Biodegradability and toxicity assessment of trans-chlordane photochemical treatment

The removal of trans-chlordane (C(10)H(6)Cl(8)) from aqueous solutions was studied using UV, UV/H(2)O(2), UV/H(2)O(2)/Fe(2+), UV/TiO(2), or UV/TiO(2)/H(2)O(2) treatment using either UV/Vis blue lamps or UVC lamps (254 nm). H(2)O(2), FeSO(4) and TiO(2) were added at 1700, 456, and 2500 mgL(-1), respectively. trans-Chlordane was not significantly removed in non-irradiated controls and in samples irradiated with UV/Vis. It was also not removed in the absence of surfactant Triton X-114 added at 250 mgL(-1). In the presence of the surfactant, trans-chlordane concentration was reduced by 95-100% after 48 h of UVC and UVC/H(2)O(2) treatments and 70-80% after UVC/H(2)O(2)/Fe(2+), UVC/TiO(2) and UVC/H(2)O(2)/TiO(2) treatments. Based on these results, UVC, UVC/H(2)O(2) and UVC/TiO(2) treatments were further investigated. UVC treatment supported the highest pollutant removal (100% in 48 h), dechlorination efficiency (81% in 48 h), and detoxification to Lepidium sativum seed germination and activated sludge respiration although irradiated samples remained toxic to Chlorella vulgaris. Biodegradation of the UVC irradiated samples removed the source of algae toxicity but this could not be clearly attributed to the removal of trans-chlordane photoproducts because the surfactant interfered with the chemical and biological assays. Evidence was found that trans-chlordane was photodegraded through photolysis causing its successive dechlorination. trans-Chlordane removal was well described by a first order kinetic model at a rate of 0.21±0.01h(-1) at the 95% confidence interval.     

MULTI INCREMENT® TCE vadose‐zone investigation

MULTI INCREMENT® and discrete sampling strategies were used to estimate the average concentration and the three‐dimensional distribution of TCE in a 3,300‐m³ zone composed of two decision units (e.g., area of concern, population, exposure unit). Authors of this article and a private contractor (Stanley Consultants Inc.), respectively, implemented these two sampling strategies independently. Compared to discrete sampling, the MULTI INCREMENT sampling strategy identified more locations where percent‐level concentrations of TCE have migrated, is more economical, and provided greater data quality. © 2008 Wiley Periodicals, Inc.     

A moving target—incorporating knowledge of the spatial ecology of fish into the assessment and management of freshwater fish populations

Freshwater fish move vertically and horizontally through the aquatic landscape for a variety of reasons, such as to find and exploit patchy resources or to locate essential habitats (e.g., for spawning). Inherent challenges exist with the assessment of fish populations because they are moving targets. We submit that quantifying and describing the spatial ecology of fish and their habitat is an important component of freshwater fishery assessment and management. With a growing number of tools available for studying the spatial ecology of fishes (e.g., telemetry, population genetics, hydroacoustics, otolith microchemistry, stable isotope analysis), new knowledge can now be generated and incorporated into biological assessment and fishery management. For example, knowing when, where, and how to deploy assessment gears is essential to inform, refine, or calibrate assessment protocols. Such information is also useful for quantifying or avoiding bycatch of imperiled species. Knowledge of habitat connectivity and usage can identify critically important migration corridors and habitats and can be used to improve our understanding of variables that influence spatial structuring of fish populations. Similarly, demographic processes are partly driven by the behavior of fish and mediated by environmental drivers. Information on these processes is critical to the development and application of realistic population dynamics models. Collectively, biological assessment, when informed by knowledge of spatial ecology, can provide managers with the ability to understand how and when fish and their habitats may be exposed to different threats. Naturally, this knowledge helps to better evaluate or develop strategies to protect the long-term viability of fishery production. Failure to understand the spatial ecology of fishes and to incorporate spatiotemporal data can bias population assessments and forecasts and potentially lead to ineffective or counterproductive management actions.     

Toxicodynamic modeling of 137Cs to estimate white-tailed deer background levels for the Department of Energy's Savannah River Site

