Adverse effects of chromium on amino acid levels in freshwater fish Clarias batrachus (Linn.)

Various heavy metals released into the rivers and lakes affect aquatic fauna including Clarias batrachus. Elevated levels of chromium (Cr) in aquatic organisms, especially fish, represent an ecological and human concern. Amino acid levels were estimated in five tissues (gills, liver, kidneys, muscle, and brain) of C. batrachus after 28 days of exposure to Cr. This study showed that Cr elevated levels of free amino acids in organs of fish C. batrachus, indicating a compensatory mechanism to counter sublethal metallic stress. Data suggest that the measurement of amino acids may serve as a biomarker for Cr toxicity in fish.     

Chemistry and aerosols in the marine boundary layer: 1-D modelling of the three ACE-2 Lagrangian experiments

Three Lagrangian experiments were conducted during IGAC's second aerosol characterization experiment (ACE-2) in the area between Portugal, Tenerife and Madeira in June/July 1997. During each Lagrangian experiment, a boundary layer air mass was followed for about 30 h, and the temporal evolution of its chemical and aerosol composition was documented by a series of vertical profiles and horizontal box pattern flown by the Meteorological Research Flight research aircraft Hercules C130. The wealth of observational data that has been collected during these three Lagrangian experiments is the basis for the development and testing of a one-dimensional Lagrangian boundary layer model with coupled gas, aqueous, and aerosol phase chemistry. The focus of this paper is on current model limitations and strengths. We show that the model is able to represent the dynamical and chemical evolution of the marine boundary layer, in some cases requiring adjustments of the subsidence velocity and of the surface heat fluxes. Entrainment of a layer rich in ozone and carbon monoxide from a residual continental boundary layer into the marine boundary layer as well as in-cloud oxidation of sulphur dioxide by hydrogen peroxide are simulated, and coherent results are obtained, concerning the evolution of the small, presumably sulphate–ammonia aerosol mode.     

Long‐term evaluation of an EHC injection permeable reactive barrier in a sulfate‐rich,high‐flow aquifer

Permeable reactive barriers (PRBs) have traditionally been constructed via trenching backfilled with granular, long‐lasting materials. Over the last decade, direct push injection PRBs with fine‐grained injectable reagents have gained popularity as a more cost‐efficient and less‐invasive approach compared to trenching. A direct push injection PRB was installed in 2005 to intercept a 2,500 feet (760 meter) long carbon tetrachloride (CT) groundwater plume at a site in Kansas. The PRB was constructed by injecting EHC^® in situ chemical reduction reagent slurry into a line of direct push injection points. EHC is composed of slow‐release plant‐derived organic carbon plus microscale zero‐valent iron (ZVI) particles, specifically formulated for injection applications. This project was the first full‐scale application of EHC into a flow‐through reactive zone and provided valuable information about substrate longevity and PRB performance over time. Groundwater velocity at the site is high (1.8 feet per day) and sulfate‐rich (~120 milligrams per liter), potentially affecting the rate of substrate consumption and the PRB reactive life. CT removal rates peaked 16 months after PRB installation with >99% removal observed. Two years post‐installation removal rates decreased to approximately 95% and have since stabilized at that level for the 12 years of monitoring data available after injection. Geochemical data indicate that the organic carbon component of EHC was mostly consumed after 2 years; however, reducing conditions and a high degree of chloromethane treatment were maintained for several years after total organic carbon concentrations returned to background. Redox conditions are slowly reverting and have returned close to background conditions after 12 years, indicating that the PRB may be nearing the end of its reactive life. Direct measurements of iron have not been performed, but stoichiometric demand calculations suggest that the ZVI component of EHC may, in theory, last for up to 33 years. However, the ZVI component by itself would not be expected to support the level of treatment observed after the organic carbon substrate had been depleted. A longevity of up to 5 years was originally estimated for the EHC PRB based on the maximum expected longevity of the organic carbon substrate. While the organic carbon was consumed faster than expected, the PRB has continued to support a high degree of chloromethane treatment for a significantly longer time period of over 12 years. Recycling of biomass and the contribution from a reduced iron sulfide mineral zone are discussed as possible explanations for the sustained reducing conditions and continued chloromethane treatment.     

