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1.
Two new methods for assessing temporal trends in stream-solute concentrations at specific streamflow ranges were applied to long (40 to 50-year) but sparse (bi-weekly to quarterly sampling) stream-water quality data collected at three forested mesoscale basins along an atmospheric deposition gradient in the northeastern United States (one in north-central Pennsylvania, one in southeastern New York, and one in eastern Maine). The three data sets span the period since the implementation of the Clean Air Act in 1970 and its subsequent amendments.Declining sulfate (O 4 2-) trends since the mid 1960s were identified for all 3 rivers by one or more of the 4 methods of trend detection used. Flow-specific trends were assessed by segmenting the data sets into 3-year and 6-year blocks, then determining concentration-discharge relationships for each block. Declining sulfate (O 4 2-) trends at median flow were similar to trends determined using a Seasonal Kendall Tau test and Sen slope estimator. The trend of declining O 4 2- concentrations differed at high, median and low flow since the mid 1980s at YWC and NR, and at high and low flow at WR, but the trends leveled or reversed at high flow from 1999 through 2002. Trends for the period of record at high flows were similar to medium- and low-flow trends for Ca2++ Mg2+ concentrations at WR, non-significant at YWC, and were more negative at low flow than at high flow at NR; trends in nitrate (NO3 -), and alkalinity (ALK) concentrations were different at different flow conditions, and in ways that are consistent with the hydrology and deposition history at each watershed. Quarterly sampling is adequate for assessing average-flow trends in the chemical parameters assessed over long time periods (∼decades). However, with even a modest effort at sampling a range of flow conditions within each year, trends at specified flows for constituents with strong concentration-discharge relationships can be evaluated and may allow early detection of ecosystem response to climate change and pollution management strategies.  相似文献   

2.
This paper examined the factors that might influence participating farmers’ willingness-to-pay for the Tree Farming Fund (TFF) established for sustainable development of participatory forest management (PFM). Information on willingness-to-pay, socioeconomic characteristics, and attitudes of participating farmers toward TFF were obtained from interviews with 581 participating farmers. Logistic regression analysis was used to determine the dominant factors that might influence participating farmers’ willingness-to-pay for the TFF. The results showed that participating farmers’ willingness-to-pay was significantly affected by (i) family income; (ii) education level; (iii) confidence that his aspired benefits will be received; (iv) agreement with the statement that ‘PFM is sustainable under the present state of management’; (v) agreement with the statement that ‘PFM is a good strategy for forest conservation’; and (vi) knowledge of PFM strategies. Thus, participating farmers with a higher level of education, higher income and positive attitudes toward TFF tended to express more willingness-to-pay. Establishment of TFF could be an effective strategy in implementing sustainable PFM in Bangladesh. For this strategy to succeed, however, active partnership between the participating farmers and Forest Department is required. Participating farmers’ attitudes toward TFF should therefore be taken into consideration as should the results of this study, which are important indicators of participating farmers’ positive attitudes toward TFF.  相似文献   

3.
The Niepoomice Forest is a large forestcomplex (110 km2) situated in southern Poland 10 to 30 kmto the east of the urban industrial Kraków agglomeration andsteelworks, which was built up on the outskirts of the city in1950. Due to prevailing westerly winds, the forest is affectedby pollutants emitted by both the steelworks and the city. Thelevel of heavy metal contamination in the Niepoomice Forestwas described using a sensitive bioindicator – the moss Pleurozium schreberi. Mean concentrations of metals in mosscollected in the Niepoomice Forest were Cd – 0.71, Cr – 2.4,Cu – 8.6, Fe – 673, Pb – 12.7, and Zn – 61 mg/kg.Concentrations of heavy metals in moss in the NiepoomiceForest decreased in time. As compared with the relatively cleanarea in north-eastern Poland (Puszcza Biaowieska), the concentration of Fe was 2–9 fold and Pb 4–6 fold higher in theNiepoomice Forest in 1975, while in 1998 4 fold and 2 fold,respectively. In both 1975 and 1998 the most polluted by heavymetals was the western part of the Niepoomice Forest (closestto the pollution sources) and the area along the roads insidethe forest complex.  相似文献   

4.
In this article the consistency of forest damageassessments on conifer trees is analysed, by usingdifferent methods in estimating the accuracy inassessments of defoliation and discolouration. The dataoriginate from control surveys in the Swedish nationalforest damage survey, as well as from national andinternational training courses. Standard deviation ofdifferences in the assessment of defoliation on singletrees is found to be about 10% units for Norway spruceand 8.5% for Scots pine. Problems in correctly assessingdamaged Scots pine trees and discoloured Norway sprucetrees are revealed by measures of agreement (Kappastatistic). Results from several years of nationaltraining courses indicate that, on an average, theobserver teams do not significantly differ from a nationalstandard, but significant differences between observerteams are found. The presented estimates indicate asubstantial within observer error compared to the betweenobserver error. The results indicate that the long-termdevelopment of forest damage, rather than short-termfluctuations, is the most important information fromthese kinds of inventories.  相似文献   

