Adsorption of aniline and toluidines on montmorillonite: Implications for the disposal of shale oil production wastes

Bentonite clay liners are commonly employed to mitigate the movement of contaminants from waste disposal sites. Solid and liquid waste materials that arise from the production of shale oil contain a vast array of organic compounds. Common among these compounds are the aromatic amines. in order to assess the ability of clay liner material to restrict organic compound mobility, the adsorption of aniline and o-, m-, and p-toluidine on Ca{sup 2+} - and K{sup +}-saturated Wyoming bentonite was investigated. Adsorption experiments were performed under conditions of varied pH, ionic strength, and dominate electrolyte cation and anion. organic adsorption on Ca{sup 2+} - and K{sup +}-saturated montmorillonite is pH dependent. For any given organic compound, maximum adsorption increases with decreasing ionic strength. organic compound adsorption is inhibited in the presence of sulfate and is greater in the Ca{sup 2+} systems than in the K{sup +} systems at any given ionic strength. High salt content and K{sup +} collapse the bentonite layers and limit access to and compete for adsorption sites. The K{sup +} ion is also more difficult to displace than Ca{sup 2+} from interlayer positions. Fourier transform infrared spectroscopic data show that the aniline compounds are adsorbed on bentonite through the hydrogen bonding of an amine hydrogen to a surface silica oxygen. Sulfate reduces amine adsorption by removing positively charged anilinium species from solution to form negatively charge sulfate complexes. Although adsorption of the substituted amines on bentonite is observed, aniline and toluidine adsorption is minimal in saline systems and not detected in alkaline systems. Thus, in shale oil process waste disposal sites, the mobility of the anilines through bentonite liners will not be mitigated by sorption processes, as spent oil shale leachates are both highly alkaline and saline

Statistical design and analysis of environmental studies for plutonium and other transuranics at NAEG ''safety-shot'' sites

This paper is centered around the use of stratified random sampling for estimating the total amount (inventory) of $sup 239-240$Pu and uranium in surface soil at ten ''safety-shot'' sites on the Nevada Test Site (NTS) and Tonopah Test Range (TTR) that are currently being studied by the Nevada Applied Ecology Group (NAEG). The use of stratified random sampling has resulted in estimates of inventory at these desert study sites that have smaller standard errors than would have been the case had simple random sampling (no stratification) been used. Estimates of inventory are given for $sup 235$U, $sup 238$U, and $sup 239-240$Pu in soil at A Site of Area 11 on the NTS. Other results presented include average concentrations of one or more of these isotopes in soil and vegetation and in soil profile samples at depths to 25 cm. The regression relationship between soil and vegetation concentrations of $sup 235$U and $sup 238$U at adjacent sampling locations is also examined using three different models. The applicability of stratified random sampling to the estimation of concentration contours of $sup 239-240$Pu in surface soil using computer algorithms is also investigated. Estimates of such contours are obtained using several different methods. The planning of field sampling plans for estimating inventory and distribution is discussed. (auth

Effect of fulvic acids on lead-induced oxidative stress to metal sensitive Vicia faba L. plant

Lead (Pb) is a ubiquitous environmental pollutant capable to induce various morphological, physiological, and biochemical functions in plants. Only few publications focus on the influence of Pb speciation both on its phytoavailability and phytotoxicity. Therefore, Pb toxicity (in terms of lipid peroxidation, hydrogen peroxide induction, and photosynthetic pigments contents) was studied in Vicia faba plants in relation with Pb uptake and speciation. V. faba seedlings were exposed to Pb supplied as Pb(NO3)2 or complexed by two fulvic acids (FAs), i.e. Suwannee River fulvic acid (SRFA) and Elliott Soil fulvic acid (ESFA), for 1, 12, and 24 h under controlled hydroponic conditions. For both FAs, Pb uptake and translocation by Vicia faba increased at low level (5 mg l−1), whereas decreased at high level of application (25 mg l−1). Despite the increased Pb uptake with FAs at low concentrations, there was no influence on the Pb toxicity to the plants. However, at high concentrations, FAs reduced Pb toxicity by reducing its uptake. These results highlighted the role of the dilution factor for FAs reactivity in relation with structure; SRFA was more effective than ESFA in reducing Pb uptake and alleviating Pb toxicity to V. faba due to comparatively strong binding affinity for the heavy metal