From lake to estuary,the tale of two waters: a study of aquatic continuum biogeochemistry

The balance of fresh and saline water is essential to estuarine ecosystem function. Along the fresh-brackish-saline water gradient within the C-43 canal/Caloosahatchee River Estuary (CRE), the quantity, timing and distribution of water, and associated water quality significantly influence ecosystem function. Long-term trends of water quality and quantity were assessed from Lake Okeechobee to the CRE between May 1978 and April 2016. Significant changes to monthly flow volumes were detected between the lake and the estuary which correspond to changes in upstream management. and climatic events. Across the 37-year period, total phosphorus (TP) flow-weighted mean (FWM) concentration significantly increased at the lake; meanwhile, total nitrogen (TN) FMW concentrations significantly declined at both the lake and estuary headwaters. Between May 1999 and April 2016, TN, TP, and total organic carbon (TOC), ortho-P, and ammonium conditions were assessed within the estuary at several monitoring locations. Generally, nutrient concentrations decreased from upstream to downstream with shifts in TN/TP from values >?20 in the freshwater portion, ~?20 in the estuarine portion, and <?20 in the marine portion indicating a spatial shift in nutrient limitations along the continuum. Aquatic productivity analysis suggests that the estuary is net heterotrophic with productivity being negatively influenced by TP, TN, and TOC likely due to a combination of effects including shading by high color dissolved organic matter. We conclude that rainfall patterns, land use, and the resulting discharges of runoff drive the ecology of the C-43/CRE aquatic continuum and associated biogeochemistry rather than water management associated with Lake Okeechobee.     

Climate Engagement in a Digital Age: Exploring the Drivers of Participation in Climate Discourse Online in the Context of COP21

Various scholars underscore the importance of public engagement with climate change to successfully respond to the challenges of global warming. However, although online media provide various new opportunities to actively engage in climate discourse so far very little is known about the drivers of this form of engagement. Against this background, this study tested a theoretical model on the effects of media and interpersonal communication on participation in climate discourse online using data from a representative online survey of German citizens (n?=?1392) carried out while COP21. Overall, the results show that receiving information on climate change from social media (social networks, Twitter, blogs), active information seeking online and interpersonal conversations about COP21 strongly encourage participation in climate discourse online. Moreover, results provide relevant insights on the role of interest in climate politics, personal issue relevance and climate scepticism as preconditions of communication effects.     

Physico-chemical characterization of grease interceptors with and without biological product addition

Hardened and insoluble fat, oil, and grease (FOG) deposits are the primary cause of sewer line blockages leading to sanitary sewer overflows (SSOs). However, there have been very few long-term assessments of the physico-chemical characteristics of full-scale grease interceptors (GIs), the first "line of defense" against FOG buildup in sewer lines. In this study, we assessed the physico-chemical characteristics of two full-scale GIs (at a restaurant and a retirement community kitchen) over a one-year period. Statistically significant differences between bioaugmented and untreated cycles were detected for several chemical and physical properties. The treated cycles had lower BOD and COD at the grease interceptor outlet. While the combined data for all treated cycles did not show lower FOG concentrations in the GI outlet compared to the combined data for all untreated cycles, comparison of specific individual treated and untreated cycles show a positive effect due to the addition of product.     

