Dissolved organic carbon fluxes under bare soil

The flux of dissolved organic carbon (DOC) in soil facilitates transport of nutrients and contaminants in soil. There is little information on DOC fluxes and the relationship between DOC concentration and water flux in agricultural soils. The DOC fluxes and concentrations were measured during 2.5 yr using 30 automatic equilibrium tension plate lysimeters (AETPLs) at 0.4 m and 30 AETPLs at 1.20-m depth in a bare luvisol, previously used as an arable soil. Average annual DOC fluxes of the 30 AETPLS were 4.9 g C m(-2) y(-1) at 0.4 m and 2.4 g C m(-2) y(-1) at 1.2 m depth. The average leachate DOC concentrations were 17 mg C L(-1) (0.4 m) and 9 mg C L(-1) (1.2 m). The DOC concentrations were unrelated to soil moisture content or average temperature and rarely dropped below 9 mg C L(-1) (0.4 m) and 5 mg C L(-1) (1.2 m). The variability in cumulative DOC fluxes among the plates was positively related to leachate volume and not to average DOC concentrations at both depths. This suggests that water fluxes are the main determinants of spatial variability in DOC fluxes. However, the largest DOC concentrations were inversely proportional to the mean water velocity between succeeding sampling periods, suggesting that the maximal net DOC mobilization rate in the topsoil is limited. Elevated DOC concentrations, up to 90 mg C L(-1), were only observed at low water velocities, reducing the risks of DOC-facilitated transport of contaminants to groundwater. The study emphasizes that water flux and velocity are important parameters for DOC fluxes and concentrations.     

Carbon allocation to ectomycorrhizal fungi correlates with belowground allocation in culture studies

Ectomycorrhizal fungi form symbioses with most temperate and boreal tree species, but difficulties in measuring carbon allocation to these symbionts have prevented the assessment of their importance in forest ecosystems. Here, I surveyed allocation patterns in 14 culture studies and five field studies of ectomycorrhizal plants. In culture studies, allocation to ectomycorrhizal fungi (NPPf) was linearly related to total belowground net primary production (NPPb) by the equation NPPf = 41.5% x NPPb - 11.3% (r2 = 0.55, P < 0.001) and ranged from 1% to 21% of total net primary production. As a percentage of NPP, allocation to ectomycorrhizal fungi was highest at lowest plant growth rates and lowest nutrient availabilities. Because total belowground allocation can be estimated using carbon balance techniques, these relationships should allow ecologists to incorporate mycorrhizal fungi into existing ecosystem models. In field studies, allocation to ectomycorrhizal fungi ranged from 0% to 22% of total allocation, but wide differences in measurement techniques made intercomparisons difficult. Techniques such as fungal in-growth cores, root branching-order studies, and isotopic analyses could refine our estimates of turnover rates of fine roots, mycorrhizae, and extraradical hyphae. Together with ecosystem modeling, such techniques could soon provide good estimates of the relative importance of root vs. fungal allocation in belowground carbon budgets.     

On the analysis of hydrocarbon leaks in the Norwegian offshore industry

There have been several major offshore accidents in different offshore regions since 2005. In Norway there have been several very serious near-misses during the last ten years, several of which involving serious hydrocarbon leaks with catastrophic fire and explosion potential. All these severe occurrences demonstrate the importance of learning from major accident precursors in order to appraise the risk potential involved in critical offshore operations. This paper is based on analysis of about 175 hydrocarbon leaks in the period 2001–2010. Regulatory requirements in Norway are aimed at preventing as far as possible such occurrences during night time, but the analysis shows that this has been far from successful. The industry has for many years claimed that the maintenance personnel are the main group of employees involved in causing these leaks. This study has shown that leaks during the execution of maintenance and modification are less than half of the leaks, and that failures during the preparation for carrying out maintenance tasks are more frequent. Such preparations have often been conducted during night shift. The analysis gives a strong incentive to change this practice.     

