most prevalent in rivers, with approximately 30% of river kilometers estimated to contain at least one of these compounds. Imidacloprid is estimated to occur in 50% or greater of the canal and river resource extents, and it is the only compound found to exceed published toxicity or environmental effects standards. Geospatial analyses show sucralose detection frequencies within Florida’s drainage basins to be significantly related to the percentage of urban land use (R²?=?0.36, p?<?0.001), and imidacloprid detection frequencies to be significantly related to the percentage of urban and agricultural land use (R²?=?0.47, p?<?0.001). The extent of the presence of these compounds highlights the need for additional emerging contaminant studies especially those examining effects on aquatic biota.     

Use of the chemical cleavage of mismatch method for prenatal deficiency diagnosis of alpha-1-antitrypsin

The most common mutation in alpha-1-antitrypsin deficiency, conversion of a G to an A at base 9989 (PI-Z), was detected with the chemical cleavage of mismatch method, demonstrating the power of the method for prenatal diagnosis. Exon V of the gene was amplified using the polymerase chain reaction and heteroduplexes were formed to test for the presence of the mutation. The predicted C mismatch was readily detectable with hydroxylamine, and by making the probe from the chorionic villus sample it was possible to determine that the fetus was heterozygous, not homozygous, for the mutation.     

The in situ treatment of synthetic musk fragrances in groundwater

Synthetic musk fragrances (SMFs) have been shown to be micropollutants in various aquatic and groundwater systems, often occurring at microgram per liter concentrations. Studies have shown that the most commonly detected SMFs in water are nitro musks and polycyclic musks. The SMFs are typically introduced into the environment in continuous streams such as from wastewater and land application of wastewater or sludge generated during wastewater treatment. Various studies for the treatment of SMFs have been undertaken for wastewater but studies for the treatment of SMFs in groundwater are limited, especially for in situ treatment. A pilot‐scale test was conducted to determine if the use of colloidal activated carbon (CAC) could effectively reduce dissolved concentrations of nitro and polycyclic synthetic musk compounds including musk xylene, musk ketone, galaxolide, and tonalide. The pilot test was carried out downgradient of a septic system in Central Canada where a series of nitrification and denitrification reactions are occurring in an unconfined aquifer. A 10‐weight percent CAC solution was injected into a series of temporary direct push injection points to target the synthetic musk plume. The plume contained galaxolide and tonalide concentrations up to 687 and 187 nanograms per liter (ng/L), respectively, while the concentrations of musk ketone and musk xylene were below the method detection limit (20 ng/L). A total of 13,950 liters of CAC solution was injected during one injection event. The pilot test results indicated that the CAC was effectively delivered to the target injection zone resulting in an increase in total organic carbon concentrations within the saturated soil greater than two orders of magnitude compared to the background concentrations. Analyses of the groundwater chemistry before and post‐injection indicated that the CAC had no detrimental impact on the groundwater quality while reducing the concentration of dissolved galaxolide and tonalide within the plume to below the method detection limits within 51 days of injection with the exception of two of the 14 wells monitored which had galaxolide and tonalide concentrations up to 78 and 35 ng/L. Within 6 months of application, the concentrations of galaxolide and tonalide had decreased to below the method detection limits. Subsequent monitoring of the groundwater quality over a one‐year period failed to detect galaxolide and tonalide, suggesting that the CAC was effective in attenuating the galaxolide and tonalide.     

The reduction of internal phosphorus loading using alum in Spring Lake, Michigan

The release of P from lake sediments, which occurs as a part of internal loading, may contribute a significant portion of the total P load to a lake. Phosphorus release rates from sediments in Spring Lake, Michigan, and the degree to which alum reduces P release from these sediments, were investigated during the summer of 2003. Triplicate sediment cores were sampled from four sites in the lake, and exposed to one of four treatments in the laboratory: (i) aerobic water column/alum, (ii) aerobic water column/no alum, (iii) anaerobic water column/alum, or (iv) anaerobic water column/no alum. Total P (TP) release rates were virtually undetectable in the alum treatments (both aerobic and anaerobic). Low, but detectable, release rates were measured in the aerobic/no alum treatment. The highest release rates were measured in the anaerobic/no alum treatments, and ranged from 1.6 to 29.5 mg P m(-2) d(-1) depending on how the calculations were derived. These fluxes translated to mean internal loads that ranged between 2.7 (low range) and 6.4 (high range) Mg yr(-1) when extrapolated to a whole-lake basis. Internal P loads accounted for between 55 and 65% of the total P load to Spring Lake. Although alum is a potentially effective means of reducing the sediment source of P, there is considerable uncertainty in how long an alum treatment would remain effective in this system given the current rates of external loading and the lack of information on wind-wave action and bioturbation in Spring Lake.     

