Forests provide ecosystem services, including timber production. In some cases, private forest owners perform management actions in order to enhance the provision of such services, or they may be encouraged by public policies and payments. This paper focuses specifically on the decision to set forest land aside for biodiversity conservation, as part of the more general question of the efficiency of multiple-use vs. specialised management of forest lands. We propose an econometric analysis to identify factors in the set-aside choice and measure the impact of this decision on forest management costs. The results show that the set-aside choice depends on the landowners’ income and motivations related to forest amenities. The choice of specialised management, as reflected in the set-aside decision, has a significant and positive impact on the intensity of management in the remainder of the forest and on management costs. From a policy implications point of view, these results suggest that instruments such as forest certification, subsidies and reverse auctions for conservation will be most likely to attract the interest of those forest owners with personal motivations and forest properties that offer both benefit and cost advantages in opting for such specialised management strategies.
Abstract This paper summarizes the sampling and analytical methods developed to identify and measure polycyclic aromatic hydrocarbons (PAH) and related aromatic compounds near a Horizontal Stud Soderberg plant at Jonquiere, Quebec, Canada. The primary source of PAH is the coal tar pitch used as a binder in Soderberg anodes. Twice a week at a number of sampling sites, airborne particulate matter was collected on glass-fiber filters using a Hi-Vol sampler for a twenty-four hour period. Organics on the filter were Soxhlet extracted with benzene. Identification was done by gas chromatography-mass spectrometry (GC-MS). The vast majority of compounds present were PAH, but small amounts of alkyl PAH and polycyclic aromatic compounds with heteroatoms such as nitrogen, oxygen and sulfur were also identified. Based on the GC-MS identification, a group of 14 PAH was selected for monitoring. Frequent PAH determinations revealed that the ratio of Benzo(a- )Pyrene to total PAH on the Hi-Vol filters is relatively constant in ambient air from one sampling station to another. 相似文献
The northern Québec-Labrador tree lines are the most climatically stressed tree ecosystems of eastern North America. In particular, white spruce (Picea glauca) tree line populations distributed between 56 degrees N and 58 degrees N and 61 degrees W and 66 degrees W show contrasted responses to recent changes in climate according to their geographic position relative to the Labrador Sea. Along the coast, the northernmost latitudinal and altitudinal tree lines responded positively to warming over the last 50 years with invading spruce several tens of meters above the current tree line. In contrast, white spruce tree lines across the wind-exposed Labrador plateau are located much higher in altitude and have receded a few tens of meters beginning around AD 1740-1750 and have not yet recovered. Whereas no field evidence of recent fire and insect damage was found, all inland tree line stands were progressively damaged likely due to mechanical defoliation of wind-exposed trees. Massive tree death in the 19th century caused a reduction in the number of seed-bearing trees, and declining tree lines were not replenished by seedlings. Recent warming reported for northern latitudes has not been strong enough to change the regressive tree line trajectory in interior Labrador. However, white spruce expansion above coastal tree line in the northernmost forest site in Labrador is in line with current climatic trends. It is hypothesized that the species is still advancing toward its potential tree line higher in altitude due to delayed postglacial migration. The slow advance of white spruce in northernmost coastal Labrador is likely caused by the rugged topography of the Torngat-Kaumajet-Kiglapait mountains. 相似文献
External shell surface (ESS) of bivalve mollusks is known to adsorb various metals dissolved in ambient water in high concentration. It is hypothesized here that the surface microtopography of the thin organic coating layer, periostracum, or calcareous shell (if periostracum was destroyed) plays a major role in the adsorption of actinides on ESS. Thorium (natural alpha-emitter) was used in short-term biosorption experiment with shell fragments of five bivalve mollusks. After a 72 h exposure to Th (∼6 kBq L−1), thorium concentration was measured on ESS using laser ablation inductively coupled plasma mass spectrometry; the distribution and density of alpha tracks were subsequently visualized by α-track autoradiography. A trend in reduced Th concentrations on the ESS was observed depending upon the species tested: (group 1 ∼4000 μg g−1) Chlamys islandica (M.), Mercenaria mercenaria (L.), Dreissena polymorpha (P.) > (group 2 ∼1200 μg g−1) Crassostrea virginica (G.) ? (group 3 ∼150 μg g−1) Mytilus edulis L. The microtopography of ESS was characterized by scanning electron microscopy revealing the high porosity of the calcareous surface of C. islandica and M. mercenaria, lamellate surface of periostracum in D. polymorpha, uneven but a weakly porous surface of periostracum of C. virginica, and a nearly smooth surface of the periostracum of M. edulis. This work has demonstrated, for the first time, the presence of a strong correlation between concentration of adsorbed Th and ESS microtopography, and the role of the periostracum in this process is discussed. 相似文献
