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61.
Pulp and paper mills are one of the major effluent generating industries in the world. In most cases, mill effluent (treated or raw) is discharged back into a river, creek, stream or other water body; resulting in negative environmental impacts, as well as social concerns, among the downstream users. Pulp and paper mill effluent management, which could result in zero discharge into downstream water bodies, would present the best management option to address socio-environmental concerns. This paper presents such an effort aimed at closing the water cycle by using treated effluent from the mill to irrigate forage and fodder crops for producing animals feed. The treated effluent is delivered from the mill through gravity into a winter storage dam of 490ML capacity. For irrigation applications on 110ha of farmland, which is 42% of the total farmland, the water is pumped from the winter storage dam to five individual paddocks with Centre Pivot (CP) irrigators and one rectangular paddock with a Soft Hose Travelling (SHT) irrigator. From October 2001 to June 2006, a total of 2651mm of wastewater was applied at the farm. The impact assessment results, obtained from field monitoring, investigations and analysis, indicated that the closed water cycle effluent management strategy described had resulted in a lessening of the impact on water resources usually associated with paper mills. However, social attitudes to the use of crops that have been irrigated with recycled waters and the resulting impact on market value of the produce may still be a major consideration. 相似文献
62.
Biogeochemical consequences of rapid microbial turnover and seasonal succession in soil 总被引:8,自引:0,他引:8
Schmidt SK Costello EK Nemergut DR Cleveland CC Reed SC Weintraub MN Meyer AF Martin AM 《Ecology》2007,88(6):1379-1385
Soil microbial communities have the metabolic and genetic capability to adapt to changing environmental conditions on very short time scales. In this paper we combine biogeochemical and molecular approaches to reveal this potential, showing that microbial biomass can turn over on time scales of days to months in soil, resulting in a succession of microbial communities over the course of a year. This new understanding of the year-round turnover and succession of microbial communities allows us for the first time to propose a temporally explicit N cycle that provides mechanistic hypotheses to explain both the loss and retention of dissolved organic N (DON) and inorganic N (DIN) throughout the year in terrestrial ecosystems. In addition, our results strongly support the hypothesis that turnover of the microbial community is the largest source of DON and DIN for plant uptake during the plant growing season. While this model of microbial biogeochemistry is derived from observed dynamics in the alpine, we present several examples from other ecosystems to indicate that the general ideas of biogeochemical fluxes being linked to turnover and succession of microbial communities are applicable to a wide range of terrestrial ecosystems. 相似文献
63.
Air protection agencies in the United States increasingly confront non-attainment of air quality standards for multiple pollutants
sharing interrelated emission origins. Traditional approaches to attainment planning face important limitations that are magnified
in the multipollutant context. Recognizing those limitations, the Georgia Environmental Protection Division has adopted an
integrated framework to address ozone, fine particulate matter, and regional haze in the state. Rather than applying atmospheric
modeling merely as a final check of an overall strategy, photochemical sensitivity analysis is conducted upfront to compare
the effectiveness of controlling various precursor emission species and source regions. Emerging software enables the modeling
of health benefits and associated economic valuations resulting from air pollution control. Photochemical sensitivity and
health benefits analyses, applied together with traditional cost and feasibility assessments, provide a more comprehensive
characterization of the implications of various control options. The fuller characterization both informs the selection of
control options and facilitates the communication of impacts to affected stakeholders and the public. Although the integrated
framework represents a clear improvement over previous attainment-planning efforts, key remaining shortcomings are also discussed. 相似文献
64.
The assessment of the toxicants in roadside soil on regular basis has become extremely essential with the increase in awareness for the metal toxicity in the environment. The present study investigates the presence of toxic metals along National Highway (N-5), Pakistan. Averages of about 1.3 million per month of automobile vehicles ply on this route. Lead (Pb), zinc (Zn), copper (Cu), nickel (Ni), cadmium (Cd), cobalt (Co), manganese (Mn), mercury (Hg), and iron (Fe) were analyzed by atomic absorption spectrophotometry in roadside soil at the nine selected locations along the highway. Strong Pearson correlations (α = 0.05) were found between Pb and Zn (r(2)?= 0.887), Fe and Mn (r(2)?= 0.880), Hg and Cd (0.864), Cu and Zn (0.838), and Cu and Pb (0.814). The correlation between the elemental compositions of the main automobile components revealed vehicular traffic as the main non-point source of roadside soil pollution. Extremely high level of mercury, 144.05 mg kg(-1), was found at S5. It was revealed that the unregulated incineration and dumping sites of hazardous waste material along N-5 were also responsible for these contaminations. Multivariate analysis on the obtained data also disclosed the same interpretation. Cluster analysis of the data grouped Pb, Zn, and Cu at 85.23% similarity, whereas, Cd, Hg, and Ni were grouped at 78.75% similarity basis. The findings need swift action against the root cause of soil pollution. 相似文献
65.
Schröder HC Brandt D Schlossmacher U Wang X Tahir MN Tremel W Belikov SI Müller WE 《Die Naturwissenschaften》2007,94(5):339-359
Biomineralization, biosilicification in particular (i.e. the formation of biogenic silica, SiO2), has become an exciting source of inspiration for the development of novel bionic approaches following “nature as model”.
Siliceous sponges are unique among silica forming organisms in their ability to catalyze silica formation using a specific
enzyme termed silicatein. In this study, we review the present state of knowledge on silicatein-mediated “biosilica” formation
in marine sponges, the involvement of further molecules in silica metabolism and their potential application in nanobiotechnology
and medicine.
Werner E. G. Müller dedicated this study to Prof. Vera Gamulin (Rudjer Boskovic Institute, Zagreb, Croatia) in honour of her
unique contributions in molecular evolution. 相似文献
66.
