The Input and Transmission of Fallout Radionuclides Through Redó, a High Mountain Lake in the Spanish Pyrenees

Fallout radionuclides have increasing value as tracers of pathways for pollutant transport through catchment/lake systems, in addition to their more traditional role in dating sediment records. The objectivesof this study, carried out within the EU MOLAR project, were tomeasure atmospheric fluxes of fallout ²¹⁰Pb, ¹³⁷Cs and ⁷Be at Redó, to establish mass balances for theseradionuclides, and test and validate models of pollutant transport through the lake and its catchment. This was achieved by comparing measured fluxes and concentrations in the water column with theoretical estimates using simple compartment models. Several interesting points emerged. Differences betweensoil core and rainwater measurements suggest that Saharan dust may be an important source of fallout ²¹⁰Pb. Fluxes throughthe water column had a clear seasonal trend reflecting winter icecover. Significant concentrations of ¹³⁷Cs are still presentin the water column, due to continued inputs from the catchment and/or remobilisation from the bottom sediments.     

掠夺俄罗斯远东地区原始森林

本文主要介绍俄罗斯远东地区的森林破坏现状和木材贸易的情况。以期让更多的人士了解和关心俄罗斯的森林生态环境。     

Rates of removal of sediment associated radiocaesium from the plynlimon experimental catchments, Powys, UK

Inventories of weapons-test and Chernobyl derived (137)Cs within the upper Wye and upper Severn catchments have been estimated using a variety of techniques. Transport rates of radiocaesium from the catchments have been determined from measurements of radionuclide activities on suspended and bedload sediments. Radiocaesium transport coefficients calculated from the results of 0.46-5.42 x 10(-3) y(-1) for freshly deposited Chernobyl (137)Cs contrast with that for older weapons-test fallout (137)Cs deposits (0.035-0.36 x 10(-3) y(-1)). These results show that freshly deposited Chernobyl (137)Cs is presently being lost at a significantly higher rate than weapons-test derived (137)Cs. For (137)Cs from both sources, residence times in the undisturbed upper Wye catchment are significantly higher than in the afforested upper Severn catchments.     

Programs assessing implementation and effectiveness of state forest practice rules and BMPs in the West

The major forest nonpoint source control programs in the West are largely regulatory, either under forest practices acts (California, Idaho, New Mexico, Nevada, Oregon, and Washington) or a streamside management act (Montana). These programs and the specific rules they enforce continue to undergo intensive scrutiny. Still, the questions are the same for these regulatory programs as for states that base nonpoint source control on voluntary BMPs (Arizona, Colorado, Utah, Wyoming). Are the rules or BMPs being applied, and are they effective in reducing nonpoint source pollution to levels that protect beneficial uses of water? The level of debate about forestry in the West has resulted in detailed monitoring and research to answer these questions. In the past, state agencies have assumed levels of BMP compliance based on the percent of operations without enforcement actions. These estimates are being replaced by statistically valid and reproducible monitoring of forest practices rules and BMP compliance levels. BMP effectiveness is being assessed using both qualitative and quantitative methods. This can involve field assessments, process-based research, and control watershed studies. Some trend monitoring is also beginning. With the regional implementation rate for forestry BMPs at about 94% and rising, it is likely that effectiveness testing will continue to be a priority and consume the majority of assessment resources for this region.     

Long-term burning interacts with herbivory to slow decomposition

Fires can generate spatial variation in trophic interactions such as insect herbivory. If trophic interactions mediated by fire influence nutrient cycling, they could feed back on the more immediate consequences of fire on nutrient dynamics. Here we consider herbivore-induced effects on oak litter quality and decomposition within a long-term manipulation of fire frequency in central Minnesota, USA. We focused on bur oak (Quercus macrocarpa) trees, which are common across the fire frequency gradient and are often heavily infested with either lace bugs (Corythuca arcuata) or aphids (Hoplochaithropsus quercicola). We used targeted exclusion to test for herbivore-specific effects on litter chemistry and subsequent decomposition rates. Lace bug exclusion led to lower lignin concentrations in litterfall and subsequently accelerated decomposition. In contrast, aphid exclusion had no effect on litterfall chemistry or on decomposition rate, despite heavy infestation levels. Effects of lace bug herbivory on litterfall chemistry and decomposition were similar in burned and unburned areas. However, lace bug herbivory was much more common in burned than in unburned areas, whereas aphid herbivory was more common in unburned areas. These results suggest that frequent fires promote oak-herbivore interactions that decelerate decomposition. This effect should amplify other influences of fire that slow nitrogen cycling.     

