Spatial distribution of metals within the liver acinus and their perturbation by PCB126

Animal studies show that exposure to the environmental pollutant 3,3′,4,4′,5-pentachlorobiphenyl (PCB126) causes alterations in hepatic metals as measured in acid-digested volume-adjusted tissue. These studies lack the detail of the spatial distribution within the liver. Here we use X-ray fluorescence microscopy (XFM) to assess the spatial distribution of trace elements within liver tissue. Liver samples from male Sprague Dawley rats, treated either with vehicle or PCB126, were formalin fixed and paraffin embedded. Serial sections were prepared for traditional H&E staining or placed on silicon nitride windows for XFM. With XFM, metal gradients between the portal triad and the central vein were seen, especially with copper and iron. These gradients change with exposure to PCB126, even reverse. This is the first report of how micronutrients vary spatially within the liver and how they change in response to toxicant exposure. In addition, high concentrations of zinc clusters were discovered in the extracellular space. PCB126 treatment did not affect their presence, but did alter their elemental makeup suggesting a more general biological function. Further work is needed to properly evaluate the gradients and their alterations as well as classify the zinc clusters to determine their role in liver function and zinc homeostasis.     

The search for an alternative to piped water and sewer systems in the Alaskan Arctic

Forty-two communities in rural Alaska are considered unserved or underserved with water and sewer infrastructure. Many challenges exist to provide centralized piped water and sewer infrastructure to the homes, and they are exacerbated by decreasing capital funding. Unserved communities in rural Alaska experience higher rates of disease, supporting the recommendation that sanitation infrastructure should be provided. Organizations are pursuing alternative solutions to conventional piped water and sewer in order to maximize water use and reuse for public health. This paper reviews initiatives led by the State of Alaska, the Alaska Native Tribal Health Consortium, and the Yukon Kuskokwim Health Corporation to identify and develop potential long-term solutions appropriate and acceptable to rural communities. Future developments will likely evolve based on the lessons learned from the initiatives. Recommendations include Alaska-specific research needs, increased end-user participation in the design process, and integrated monitoring, evaluation, and information dissemination in future efforts.     

Quantification of nitrogen in the liquid fraction and in vitro assessment of lysine bioavailability in the solid fraction of soybean meal hydrolysates

Soybean meal (SBM) is a product generated from the manufacture of soybean oil and has the potential for use as a source of fermentable sugars for ethanol production or as a protein source for animal feeds. Knowing the levels of nitrogen available from ammonium is a necessary element of the ethanolic fermentation process while identifying the levels of essential amino acids such as lysine is important in determining usage as a feed source. As such the purpose of this study was to quantify total nitrogen and ammonium in the liquid fraction of hydrolyzed SBM and to evaluate total and bioavailable lysine in the solid fraction of the hydrolyzed SBM. The effects of acid concentration, cellulase and β-glucosidase on total and ammonium nitrogen were studied with analysis indicating that higher acid concentrations increased nitrogen compounds with ammonium concentrations ranging from 0.20 to 1.24 g L^?1 while enzymatic treatments did not significantly increase nitrogen levels. Total and bioavailable lysine was quantified by use of an auxotrophic gfpmut3 E.coli whole-cell bioassay organism incapable of lysine biosynthesis. Acid and enzymatic treatments were applied with lysine bioavailability increasing from a base of 82% for untreated SBM to up to 97%. Our results demonstrated that SBM has the potential to serve in ethanolic fermentation and as an optimal source essential amino acid lysine.     

Deriving fuel-based emission factor thresholds to interpret heavy-duty vehicle roadside plume measurements

