Recovery of mercury-contaminated fisheries

In this paper, we synthesize available information on the links between changes in ecosystem loading of inorganic mercury (Hg) and levels of methylmercury (MeHg) in fish. Although it is widely hypothesized that increased Hg load to aquatic ecosystems leads to increases in MeHg in fish, there is limited quantitative data to test this hypothesis. Here we examine the available evidence from a range of sources: studies of ecosystems contaminated by industrial discharges, observations of fish MeHg responses to changes in atmospheric load, studies over space and environmental gradients, and experimental manipulations. A summary of the current understanding of the main processes involved in the transport and transformation from Hg load to MeHg in fish is provided. The role of Hg loading is discussed in context with other factors affecting Hg cycling and bioaccumulation in relation to timing and magnitude of response in fish MeHg. The main conclusion drawn is that changes in Hg loading (increase or decrease) will yield a response in fish MeHg but that the timing and magnitude of the response will vary depending of ecosystem-specific variables and the form of the Hg loaded.     

Variation of stabilised,microbial and biologically active carbon and nitrogen in soil under contrasting land use and agricultural management practices

Land use and agricultural practices modify both the amounts and properties of C and N in soil organic matter. In order to evaluate land use and management-dependent modifications of stable and labile C and N soil pools, (i). organic C and total N content, (ii). microbial (C(mic)) and N (N(mic)) content and (iii). C and N mineralisation rates, termed biologically active C and N, were estimated in arable, grassland and forest soils from northern and southern Germany. The C/N-ratios were calculated for the three levels (i)-(iii) and linked to the eco-physiological quotients of biotic-fixed C and N (C(mic)/C(org), N(mic)/N(t)) and biomass-specific C and N mineralisation rate (qCO(2), qN(min)). Correlations could mainly be determined between organic C, total N, C(mic), N(mic) and C mineralisation for the broader data set of the land use systems. Generally, the mineralisation activity rate at 22 degrees C was highly variable and ranged between 0.11 and 17.67 microg CO(2)-C g(-1) soil h(-1) and -0.12 and 3.81 microg (deltaNH(4)(+)+deltaNO(3)(-))-N g(-1) soil h(-1). Negative N data may be derived from both N immobilisation and N volatilisation during the experiments. The ratio between C and N mineralisation rate differed significantly between the soils ranging from 5 to 37, and was not correlated to the soil C/N ratio and C(mic)/N(mic) ratio. The C/N ratio in the 'biologically active' pool was significantly smaller in soils under conventional farming than those under organic farming systems. In a beech forest, it increased from the L, Of to the Ah horizon. The biologically active C and N pools refer to the current microbial eco-physiology and are related to the need for being C and N use efficient as indicated by metabolic qCO(2) and qN(min) quotients.     

Appraising different models for predicting biomethane potential: the case of avocado oil processing by-products

Journal of Material Cycles and Waste Management - Biomethane potentials (BMPs) for avocado oil processing by-products were determined using six different theoretical BMP prediction models and...     

Potential interferences in photolytic nitrogen dioxide converters for ambient air monitoring: Evaluation of a prototype

ABSTRACT

Mixing ratios of the criteria air contaminant nitrogen dioxide (NO₂) are commonly quantified by reduction to nitric oxide (NO) using a photolytic converter followed by NO-O₃ chemiluminescence (CL). In this work, the performance of a photolytic NO₂ converter prototype originally designed for continuous emission monitoring and emitting light at 395 nm was evaluated. Mixing ratios of NO₂ and NO_x (= NO + NO₂) entering and exiting the converter were monitored by blue diode laser cavity ring-down spectroscopy (CRDS). The NO₂ photolysis frequency was determined by measuring the rate of conversion to NO as a function of converter residence time and found to be 4.2 s^?1. A maximum 96% conversion of NO₂ to NO over a large dynamic range was achieved at a residence time of (1.5 ± 0.3) s, independent of relative humidity. Interferences from odd nitrogen (NO_y) species such as peroxyacyl nitrates (PAN; RC(O)O₂NO₂), alkyl nitrates (AN; RONO₂), nitrous acid (HONO), and nitric acid (HNO₃) were evaluated by operating the prototype converter outside its optimum operating range (i.e., at higher pressure and longer residence time) for easier quantification of interferences. Four mechanisms that generate artifacts and interferences were identified as follows: direct photolysis, foremost of HONO at a rate constant of 6% that of NO₂; thermal decomposition, primarily of PAN; surface promoted photochemistry; and secondary chemistry in the connecting tubing. These interferences are likely present to a certain degree in all photolytic converters currently in use but are rarely evaluated or reported. Recommendations for improved performance of photolytic converters include operating at lower cell pressure and higher flow rates, thermal management that ideally results in a match of photolysis cell temperature with ambient conditions, and minimization of connecting tubing length. When properly implemented, these interferences can be made negligibly small when measuring NO₂ in ambient air.

Implications: A new near-UV photolytic converter for measurement of the criteria pollutant nitrogen dioxide (NO₂) in ambient air by CL was characterized. Four mechanisms that generate interferences were identified and investigated experimentally: direct photolysis of HONO which occurred at a rate constant 6% that of NO₂, thermal decomposition of PAN and N₂O₅, surface promoted chemistry involving HNO₃, and secondary chemistry involving NO in the tubing connecting the converter and CL analyzer. These interferences are predicted to occur in all NO₂ P-CL systems but can be avoided by appropriate thermal management and operating at high flow rates.     