5.
We developed a simple conceptual model that tracks nitrogen and carbon jointly through an N fertilized forest ecosystem. The stimulation of growth increases the litterfall and imports substrate for soil microorganisms. Microbial biomass forms according to the supply of C and N. The formation of microbial biomass is accompanied by respiratory C losses. The quantity of CO2 efflux depends on the C use efficiency of microbes. When excess N is available, the microbial activity is accelerated and the demand for substrate is high. Litterfall supplies an insufficient amount of C to the soil. In such a case, labile soil C is mineralized and the net effect of N fertilization is a loss of soil C. A strong N fertilization effect on the aboveground biomass can offset the soil C loss. In the case of a low N dosage or high N losses due to leaching or emission of nitrogen oxides, the soil C loss is small. The conceptual model was applied to a case study. The field data, collected over a time span of several decades, could not support sound conclusions on the temporal trend of soil C because the spatial and temporal variability of the chemical data was high. The conceptual model allowed to give an evaluation of the fertilization effect on soil C based on reproducible principles.  相似文献   

6.
Trends in atmospheric acid deposition and in soil solution acidity from 1995 or later until 2007 were investigated at several forest sites throughout Switzerland to assess the effects of air pollution abatements on deposition and the response of the soil solution chemistry. Deposition of the major elements was estimated from throughfall and bulk deposition measurements at nine sites of the Swiss Long-Term Forest Ecosystem Research network (LWF) since 1995 or later. Soil solution was measured at seven plots at four soil depths since 1998 or later. Trends in the molar ratio of base cations to aluminum (BC/Al) in soil solutions and in concentrations and fluxes of inorganic N (NO(3)-N + NH(4)-N), sulfate (SO(4)-S), and base cations (BC) were used to detect changes in soil solution chemistry. Acid deposition significantly decreased at three out of the nine study sites due to a decrease in total N deposition. Total SO(4)-S deposition decreased at the nine sites, but due to the relatively low amount of SO(4)-S load compared to N deposition, it did not contribute to decrease acid deposition significantly. No trend in total BC deposition was detected. In the soil solution, no trend in concentrations and fluxes of BC, SO(4)-S, and inorganic N were found at most soil depths at five out of the seven sites. This suggests that the soil solution reacted very little to the changes in atmospheric deposition. A stronger reduction in base cations compared to aluminum was detected at two sites, which might indicate that acidification of the soil solution was proceeding faster at these sites.  相似文献   

7.
A conceptual model of sustainable forest management is described based on three connected and necessary components: Policy/Strategic Planning, Operational Planning, and EffectivenessMonitoring/Science.Alberta’s proposed Forest Management Planning Standard is described as an example of operational planning. The standard utilizes coarse and fine filter approaches to conserving biodiversity and sets requirements for implementation monitoring.The Alberta Biodiversity Monitoring Program (ABMP) is described as an example of effectiveness monitoring supporting Operational Planning. The ABMP is a rigorous science-based initiative that is being developed to monitor and report on biodiversity status and trends throughout the province of Alberta, Canada. The basic survey design consists of 1656 sites, 20 km apart, evenly spaced on a grid pattern across Alberta. Sites will be sampled over a five-year period at a rate of 350 sites/year. Standardized sampling protocols will be used to cover a broad range of species and habitat elements within terrestrial and aquatic environments, as well as broader landscape-level features.Trends and associations detected by ABMP products will be validated through cause-effect research. ABMP focuses research on critical issues and informs both operational planning and the development of policy and strategic-level plans. The Alberta Forest Management Planning Standard and the ABMP are described as key components to implementing resource planning based on ecosystem management principles.  相似文献   

8.
As part of the U.S. 2003 National Report on Sustainable Forests, four metrics of forest fragmentation--patch size, edge amount, inter-patch distance, and patch contrast--were measured within 137744 non-overlapping 5625 ha analysis units on land-cover maps derived from satellite imagery for the 48 conterminous States. The perimeter of a typical forest patch is about 100 m from the perimeter of its nearest neighbor, except when there is not much forest, in which case that distance is 200 to 300 m. A typical analysis unit has from 10 to 40% as much forest edge as it could possibly have, given the amount of forest present. Most analysis units contain a large number of patches that are less than one hectare in size, and about 10% contain one or more 2000 to 5000 ha patches. Forest often defines the background landscape, and patch contrast is generally either very high or very low in eastern regions and intermediate in western regions. Many research needs were identified by this experimental analysis of available data and metrics.  相似文献   

