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Climate change is projected to cause significant alterations to aquatic biogeochemical processes, (including carbon dynamics), aquatic food web structure, dynamics and biodiversity, primary and secondary production; and, affect the range, distribution and habitat quality/quantity of aquatic mammals and waterfowl. Projected enhanced permafrost thawing is very likely to increase nutrient, sediment, and carbon loadings to aquatic systems, resulting in both positive and negative effects on freshwater chemistry. Nutrient and carbon enrichment will enhance nutrient cycling and productivity, and alter the generation and consumption of carbon-based trace gases. Consequently, the status of aquatic ecosystems as carbon sinks or sources is very likely to change. Climate change will also very likely affect the biodiversity of freshwater ecosystems across most of the Arctic. The magnitude, extent, and duration of the impacts and responses will be system- and location-dependent. Projected effects on aquatic mammals and waterfowl include altered migration routes and timing; a possible increase in the incidence of mortality and decreased growth and productivity from disease and/or parasites; and, probable changes in habitat suitability and timing of availability.  相似文献   

Polychlorinated dibenzothiophenes (PCDTs) could be classified as persistent organic pollutants (POPs) in the environment and are particularly interesting due to their structural resemblance to highly toxic dioxins. We show here some basic environmental properties such as n-octanol water (KOW), n-octanol/air (KOA) and air/water (KAW) partition coefficients as well as Henry’s law constants (KH) for all 135 congeners of chlorodibenzothiophene. Predictions were made by regression of principal components (PCR) and with aid of a set of standard chemicals, for which physical–chemical properties are well featured. Computed KOW, KOA, KAW and KH values for mono-CDTs ranged, respectively, between 4.66 and 4.71, 7.48 and 7.55, −2.84 and −2.82, 3.56 and 3.74; for di-CDTs between 5.02 and 5.28, 8.03 and 8.29, −3.01 and −2.95, 2.42 and 2.75; for tri-CDTs between 5.53 and 5.70, 8.65 and 8.87, −3.2 and −3.11, 1.58 and 1.92; for tetra-CDTs between 5.95 and 6.13, 9.27 and 9.50, −3.39 and −3.27, 1.02 and 1.33; for penta-CDTs between 6.38 and 6.51, 9.88 and 10.05, −3.54 and −3.45, 0.72 and 0.88; for hexa-CDTs between 6.83 and 6.97, 10.54 and 10.66, −3.72 and −3.64, 0.47 and 0.56; for hepta-CDTs between 7.28 and 7.35, 11.12 and 11.20, −3.81 and −3.87, 0.33 and 0.38; for octa-CDT 7.74, 11.78, −4.04 and 0.23. An estimated value of the three types of partition coefficient and Henry’s law constants suggest that polychlorinated dibenzothiophenes are lipophilic and semi-volatile persistent organic pollutants. Their mobility in the environment seems to be very similar to that of some well-known POPs such as polychlorinated dibenzofurans, -dibenzo-p-dioxins, and -biphenyls or organochlorine pesticides.  相似文献   

Background N-methylcarbamate insecticides are widely used chemicals for crop protection. This study examines the hydrolytic and photolytic cleavage of benfuracarb, carbosulfan and carbofuran under natural conditions. Their toxicity and that of the corresponding main degradation products toward aquatic organisms were evaluated. Methods Suspensions of benfuracarb, carbosulfan and carbofuran in water were exposed to sunlight, with one set of dark controls, for 6 days, and analyzed by 1H-NMR and HPLC. Acute toxicity tests were performed on Brachionus calyciflorus, Daphnia magna, and Thamnocefalus platyurus. Chronic tests were performed on Pseudokirchneriella subcapitata, and Ceriodaphnia dubia. Results and Discussion Under sunlight irradiation, benfuracarb and carbosulfan gave off carbofuran and carbofuran-phenol, while only carbofuran was detected in the dark experiments. The latter was degraded to phenol by exposure to sunlight. Effects of pH, humic acid and KNO3 were evaluated by kinetics on dilute solutions in the dark and by UV irradiation, which evidenced the lability of the pesticide at pH 9. All three pesticides and phenol exhibited acute and higher chronic toxicity towards the aquatic organisms tested. Conclusion Investigation on the hydrolysis and photolysis of benfuracarb and carbosulfan under natural conditions provides evidence concerning the selective decay to carbofuran and/or phenol. Carbofuran is found to be more persistent and toxic. Recommendations and Outlook The decay of benfuracarb and carbosulfan to carbofuran and the relative stability of this latter pesticide account for many papers that report the detection of carbofuran in water, fruits and vegetables.  相似文献   

