Assessing the Effects of Alternative Setback Channel Constraint Scenarios Employing a River Meander Migration Model

River channel migration and cutoff events within large river riparian corridors create heterogeneous and biologically diverse landscapes. However, channel stabilization (riprap and levees) impede the formation and maintenance of riparian areas. These impacts can be mitigated by setting channel constraints away from the channel. Using a meander migration model to measure land affected, we examined the relationship between setback distance and riparian and off-channel aquatic habitat formation on a 28-km reach of the Sacramento River, California, USA. We simulated 100 years of channel migration and cutoff events using 11 setback scenarios: 1 with existing riprap and 10 assuming setback constraints from about 0.5 to 4 bankfull channel widths (bankfull width: 235 m) from the channel. The percentage of land reworked by the river in 100 years relative to current (riprap) conditions ranged from 172% for the 100-m constraint setback scenario to 790% for the 800-m scenario. Three basic patterns occur as the setback distance increases due to different migration and cutoff dynamics: complete restriction of cutoffs, partial restriction of cutoffs, and no restriction of cutoffs. Complete cutoff restriction occurred at distances less than about one bankfull channel width (235 m), and no cutoff restriction occurred at distances greater than about three bankfull widths (∼700 m). Managing for point bars alone allows the setbacks to be narrower than managing for cutoffs and aquatic habitat. Results suggest that site-specific “restriction of cutoff” thresholds can be identified to optimize habitat benefits versus cost of acquired land along rivers affected by migration processes.     

Estimating plant-available nitrogen release from manures, composts, and specialty products

Recent adoption of national rules for organic crop production have stimulated greater interest in meeting crop N needs using manures, composts, and other organic materials. This study was designed to provide data to support Extension recommendations for organic amendments. Specifically, our objectives were to (i) measure decomposition and N released from fresh and composted amendments and (ii) evaluate the performance of the model DECOMPOSITION, a relatively simple N mineralization/immobilization model, as a predictor of N availability. Amendment samples were aerobically incubated in moist soil in the laboratory at 22 degrees C for 70 d to determine decomposition and plant-available nitrogen (PAN) (n = 44), and they were applied preplant to a sweet corn crop to determine PAN via fertilizer N equivalency (n = 37). Well-composted materials (n = 14) had a single decomposition rate, averaging 0.003 d(-1). For uncomposted materials, decomposition was rapid (>0.01 d(-1)) for the first 10 to 30 d. The laboratory incubation and the full-season PAN determination in the field gave similar estimates of PAN across amendments. The linear regression equation for lab PAN vs. field PAN had a slope not different from one and a y-intercept not different than zero. Much of the PAN released from amendments was recovered in the first 30 d. Field and laboratory measurements of PAN were strongly related to PAN estimated by DECOMPOSITION (r(2) > 0.7). Modeled PAN values were typically higher than observed PAN, particularly for amendments exhibiting high initial NH(4)-N concentrations or rapid decomposition. Based on our findings, we recommend that guidance publications for manure and compost utilization include short-term (28-d) decomposition and PAN estimates that can be useful to both modelers and growers.     

Bioconversion of selenate in methanogenic anaerobic granular sludge

The capacity of anaerobic granular sludge to remove selenate from contaminated wastewater was investigated. The potential of different types of granular sludge to remove selenate from the liquid phase was compared to that of suspended sludge and contaminated soil and sediment samples. The selenate removal rates ranged from 400 to 1500 microg g VSS(-1) h(-1), depending on the source of biomass, electron donor, and the initial selenate concentration. The granular structure protects the microorganisms when exposed to high selenate concentrations (0.1 to 1 mM). Anaerobic granular sludge "Eerbeek," originating from a UASB reactor treating paper mill wastewater, removed about 90, 50, and 36% of 0.1, 0.5, and 1 mM of Se, respectively, from the liquid phase when incubated with 20 mM lactate at 30 degrees C and pH 7.5. Selenite, elemental Se (Se(o)), and metal selenide precipitates were the conversion products. Enrichments from the anaerobic granular sludge "Eerbeek" were able to convert 90% of the 10-mM selenate to Se(o) at a rate of 1505 microg Se(VI) g cells(-1) h(-1), a specific growth rate of 0.0125 g cells h(-1), and a yield of 0.083 g cells mg Se(-1). Both microbial metabolic processes (e.g dissimilatory reduction) as well as microbially mediated physicochemical mechanisms (adsorption and precipitation) contribute to the removal of selenate from the Se-containing medium.     