Remote sensing devices have been used for decades to measure gaseous emissions from individual vehicles at the roadside. Systems have also been developed that entrain diluted exhaust and can also measure particulate matter (PM) emissions. In 2015, the California Air Resources Board (CARB) reported that 8% of in-field diesel particulate filters (DPF) on heavy-duty (HD) vehicles were malfunctioning and emitted about 70% of total diesel PM emissions from the DPF-equipped fleet. A new high-emitter problem in the heavy-duty vehicle fleet had emerged. Roadside exhaust plume measurements reflect a snapshot of real-world operation, typically lasting several seconds. In order to relate roadside plume measurements to laboratory emission tests, we analyzed carbon dioxide (CO₂), oxides of nitrogen (NO_X), and PM emissions collected from four HD vehicles during several driving cycles on a chassis dynamometer. We examined the fuel-based emission factors corresponding to possible exceedances of emission standards as a function of vehicle power. Our analysis suggests that a typical HD vehicle will exceed the model year (MY) 2010 emission standards (of 0.2 g NO_X/bhp-hr and 0.01 g PM/bhp-hr) by three times when fuel-based emission factors are 9.3 g NO_X/kg fuel and 0.11 g PM/kg using the roadside plume measurement approach. Reported limits correspond to 99% confidence levels, which were calculated using the detection uncertainty of emissions analyzers, accuracy of vehicle power calculations, and actual emissions variability of fixed operational parameters. The PM threshold was determined for acceleration events between 0.47 and 1.4 mph/sec only, and the NO_X threshold was derived from measurements where after-treatment temperature was above 200°C. Anticipating a growing interest in real-world driving emissions, widespread implementation of roadside exhaust plume measurements as a compliment to in-use vehicle programs may benefit from expanding this analysis to a larger sample of in-use HD vehicles.

Implications: Regulatory agencies, civil society, and the public at large have a growing interest in vehicle emission compliance in the real world. Leveraging roadside plume measurements to identify vehicles with malfunctioning emission control systems is emerging as a viable new and useful method to assess in-use performance. This work proposes fuel-based emission factor thresholds for PM and NOx that signify exceedances of emission standards on a work-specific basis by analyzing real-time emissions in the laboratory. These thresholds could be used to prescreen vehicles before roadside enforcement inspection or other inquiry, enhance and further develop emission inventories, and potentially develop new requirements for heavy-duty inspection and maintenance (I/M) programs, including but not limited to identifying vehicles for further testing.     

Silver near municipal wastewater discharges into western Lake Ontario,Canada

Because of the widespread use of silver nanoparticles in commercial products, discharges of municipal wastewater may be a point source of silver in the aquatic environment. We monitored two sites in western Lake Ontario impacted by discharges from wastewater treatment plants serving the City of Toronto. Concentrations of silver were elevated in bottom sediments and suspended sediments collected at the two sites. We also deployed two types of passive samplers in the water column at the two sites, the newly developed Carbon Nanotube Integrative Samplers for monitoring “CNIS-labile” silver and Diffusive Gradient in Thin Film samplers for monitoring “DGT-labile” silver. Results from these passive samplers indicated that the concentrations of silver at the two sites were either below detection limits or were in the ng/L range. In laboratory experiments where the sediments were re-suspended in Milli-Q water, a small proportion of the silver (i.e., <?25%) was labile and partitioned as colloidal or dissolved silver into the liquid phase after agitation. Nanoparticles tentatively identified as silver nanoparticles were detected by single-particle ICP-MS in suspension after agitation of both suspended and bottom sediments. Therefore, there is a need to assess whether silver species, including silver nanoparticles are transported from wastewater treatment plants into sediments in the aquatic environment. This study is unique in focusing on the in situ distribution of silver in natural waters and in sediments that are potentially impacted by urban sources of nanoparticles.     

Investigating toxic metal levels in popular edible fishes from the South Durban basin: implications for public health and food security

Contamination of the ocean by heavy metals may have ecosystem-wide implications because they are toxic even if present in trace levels, and the relative ease of their bioaccumulation by marine organisms may affect human health, primarily through consumption of contaminated fish. We evaluated metal concentrations in six different popular edible fish species and estimated the potential health risks from consumption of contaminated fish. There was no correlation between fish length and average metal accumulation although the fish species tended to accumulate significantly more Al and Zn (P?<?0.05) than any of the other metals. Significantly higher Mn concentrations were found in fish gills compared to other body parts in all fish species. Bronze seabream, Catface rockcod, and Slinger seabream had significantly higher mean Cr concentration in the liver than in either the tissues or gills. The highest concentration of Zn in fleshy tissue was in Horse mackerel (56.71 μg g^?1) followed by Bronze seabream (31.07 μg g^?1). Al levels ranged from 5.6 μg g^?1 in Atlantic mackerel to 35.04 μg g^?1 in Horse mackerel tissue while Cu and Cr concentrations were highest in the tissues of Horse mackerel (6.83 and 1.81 μg g^?1, respectively) followed by Santer seabream (3.15; 1.09 μg g^?1) and Bronze seabream (3.09; 1.30 μg g^?1), respectively. The highest tissue concentration of Mn was detected in Bronze seabream (8.23 μg g^?1) followed by Catface rockcod (6.05 μg g^?1) and Slinger seabream (5.21 μg g^?1) while Pb concentrations ranged from a high of 8.44 μg g^?1 in Horse mackerel to 1.09 μg g^?1 in Catface rockcod. However, the estimated potential health risks from fish consumption as determined by the target hazard quotient (THQ) and hazard index (HI) were significantly lower than 1, implying that metals were not present in sufficiently high quantities to be of any health and/or food and security concern in the studied fishes.     