Accident investigation in the Norwegian petroleum industry - Common features and future challenges

In their regulations, the Petroleum Safety Authority Norway (PSA) states that the companies responsible for oil and gas exploration and production activities in Norway shall record and investigate accidents and serious incidents. This paper introduces a general model for the accident investigation process in the Norwegian petroleum industry, and presents some results derived from a comparative study of causal factors identified in offshore accident investigation reports from 2002 to 2006. The paper also offers a discussion of the improvement potential in the use of investigation methods. Finally, a discussion of future challenges in accident investigations is provided.     

Can food safety policy-making be both scientifically and democratically legitimated? If so,how?

This paper provides an analysis of the evolution of thinking and talking about the role of scientific knowledge and expertise in food safety policy-making, and in risk policy-making more generally from the late 19th century to the present day. It highlights the defining characteristics of several models that have been used to represent and interpret the relations between policy-makers and expert scientific advisors and between scientific and political considerations. Both conceptual and empirical strengths and weaknesses of those models are identified, focusing in particular on the ways in which they deal with scientific uncertainties and social choices. By drawing on both empirical evidence and conceptual analysis, a novel and more realistic model is provided along with an account of some conditions for food safety policy-making achieving both scientific and democratic legitimacy.     

Review of Singapore's air quality and greenhouse gas emissions: Current situation and opportunities

Singapore has many environmental accomplishments to its credit. Accessible data on air quality indicates that all criteria pollutants satisfy both U.S. Environmental Protection Agency (EPA) and World Health Organization (WHO) air quality standards and guidelines, respectively. The exception is PM_2.5 (particles with an aerodynamic diameter ≤2.5 μm), which is not currently considered a criteria pollutant in Singapore but may potentially be the major local air pollution problem and cause for health concern. Levels of other airborne pollutants as well as their physical and chemical processes associated with local formation, transformation, dispersion, and deposition are not known. According to available emission inventories, Singapore's contribution to the total atmospheric pollution and carbon budget at the regional and global scales is small. Emissions per unit gross domestic product (GDP) are low compared with other countries, although Singapore's per-capita GDP and per-capita emissions are among the highest in the world. Some information is available on health effects, but the impacts on the ecosystem and the complex interactions of air pollution and climate change at a regional level are also unknown. This article reviews existing available information on atmospheric pollution and greenhouse gas emissions and proposes a multipollutant approach to greenhouse gas mitigation and local air quality. Singapore, by reducing its per-capita emissions, increasing the availability of information (e.g., through regularly publishing hourly and/or daily PM_2.5 concentrations) and developing a research agenda in this area, would likely be seen to be a model of a high-density, livable, and sustainable city in Southeast Asia and other tropical regions worldwide.

Implications Singapore is widely recognized for its environmental achievements and often cited as a model of a high-density, livable, and sustainable city. This article reviews available information with the aim to provide a reference for future scientific research of strategic relevance for Singapore's air quality and greenhouse gas mitigation management under a multipollutant framework. However, the limited publicly accessible data and little scientific information prevent a comprehensive assessment of the local air quality and greenhouse gas emissions. Singapore's dynamic economy and strong profile in advanced science and technological innovation have the potential to enhance the research agenda in this area, which is not yet well developed in tropical cities.     

Challenges of soil mixing using catalyzed hydrogen peroxide with rotating dual axis blending technology