The U.S. Department of Energy's (USDOE) Savannah River Site (SRS) is a former nuclear weapon material production and current research facility adjacent to the Savannah River in South Carolina, USA. The purpose of this study was to determine the background radiocesium (¹³⁷Cs) body burden (e.g., from global fallout) for white-tailed deer (Odocoileus virginianus) inhabiting the SRS. To differentiate what the background burden is for the SRS versus ¹³⁷Cs obtained from SRS nuclear activities, data were analyzed spatially, temporally and compared to other off-site hunting areas near the SRS. The specific objectives of this study were: to compare SRS and offsite deer herds based on time and space; to interpret comparisons based on how data were collected as well as the effect of environmental and anthropogenic influences; to determine what the ecological half-life/decay rate is for ¹³⁷Cs in the SRS deer herd; and to give a recommendation to what should be considered the background ¹³⁷Cs level in the SRS deer herd. Based on the available information and analyses, it is recommended that the determination of what is considered background for the SRS deer herd be derived from data collected from the SRS deer herd itself and not offsite collections for a variety of reasons. Offsite data show extreme variability most likely due to environmental factors such as soil type and land-use patterns (e.g., forest, agriculture, residential activities). This can be seen from results where samples from offsite military bases (Fort Jackson and Fort Stewart) without anthropogenic ¹³⁷Cs sources were much higher than both the SRS and a nearby (Sandhills) study site. Moreover, deer from private hunting grounds have the potential to be baited with corn, thus artificially lowering their ¹³⁷Cs body burdens compared to other free-ranging deer. Additionally, sample size for offsite collections were not robust enough to calculate a temporal decay curve with an upper confidence level to determine if the herds are following predicted radioactive decay rates like the SRS or if the variability is due to those points described above. Using mean yearly values, the ecological half-life for ¹³⁷Cs body burdens for SRS white-tailed deer was determined to be 28.79 years—very close to the 30.2 years physical half-life.     

Characterization of food waste and bulking agents for composting

The characterization of food waste (FW) and locally available bulking agents (BA) are a prerequisite to optimizing compost recipes. This study measured the variation in FW characteristics (pH, dry matter (DM), carbon (C), wet bulk density and Total Kjeldahl Nitrogen (TKN)) produced by a restaurant and a community kitchen in downtown Montreal, Canada from May to August 2004. The project also measured the mass of FW produced by another restaurant and a group of 20-48 households, from June to August 2004. Locally available BA (hay, straw, pine wood shavings, cardboard, left over cattle feed and wheat residue pellets) were also characterized to formulate composting recipes based on the FW characteristics observed during a period representative of winter and summer conditions. Residential and restaurant FW characteristics varied significantly over the summer months, although the mass produced remained constant at 0.61 and 0.56 kg capita(-1)day(-1), respectively. In addition, the number of customers served by the restaurant increased by nearly 50% from June to August. The BA with the highest moisture adsorption capacity was found to be the wheat residue pellets, followed by chopped straw. Wheat residue pellets, chopped hay and left over cattle feed all presented a balanced C/N ratio. Wheat residue pellets and wheat straw, chopped hay and cardboard demonstrated neutral pH values. Based on the variable FW characteristics and monthly production rates, the formulation of recipes indicates that compost facilities must be flexible enough to handle seasonal variations of as much as 50% by volume.     

Enzyme-based resource allocated decomposition and landscape heterogeneity in the Florida Everglades

Enzyme catalyzed reactions are generally considered the rate-limiting step in organic matter degradation and may be significantly influenced by the structure and composition of plant communities. Changes in these rates have the potential to effect long-term peat accumulation and influence the topography of a wetland ecosystem. To determine habitat influences on enzyme activities, we examined slough and sawgrass plots within enriched and reference phosphorus (P) sites in the Everglades. Assays were performed for the enzymes involved in carbon (C), nitrogen (N), and P cycling and lignin depolymerization. Enzyme activities were normalized and analyzed in terms of a resource allocation strategy. Plant composition was found to significantly alter the allocation of enzymatic resources due to varying substrate complexities. Potential decomposition in the slough was less influenced by lignin than in the sawgrass habitats. Additionally, an index relating hydrolytic and oxidative enzymes was significantly greater in the slough habitats, whereas C/N ratios were significantly lower. These indices suggest more favorable decomposition conditions and thus slower peat accretion within the slough communities, which may contribute to the development of elevation differences within the sawgrass ridge and slough topography of the Everglades.     

Assessment of the Enabling Rural Innovation (ERI) approach: Case studies from Malawi and Uganda

This paper presents lessons from applying an innovative action research approach for linking smallholder farmers to markets, in eastern and southern Africa. The Enabling Rural Innovation (ERI) approach aims to strengthen social organization and entrepreneurial capacity in rural communities. It focuses on fostering community‐based capacity for the inclusion of rural women and the poor in analyzing and accessing market opportunities. Using case studies from Malawi and Uganda the paper assesses the outcomes of ERI on rural communities with a focus on human capital, gender issues and investment in natural resource management. Results show that households are benefiting significantly from linkages to markets in terms of increasing household incomes, and accumulating assets. Skills in analyzing markets and in negotiating with traders have increased among smallholder farmers. The integration of gender in the approach has led to changes in gender decision making patterns at household and community level towards a more shared decision‐making process. The results however show a difference in skills between men and women, with women showing lower levels of skills acquisition. Farmer participatory research has increased investments in improved technologies such as fertilizer applications for soil fertility management.     

Importance of public information and perception for managing recreational activities in the Peel-Harvey estuary, Western Australia

Surveys of water recreational activities were conducted in the Peel-Harvey estuary. Channels used by recreationists to gain information about water quality, the perception of water quality and resulting behaviour were investigated. This study showed that personal perception, local knowledge and history, absence of warnings and residency were major factors contributing to risk perception and behaviour in this recreational community. Management strategies should take this information into account to achieve maximal outcomes.