Offsetting impacts of development on biodiversity and ecosystem services

Ambio - Offsetting—trading losses in one place for commensurate gains in another—is a tool used to mitigate environmental impacts of development. Biodiversity and carbon are the most...     

Assessing biodegradation potential of PAHs in complex multi-contaminant matrices

This study sought to extend validation of a cyclodextrin based extraction method for the assessment of PAH-biodegradation potential to complex multi-contaminant matrices. To this end, four reference materials (RMs) were produced by blending, in different proportions, soils impacted with diesel, lubricating oil and spent oxide. These reference materials had modest ∑PAH (16 US EPA) concentrations that ranged from 5.6 ± 0.5 to 44.4 ± 4.5 mg kg⁻¹. However, extractable petroleum hydrocarbon (EPH) concentrations were comparatively high (up to 2520 ± 204 mg kg⁻¹). To complement these RMs, two further soils from a municipal gas plant (MGP) with highly elevated concentration of PAHs ranging from 877 ± 52 to 2620 ± 344 mg kg⁻¹ were also tested. Results showed, regardless of matrix complexity, that PAH biodegradation within the four RM substrates, and two MGP soils correlated well with biodegradation predicted by hydroxypropyl-β-cyclodextrin (HPCD) extraction.     

Reducing Livestock Effects on Public Lands in the Western United States as the Climate Changes: A Reply to Svejcar et al

Svejcar et al. (Environ Manage, 2014) offered several perspectives regarding Beschta et al. (Environ Manage 51:474–491, 2013)—a publication that addressed the interacting ecological effects of climate change and domestic, wild, and feral ungulates on public lands in the western United States (US)—by largely focusing on three livestock grazing issues: (1) legacy versus current day impacts; (2) grazing as a fire reduction tool; and (3) the complexity of grazing. Regarding these issues, we indicate that (1) legacy effects to western ecosystems were indeed significant and contemporary livestock use on public lands generally maintains or exacerbates many of those effects; (2) livestock grazing has been a major factor affecting fire frequency, fire severity, and ecosystem trajectories in the western US for over a century; and (3) the removal or reduction of grazing impacts in these altered ecosystems is the most effective means of initiating ecological recovery. Svejcar et al. (Environ Manage, 2014) offer no evidence that livestock use is consistent with the timely recovery of grazing-degraded uplands, riparian areas, or stream systems. We thus conclude that public-land ecosystems can best persist or cope with a changing climate by significantly reducing ungulate grazing and related impacts.     

Acid rain and drinking water degradation

Acid deposition-induced drinking water degradation is discussed with respect to the geographical extent of and the potential for dealing with possibly adverse human health impacts. Qualitative evidence from the northeastern United States and Sweden strongly suggests the existence of a linkage between these two environmental concerns. It is argued that water treatment and reduction of acid rain as solutions to the problem of water toxicity need closer evaluation. More research into the causal link is warranted since the addition of human health impacts to acid rain's environmental insults could have a significant bearing on discussions relating to acid rain controls.The National Center for Atmospheric Research is operated by the University Corporation for Atmospheric Research and is sponsored by the National Science Foundation.     

Small farm ponds: overlooked features with important impacts on watershed sediment transport

Despite their size, small farm ponds are important features in many landscapes. Yet hydrographical databases often fail to capture these ponds, and their impacts on watershed processes remain unclear. For a 230‐km² portion of central Texas, United States (U.S.), we created a historical inventory of ponds and quantified the accuracy of automated detection methods under varying drought conditions. In addition, we documented pond dredging/enlargement events and identified sites that had been abandoned. We also analyzed sediment cores from downstream reservoirs to track changes in watershed sediment transport. Over 75 years, pond densities increased more than 350% — to among the highest documented in the U.S. — and the ability of automated methods to detect these ponds was highly dependent on drought severity (R² = 0.96). Approximately 5% of ponds present in the 1950s were no longer present in 2012, while 33% were dredged between 1937 and 2012. Downstream reservoir sedimentation has decreased by an average of 55% as ponds have increased in number. These findings suggest that small ponds and the maintenance of trapping efficiency have large‐scale impacts on sediment dynamics. Accurately accounting for these storage effects is vital to water resource planning efforts.     