9.
Environmental Modeling & Assessment - Extreme or recurrent drought events are the principal source of stress on forests, impairing their overall health. They result in financial losses for...  相似文献   

10.
11.
The study was conducted to test the hypothesis that the regional variability of nitrogen (N) and metal accumulations in terrestrial ecosystems are due to historical and recent ways of landuse. To this end, two regions of Central Europe were selected for investigation: the Weser-Ems Region (WER) and the Euro Region Nissa (ERN). They were assumed to have land use-specific accumulation profiles. Thus, the metal and N accumulations in both regions were examined by means of geostatistically based comparative moss analysis. The sampling and chemical analysis of mosses were conducted in accordance with the convenient guidelines and methods, respectively. The spatial representativity of the sampling sites was computed by means of a land classification which was calculated for Europe by means of classification trees and GIS-techniques. The differences of deposition loads were tested for statistical significance with regard to time and space. The measurement values corroborated the decline of metal accumulation observed since the beginning of the European Metals in Mosses Surveys in 1990. The metal loads of the mosses in the ERN exceeded those in the WER significantly. The opposite holds true for the N concentrations: those in the WER were significantly higher than those in the ERN. The reduction of emissions from power plants, factories and houses was strongly correlated with the decline of deposition and bioaccumulation of metals. As proved by the European Metals in Mosses Surveys, this tendency is due to successful environmental policies. But no such success could be verified by monitoring the accumulation of N in mosses.  相似文献   

12.
The variations of Cl???, F???, and Fe?+?+? in the underground water during pre- and post-monsoon periods for 2003 have been examined, for two places in Unnao district, by argentrometric titration method (Sodic Land Reclamation Project Uttar Pradesh 1998) and atomic absorption spectrometry (Sodic Land Reclamation Project Uttar Pradesh 1998). The concentration of these ions falls outside the limits prescribed by the World Health Organization (WHO 1984).  相似文献   

13.
If it is assumed that the Pb collected in grass samples is derived mainly from atmospheric deposition then grass samples can be used as a convenient and easily analysed monitor for Pb deposition, in particular to establish the isotopic composition of current deposition in remote locations. As some studies have demonstrated a strong correlation between soil and grass Pb concentrations, it was considered important to establish the proportion of soil Pb in the grasses used to monitor atmospheric deposition at upland locations in Scotland. Consideration of earlier studies provided evidence that very little, if any, Pb in grass was derived from soil. Lead isotope analysis, by thermal ionisation mass spectrometry, of grasses grown on soils spiked with enriched (207)Pb in the field situation allowed the relative contribution of atmospheric deposition and soil to the grass Pb to be calculated. In most cases, >80% of Pb in grass was derived from atmospheric deposition and in recent years this value was >90%. Recalculation of the (206)Pb/(207)Pb ratio in grass samples showed that there was very little error in the results, published previously, which were based on the assumption that all the Pb collected with grass was derived from the atmosphere. The trends established by measuring the (206)Pb/(207)Pb ratio in grasses were confirmed and remain valid.  相似文献   

14.
Heavy metals in honey are of interest not only for quality control, but also for determination environmental contamination. The objective of this work was to determine distribution of the levels of selected heavy metals. Levels of copper (Cu), cadmium (Cd), manganese (Mn), Iron (Fe), magnesium (Mg) and nickel (Ni) in honey samples (21) in Kahramanmaraş region were determined by atomic absorption spectrometer (AAS). The mean values for Cu, Cd, Mn, Fe, and Mg were 0.01, 0.32, 0.03, 0.36 and 10.45 ppm, respectively. Nickel was not detected in honey samples. Kahramanmaraş honey samples were not free of heavy metals but the levels of them were found well below the permitted levels. The results suggested that honey may be useful for assessing the presence of environmental contaminants.  相似文献   

15.
16.
In this study, aluminium (Al), lead (Pb), cadmium (Cd), selenium (Se) and arsenic (As) contents in milk and different dairy product samples were measured. Pb, Cd, As, Al and Se contents in the milk and different dairy products ranged from 0.054 mg/kg (milk powder)?1.100 mg/kg (Ka?ar cheese), 0.009 mg/kg (whey powder and yogurt)?1.051 mg/kg (Tulum cheese), 0.010 mg/kg (whey powder)?0.146 mg/kg (butter), 2.848 mg/kg (ice cream)?8.778 (drained yogurt) and n.d. (ice cream, milk and whey powder, yogurt, ayran and Lor cheese)?0.434 mg/kg (Tulum cheese), respectively. The 75% of White and Ka?ar cheeses, 50% of Lor and 12.5% of Tulum cheese samples contained higher Pb according to the legal limits established by the Turkish Food Codex and European Communities regulation and 12.5% of Tulum cheese sample contained Cd. It was concluded that Pb contents of milk and dairy products from this region might be highly hazardous to human  相似文献   