本文论述了环境美学原理的基本原则和主要形式,环境绿化美化,环境美学与植物生态学的关系,以及环境的美学功能。环境美学的基本原则是多样统一、调和对比、对称均衡和韵律节奏。环境美学的主要形式是表现环境外观特征的色彩、线条和形体。环境绿化美化艺术,绿化是基础,美化是主题。环境美学与植物生态学,说明环境与大自然的协调发展,人与自然的和谐统一。环境的美学功能是陶冶人的情操,提高人的思想境界,增进身心健康  相似文献   

Dilly O  Blume HP  Sehy U  Jimenez M  Munch JC 《Chemosphere》2003,52(3):557-569
Land use and agricultural practices modify both the amounts and properties of C and N in soil organic matter. In order to evaluate land use and management-dependent modifications of stable and labile C and N soil pools, (i). organic C and total N content, (ii). microbial (C(mic)) and N (N(mic)) content and (iii). C and N mineralisation rates, termed biologically active C and N, were estimated in arable, grassland and forest soils from northern and southern Germany. The C/N-ratios were calculated for the three levels (i)-(iii) and linked to the eco-physiological quotients of biotic-fixed C and N (C(mic)/C(org), N(mic)/N(t)) and biomass-specific C and N mineralisation rate (qCO(2), qN(min)). Correlations could mainly be determined between organic C, total N, C(mic), N(mic) and C mineralisation for the broader data set of the land use systems. Generally, the mineralisation activity rate at 22 degrees C was highly variable and ranged between 0.11 and 17.67 microg CO(2)-C g(-1) soil h(-1) and -0.12 and 3.81 microg (deltaNH(4)(+)+deltaNO(3)(-))-N g(-1) soil h(-1). Negative N data may be derived from both N immobilisation and N volatilisation during the experiments. The ratio between C and N mineralisation rate differed significantly between the soils ranging from 5 to 37, and was not correlated to the soil C/N ratio and C(mic)/N(mic) ratio. The C/N ratio in the 'biologically active' pool was significantly smaller in soils under conventional farming than those under organic farming systems. In a beech forest, it increased from the L, Of to the Ah horizon. The biologically active C and N pools refer to the current microbial eco-physiology and are related to the need for being C and N use efficient as indicated by metabolic qCO(2) and qN(min) quotients.  相似文献   

为综合利用黄磷尾气中的CO,通过计算平均活化能和测定XPS、TG/DTA和氮吸附特性的方法,研究了Cu2+和某金属离子M^n+改性碳脱除PH,和H2S的动力学和反应机理问题。结果表明:H2S在金属改性碳上反应时平均活化能为134.4J/mol为-0.76级反应,PH,在金属改性碳上反应时平均活化能为1247.6J/mol为-0.8级反应;减小改性碳粒径增加流量可以显著提高其脱除PH,和H。S的速率;XPS、TG/DTA和孔径分布分析证明,改性碳净化H2S和PH3是一个催化吸附过程,H2S和PH3首先与氧在改性碳表面进行催化氧化反应,然后生成S和P2O5沉积吸附在改性碳表面。  相似文献   