Fate and behaviour of phenanthrene in the natural and artificial soils

For the assessment of contaminated soils ecotoxicological tests are used to estimate the bioavailability of contaminants in soil samples. Terrestrial tests reveal the habitat function of soils, and parameters applied in tests involving microorganisms include respiration activity and potential ammonium oxidation. For such tests, the threshold values needed to assess the results have already been established in guidelines ISO 17155 and ISO 15685. In this paper, we discuss about the respiration activity and potential ammonium oxidation results obtained from a wide variety of soils with different physico-chemical properties and levels of contamination. These results show that microbial respiration and potential ammonium oxidation have different sensitivities to various classes of contaminants. We demonstrated that both organic and inorganic contaminants influence potential ammonium oxidation, whereas microbial respiration is predominantly affected by biodegradable organic contaminants. These differences might be useful for more detailed assessments of soil contamination, leading to different recommended actions depending on which parameter is affected.     

Use of surrogate species to cost-effectively prioritize conservation actions

Conservation efforts often focus on umbrella species whose distributions overlap with many other flora and fauna. However, because biodiversity is affected by different threats that are spatially variable, focusing only on the geographic range overlap of species may not be sufficient in allocating the necessary actions needed to efficiently abate threats. We developed a problem-based method for prioritizing conservation actions for umbrella species that maximizes the total number of flora and fauna benefiting from management while considering threats, actions, and costs. We tested our new method by assessing the performance of the Australian federal government's umbrella prioritization list, which identifies 73 umbrella species as priorities for conservation attention. Our results show that the federal government priority list benefits only 6% of all Australia's threatened terrestrial species. This could be increased to benefit nearly half (or 46%) of all threatened terrestrial species for the same budget of AU$550 million/year if more suitable umbrella species were chosen. This results in a 7-fold increase in management efficiency. We believe nations around the world can markedly improve the selection of prioritized umbrella species for conservation action with this transparent, quantitative, and objective prioritization approach.     

Linking desorption kinetics to phenanthrene biodegradation in soil

The desorption of polycyclic aromatic hydrocarbons (PAHs) often exhibits a biphasic profile similar to that observed for biodegradation whereby an initial rapid phase of degradation or desorption is followed by a phase of much slower transformation or release. Most investigations to-date have utilised a polymeric sorbent, such as Tenax, to characterise desorption, which is methodologically unsuitable for the analysis of soil. In this study, desorption kinetics of ¹⁴C-phenanthrene were measured by consecutive extraction using aqueous solutions of hydroxypropyl-β-cyclodextrin (HPCD). The data indicate that the fraction extracted after 24 h generally approximated the linearly sorbed, rapidly desorbing fraction (F_rap), calculated using a three-compartment model. A good linear correlation between phenanthrene mineralised and F_rap was observed (r² = 0.89; gradient = 0.85; intercept = 8.20). Hence HPCD extraction (24 h) and first-order three-compartment modelling appear to provide an operationally straightforward tool for estimating mass-transfer limited biodegradation in soil.     

Stratospheric Ozone Protection: An EPA Engineering Perspective

Chlorine released into the atmosphere is a major factor in the depletion of the protective stratospheric ozone layer. The Montreal Protocol, as amended in 1990, and the Clean Air Act Amendments of 1990, address the limits and reduction schedules to be placed on chlorine- and bromine-containing chemicals. The status of technical solutions to the problem of chlorofluorocarbons, halons, methyl chloroform, and carbon tetrachloride in the major use areas of refrigeration, foam, aerosols, fire protection, and solvents is discussed here. The discussion includes the cooperative efforts involving academia, industry, U.S. governmental organizations, and other nations who are contributing solutions to these problems.