Field-Grown Transgenic Switchgrass (Panicum virgatum L.) with Altered Lignin Does Not Affect Soil Chemistry, Microbiology, and Carbon Storage Potential

Cell wall recalcitrance poses a major challenge on cellulosic biofuel production from feedstocks such as switchgrass (Panicum virgatum L.). As lignin is a known contributor of recalcitrance, transgenic switchgrass plants with altered lignin have been produced by downregulation of caffeic acid O-methyltransferase (COMT). Field trials of COMT-downregulated plants previously demonstrated improved ethanol conversion with no adverse agronomic effects. However, the rhizosphere impacts of altering lignin in plants are unknown. We hypothesized that changing plant lignin composition may affect residue degradation in soils, ultimately altering soil processes. The objective of this study was to evaluate effects of two independent lines of COMT-downregulated switchgrass plants on soils in terms of chemistry, microbiology, and carbon cycling when grown in the field. Over the first two years of establishment, we observed no significant differences between transgenic and control plants in terms of soil pH or the total concentrations of 19 elements. An analysis of soil bacterial communities via high-throughput 16S rRNA gene amplicon sequencing revealed no effects of transgenic plants on bacterial diversity, richness, or community composition. We also did not observe a change in the capacity for soil carbon storage: There was no significant effect on soil respiration or soil organic matter. After five years of establishment, δ13C of plant roots, leaves, and soils was measured and an isotopic mixing model used to estimate that 11.2 to 14.5% of soil carbon originated from switchgrass. Switchgrass-contributed carbon was not significantly different between transgenic and control plants. Overall, our results indicate that over the short term (two and five years), lignin modification in switchgrass through manipulation of COMT expression does not have an adverse effect on soils in terms of total elemental composition, bacterial community structure and diversity, and capacity for carbon storage

Forage fish interactions: A symposium on creating the tools for ecosystem-based management of marine resources

Forage fish (FF) have a unique position within marine foodwebs and the development of sustainable harvest strategies for FF will be a critical step in advancing and implementing the broader, ecosystem-based management of marine systems. In all, 70 scientists from 16 nations gathered for a symposium on 12–14 November 2012 that was designed to address three key questions regarding the effective management of FF and their ecosystems: (i) how do environmental factors and predator–prey interactions drive the productivity and distribution of FF stocks across ecosystems worldwide, (ii) what are the economic and ecological costs and benefits of different FF management strategies, and (iii) do commonalities exist across ecosystems in terms of the effective management of FF exploitation

Considerations for management strategy evaluation for small pelagic fishes

Management strategy evaluation (MSE) is the state-of-the-art approach for testing and comparing management strategies in a way that accounts for multiple sources of uncertainty (e.g. monitoring, estimation, and implementation). Management strategy evaluation can help identify management strategies that are robust to uncertainty about the life history of the target species and its relationship to other species in the food web. Small pelagic fish (e.g. anchovy, herring and sardine) fulfil an important ecological role in marine food webs and present challenges to the use of MSE and other simulation-based evaluation approaches. This is due to considerable stochastic variation in their ecology and life history, which leads to substantial observation and process uncertainty. Here, we summarize the current state of MSE for small pelagic fishes worldwide. We leverage expert input from ecologists and modellers to draw attention to sources of process and observation uncertainty for small pelagic species, providing examples from geographical regions where these species are ecologically, economically and culturally important. Temporal variation in recruitment and other life-history rates, spatial structure and movement, and species interactions are key considerations for small pelagic fishes. We discuss tools for building these into the MSE process, with examples from existing fisheries. We argue that model complexity should be informed by management priorities and whether ecosystem information will be used to generate dynamics or to inform reference points. We recommend that our list of considerations be used in the initial phases of the MSE process for small pelagic fishes or to build complexity on existing single-species models.publishedVersio

Influential factors on the levels of cation exchange capacity in sediment at Langat river.