A novel differential pulse voltammetry method (DPV) was researched and developed for the simultaneous determination of Pendimethalin, Dinoseb and sodium 5-nitroguaiacolate (5NG) with the aid of chemometrics. The voltammograms of these three compounds overlapped significantly, and to facilitate the simultaneous determination of the three analytes, chemometrics methods were applied. These included classical least squares (CLS), principal component regression (PCR), partial least squares (PLS) and radial basis function-artificial neural networks (RBF-ANN). A separately prepared verification data set was used to confirm the calibrations, which were built from the original and first derivative data matrices of the voltammograms. On the basis relative prediction errors and recoveries of the analytes, the RBF-ANN and the DPLS (D - first derivative spectra) models performed best and are particularly recommended for application. The DPLS calibration model was applied satisfactorily for the prediction of the three analytes from market vegetables and lake water samples. 相似文献
Bioaccumulation is essential for gaining insight into the impact of exposure to organic micropollutants in aquatic fauna. Data are currently available on the bioaccumulation of persistent organic pollutants, but there is very little documentation on the bioaccumulation of pharmaceuticals and personal care products (PPCPs). The bioconcentration of selected PPCPs was studied in marine mussels (Mytilus galloprovincialis). The selected PPCPs were two organic UV filters, i.e., 2-ethylhexyl-4-trimethoxycinnamate (EHMC) and octocrylene (OC), and two benzodiazepines (BZP), i.e., diazepam (DZP) and tetrazepam (TZP). Laboratory experiments were performed in which M. galloprovincialis was exposed to these compounds either directly from water, for the less lipophilic substances (BZP) or via spiked food for lipophilic UV filters. M. galloprovincialis uptook and eliminated BZP following first-order kinetics. The biological half-life (t (1/2)) of TZP was 1.4?days, resulting in a bioconcentration factor of 64 and 99?mL?g(-1) dry weight (dw), respectively, for 2.3 and 14.5?μg?L(-1) of exposure, while the biological half-life (t (1/2)) of DZP was 0.4?days, resulting in a bioconcentration factor of 51?mL?g(-1) dw for 13.2?μg?L(-1) of exposure. The uptake of UV filter was rapid in mussels, followed by elimination within 24?h. EHMC increased from 15 to 138?ng?g(-1) dw in 1?h and decreased to 25?ng?g(-1) after 24?h for 11.9?μg?L(-1) exposure. OC reached 839?ng?g(-1) dw after 1?h and decreased to 33?ng?g(-1) after 24?h for 11.6?μg?L(-1) exposure. However, EHMC and OC were slightly accumulated in 48?h, i.e., 38 and 60?ng?g(-1) dw, respectively. 相似文献
This paper investigates social and environmental injustices in solid waste management in Kinshasa, the capital of the Democratic Republic of Congo. The urban poor in most parts of Kinshasa bear a huge encumbrance of the solid waste burden and face multiple challenges associated with poor management of solid waste. This situation has resulted in poor and unhealthy living conditions for the majority of the urban residents. The problem of solid waste management in Kinshasa has further been compounded by rapid urbanisation which has occurred in the face of poor urban governance, civil conflict and weak institutional set-up. The combination of these challenges has resulted in increased overcrowding, poor sanitary conditions, lack of water and an unprecedented accumulation of solid waste which have triggered a myriad of urban problems. The worst affected are the poor urban who reside in locations that receive little or no socio-economic services from the Kinshasa Municipal authority. Using secondary data collected through a desk study, this paper argues that the poor solid waste situation in Kinshasa is not only a health risk, but also presents issues of both social and environmental injustices. These issues are analysed within the context of evolving arguments that focus on the need to develop a pro-poor approach in solid waste management that may present an opportunity for achieving both social and environmental justice for the urban poor in Kinshasa. 相似文献
This article discusses an approach for identification and evaluation of short-term greenhouse gas (GHG) emission reduction
options in firms. The approach is based on lessons learnt from a project using Participatory Integrated Assessment (PIA) and
builds on the idea that effective public climate policy for firms requires options that have support from stakeholders and
are practically feasible. Scenarios are used to provide a link with short-term policy developments and a model assists to
communicate quantitative effects of options to participating stakeholders. Our approach can be seen as a first step towards
a framework that meets the need for more systematic approaches to PIAs identifying effective public policies for short-term
GHG emission reduction options in firms. In order to identify effective options for non-carbon dioxide GHG emission reductions,
our approach has been applied to Dutch dairy farms, after which it has been refined. The case study suggests that our approach
can provide balance between practical, context specific issues and scientific-theoretical aspects, thereby avoiding common
pitfalls of participatory research projects to focus too much on either theory or practical issues.
This article discusses the outcomes of a research project on nutrients build-up on urban road surfaces.Nutrient build-up was investigated on road sites belonging to residential,industrial and commercial land use.Collected build-up samples were separated into five particle size ranges and were tested for total nitrogen (TN),total phosphorus (TP) and sub species of nutrients,namely,NO 2- ,NO 3- ,TKN and PO 43-.Multivariate analytical techniques were used to analyse the data and to develop detailed understanding on build- up.Data analysis revealed that the solids loads on urban road surfaces are highly influenced by factors such as land use,antecedent dry period and traffic volume.However,the nutrient build-up process was found to be independent of the type of land use.It was solely dependent on the particle size of solids build-up.Most of the nutrients were associated with the particle size range 150 μm.Therefore,the removal of particles below 150 μm from road surfaces is of importance for the removal of nitrogen and phosphorus from road surface solids build-up.It is also important to consider the difference in the composition of nitrogen and phosphorus build-up in the context of designing effective stormwater quality mitigation strategies. 相似文献