Can the legacy of industrial pollution influence antimicrobial resistance in estuarine sediments?

Antimicrobial resistance (AMR) represents a major global health threat, as well as a major hazard to sustainable economic development and national security. It remains, therefore, vital that current research aligns to policy development and implementation to alleviate a potential crisis. One must consider, for example, whether drivers of antibiotic resistance can be controlled in the future, or have they already accumulated in the past, whether from antibiotics and/or other pollutants? Unfortunately, industrial heritage and its pollution impact on the prevalence of environmental AMR have largely been ignored. Focussing on industrialised estuaries, we demonstrate that anthropogenic pollution inputs in addition to the natural diurnal environmental conditions can sufficiently create stressful conditions to the microbiome and thus promote selective pressures to shift the resistome (i.e., collection of resistance traits in the microbiological community). Unfortunately, the bacteria’s survival mechanisms, via co-selective pressures, can affect their susceptibility to antibiotics. This review highlights the complexity of estuarine environments, using two key contaminant groups (metals/toxic elements and polyaromatic hydrocarbons), through which a variety of possible chemical and biological pollutant stressors can promote the emergence and dissemination of antimicrobial resistance. We find compelling divers to call on more focused research on historically disrupted ecosystems, in propagating AMR in the real world.

     

Assisted species migration and hybridization to conserve cold-adapted plants under climate change

Temperature rise due to climate change is putting many arctic and alpine plants at risk of extinction because their ability to react is outpaced by the speed of climate change. We considered assisted species migration (ASM) and hybridization as methods to conserve cold-adapted species (or the genes thereof) and to minimize the potential perturbation of ecosystems due to climate change. Assisted species migration is the deliberate movement of individuals from their current location to where the species’ ecological requirements will be matched under climate projections. Hybridization refers to crossbreeding of closely related species, where for arctic and alpine plants, 1 parent is the threatened cold-adapted and the other its reproductively compatible, warm-adapted sibling. Traditionally, hybridization is viewed as negative and leading to a loss of biodiversity, even though hybridization has increased biodiversity over geological times. Furthermore, the incorporation of warm-adapted genes into a hybrid may be the only means for the persistence of increasingly more maladapted, cold-adapted species. If approached with thorough consideration of fitness-related parameters of the source population and acknowledgement of the important role hybridization has played in shaping current biodiversity, ASM and hybridization could help save partial or whole genomes of key cold-adapted species at risk due to climate change with minimal negative effects on ecosystem functioning.     

THE SOCIAL CONTEXT OF WESTERN WATER DEVELOPMENT1

ABSTRACT: Social scientists were included in the planning and design for an integrated, trans-basin water resource project. Within this complex project, a socioeconomic impact assessment (SIA) concentrated on identifying the social, political, and economic issues and potential impacts inherent in developing a city's water rights. Before the SIA began, some of the development alternatives had already generated widespread hostility and organized opposition from communities within the watershed. The SIA involved residents of affected communities in the study design and project planning. The study found a number of components that constituted the concerns, beliefs, and expectations about perceived, potential impacts that might result from the different alternatives. In most cases these issues constituted threats to valued environmental resources, valued community resources, the social environment, the economic base, and a secure future. The social science component was a key factor in the ultimate decision to pursue a particular alternative which was sensitive to the social and political issues, minimized environmental and socioeconomic impacts, and ultimately had support among the communities potentially affected. The experience from this case study suggests that the approach used can be applied successfully in the planning of other water development projects and result in cooperation from the wide range of interest groups that often present costly obstacles to such projects.     

Managing environmental problems during transitions: The department of energy as a case study

Many federal, state, and private agencies deal with long‐term environmental problems within a transition framework where political administrations, funds, regulators, regulatory requirements, environmental conditions, and tribal and stakeholder concerns change. In this article, we examine the types of transitions, as well as important stabilities, that agencies face, the interactions with stakeholders that are vulnerable to disruption or failure, and some of the problems that develop as a result of these conditions, using the U.S. Department of Energy (US DOE's) Office of Environmental Management (EM) as a case study. Transitions, or instabilities, include changes in administrations at the federal, state, and local level; public perceptions and concerns; political climate; available funds; environmental conditions (e.g., global climate change, global contaminant transport, local and regional contamination); international and national business conditions; and site conditions (physical, chemical, biological). Governmental agencies operate under several different kinds of uncertainties, including scientific, fiscal‐year economic, technological, and societal. Not all information can be known, and the outcomes from scientific issues or technologies cannot always be predicted. The authors believe that transitions from one set of conditions to another can be more effectively integrated with the long‐term stability of environmental laws and regulations, and with the stability of the treaty rights and concerns of tribal nations, as well as the shorter‐term stability of career personnel and established programs. A sense of stability for government agencies allowing maintenance of ongoing environmental management programs can also be achieved through processes and programs, such as establishing long‐term contracts (for remediation or restoration work), schedule and scope documents, future land‐use documents, National Environmental Research Parks (which obligate lands to study and conservation), and other programs that set the direction of work and activities for many years. Further, two other factors are essential for success within any agency facing transitions: (1) expectations should be both forward‐looking and realistic, and (2) there must be flexibility in both programs and processes. The authors conclude that several features are essential to addressing some of the problems created by transitions, including information, integration, iteration, interaction, and inclusion. © 2009 Wiley Periodicals, Inc.