A Comparison of Alternative Strategies for Cost-Effective Water Quality Management in Lakes

Roughly 45% of the assessed lakes in the United States are impaired for one or more reasons. Eutrophication due to excess phosphorus loading is common in many impaired lakes. Various strategies are available to lake residents for addressing declining lake water quality, including septic system upgrades and establishing riparian buffers. This study examines 25 lakes to determine whether septic upgrades or riparian buffers are a more cost-effective strategy to meet a phosphorus reduction target. We find that riparian buffers are the more cost-effective strategy in every case but one. Large transaction costs associated with the negotiation and monitoring of riparian buffers, however, may be prohibiting lake residents from implementing the most cost-effective strategy. An erratum to this article is available at .     

Use of Airborne γ-Ray Spectrometry for Environmental Assessment of the Rehabilitated Nabarlek Uranium Mine, Australia

This article describes an airborne γ survey of a 7 × 5 km region around the rehabilitated Nabarlek uranium mine in northern Australia. An unusually tight line spacing (100 m) and low aircraft height (50 m) were used, enabling the survey to distinguish man-made structures such as ponds and accommodation areas, as well as creek lines. Positive correlations between airborne data and ground-based readings enabled an estimation of the average absorbed dose rate arising from terrestrial γ radiation over large areas of the site to be derived. For the fenced minesite area this estimate was 0.31 μ Gy hr^{− 1}. The airborne survey data were found to be invaluable in helping to plan further ground-level investigations and showed promise as an assessment tool for rehabilitated minesites.     

Levels of polybrominated diphenyl ethers (PBDEs) in dust from personal automobiles in conjunction with studies on the photochemical degradation of decabromodiphenyl ether (BDE-209)

The levels of 21 PBDE congeners were detemined in the dust sampled from 66 personal automobiles. The dominant congener in automobile dust was BDE-209 with a median level of 8.12 μg g?1. Personal vehicle dust samples contained the characteristic profile of the PBDE congeners that comprise the PentaBDE and DecaBDE commercial formulations. Levels of PBDEs in personal automobiles are generally reduced in comparison to our previously reported levels in resale vehicles on dealership lots presumably due to a dilution effect introduced by dust or debris that does not originate from the vehicle. Laboratory photochemical studies were conducted on both automobile dust collected from personal vehicles as well as BDE-209 adsorbed to sodium sulfate. No significant degradation occurred in the personal vehicle dust after 56 days of constant UVA irradiation while significant degradation did occur with BDE-209 adsorbed to sodium sulfate. PBDEs from the degradation of BDE-209 were identified and potential degradation pathways elucidated. Human exposure potential to PBDEs from automobile dust ingestion remains a serious concern in the U.S. population.     

The possibility of sustainable pest management by introducing bio-diversity: simulations of pest mite outbreak and regulation

Since the late 1980s, spider mite pests have caused serious damage to many moso bamboo (Phyllostachys pubescens) forests in China’s Fujian province. The culms of this plant are an essential component of the building and handicraft industries, and the shoots are a prized food item in many Asian countries. Furthermore, bamboo forests play an important soil conservation role in mountainous areas. We examined pest mite outbreaks in several moso bamboo plantations in Fujian, and could show that a change in cultivation style from polyculture (a kind of mixed forest) to monoculture (all plants other than bamboo were removed) was primarily responsible for the local extinction of an important predaceous mite species. This phenomenon is due to the periodic shedding of leaves by the bamboo, which forces the predator mites occurring on bamboo to switch to prey mite species that occur on other plants. We then tried to elucidate the factors that resulted from such a cultivation change. Adopting a computer simulation approach, we could successfully show that at least two plants, moso bamboo and Chinese silvergrass, are necessary to maintain stable predator–prey interactions in moso forests. That is, systems consisting of one common predator and two host-specific pest mites on different host plant species frequently became stable when the pest mites were at low density. This finding indicates clearly that bio-diversity, even when it consists of only two plants and three mite species as in this study, is necessary for the sustainable regulation of large-scale forests, such as moso bamboo plantations.     

Perceived Collective Efficacy and Trust in Government Influence Public Engagement with Climate Change-Related Water Conservation Policies

Water insecurity, induced or intensified due to climate change, has emerged as a key policy challenge in poor and developing countries such as India. Drawing on social cognitive theory, this paper examines the role of perceived collective efficacy—people's shared beliefs about their group's capabilities to accomplish collective tasks—and trust in government as factors influencing Indians' engagement with government water conservation policies. Using a national survey of Indians (N = 4031), we found that individuals with high levels of perceived collective efficacy and trust in government are more likely to support government water conservation policies. Moreover, for individuals with low trust in government, higher collective efficacy is associated with greater policy support. Perceived collective efficacy is also associated with activist behaviours, while distrust is not. Increasing collective efficacy beliefs, for example through mass media channels and targeted campaigns, could help increase citizens' engagement with climate change adaptation policies.     

Removing cadmium from aqueous solutions utilizing agricultural wastes

The purpose of this study was to determine the cadmium (Cd) biosorption capacities of several agricultural wastes from aqueous solutions. Samples were tested unaltered and after hydrochloric acid treatment. Additional parameters tested include sample dose, contact time, particle size, mixing temperature, and the concentrations and pH of the Cd solutions. Desorption studies were performed to determine if the removed Cd could be recovered. In addition, tests were conducted to determine if the agricultural waste samples (AWS) could be reused for additional Cd biosorption cycles. The results of this study demonstrate a wide range of Cd biosorption proficiencies ranging from 33 to 100% removal. The parameters that resulted in higher Cd removal include higher sample dose, higher pH, and lower Cd solution concentration. Desorption results showed a 36–56% Cd recovery rate. Reused AWS were effective at removing Cd during subsequent trials. Therefore, all AWS types tested in this study can be reused for additional Cd biosorption cycles. Hence, it is possible that using AWS for metal treatment could reduce hazardous waste disposal inefficiencies and costs by avoiding disposing of spent AWS following each Cd biosorption cycle.     

