是负责任的行动还是公关?非政府组织对志愿举措的看法

非政府组织倾向于高度怀疑工业界对志愿举措的促进,特别是当它们似乎被用来证明去掉法规有理或妨碍独立监测与评估时更加如此.此外,非政府组织还把矛头指向由于缺乏信息或缺乏多利害攸关者参与而产生的严重可信度差距.减少可信度差距和提高志愿举措的有效性的行动,要包括创造更大的透明度、允许独立验证、包含性、可持续性价值的内化、和互补性使用一种使之有能力的法规框架.1998年联合国可持续发展委员会会议是第一次包括一个"工业片"的.来自工会、非政府组织、工业界及其它有关方面的代表出席了会议.介绍了工商界对志愿举措的使用，以及监测和确保其有效性的办法(见第26页方框).本文是在该可持续发 展委员会1998年会议举行前不久写的.     

A Simplified Model for Predicting the Pollution Exchange Coefficient of Small Tidal Embayments

In recent years there has been a significant increase in the development and application of ever more sophisticated multi-dimensional models for solving the hydrodynamic and constituent transport equations which govern the flushing of pollution. However, advanced numerical modelling techniques can sometimes be augmented by alternative mathematical approaches which use simplified analytical solutions to predict the dispersion of contaminants. In the present article, a novel analytical tidal prism model is described for predicting the pollution flushing characteristics of small tidal embayments. The model relates the water quality response of the basin to the external forcing effects of the tide, the initial pollutant loading and the freshwater inflow rate. In general, the pollution flushing not only depends upon the geometry of the embayment and the tidal range but also on the proportion of effluent water which leaves the basin on an ebb tide, mixes with the surrounding coastal water and returns on subsequent flood tides. This effect has been taken into account in the mathematical model by the inclusion of a ‘pollution-return’ parameter. The analytical approach offers a viable and computationally inexpensive alternative to conventional multi-dimensional pollutant transport simulations and, more importantly, provides an increased understanding of the flushing characteristics of semi-enclosed tidal basins. The efficiency of the tidal flushing can be expressed in terms of the pollution exchange coefficient which measures the proportion of water exchanged with the sea each tidal cycle. To demonstrate the accuracy of the proposed mathematical formulation, analytical water quality predictions are compared against experimental pollution data from a 1:400 scale laboratory model of a generic square harbour. The results demonstrate that the analytical approach provides a simple and robust method of determining the water quality response of well-mixed tidal embayments.     

A note concerning time parameterization of Markovian models of ecosystem flow analysis

A continuous Markovian model of resource flow in a steady state ecosystem model is developed. This model calculates the mean and variance of the frequency of intercompartmental cyclings and duration of compartmental residence times. This model is compared with an analogous discrete Markovian flow model to demonstrate the sensitivity of discrete and continuous ecosystem flow analyses. Appropriate time parameterization of of discrete Markovian flow models is then discussed with special reference to Shannon's theorem of dynamic system sampling.     

Ultrasonic decomposition of atrazine and alachlor in water.

Abstract

The collapse of ultrasonically‐generated cavitation bubbles can result in sonochemical reactions. The kinetics of sonochemical decomposition of alachlor and atrazine in water were determined using a sonicator operating in the continuous mode at maximum output. Alachlor and atrazine solutions, 3.1 nmol L^‐1, were kept at constant temperature during the sonication. Decomposition at 30°C followed first‐order kinetics: k = 8.01 × 10^‐3 min^‐1 and 2.10 × 10^‐3 min^‐1 for alachlor and atrazine, respectively. It is not clear from the product analysis whether the decomposition was due to a thermal or free radical reaction. However, regardless of the decomposition mechanisms, the extrapolated half‐lives (86 and 330 min for alachlor and atrazine, respectively) support the potential development of ultrasonic waves to decompose herbicides in contaminated water.     