Environmental Justice 2.0: new Latino environmentalism in Los Angeles

This paper presents the results of ethnographic research conducted with several environmental justice (EJ) organisations in Latino communities of Los Angeles, California. Traditional EJ politics revolves around research and advocacy to reduce discriminatory environmental exposures, risks, and impacts. However, I argue that in recent years there has been a qualitative change in EJ politics, characterised by four main elements: (1) a move away from the reaction to urban environmental “bads” (e.g. polluting industries) in the city towards a focus on the production of nature in the city; (2) strategies that are less dependent on the legal, bureaucratic, and technical “regulatory route”; (3) the formation of a distinctive “Latino environmental ethic” that offers a more complex consideration of the place of race in EJ organising; and (4) a spatial organisation of EJ politics that moves away from hyperlocal, vertical organisation towards diversified city-wide networks that include EJ organisations, mainstream environmental groups, nonprofits, foundations, and entrepreneurs. This shift in EJ movement politics is shaped by broader political-economic changes, including the shift from post-Fordist to neoliberal and now green economy models of urban development; the influence of neoliberal multiculturalism in urban politics; and the increasingly prominent role of Latinos in city, state, and national politics. New spaces of Latino EJ also reflect the ambitions of Los Angeles as a global city, with urban growth increasingly framed in an international discourse of sustainability that combines quality of life, environmental, and economic development rationales.     

Characterization of coffee residues pellets and their performance in a residential combustor

Spent coffee grounds (SCG) and coffee husks (CH) were evaluated as biofuels, after densification, for energy production. CH represent a specific problem for the coffee industry due to a low calorific value, high ash content, and a very low bulk density. Hence, the energetic potential of SCG (95 wt%)/CH (5 wt%) blend and pure SCG (100%) were examined. The blend of SCG and CH was limited to 5 wt% of CH because of the low bulk density of CH. Therefore, physicochemical and energetic characterizations of the produced pellets were performed. Thermogravimetric analyses were performed under nitrogen and air atmospheres to evaluate the CH behavior in the blend. Characterization study shows that both produced pellets could reach the French Agropellets standard (AQI). Thermal degradation showed that the mean reactivity of the SCG/HC pellets was higher than pure SCG. Then, combustion experiments were performed in a domestic combustor, after modification of the boiler power in order to improve its energetic performances. The presence of CH led to a rise of CO, NOx, VOC’s, and particle emissions. Nevertheless, the performances of the biofuels are almost in agreement the NF EN 12809 standard.     

Molecular tools for bathing water assessment in Europe: Balancing social science research with a rapidly developing environmental science evidence-base

The use of molecular tools, principally qPCR, versus traditional culture-based methods for quantifying microbial parameters (e.g., Fecal Indicator Organisms) in bathing waters generates considerable ongoing debate at the science–policy interface. Advances in science have allowed the development and application of molecular biological methods for rapid (~2 h) quantification of microbial pollution in bathing and recreational waters. In contrast, culture-based methods can take between 18 and 96 h for sample processing. Thus, molecular tools offer an opportunity to provide a more meaningful statement of microbial risk to water-users by providing near-real-time information enabling potentially more informed decision-making with regard to water-based activities. However, complementary studies concerning the potential costs and benefits of adopting rapid methods as a regulatory tool are in short supply. We report on findings from an international Working Group that examined the breadth of social impacts, challenges, and research opportunities associated with the application of molecular tools to bathing water regulations.     

In situ immobilization of cadmium in soil by stabilized biochar-supported iron phosphate nanoparticles

The potential for nanoscale phosphate amendments to remediate heavy metal contamination has been widely investigated, but the strong tendency of nanoparticles to form aggregates limits the application of this technique in soil. This study synthesized a composite of biochar-supported iron phosphate nanoparticle (BC@Fe₃(PO₄)₂) stabilized by a sodium carboxymethyl cellulose to improve the stability and mobility of the amendment in soil. The sedimentation test and column test demonstrated that BC@Fe₃(PO₄)₂ exhibited better stability and mobility than iron phosphate nanoparticles. After 28 days of simulated in situ remediation, the immobilization efficiency of Cd was 60.2 %, and the physiological-based extraction test bioaccessibility was reduced by 53.9 %. The results of sequential extraction procedures indicated that the transformation from exchangeable (EX) Cd to organic matter (OM) and residue (RS) was responsible for the decrease in Cd leachability in soil. Accordingly, the pot test indicated that Cd uptake by cabbage mustard was suppressed by 86.8 %. Compared to tests using iron phosphate nanoparticles, the addition of BC@Fe₃(PO₄)₂ to soil could reduce the Fe uptake of cabbage mustard. Overall, this study revealed that BC@Fe₃(PO₄)₂ could provide effective in situ remediation of Cd in soil.     