Payet R  Obura D 《Ambio》2004,33(1-2):24-33
The complex interactions between human activities and the environment at the interface of land and water is analyzed with a focus on the Somali Current (East Africa), and Indian Ocean Island States, subregions of the Global International Waters Assessment (GIWA). These 2 subregions contain some of the world's richest ecosystems, including the high biodiversity forests of Madagascar and the diverse coastal habitats of the eastern African coast. These ecosystems support local communities and national and regional economies. Current and future degradation of these systems, from water basins to continental shelves, affects the livelihoods and sustainability of the countries in the region, and long-term efforts to reduce poverty. The assessments determined that pollution and climate change are the primary environmental and social concerns in the Islands of the Indian Ocean, while freshwater shortage and unsustainable exploitation of fisheries and other living resources are the primary environmental and social concerns in East Africa. The GIWA approach, through assessing root causes of environmental concerns, enables the development of policy approaches for mitigating environmental degradation. This paper explores policy frameworks for mitigating the impacts, and reducing the drivers, of 3 environmental concerns--freshwater shortage; solid waste pollution; and climate change--addressing social and institutional causes and effects, and linking the subregions to broad international frameworks. The common theme in all 3 case studies is the need to develop integrated ecosystem and international waters policies, and mechanisms to manage conflicting interests and to limit threats to natural processes.  相似文献   

Research has shown that many chemicals form persistent and permanently bound residues in soils and sediments that play an important role in soil and sediment detoxification processes, long-term compound partitioning behaviour and compound bioavailability and toxicity in soil and sediment. This article reviews the methodological approaches that have been applied to determine the nature of bound residues in soil and sediment, the application of specific analytical techniques, the type of information they generate, and their relative advantages and disadvantages. It begins by defining bound residues and discussing soil-compound interactions. The application of model compound studies for elucidating specific binding interactions is reviewed along with long-term laboratory and field soil incubation experiments. The use of radiolabelled compounds, isotopically labelled compounds and combinations of both in these experiments are outlined by examples from the literature, along with sequential extraction schemes for releasing bound residues from soil, sediment and humic materials. The importance of spectroscopic methods, and particularly nuclear magnetic resonance techniques for characterising the structure of bound residues in soil and sedimentary humic substances is discussed and illustrated by examples from the literature on the subject. The process of bound residue formation is highly complex and requires further research to establish the mechanisms of bound residue formation and their subsequent environmental and toxicological fate. Much of the uncertainty regarding the elucidation of bound residue formation arises from our poor understanding of the structure of soil and sedimentary organic matter. Significant advances in our understanding of the formation and fate of bound residues will be made when we develop a deeper insight into the complex and heterogeneous structure of soil and sedimentary organic matter.  相似文献   

Human society has experienced, and will continue to experience, extensive loss and damage from worsening anthropogenic climate change. Despite our natural tendencies to categorise and organise, it can be unhelpful to delineate clean boundaries and linear understandings for complex and messy concepts such as loss and damage. Drawing on the perspectives of 42 local and regional Pacific Islander stakeholders, an underexplored resource for understanding loss and damage, we explore the complexity and interconnectedness of non-economic loss and damage (NELD). According to participants, Pacific Islander worldviews, knowledge systems and cosmologies often make it difficult to separate and evaluate NELD independently, challenging the nomenclature of NELD categories developed through international mechanisms. Instead, NELD understandings are often centred on the interdependencies between losses, including the cascading flow-on effects that can occur and the nature of some losses as risk multipliers (i.e. one loss creating the risk for further losses). Most notably, losses to biodiversity, ecosystem services and land are critically linked to, and have cascading effects on, livelihoods, knowledge, ways of life, wellbeing, and culture and heritage. We argue that loss and damage is not always absolute, and that there are NELD that are arguably reparable. Concerning, however, is that biodiversity loss, as a risk multiplier, was considered the least reparable by participants. We put forward that NELD understandings must consider interconnectivity, and that biodiversity and ecosystem conservation and restoration must be the focus for interventions to prevent irreparable and cascading losses from climate change in the Pacific Islands.  相似文献   

Chlorpyrifos (Lorsban emulsifiable concentrate) was applied at 3.4 kg AI/ha and incorporated into sand and muck soil contained in small field plots. Soil samples were taken at intervals over 2 yr. Radishes and carrots, seeded yearly, served as indicator crops for absorption of insecticide residues. Samples were extracted and analyzed, by gas-liquid chromatography, for chlorpyrifos, oxychlorpyrifos, and 3,5,6-trichloro-2-pyridinol. Chlorpyrifos residues declined rapidly, with 50% of the initial application remaining after 2 and 8 wk in sand and muck, respectively, and 4 and 9% after 1 yr. Pyridinol residues increased to 13 and 39% of the initial chlorpyrifos application in sand and muck after 1 and 8 wk, respectively, and declined thereafter. Oxychlorpyrifos was detected in the 2 soils at very low levels only in immediate posttreatment samples. In the first year of the study low levels (less than 0.1 ppm) of chlorpyrifos and the pyridinol were detected in radishes and carrots.  相似文献   