A protocol for assessing the effectiveness of oil spill dispersants in stimulating the biodegradation of oil

Dispersants are important tools in oil spill response. Taking advantage of the energy in even small waves, they disperse floating oil slicks into tiny droplets (<70 μm) that entrain in the water column and drift apart so that they do not re-agglomerate to re-form a floating slick. The dramatically increased surface area allows microbial access to much more of the oil, and diffusion and dilution lead to oil concentrations where natural background levels of biologically available oxygen, nitrogen, and phosphorus are sufficient for microbial growth and oil consumption. Dispersants are only used on substantial spills in relatively deep water (usually >10 m), conditions that are impossible to replicate in the laboratory. To date, laboratory experiments aimed at following the biodegradation of dispersed oil usually show only minimal stimulation of the rate of biodegradation, but principally because the oil in these experiments disperses fairly effectively without dispersant. What is needed is a test protocol that allows comparison between an untreated slick that remains on the water surface during the entire biodegradation study and dispersant-treated oil that remains in the water column as small dispersed oil droplets. We show here that when this is accomplished, the rate of biodegradation is dramatically stimulated by an effective dispersant, Corexit 9500®. Further development of this approach might result in a useful tool for comparing the full benefits of different dispersants.     

Distribution of total and methylmercury in different ecosystem compartments in the Everglades: implications for mercury bioaccumulation

We analyzed Hg species distribution patterns among ecosystem compartments in the Everglades at the landscape level in order to explore the implications of Hg distribution for Hg bioaccumulation and to investigate major biogeochemical processes that are pertinent to the observed Hg distribution patterns. At an Everglade-wide scale, THg concentrations were significantly increased in the following order: periphyton相似文献   

Case studies in co-benefits approaches to climate change mitigation and adaptation

Attempts to mitigate greenhouse gas emissions or manage the effects of climate change traditionally focus on management or policy options that promote single outcomes (e.g., either benefiting ecosystems or human health and well-being). In contrast, co-benefits approaches to climate change mitigation and adaptation address climate change impacts on human and ecological health in tandem and on a variety of spatial and temporal scales. The article engages the concept of co-benefits through four case studies. The case studies emphasize co-benefits approaches that are accessible and tractable in countries with human populations that are particularly vulnerable to climate change impacts. They illustrate the potential of co-benefits approaches and provide a platform for further discussion of several interdependent principles relevant to the implementation of co-benefits strategies. These principles include providing incentives across multiple scales and time frames, promoting long-term integrated impact assessment, and fostering multidimensional communication networks.     

Gas Chromatographic Analysis of Ambient Halogenated Compounds

Abstract

Fugitive dust emission from limestone extraction areas is a significant pollution source. The cracking operation in limestone extraction areas easily causes high total suspended particulate (TSP) concentrations in the atmosphere, occasionally exceeding the 1-hr national emission standard of Taiwan (500 μg/m³). The concentration and size distribution were measured at different distances (0.05–15 km) in the extraction areas. The highest hourly concentrations of TSP, PM₁₀ (suspended particulate matter [PM] smaller than 10 μm), and PM_2.5 (suspended PM smaller than 2.5 μm) are 1111, 825, and 236 μg/m³, respectively, during the cracking process. Measurement results obtained from the Micro-Orifice Uniform Deposit Impactor indicated that the mass median aerodynamic diameter is ～0.7 μm, with the geometric standard deviation exceeding 7. In addition, the emission factors are 0.143 and 0.211 kg/t for both vertical well and stair extraction operations, respectively. Experimental results demonstrate that the corresponding TSP control efficiencies for spraying water, planting grass, setting short walls, paving gravel roads, and establishing vertical well transportation are ～55, 50, 44, 22, and 30%, respectively. Furthermore, the PM₁₀ control efficiencies are ～45, 41, 54, 35, and 30%, respectively, whereas the PM_2.5 control efficiencies are roughly 23, 31, 15, 11, and 10%, individually.     

Statistical evaluation of photon count rate data for nanoscale particle measurement in wastewaters

The dynamic light scattering (DLS) technique can detect the concentration and size distribution of nanoscale particles in aqueous solutions by analyzing photon interactions. This study evaluated the applicability of using photon count rate data from DLS analyses for measuring levels of biogenic and manufactured nanoscale particles in wastewater. Statistical evaluations were performed using secondary wastewater effluent and a Malvern Zetasizer. Dynamic light scattering analyses were performed equally by two analysts over a period of two days using five dilutions and twelve replicates for each dilution. Linearity evaluation using the sixty sample analysis yielded a regression coefficient R(2) = 0.959. The accuracy analysis for various dilutions indicated a recovery of 100 ± 6%. Precision analyses indicated low variance coefficients for the impact of analysts, days, and within sample error. The variation by analysts was apparent only in the most diluted sample (intermediate precision ~12%), where the photon count rate was close to the instrument detection limit. The variation for different days was apparent in the two most concentrated samples, which indicated that wastewater samples must be analyzed for nanoscale particle measurement within the same day of collection. Upon addition of 10 mg l(-1) of nanosilica to wastewater effluent samples, the measured photon count rates were within 5% of the estimated values. The results indicated that photon count rate data can effectively complement various techniques currently available to detect nanoscale particles in wastewaters.