Mitigation of odor causing emissions—Bench-scale investigation

Emissions of malodors are considered to be the greatest threat to the compost industry. In work presented here, several simple odor mitigation alternatives were investigated for their effectiveness in preventing the release of common odorants, such as terpenes, ammonia, and reduced sulfur compounds. The mitigation methods studied included the use of a blanket of finished compost, compost amendment mixed within the feedstock, odor neutralizing agents (ONAs), and oxygen release compounds (ORCs). Among the mitigation alternatives investigated in this study, the use of finished compost as a blanket and finished compost as an amendment yielded the most conclusive and significant results. Both of these alternatives yielded a substantial emission reduction for terpenes, ammonia, and reduced sulfur compounds. The application of finished compost blanket resulted in up to 95% reduction of terpene and 25% reduction of ammonia emissions. Blending the feedstock with finished compost also provided substantial reduction of terpene emissions ranging from 73.6 to 93.1% at the 24% blending ratio, and up to 85% ammonia reduction a the 35% blending ratio. Use of finished compost also provided 75% lower reduced sulfur compound emissions at the 12% blending ratio. Misting and application of odor neutralizing agents did not result in any consistent reduction in emissions for any of the odorous compounds tested.

Implications The odor emissions from composting are often considered to be the biggest threat to composting facilities. Because most facilities cannot afford enclosures and contained composting vessels, there is a need to inexpensively and effectively control the odor emissions from composting facilities. The findings of this research can lead the way for efforts to control odor easily and cost effectively. In fact, the application of a compost blanket for odor control is already gaining acceptance by the composting industry.     

Ultrafine particle fluxes above four major European cities

Little information is known about the behaviour of ultrafine particles (UFP) on a citywide scale. Total particle number flux, dominated by UFP, and other meteorological parameters were collected from tower sites in Manchester, London, Edinburgh and Gothenburg between 1999 and 2006 using the eddy covariance technique. Averaged diurnal cycles were produced for particle number flux, concentration, sensible heat flux, emission velocity, friction velocity, wind speed and temperature. UFP flux cycles showed clear diurnal trends which were linked to traffic activity and local sources. Wind sector analysis showed contributions to flux from local heavily urbanised areas. A simple parameterised model linking UFP flux to traffic activity, sensible heat and friction velocity above the city was produced.     

Application of Zoning and “Limits of Acceptable Change” to Manage Snorkelling Tourism

Zoning and applying Limits of Acceptable Change (LAC) are two promising strategies for managing tourism in Marine Protected Areas (MPAs). Typically, these management strategies require the collection and integration of ecological and socioeconomic data. This problem is illustrated by a case study of Koh Chang National Marine Park, Thailand. Biophysical surveys assessed coral communities in the MPA to derive indices of reef diversity and vulnerability. Social surveys assessed visitor perceptions and satisfaction with conditions encountered on snorkelling tours. Notably, increased coral mortality caused a significant decrease in visitor satisfaction. The two studies were integrated to prescribe zoning and “Limits of Acceptable Change” (LAC). As a biophysical indicator, the data suggest a LAC value of 0.35 for the coral mortality index. As a social indicator, the data suggest that a significant fraction of visitors would find a LAC value of under 30 snorkellers per site as acceptable. The draft zoning plan prescribed four different types of zones: (I) a Conservation Zone with no access apart from monitoring or research; (II) Tourism Zones with high tourism intensities at less vulnerable reefs; (III) Ecotourism zones with a social LAC standard of <30 snorkellers per site, and (IV) General Use Zones to meet local artisanal fishery needs. This study illustrates how ecological and socioeconomic field studies in MPAs can be integrated to craft zoning plans addressing multiple objectives.