Influence of toxic cyanobacteria on community structure and microcystin accumulation of freshwater molluscs

Community structure and microcystin accumulation of freshwater molluscs were studied before and after cyanobacterial proliferations, in order to assess the impact of toxic blooms on molluscs and the risk of microcystin transfer in food web. Observed decrease in mollusc abundance and changes in species richness in highly contaminated waters were not significant; however, relative abundances of taxa (prosobranchs, pulmonates, bivalves) were significantly different before and after cyanobacterial bloom. Pulmonates constituted the dominant taxon, and bivalves never occurred after bloom. Microcystin accumulation was significantly higher in molluscs from highly (versus lowly) contaminated waters, in adults (versus juveniles) and in pulmonates (versus prosobranchs and bivalves). Results are discussed according to the ecology of molluscs, their sensitivity and their ability to detoxify.     

Pathology and failure in the design and implementation of adaptive management

The conceptual underpinnings for adaptive management are simple; there will always be inherent uncertainty and unpredictability in the dynamics and behavior of complex ecological systems as a result non-linear interactions among components and emergence, yet management decisions must still be made. The strength of adaptive management is in the recognition and confrontation of such uncertainty. Rather than ignore uncertainty, or use it to preclude management actions, adaptive management can foster resilience and flexibility to cope with an uncertain future, and develop safe to fail management approaches that acknowledge inevitable changes and surprises. Since its initial introduction, adaptive management has been hailed as a solution to endless trial and error approaches to complex natural resource management challenges. However, its implementation has failed more often than not. It does not produce easy answers, and it is appropriate in only a subset of natural resource management problems. Clearly adaptive management has great potential when applied appropriately. Just as clearly adaptive management has seemingly failed to live up to its high expectations. Why? We outline nine pathologies and challenges that can lead to failure in adaptive management programs. We focus on general sources of failures in adaptive management, so that others can avoid these pitfalls in the future. Adaptive management can be a powerful and beneficial tool when applied correctly to appropriate management problems; the challenge is to keep the concept of adaptive management from being hijacked for inappropriate use.     

Resilience and sustainable development: building adaptive capacity in a world of transformations

Emerging recognition of two fundamental errors underpinning past polices for natural resource issues heralds awareness of the need for a worldwide fundamental change in thinking and in practice of environmental management. The first error has been an implicit assumption that ecosystem responses to human use are linear, predictable and controllable. The second has been an assumption that human and natural systems can be treated independently. However, evidence that has been accumulating in diverse regions all over the world suggests that natural and social systems behave in nonlinear ways, exhibit marked thresholds in their dynamics, and that social-ecological systems act as strongly coupled, complex and evolving integrated systems. This article is a summary of a report prepared on behalf of the Environmental Advisory Council to the Swedish Government, as input to the process of the World Summit on Sustainable Development (WSSD) in Johannesburg, South Africa in 26 August 4 September 2002. We use the concept of resilience--the capacity to buffer change, learn and develop--as a framework for understanding how to sustain and enhance adaptive capacity in a complex world of rapid transformations. Two useful tools for resilience-building in social-ecological systems are structured scenarios and active adaptive management. These tools require and facilitate a social context with flexible and open institutions and multi-level governance systems that allow for learning and increase adaptive capacity without foreclosing future development options.     

The effect of opening windows on air change rates in two homes

More than 300 air change rate experiments were completed in two occupied residences: a two-story detached house in Redwood City, CA, and a three-story townhouse in Reston, VA. A continuous monitor was used to measure the decay of SF6 tracer gas over periods of 1-18 hr. Each experiment first included a measurement of the air change rate with all exterior doors and windows closed (State 0), then a measurement with the single change from State 0 conditions of opening one or more windows. The overall average State 0 air change rate was 0.37 air changes per hour (hr(-1)) (SD = 0.10 hr(-1); n = 112) for the California house and 0.41 hr(-1) (SD = 0.19 hr(-1); n = 203) for the Virginia house. Indoor/outdoor temperature differences appeared to be responsible for the variation at the Virginia house of 0.15-0.85 hr(-1) when windows were closed. Opening a single window increased the State 0 air change rate by an amount roughly proportional to the width of the opening, reaching increments as high as 0.80 hr(-1) in the California house and 1.3 hr(-1) in the Virginia house. Multiple window openings increased the air change rate by amounts ranging from 0.10 to 2.8 hr(-1) in the California house and from 0.49 to 1.7 hr(-1) in the Virginia house. Compared with temperature differences and wind effects, opening windows produced the greatest increase in the air change rates measured in both homes. Results of this study indicate the importance of occupant window-opening behavior on a home's air change rate and the consequent need to incorporate this factor when estimating human exposure to indoor air pollutants.     

WATER EXCHANGES: TOOLS TO BEAT EL NIÑO CLIMATE VARIABILITY IN IRRIGATED AGRICULTURE1

ABSTRACT: Using a case study of the Yakima River Valley in Washington State, this paper shows that relatively simple tools can be used to forecast the impact of the El Niño phenomenon on water supplies to irrigated agriculture, that this information could be used to estimate the significantly shifted probability distribution of water shortages in irrigated agriculture during El Niño episodes, and that these shifted probabilities can be used to estimate the value of exchanges of water between crops to relieve some of the adverse consequences of such shortages under western water law. Further, recently devised water‐trading tools, while not completely free under western water law to respond to forecasted El Niño episodes (ocean circulation patterns), are currently being employed during declared drought to reduce the devastating effects of water shortages in junior water districts on high valued perennial crops. Additional institutional flexibility is needed to take full advantage of climate forecasting, but even current tools clearly could prove useful in controlling the effects of climate variability in irrigated agriculture. Analysis shows the significant benefit of temporarily transferring or renting water rights from low‐value to high‐value crops, based on El Niño forecasts.     

Recent progress in developing and using personal monitors to measure human exposure to air pollutants

Within the last two years, great progress has been made in the field of personal air quality monitors. Improvements in pump design, miniaturization, adsorption techniques, and new collection principles have produced about a dozen sensitive monitors capable of being used by the general public to measure their normal everyday exposure to many toxic or carcinogenic compounds. This article reviews recent progress in this field, particularly as it relates to U.S. Environmental Protection Agency programs.     

Enhanced anaerobic bioremediation in a DNAPL residual source zone: Test Area North case study

An Interstate Technology and Regulatory Council (ITRC) forum was recently held that focused on case studies in which bioremediation of dense nonaqueous‐phase liquids (DNAPLs) was performed. This first case study, the Test Area North (TAN) site of the Idaho National Engineering and Environmental Laboratory, involves a trichloroethene (TCE) residual source area in a deep, fractured basalt aquifer that has been undergoing enhanced bioremediation since January 1999. Complete dechlorination from TCE to ethene was documented within nine months of operation, and sodium lactate injections were shown to enhance TCE mass transfer from the residual source. Since that time, optimization of injection strategies has maintained efficient dechlorination while demonstrating accelerated cleanup at a lower cost by changing to a whey powder amendment that solubilizes DNAPL. © 2006 Wiley Periodicals, Inc.