17.
Health Impact Assessment (HIA) is a decision support approach which is applied in various shapes and forms throughout the world. In England, amongst a range of areas of application, HIA is applied in local (spatial) plan making and project development planning. Whilst various authors have reflected on HIA practice in England, the extent of application and its quality has remained unclear. This paper aims at addressing this gap by reporting on the results of a systematic review of HIA in planning. It is found that between 100 and 200 HIAs are likely being produced each year in England. Whilst most assessments are rapid (desk based), there are also examples of comprehensive and intermediate HIAs, where a participatory procedural approach is followed. An important finding is that those HIAs applied within the context of other assessments (integrated impact assessment -IIA, strategic environmental assessment - SEA/ sustainability appraisal -SA and environmental impact assessment – EIA) tend to be of a higher quality than standalone HIAs, mainly because of the existing comprehensive statutory procedural requirements for these other assessments into which HIA can be integrated.  相似文献   

18.
A national dataset on concentrations of mercury in fish, compiled mainly from state and federal monitoring programs, was used to evaluate trends in mercury (Hg) in fish from US rivers and lakes. Trends were analyzed on data aggregated by site and by state, using samples of the same fish species and tissue type, and using fish of similar lengths. Site-based trends were evaluated from 1969 to 2005, but focused on a subset of the data from 1969 to 1987. Data aggregated by state were used to evaluate trends in fish Hg concentrations from 1988 to 2005. In addition, the most recent Hg fish data (1996?C2005) were compared to wet Hg deposition data from the Mercury Deposition Network (MDN) over the same period. Downward trends in Hg concentrations in fish from data collected during 1969?C1987 exceeded upward trends by a ratio of 6 to 1. Declining Hg accumulation rates in sediment and peat cores reported by many studies during the 1970s and 1980s correspond with the period when the most downward trends in fish Hg concentrations occurred. Downward Hg trends in both sediment cores and fish were also consistent with the implementation of stricter regulatory controls of direct releases of Hg to the atmosphere and surface waters during the same period. The southeastern USA had more upward Hg trends in fish than other regions for both site and state aggregated data. Upward Hg trends in fish from the southeastern USA were associated with increases in wet deposition in the region and may be attributed to a greater influence of global atmospheric Hg emissions in the southeastern USA. No significant trends were found in 62% of the fish species from six states from 1996 to 2005. A lack of Hg trends in fish in the more recent data was consistent with the lack of trends in wet Hg deposition at MDN sites and with relatively constant global emissions during the same time period. Although few significant trends were observed in the more recent Hg concentrations in fish, it is anticipated that Hg concentrations in fish will respond to changes in atmospheric Hg deposition, however, the magnitude and timing of the response is uncertain.  相似文献   

19.
In this study, 74 soil samples collected from the Pearl River Delta were analyzed for polycyclic aromatic hydrocarbons (PAHs). The PAH mixture in the soils is mainly of low molecular weight compounds, with naphthalene (21.4%) and phenanthrene (21.8%) being dominant. Soil PAH levels from the Pearl River Delta are relatively low (28?C711 ng/g, averaged 192 ng/g) compared to those from urban soils in temperate regions. The mean concentration of ??PAHs generally decrease with increasing distance from the city center, with ??PAHs of paddy soils > crop soil > natural soil. PAHs in the air were measured during a year-round sampling campaign using semipermeable membrane devices, and the transfer of chemicals between the soil and air compartments were estimated. Soil?Cair fugacity quotient calculations showed a highly uncertain equilibrium position of PAHs, with net volatilization of naphthalene and fluorene, whereas net deposition of phenanthrene, fluoranthene, and pyrene, indicating a capacity for the air to supply the soil with more substances.  相似文献   

20.
Nowadays, high-time resolved aerosol studies are mandatory to better understand atmospheric processes, such as formation, removal, transport, deposition or chemical reactions. This work focuses on PM10 physical and chemical characterisation with high-time resolution: elements (from Na to Pb), ions and OC/EC fractions concentration were determined during two weeks in summer and two in winter 2006 with 4-hours resolution. Further measurements aimed at hourly elemental characterisation of fine and coarse fractions and at the determination of particles number concentration in the 0.25-32 microm size range in 31 bins. The chemical mass closure was carried out in both seasons, enhancing intra-day differences in PM10 composition. In Milan, the highest contribution came from organic matter (34% and 33% in summer and winter, respectively); other important contributors were secondary inorganic compounds (16% and 24% in summer and winter, respectively) and, in summer, crustal matter (14%). Temporal trends showed strong variations in PM10 composition during contiguous time-slots and diurnal variations in different components contribution were identified. Moreover, peculiar phenomena, which would have hardly been detected with 24-hours samplings, were evidenced. Particles removal due to precipitations, aerosol local production and long range transport were studied in detail.  相似文献   

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