Recent Changes in Soil Total Phosphorus in the Everglades: Water Conservation Area 3

We assessed recent changes in the distribution of soil total phosphorus (TP) in Water Conservation Area 3 (WCA-3) of the Everglades. Soil cores were collected in 1992 and 2003 at 176 sites. To reflect hydrologic boundaries within the system, WCA-3 was divided into three zones (3AN, 3AS, and 3B). Total P was mapped on both a mass (TPm) and a volumetric basis (TPv) to determine if spatial distributions varied depending on the choice of units. Interpolated maps for both years showed that the highest levels of TPm were located in 3AN and in boundary areas of all zones that received surface water inputs of P from canals. Increases in TPm were greatest in central 3AN in an area adjacent to the Miami Canal that received inputs from a water control structure. Interpolated maps for TPv illustrated that a hotspot present in 1992 had disappeared by 2003. The highest levels of TPv in 2003 were located in northwestern 3AN, a region of WCA-3 that has been chronically overdrained and burned in 1999. From 1992 to 2003, increases in TPm were observed for 53% of the area of WCA-3, while only 16% of WCA-3 exhibited increases in TPv. In 1992, approximately 21% of WCA-3 had TPm concentrations in the 0–10 cm layer >500 mg kg⁻¹, indicating P enrichment beyond historic levels. Eleven years later, 30% of the area of WCA-3 had TPm >500 mg kg⁻¹. This indicated that during this period, the area of WCA-3 with enriched TPm concentrations increased about one % year⁻¹.     

Emissions of Chlorinated Organics from Two Municipal Incinerators in Ontario

In this paper the results of sampling for trace chlorinated organics at two municipal refuse incinerators in Ontario are presented. The information may be of Interest to individuals concerned with the assessment of PCDD/PCDF (polychlorinated dibenzo-p-dioxin/polychlorinated dibenzofuran) emissions from incineration of refuse and their impact on the energyfrom- waste program. PCDDs, PCDFs, PCBs (polychlorinated biphenyls), CBs (chlorobenzenes) and CPs (chlorophenols) were quantified in all process streams including refuse, ash and stack emissions. Manual sorting of refuse and collection of ash samples were carried out simultaneously with three 24-hour continuous stack sampling tests at each plant. The results suggested that the total output of PCDDs and PCDFs varied proportionately with their input at both incinerators. However, the input of PCDDs/PCDFs could not account for their total output. The chemistry of PCDDs/PCDFs in the input and output streams were different in that only heptachlorinated and octachlorinated species were present in significant quantities in the refuse while lower chlorinated species were predominant in stack emissions and ash streams. There was no correspondence between the Input of PCBs/CBs/CPs and the output of PCDDs/PCDFs. The output of PCDDs/PCDFs, however, varied Inversely with the total output of PCBs/CBs/CPs, suggesting that the latter compounds could have been partially responsible for the formation of PCDDs and PCDFs. The PCDF emissions were also affected by combustion conditions; they were higher in magnitude and consisted of predominantly tetrachlorinated and pentachlorinated species at the plant where the combustion temperatures were lower.     

Southwest climate gap: poverty and environmental justice in the US Southwest

This article examines the “climate gap” in the Southwest US (Arizona and New Mexico), referring to the “disproportionate and unequal implications of climate change and climate change mitigation” for “people of color and the poor” [Shonkoff, S.B., et al., 2011. The climate gap: environmental health and equity implications of climate change mitigation policies in California. Climatic Change, 109 (Suppl. 1), S485–S503]. The climate and poverty relationship is examined using multi-scaled analysis across three indicators of climate vulnerability, focusing on connections to health, food, and energy during the period 2010–2012. We provide an overview of climate-related social vulnerability in the Southwest based on available federal, state, and county-level census data. We then summarise the results from a stakeholder workshop and in-depth interviews about climate vulnerabilities with social service providers in southern Arizona. We identify a significant Southwest climate gap based on census data and interview findings about climate vulnerability especially relating to high levels of poverty, health disparities, and increasing costs for energy, water, and food. We find that grassroots and community organisations have mobilised to respond to climate and social vulnerability, yet resources for mitigation and adaptation are insufficient given the high level of need. Confronting a changing climate that is projected to be hotter, drier, and with the potential to reach new thresholds, we suggest that more research needs to be done to understand the social and spatial characteristics of climate risk and how low-income populations embody and experience climate risk, and adapt to a changing climate.