Although known to be one of the most effective oxidants for treatment of organic contaminants, catalyzed hydrogen peroxide (CHP) is typically not used for soil mixing applications because of health and safety concerns related to vapor generation and very rapid rates of reaction in open excavations. In likely the first large‐scale in situ CHP soil mixing application, an enhanced CHP, modified Fenton's reagent (MFR), was applied during soil mixing at the Kearsarge Metallurgical Superfund Site in New Hampshire. An innovative rotating dual‐axis blender (DAB) technology was used to safely mix the MFR into low‐plasticity silt and clay soils to remediate residual 1,1,1‐trichloroethane (111TCA); 1,1‐dichloroethene (11DCE); and 1,4‐dioxane (14D). It was expected that the aggressive treatment approach using relatively “greener” hydrogen peroxide (HP) chemistry would effectively treat Site contaminants without significant byproduct impacts to groundwater or the adjacent pond. The remediation program was designed to treat approximately 3,000 cubic yards of residual source area soil in situ by aggressively mixing MFR into the soils. The subsurface interval treated was from 7 to 15 feet below ground surface. To accurately track the soil mixing process and MFR addition, the Site was divided into 109 10‐foot square treatment cells that were precisely located, dosed, and mixed using the DAB equipped with an on‐board GPS system. The use of stabilizing agents along with careful calculation of the peroxide dose helped to ensure vapor‐free conditions in the vicinity of the soil mixing operation. Real‐time sampling and monitoring were critical in identifying any posttreatment exceedences of the cleanup goals. This allowed retreatment and supplemental testing to occur without impacting the soil mixing/in situ chemical oxidation (ISCO) schedule. Posttreatment 24‐hr soil samples were collected from 56 random locations after ensuring that the HP had been completely consumed. The posttreatment test results showed that 111TCA and 11DCE concentrations were reduced to nondetect (ND) or below the cleanup goals of 150 μg/kg for 111TCA and 60 μg/kg for 11DCE. Supplemental posttreatment soil samples, collected six months after treatment, showed 100 percent compliance with the soil treatment goals. Groundwater samples collected one year after the MFR soil mixing treatment program showed either ND or low concentrations for 111TCA, 11DCE, and 14D. Successful stabilization and site restoration was performed after overcoming considerable challenges associated with loss of soil structure, high liquid content, and reduced bearing capacity of the blended soils.     

Is Indonesian peatland loss a cautionary tale for Peru? A two-country comparison of the magnitude and causes of tropical peatland degradation

Mitigation and Adaptation Strategies for Global Change - Indonesia and Peru harbor some of the largest lowland tropical peatland areas. Indonesian peatlands are subject to much greater...     

Place-based management at different spatial scales

Place-based management is any management action having implications for a specified area. Place-based management is seen as a key component to practical implementation of ecosystem approach to management, with marine spatial planning (MSP) being the currently most promoted approach. In the present paper we address the challenges of place-based management at local, regional and global (oceanic) spatial scales using case studies from the Northeast Atlantic with examples from Norway. Both ecological, governance and management complexity increases with increasing geographic scale, with associated increases in uncertainty and thus increasing need for managing under the precautionary approach. A process where (ecologically) valuable and vulnerable areas are defined early on is essential to successful place-based management under the ecosystem approach. Integrating across sectors and achieving necessary cooperation between involved institutions and stakeholders is also necessary.     

Investigation of drugs of abuse and relevant metabolites in Dutch sewage water by liquid chromatography coupled to high resolution mass spectrometry

An extensive study on the presence of illicit drugs and pharmaceuticals with potential for abuse in sewage waters was made for the first time in the Netherlands. A total number of 24 target drugs were investigated in influent and effluent wastewater using liquid chromatography coupled to a high resolution Orbitrap mass spectrometer. This powerful analyzer has allowed not only the detection and identification of the compounds under investigation, but also their quantification at very low levels, which is highly innovative in the field of drugs of abuse. Samples were taken from five sewage treatment plants (STPs) during a whole week. The selected STPs served four cities of different size and an international airport. Daily variances of drug loads were demonstrated and removal efficiencies calculated for each drug and STP individually. Twelve target compounds were found in at least one influent or effluent, and highest concentrations were observed in influents collected from more urbanized areas. The compounds more frequently detected were amphetamine, benzoylecgonine, cocaine and THCCOOH together with the pharmaceuticals codeine, oxazepam and temazepam. Established week trends in consumption of drugs showed distinct differences between individual drugs. A slightly different occurrence pattern was observed in wastewaters from the airport. Thus, methamphetamine was only detected at Schiphol, a fact that was interpreted to be caused by consumption of this drug by travelers. Despite the fact that the Netherlands has frequently been criticized for its liberal drug policy the results from this study did not reveal higher drug consumption than found elsewhere, with the exception of cannabis.