Movement and fate of detergents in groundwater: a field study

The major cations, anions, and detergents in a plume of contaminated groundwater at Otis Air Base on Cape Cod (Mass., U.S.A.) have moved approximately 3.5 km down gradient from the disposal beds. We hypothesize that the detergents form two distinct plumes, which consist of alkyl benzene sulfonates (ABS) detergents and linear alkyl sulfonates (LAS) and sodium dodecyl sulfate (NaLS) detergents. The ABS detergents were deposited from approximately 1940 through 1965, when ABS detergents were banned. From 1965 to the present, LAS and NaLS detergents were in the sewage. The ABS detergents appear to be transported in the aquifer at the same rate as the specific conductance (major cations and anions) and boron, which are currently used as conservative tracers of the plume of contaminated groundwater. There appears to be little or no biological degradation of the ABS detergents in the aquifer, based on their concentration in the plume. On the other hand, the LAS and NaLS detergents have degraded rapidly and have been detected only 0.6 km down gradient. The roleof the detergents in the transport of other organic compounds in the plume is nuclear. There is a separation of the ABS detergent plume and the volatile organic compound plume; however, the time of entry of the detergents and the volatile organic compounds is unknown. Therefore, it is not possible to conclude on the interaction of these two classes of compounds.     

Invasive prey impacts the abundance and distribution of native predators

While an extensive literature exists on the negative effects of invasive species, little is known about their facilitative effects on native species, particularly the role of invasives as trophic subsidies to native predators. The invasive gypsy moth (Lymantria dispar) undergoes periodic outbreaks during which it represents a super-abundant food source for predators capable of consuming it, particularly native cuckoos (Coccyzus erythropthalmus and C. americanus). We examined how gypsy moth outbreaks affect the abundance and distribution of cuckoos using the North American Breeding Bird Survey and 29 years of U.S. Forest Service gypsy moth defoliation records. Abundances of both Black-billed and Yellow-billed Cuckoos were significantly above average during outbreaks, but populations were average or below average in preceding and subsequent years, suggesting that cuckoos are immigrating to defoliations during outbreak years. Spatial analyses showed that cuckoo abundances approximately 40-150 km outside of defoliation areas were significantly below average, and these under-occupied breeding areas extended in all four compass directions around outbreaks. This result supports the idea that cuckoos locate gypsy moth outbreaks during a post-migratory nomadic phase. By shifting the annual distribution of cuckoos, gypsy moths may be shifting the trophic impact of cuckoos across large distances, which could affect native insect herbivores and plants.     

Foodweb modeling for polychlorinated biphenyls (PCBs) in the Twelvemile Creek Arm of Lake Hartwell,South Carolina,USA

PCBs from the Sangamo-Weston Superfund Site near Clemson, South Carolina, USA, were released into the Twelvemile Creek Arm of Lake Hartwell until the early 1990s. Monitoring data have shown that while PCB concentration in sediments declined since 1995, PCB concentrations in fish have remained elevated, e.g., largemouth bass (Micropterus salmoides) concentrations have ranged from 5 to 10 ppm. The EPA aquatic ecosystem model AQUATOX was applied to this system to better characterize foodweb dynamics that lead to biomagnification of PCBs. The model was calibrated with observed fish biomass data. Simulated PCB loading over a 12-year period provided a reasonable fit to observed PCB data in fish. The model demonstrated that contaminated labile detritus loaded to the system was incorporated into the foodweb rather than deposited, thereby maintaining the PCB concentrations in fish while concentrations in the sediment declined. A dominant PCB pathway was from detritus to daphnia to shad to largemouth bass. Fish PCB concentrations showed moderate sensitivity to toxicant parameters; model runs incorporating uncertainty in these parameters predicted recovery (<2 ppm PCB) for all species in the range of years from 2008 to 2013. The high sensitivity of the model to parameters related to growth strongly affected PCB concentrations in fish and should be considered in future AQUATOX applications.