Forest protection and economic development by offshoring wood extraction: Bhutan’s clean development path

With globalization, virtual exchanges of natural resources embodied in traded commodities redistribute geographically land use and its environmental impacts. Benefits of national forest protection may be undermined at the global-scale by leakage through international trade. We studied land use displacement associated with national policies to protect forests in Bhutan. This case study provides a simple situation: a dominant forest cover almost unaffected by agricultural expansion, a rural economy dominated by the primary sector, centralized forest conservation policies, and a dominant trading partner. We assessed the net effects at the international level of the Bhutanese forest protection policies by accounting for trade in wood products with India. Our results show that these policies have been effective in maintaining a high forest cover, but have been accompanied by an increasing displacement of forest use to India. In 1996–2011, the difference between the total volume of wood imported from India and the total volume exported from Bhutan—i.e., the net displacement—corresponds to 27 % of the total volume consumed in Bhutan. In 2011, 68 % of the total forest area required to produce the wood consumed in Bhutan was located in India. The wood imported by Bhutan was likely originating from tree plantations in the northeastern Indian states. Since Bhutan has few tree plantations and very valuable natural forests, the net international-level ecological impacts of this land use displacement is arguably positive. Most of the wood imports of Bhutan were wood charcoal for its emerging chemical industries. This case of displacement reflects functional upgrading in the value-chain rather than an externalization of consumption-based environmental costs. Through its government policies, Bhutan has managed to support its economic development while protecting its forests and leapfrogging the negative impacts on forests generally associated with the early stages of modernization.     

Pyrolysis of permethrin and formation of precursors of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/F) under non-oxidative conditions

This article reports the computational and experimental results of the thermal decomposition of permethrin, a potential source of dibenzo-p-dioxins (PCDD) and polychlorinated dibenzofurans (PCDF). We have performed a quantum chemical analysis by applying density functional theory to obtain the decomposition pathways of permethrin and the formation mechanism of dibenzofuran. We have conducted the pyrolysis experiments in a tubular reactor and identified the pyrolysis products to demonstrate the agreement between the experimental measurements and quantum chemical calculations. The initiation of the decomposition of permethrin involves principally the aromatisation of permethrin into 3-phenoxyphenylacetic acid, 2-methylphenyl ester (J) and concomitant loss of 2HCl. This rearrangement is followed by the rupture of the O–CH₂ linkage in J, with a rate constant derived from the quantum chemical results of 1 × 10¹⁵ exp(−68 kcal/mol/RT) s⁻¹ for temperatures between 700 and 1300 K. This is confirmed by finding that the rate constant for unimolecular rearrangement of permethrin into J is 1.2 × 10¹² exp(−53 kcal/mol/RT) s⁻¹ over the same range of temperatures and exceeds the direct fission rate constant at all temperatures up to 850 ± 120 °C as well as by the experimental detection of J prior to the detection of the initial products incorporating diphenyl ether, 1-methyl-3-phenoxybenzene, 3-phenoxybenzaldehyde and 1-chloromethyl-3-phenoxybenzene. As the temperature increases, we observe a rise in secondary products formed directly or indirectly (via phenol/phenoxy) including aromatics (naphthalene), biphenyls (biphenyl, 4-methyl-1,1′-biphenyl) and dibenzofuran (DF). In particular, we discover by means of quantum chemistry a direct route from 2-phenoxyphenoxy to naphthalene. We detect no polychlorinated dibenzo-p-dioxins and dibenzofurans. Unlike the case of oxidative pyrolysis [Tame, N.W., Dlugogorski, B.Z., Kennedy, E.M., 2007b. Formation of dioxins in fires of arsenic-free treated wood: Role of organic preservatives. Environ. Sci. Technol. 41, 6425–6432] where significant yields of both PCDD and PCDF were obtained, under non-oxidative conditions the thermal decomposition of permethrin does not form appreciable amounts of PCDD or PCDF and the presence of oxygen (and/or a sizable radical pool) appears necessary for the formation of dibenzo-p-dioxin itself or PCDD/F from phenol/phenoxy.