An exploratory study was carried out at 22 sampling stations along the Langat River, Selangor in order to investigate on the vitality of cation exchange capacity (CEC) in sediment (0–5 cm). Parameters such as pH, Eh, salinity, and electrical conductivity (EC) were determined. The CEC in sediment has been calculated by the determination of Ca2+, Na+, Mg2+, and K+ using the flame atomic absorption spectrophotometer, while the organic matter content in sediment was ascertained using the loss on ignition method. The characteristic of the sediment shows that pH (3.09–7.46), salinity (0.02–10.71 ppt), EC (3.39–517 μS/cm) and Eh (−16.20–253.10 mV) were substantially high in variation. This study also revealed that exchangeable Ca2+ and Mg2+ were controlled by organic matter contents, while exchangeable Na+ and K+ were influenced by salinity. Salinity was observed to play a major part in controlling all the exchangeable cations, as it gives strong significant correlations with Na+, K+, Mg2+, CEC, and organic matter at p < 0.01. The presence of seawater, clay mineralogy, and organic matter proves that it does play an important role in determining the CEC and soon relates to the pollution magnitude in the sediment

Catch shares, fisheries, and ecological stewardship: a comparative analysis of resource responses to a rights-based policy instrument

Rights-based approaches are potentially promising tools to meet conservation objectives in natural resource management. Here, we evaluated how population status and fishery production respond to catch shares, a rights-based policy instrument in fisheries whereby participants are granted a right to harvest a fraction of the allowable catch. By analyzing time series of landings, exploitation rate, and population biomass for >150 fisheries, we find that catch shares tended to dampen variance in fishery landings and exploitation rate, that they had no effect on population biomass, and that the responses were unrelated to population status prior to catch shares. Variance dampening was strongest when harvesting rights were durable and secure but was absent otherwise. Reductions in exploitation rate were strongest in multispecies fisheries with high levels of at-sea observers. Although benefits are not guaranteed, successful catch share programs share common elements that can be incorporated in the design of future programs.Keywords: marine conservation, Catch shares, market-based approaches, fisheries, policy evaluation, property-rightsKeywords: marine conservation, Catch shares, market-based approaches, fisheries, policy evaluation, property-right

Multiscale Drivers of Water Chemistry of Boreal Lakes and Streams

The variability in surface water chemistry within and between aquatic ecosystems is regulated by many factors operating at several spatial and temporal scales. The importance of geographic, regional-, and local-scale factors as drivers of the natural variability of three water chemistry variables representing buffering capacity and the importance of weathering (acid neutralizing capacity, ANC), nutrient concentration (total phosphorus, TP), and importance of allochthonous inputs (total organic carbon, TOC) were studied in boreal streams and lakes using a method of variance decomposition. Partial redundancy analysis (pRDA) of ANC, TP, and TOC and 38 environmental variables in 361 lakes and 390 streams showed the importance of the interaction between geographic position and regional-scale variables. Geographic position and regional-scale factors combined explained 15.3% (streams) and 10.6% (lakes) of the variation in ANC, TP, and TOC. The unique variance explained by geographic, regional, and local-scale variables alone was <10%. The largest amount of variance was explained by the pure effect of regional-scale variables (9.9% for streams and 7.8% for lakes), followed by local-scale variables (2.9% and 5.8%) and geographic position (1.8% and 3.7%). The combined effect of geographic position, regional-, and local-scale variables accounted for between 30.3% (lakes) and 39.9% (streams) of the variance in surface water chemistry. These findings lend support to the conjecture that lakes and streams are intimately linked to their catchments and have important implications regarding conservation and restoration (management) endeavors

Challenges for Implementing an Ecosystem Approach to Fisheries Management

The ecosystem approach is being promoted as the foundation of solutions to the unsustainability of fisheries. However, because the ecosystem approach is broadly inclusive, the science for its implementation is often considered to be overly complex and difficult. When the science needed for an ecosystem approach to fisheries is perceived this way, science products cannot keep pace with fisheries critics, thus encouraging partisan political interference in fisheries management and proliferation of “faith-based solutions. In this paper we argue that one way to effectively counter politicization of fisheries decision-making is to ensure that new ecosystem-based approaches in fisheries are viewed only as an emergent property of innovation in science and policy. We organize our essay using three major themes to focus the discussion: empirical, jurisdictional, and societal challenges. We undertake at least partial answers to the following questions: (1) has conventional fisheries management really failed?; (2) can short-comings in conventional fisheries management be augmented with new tools, such as allocation of rights?; (3) is the Ecosystem Approach to Fisheries (EAF) equivalent to Ecosystem-Based Management?; and (4) is restoration of degraded ecosystems a necessary component of an EAF