We investigated PCDDs and related compounds in the blood of young Japanese women, approximately 20 years of age, who had not yet had children, and discussed how the TEQ level of PCDDs and related compounds in their blood may affect the next generation. Means of total TEQ levels were 0.063 pg/g for whole blood basis and 21 pg/g for lipid basis. TEQ of PCDDs, PCDFs and coplanar PCBs accounted for about 43, 34 and 23% of the total TEQ in the whole blood basis, respectively. In the lipid basis, their values were about 44, 34 and 22%, respectively. Previously, we investigated PCDDs and related compounds levels in mother's breast milk, lymphocyte subpopulation and thyroid function of their children, and found negative correlations between the TEQ level of PCDDs and related compounds and CD4+/CD8+, and/or the TEQ level of PCDDs and related compounds and the T4 level in 36 mothers and children. Of these cases, the average age was approximately 28 years. PCDDs and related compounds may be related to immunopathy, such as atopic dermatitis. The effects of PCDDs and related compounds on babies of young Japanese women are important and must be further evaluated.  相似文献   

DeVantier L  Alcala A  Wilkinson C 《Ambio》2004,33(1-2):88-97
The Sulu-Sulawesi Sea, with neighboring Indonesian Seas and South China Sea, lies at the center of the world's tropical marine biodiversity. Encircled by 3 populous, developing nations, the Philippines, Indonesia and Malaysia, the Sea and its adjacent coastal and terrestrial ecosystems, supports ca. 33 million people, most with subsistence livelihoods heavily reliant on its renewable natural resources. These resources are being impacted severely by rapid population growth (> 2% yr-1, with expected doubling by 2035) and widespread poverty, coupled with increasing international market demand and rapid technological changes, compounded by inefficiencies in governance and a lack of awareness and/or acceptance of some laws among local populations, particularly in parts of the Philippines and Indonesia. These key root causes all contribute to illegal practices and corruption, and are resulting in severe resource depletion and degradation of water catchments, river, lacustrine, estuarine, coastal, and marine ecosystems. The Sulu-Sulawesi Sea forms a major geopolitical focus, with porous borders, transmigration, separatist movements, piracy, and illegal fishing all contributing to environmental degradation, human suffering and political instability, and inhibiting strong trilateral support for interventions. This review analyzes these multifarious environmental and socioeconomic impacts and their root causes, provides a future prognosis of status by 2020, and recommends policy options aimed at amelioration through sustainable management and development.  相似文献   

This study surveyed emissions from 2- and 4-stroke new and in-use motorcycles. Emission tests were carried out on a dynamometer following the designated test procedure of the Economic Commission for Europe (ECE). Samples were derived during various driving stages, which included idle, acceleration, 30 km/hr cruise, 50 km/hr cruise, and deceleration. All test motorcycles (10 new and 15 in-use) complied with Taiwan Environmental Protection Administration's Phase III Motorcycle Emission Standards. The dominant volatile organic carbon (VOC) species were isopentane (53 and 295 mg/km, 2- and 4-stroke, respectively), 2-methylpentane (75 and 83 mg/km), 3-methylpentane (34 and 66 mg/km), and toluene (30 and 100 mg/km). The VOC emission factors for the 2-/4-stroke motorcycles were 311/344 (new) and 1479/433 (in-use) mg/km, respectively. In addition, the dominant carbonyl species for the new and in-use motorcycles were formaldehyde (0.4 and 0.7 mg/km, respectively), acetaldehyde (0.6 and 1.2 mg/km), and acetone (0.5 and 0.7 mg/km). The carbonyl compound emission factors for the 2- and 4-stroke motorcycles were 3.2/3.1 (new) and 5.3/4.6 (in-use) mg/km, respectively. The ozone formation potentials, based on an ECE test cycle, show that the values from the in-use motorcycles were higher than those from the new motorcycles. The dominant VOC species for the ozone formation potential were propylene (65 and 502 mg-O3/km, respectively), isopentane (98 and 501 mg-O3/km), 2-methylpentane (152 and 167 mg-O3/ km), 3-methylpentane (79 and 253 mg-O3/km), and toluene (127 and 398 mg-O3/km). Further, the dominant carbonyl species were formaldehyde (4.1 and 6.2 mg-O3/ km, new and in-use, respectively) and acetaldehyde (4.8 and 9 mg-O3/km).  相似文献   