67.
Population dynamics of Digitaria spp submitted to selection pressure by herbicides in sugarcane crop
Dias MN Pereira MR López-Ovejero RF Christoffoleti PJ Barela JF Tornisielo VL 《Journal of environmental science and health. Part. B》2005,40(1):21-28
The objective of this research was to study population dynamics of the weed crabgrass, genus Digitaria, submitted to selection pressure by herbicides currently applied in sugarcane crops in Brazil. In the first experiment two crabgrass species (Digitaria nuda and Digitaria ciliaris) and eight herbicide treatments applied in preemergence were used, and control percentage was evaluated at 7, 14, and 21 days after herbicide application (DAA). In the second experiment the level of tolerance through dose-response curve was determined for the species D. nuda and D. ciliaris, to the herbicides imazapyr, tebuthiuron, ametryne, and metribuzin. All the herbicides studied were efficient in controlling D. ciliaris, however, for D. nuda the best results were obtained only with ametryne, metribuzin, and isoxaflutole. The relation (T/S) between the rate required to reduce plant dry biomass (GR50) at 21 DAA of D. nuda and D. ciliaris was 16 for imazapyr and 6.3 for tebuthiuron, showing differential susceptibility of species; however for ametryne the rate T/S of 1.1 showed that D. nuda was not tolerant to this herbicide. For metribuzin, at 1.92 kg a.i. ha(-1), reduction of dry biomass was 80 and 90% to D. nuda and D. ciliaris, respectively. Even being controlled by metribuzin, D. nuda presented a higher level of tolerance to this herbicide, what was confirmed by the relationship T/S 14.4. As general conclusion of the research, it can be stated that the species D. nuda is more tolerant to ALS inhibiting herbicides and substituted urea, when compared with D. ciliaris; probably, D. nuda was selected by repetitive use of these herbicides. 相似文献
68.
Key methodological aspects are presented for a study of concentrations of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), polychlorinated biphenyls (PCBs), and organochlorine pesticides in the serum of a sample of the New Zealand population aged 15 years and older. The study took advantage of the sampling frame and sample collection and interview processes of the National Nutrition Study (NNS). An additional blood sample for this organochlorines study was collected by the NNS and questions added to the NNS questionnaire. Serum was obtained from the blood and, based on responses to questions in the questionnaire, samples with possible occupational exposure to organochlorines were excluded. Remaining samples providing at least 2 ml of serum were pooled within 80 strata defined according to geographic area, age group, sex and ethnicity. A minimum number of five individual serum samples was required for pooling within a stratum. Within strata with sufficient samples, two or three pooled samples were created for variance calculation. Eligible for inclusion in the study were 2497 individual serum samples. Sixty strata had sufficient serum samples for pooling and chemical analysis. This was the first study of organochlorine compounds with a national population-based sample. Two factors that made the study feasible deserve emphasis. First, being able to "piggy-back" on another study. Second, pooling of samples to reduce analytic expenses. It is hoped that the methods used in this study will form the basis for other studies investigating organochlorine concentrations in national populations. 相似文献
69.
We present an integrated methodology for the optimal management of nitrate contamination of ground water combining environmental assessment and economic cost evaluation through multi-criteria decision analysis. The proposed methodology incorporates an integrated physical modeling framework accounting for on-ground nitrogen loading and losses, soil nitrogen dynamics, and fate and transport of nitrate in ground water to compute the sustainable on-ground nitrogen loading such that the maximum contaminant level is not violated. A number of protection alternatives to stipulate the predicted sustainable on-ground nitrogen loading are evaluated using the decision analysis that employs the importance order of criteria approach for ranking and selection of the protection alternatives. The methodology was successfully demonstrated for the Sumas-Blaine aquifer in Washington State. The results showed the importance of using this integrated approach which predicts the sustainable on-ground nitrogen loadings and provides an insight into the economic consequences generated in satisfying the environmental constraints. The results also show that the proposed decision analysis framework, within certain limitations, is effective when selecting alternatives with competing demands. 相似文献
70.
Implementation of the semi-aerobic landfill system (Fukuoka method) in developing countries: a Malaysia cost analysis 总被引:5,自引:0,他引:5
Most of the existing solid waste landfill sites in developing countries are practicing either open dumping or controlled dumping. Proper sanitary landfill concepts are not fully implemented due to technological and financial constraints. Implementation of a fully engineered sanitary landfill is necessary and a more economically feasible landfill design is crucial, particularly for developing countries. This study was carried out by focusing on the economics from the development of a new landfill site within a natural clay area with no cost of synthetic liner up to 10 years after its closure by using the Fukuoka method semi-aerobic landfill system. The findings of the study show that for the development of a 15-ha landfill site in Malaysia with an estimated volume of 2,000,000 m(3), the capital investment required was about US 1,312,895 dollars, or about US 0.84 dollars/tonne of waste. Assuming that the lifespan of the landfill is 20 years, the total cost of operation was about US 11,132,536 dollars or US 7.15 dollars/tonne of waste. The closure cost of the landfill was estimated to be US 1,385,526 dollars or US 0.89 dollars/tonne of waste. Therefore, the total cost required to dispose of a tonne of waste at the semi-aerobic landfill was estimated to be US 8.89 dollars. By considering an average tipping fee of about US 7.89 dollars/tonne of waste in Malaysia in the first year, and an annual increase of 3% to about US 13.84 dollars in year-20, the overall system recorded a positive revenue of US 1,734,749 dollars. This is important information for the effort of privatisation of landfill sites in Malaysia, as well as in other developing countries, in order to secure efficient and effective landfill development and management. 相似文献