A review of regulations and guidelines related to winter manure application

Winter manure application elevates nutrient losses and impairment of water quality as compared to manure applications in other seasons. In conjunction with reviewing global distribution of animal densities, we reviewed worldwide mandatory regulations and voluntary guidelines on efforts to reduce off-site nutrient losses associated with winter manure applications. Most of the developed countries implement regulations or guidelines to restrict winter manure application, which range from a regulative ban to guidelines based upon weather and field management conditions. In contrast, developing countries lack such official directives, despite an increasing animal production industry and concern over water quality. An analysis of five case studies reveals that directives are derived from a common rationale to reduce off-site manure nutrient losses, but they are also affected by local socio-economic and biophysical considerations. Successful programs combine site-specific management strategies along with expansion of manure storage to offer farmers greater flexibility in winter manure management.     

Bird on the wire: Landscape planning considering costs and benefits for bird populations coexisting with power lines

Power-line grids are increasingly expanding worldwide, as well as their negative impacts on avifauna, namely the direct mortality through collision and electrocution, the reduction of breeding performance, and the barrier effect. On the other hand, some bird species can apparently benefit from the presence of power lines, for example perching for hunting purposes or nesting on electricity towers. In this perspective essay, we reviewed the scientific literature on both costs and benefits for avifauna coexisting with power lines. Overall, we detected a generalized lack of studies focusing on these costs or benefits at a population level. We suggest that a switch in research approach to a larger spatio-temporal scale would greatly improve our knowledge about the actual effects of power lines on bird populations. This research approach would facilitate suitable landscape planning encompassing both mitigation of costs and promotion of benefits for bird populations coexisting with power lines. For example, the strategic route planning of electricity infrastructures would limit collision risk or barrier effects for threatened bird populations. Concurrently, this strategic route planning would promote the range expansion of threatened populations of other bird species, by providing nesting structures in treeless but potentially suitable landscapes. We suggest establishing a collaborative dialogue among the scientific community, governments, and electricity companies, with the aim to produce a win–win scenario in which both biodiversity conservation and infrastructure development are integrated in a common strategy.     

Social representations of governance for change towards sustainability: perspectives of sustainability advocates

There is a substantial body of literature on public understandings of large-scale ‘environmental’ phenomena such as climate change and resource degradation. At the same time, political science and economics analyse the governance arrangements to deal with such issues. These realms of research rarely meet: there has been little research into people’s understandings of the governance of environmental change. This study adds a psychological perspective to governance research by investigating social representations of governance that promotes societal change towards sustainability, and related practices. It examines data from qualitative interviews with sustainability-interested people in seven European countries (n = 105). The analysis identified building blocks of representations suitable as an analytical framework for future research on governance representations. The diversity of their content reflected a range of pathways to societal change. Representations often seemed to have a creative function as a guiding vision for individuals’ own practices, but their wider transformative potential was constrained.     

The spillover of race and racial attitudes into public opinion about climate change

The relationship between racial attitudes and public opinion about climate change is examined. Public opinion data from Pew and American National Election Studies surveys are used to show that racial identification and prejudices are increasingly correlated with opinions about climate change during the Obama presidency. Results show that racial identification became a significant predictor of climate change concern following Obama’s election in 2008, and that high levels of racial resentment are strongly correlated with reduced agreement with the scientific consensus on climate change. These results offer evidence for an effect termed the spillover of racialization. This helps further explain why the public remains so polarized on climate change, given the extent to which racial grievances and identities have become entangled with elite communication about climate change and its related policies today.