Assmuth T 《Ambio》2011,40(2):158-169
Policy and research issues in the framing and qualities of uncertainties in risks are analyzed, based on the assessments of dioxin-like compounds (DLCs) and other ingredients in Baltic Sea fish, a high-profile case of governance. Risks are framed broadly, to then focus on dioxins and beneficial fatty acids, fish consumption, human health, and science-management links. Hierarchies of uncertainty (data, model, decision rule, and epistemic) and ambiguity (of values) are used to identify issues of scientific and policy contestation and opportunities for resolving them. The associated complexity of risks is illustrated by risk–benefit analyses of fish consumption and by evaluations of guideline values, highlighting value contents and policy factors in presumably scientific decision criteria, and arguments used in multi-dimensional risk and benefit comparisons. These comparisons pose challenges to narrow assessments centered, for e.g., on toxicants or on food benefits, and to more many-sided and balanced risk communication and management. It is shown that structured and contextualized treatment of uncertainties and ambiguities in a reflexive approach can inform balances between wide and narrow focus, detail and generality, and evidence and precaution.  相似文献   

Trace element definition and functions, and inputs into soils from the most important anthropogenic sources, related and not related to agricultural practices, of general and local or incidental concern, are discussed in the first part of this review. Trace element inputs include those from commercial fertilizers, liming materials and agrochemicals, sewage sludges and other wastes used as soil amendments, irrigation waters, and atmospheric depositions from urban, industrial, and other sources. In the second part of the review, the most important ascertained effects of soil trace elements on human health are presented. The possible relations found between some specific soil trace elements, such as Cd, Se, As and others, and cancer incidence and mortality, and diffusion of other important human diseases are reviewed. Brief conclusions and recommendations conclude this review.  相似文献   

To evaluate the environmental risk of irrigating crops with treated wastewater, an experiment was conducted using two growth chambers, each offering a different vapour pressure deficit (VPD) for high and low transpiration rates (TR), respectively. One of the two sets of 24 pots planted with 6 week old wheat (Triticum aestivum L.), was placed in each growth chamber, and irrigated in triplicates for 20 days with 8 Zn and Cu solutions (0 and 25 mg Zn/L combined with 0, 5, 15 and 30 mg Cu/L). Water losses from planted and non-planted pots served to measure evapo-transpiration and evaporation, respectively. Pots were monitored for Cu and Zn uptake by collecting three plants (shoot and grain)/pots after 0, 10 and 20 days, and roots in each pot after 20 days, and analyzing these plant parts for dry mass, and Cu and Zn levels. Transpiration rate was not affected by any Cu/Zn treatment, but Cu and Zn uptake increase with the time, irrigation solution level and higher TR, with the roots retaining most Cu and Zn, compared to the shoot followed by the grain. For the shoot and grain, Cu had a significant synergetic effect on Zn uptake, when Zn had slight but insignificant antagonistic effects on Cu uptake. For the roots, Cu and Zn had significant synergetic effect on each other. Regression equations obtained from the data indicate that Cu and Zn levels normally found in treated wastewater (0.08 mg/L) are 300 times lower than those used for the most concentrated experimental solutions (30 and 25 mg/L, respectively) and may, on a long term basis, be beneficial rather than toxic to wheat plants and do not acidify soil pH.  相似文献   