Open-path,closed-path,and reconstructed aerosol extinction at a rural site

The Handix Scientific open-path cavity ringdown spectrometer (OPCRDS) was deployed during summer 2016 in Great Smoky Mountains National Park (GRSM). Extinction coefficients from the relatively new OPCRDS and from a more well-established extinction instrument agreed to within 7%. Aerosol hygroscopic growth (f(RH)) was calculated from the ratio of ambient extinction measured by the OPCRDS to dry extinction measured by a closed-path extinction monitor (Aerodyne’s cavity-attenuated phase shift particulate matter extinction monitor [CAPS PMex]). Derived hygroscopicity (relative humidity [RH] < 95%) from this campaign agreed with data from 1995 at the same site and time of year, which is noteworthy given the decreasing trend for organics and sulfate in the eastern United States. However, maximum f(RH) values in 1995 were less than half as large as those recorded in 2016—possibly due to nephelometer truncation losses in 1995. Two hygroscopicity parameterizations were investigated using high-time-resolution OPCRDS+CAPS PMex data, and the κ_ext model was more accurate than the gamma model. Data from the two ambient optical instruments, the OPCRDS and the open-path nephelometer, generally agreed; however, significant discrepancies between ambient scattering and extinction were observed, apparently driven by a combination of hygroscopic growth effects, which tend to increase nephelometer truncation losses and decrease sensitivity to the wavelength difference between the two instruments as a function of particle size. There was not a statistically significant difference in the mean reconstructed extinction values obtained from the original and the revised IMPROVE (Interagency Monitoring of Protected Visual Environments) equations. On average, IMPROVE reconstructed extinction was ~25% lower than extinction measured by the OPCRDS, which suggests that the IMPROVE equations and 24-hr aerosol data are moderately successful in estimating current haze levels at GRSM. However, this conclusion is limited by the coarse temporal resolution and the low dynamic range of the IMPROVE reconstructed extinction.

Implications: Although light extinction, which is directly related to visibility, is not directly measured in U.S. National Parks, existing IMPROVE protocols can be used to accurately infer visibility for average humidity conditions, but during the large fraction of the year when humidity is above or below average, accuracy is reduced substantially. Furthermore, nephelometers, which are used to assess the accuracy of IMPROVE visibility estimates, may themselves be biased low when humidity is very high. Despite reductions in organic and sulfate particles since the 1990s, hygroscopicity, particles’ affinity for water, appears unchanged, although this conclusion is weakened by the previously mentioned nephelometer limitations.     

Predicting Pesticide Volatility Through Coupled Above- and Belowground Multiphysics Modeling

Pesticides are applied to agricultural fields to control unwanted pests but can volatilize and be transported downwind by wind currents to create the potential for non-target organism exposure. Volatilization rates change through the growing season due to pesticide application timing, meteorological differences, and the differential flux rates from soil and vegetation matrices. Field studies quantifying pesticide volatility are expensive and cannot capture the semi-infinite parameter combinations of soil, crop, management, and meteorological conditions encountered under regional agronomic practices. A numerical approach was used to simulate pesticide dissipation above- and belowground to augment field and laboratory experimental observations. Above- and belowground physics are coupled into a single numerical tool using the COMSOL Multiphysics® software package with the current emphasis on pesticide volatility into air from soil and vegetation and resulting near field neighboring air concentrations. Comparison of simulation results against experimental observations for an insecticide (chlorpyrifos) applied to potato and alfalfa fields shows good agreement (R² 0.68–0.98). Chlorpyrifos volatility from plant surfaces drives the overall volatility within the first several days post application. The maximum volatility flux rate simulated and observed were 0.79 and 0.66 μg m^?2 s^?1 for the alfalfa trial and 2.72 and 2.17 μg m^?2 s^?1 for the potato field, respectively. This coupled multiphysics tool [computational fluid dynamics (CFD), mass transfer coefficients, and variably saturated flow in soil] can be used to estimate volatility flux rates of pesticides when little or no prior knowledge is available and for extrapolating field study observations to different and diverse scenarios.     

Public opinion on climate change: Is there an economy–environment tradeoff?

Does the state of the economy condition public concern for the environment? Scholars have long argued that environmental preferences decline during economic downturns as individuals prioritize short-term economic needs over longer-term environmental concerns. Yet, this assumption has rarely been subjected to rigorous empirical scrutiny at the individual level. The presumed link between economic and environmental preferences is revisited, using the first individual-level opinion panel (n = 1043) of US climate attitudes, incorporating both self-reported and objective economic data. In contrast with prior studies that emphasize the role of economic downturns in driving environmental preference shifts, using a stronger identification strategy, there is little evidence that changes in either individual economic fortunes or local economic conditions are associated with decreased belief that climate change is happening or reduced prioritization of climate policy action. Instead, the evidence suggests that climate belief declines are associated with shifting political cues. These findings have important implications for understanding the dynamics of political conflict over environmental policy globally.