Hu X  Ding Z  Chen Y  Wang X  Dai L 《Chemosphere》2002,48(6):621-629
Through short-term exposure (7-d exposure), long-term exposure (16-d exposure) and exposure-recovery (7-d exposure + 9-d recovery), the bioaccumulation and distribution of La and Ce and their effects on growth of wheat seedlings were studied. Addition of La (0.5-25 mg/l) and Ce (0.5-25 mg/l) to the culture medium individually and in combination inhibited primary root elongation, reduced the dry weight of roots and shoots and the content of mineral elements (Ca, Mg, K, Cu, Zn). The damage increased with an increase in the concentrations of La and Ce in culture medium. Relative damage ratio increased with an increase in concentrations of La and Ce in the culture medium and with exposure time. Comparing exposure-recovery groups with long-term exposure groups, primary root lengths, dry weight of roots and shoots and the content of five mineral elements were higher. The accumulation of La and Ce in the seedlings was positively correlated with the concentrations of La and Ce in the culture medium and with exposure time. Bioaccumulation factors of La and Ce in roots were much higher than those of shoots. The uptake rates of La and Ce by the plants were much higher than the translocation rates from roots to shoots. The accumulation and distribution of La and Ce in the seedlings in exposure-recovery groups showed that there was very little excretion through metabolism during the recovery period, but redistribution occurred throughout the whole plant. No apparent selective uptake was found between La and Ce by the plants when they were applied in combination.  相似文献   

Concentrations and congener profile patterns of 2378-substituted PCDD/Fs and DLPCBs in offshore, nearshore and tributary sediments of Lakes Superior and Huron are reported, and spatial trends and source contributions assessed. PCDD/F concentrations ranged from 5 to 18 000 pg/g dw (Lake Superior) and 3 to 6100 pg/g dw (Lake Huron); DLPCBs ranged from 9 to 11 000 pg/g dw (Lake Superior) and 9 to 27 000 pg/g dw (Lake Huron). Our analysis indicated atmospheric deposition is a primary source to depositional areas of both lakes; however, greater PCDD/F and DLPCB concentrations were observed at several nearshore and tributary sites, and were attributed to corresponding land use in the watershed. Statistical analysis and pattern comparison suggested that industrial inputs mainly associated with wood treatment plants, pulp and paper mills, mining operations, and chlorine-based chemical manufacturing also contributed to contamination by PCDD/Fs and DLPCBs in certain nearshore and offshore areas of Lakes Superior and Huron.  相似文献   

A wide range of delta morphologies occurs along the fringes of the Young Sound in Northeast Greenland due to spatial heterogeneity of delta regimes. In general, the delta regime is related to catchment and basin characteristics (geology, topography, drainage pattern, sediment availability, and bathymetry), fluvial discharges and associated sediment load, and processes by waves and currents. Main factors steering the Arctic fluvial discharges into the Young Sound are the snow and ice melt and precipitation in the catchment, and extreme events like glacier lake outburst floods (GLOFs). Waves are subordinate and only rework fringes of the delta plain forming sandy bars if the exposure and fetch are optimal. Spatial gradients and variability in driving forces (snow and precipitation) and catchment characteristics (amount of glacier coverage, sediment characteristics) as well as the strong and local influence of GLOFs in a specific catchment impede a simple upscaling of sediment fluxes from individual catchments toward a total sediment flux into the Young Sound.  相似文献   

The inhibitory activity of amphotericin B, clotrimazole, econazole, miconazole and nystatin was compared against Fusarium oxysporum f.sp. radicis-cucumerinum. The most efficient antifungal agent against the growth of Fusarium oxysporum was econazole, followed by clotrimazole, miconazole, amphotericin and nystatin. The ED50 and ED90 values were 0.053 and 1.002 ppm for econazole, 0.088 and 1.100 ppm for clotrimazole, 0.173 and 3.210 ppm for miconazole, 0.713 and greater than 48 ppm for amphotericin and 3.860 and 16.702 ppm for nystatin. The ED50 values of nystatin and amphotericin against spore germination of Fusarium oxysporum were determined at 3.1427 ppm and 8.3990 ppm respectively, nystatin was 2.76 times more effective than amphotericin, while no effect was observed after the addition of econazole, clotrimazole and miconazole. The tested azoles were more effective than amphotericin and nystatin on growth inhibition of Fusarium oxysporum but amphotericin and nystatin acted significantly better on spore germination of Fusarium.  相似文献   

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