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91.
A directional passive air sampler for monitoring polycyclic aromatic hydrocarbons (PAHs) in air mass
Tao S Liu YN Lang C Wang WT Yuan HS Zhang DY Qiu WX Liu JM Liu ZG Liu SZ Yi R Ji M Liu XX 《Environmental pollution (Barking, Essex : 1987)》2008,156(2):435-441
A passive air sampler was developed for collecting polycyclic aromatic hydrocarbons (PAHs) in air mass from various directions. The airflow velocity within the sampler was assessed for its responses to ambient wind speed and direction. The sampler was examined for trapped particles, evaluated quantitatively for influence of airflow velocity and temperature on PAH uptake, examined for PAH uptake kinetics, calibrated against active sampling, and finally tested in the field. The airflow volume passing the sampler was linearly proportional to ambient wind speed and sensitive to wind direction. The uptake rate for an individual PAH was a function of airflow velocity, temperature and the octanol-air partitioning coefficient of the PAH. For all PAHs with more than two rings, the passive sampler operated in a linear uptake phase for three weeks. Different PAH concentrations were obtained in air masses from different directions in the field test. 相似文献
92.
In this study, the heterogeneous photocatalytic degradation of prometryn using TiO(2) as photocatalyst was investigated. The main objectives of the study were: (I) to evaluate the kinetics of the pesticide disappearance, (II) to compare the photocatalytic efficiency of two different types of TiO(2), (III) to examine the influence of various parameters such as initial concentration of pesticide or catalyst and presence of oxidants (H(2)O(2) and K(2)S(2)O(8)), (IV) to evaluate the degree of mineralization and (V) to assess the detoxification efficiency of the studied processes. The experiments were carried out in a 500 ml pyrex UV reactor equipped with a 125 W high-pressure mercury lamp surrounded by a pyrex filter blocking wavelengths below 290 nm. Prometryn concentration was determined using HPLC. It was found that the degradation of the pesticide follows the first order kinetics according to the Langmuir-Hinshelwood model. Parameters like the type and concentration of the catalyst affect the degradation rate. A synergistic effect was observed when an oxidant was added in the TiO(2) suspensions increasing the reaction rate of photodegradation. In order to examine the extent of pesticide mineralization, DOC measurements were carried out. After 6h of illumination, mineralization was achieved up to almost 70%. The toxicity of the treated solution was evaluated using the Microtox test based on the luminescent bacteria Vibrio fisheri, in order to compare the acute toxicity of prometryn and its photoproducts. The detoxification efficiency was found to be dependent on the studied system and it did not follow the rate of pesticide disappearance. 相似文献
93.
The potential health risks due to inorganic substances, mainly metals, was evaluated for the two resident marine mammals in Hong Kong, the Indo-Pacific Humpback Dolphin (Sousa chinensis) and the Finless Porpoise (Neophocaena phocaenoides). The stomachs from the carcasses of twelve stranded dolphins and fifteen stranded porpoises were collected and the contents examined. Concentrations of thirteen trace elements (Ag, As, Cd, Co, Cr, Cs, Cu, Hg, Mn, Ni, Se, V and Zn) were determined by inductively coupled plasma mass spectrometer (ICP-MS). An assessment of risks of adverse effects was undertaken using two toxicity guideline values, namely the Reference Dose (RfD), commonly used in human health risk assessment, and the Toxicity Reference Value (TRV), based on terrestrial mammal data. The levels of trace metals in stomach contents of dolphins and porpoises were found to be similar. Risk quotients (RQ) calculated for the trace elements showed that risks to the dolphins and porpoises were generally low and within safe limits using the values based on the TRV, which are less conservative than those based on the RfD values. Using the RfD-based values the risks associated with arsenic, cadmium, chromium, copper, nickel and mercury were comparatively higher. The highest RQ was associated with arsenic, however, most of the arsenic in marine organisms should be in the non-toxic organic form, and thus the calculated risk is likely to be overestimated. 相似文献
94.
Bhattacharyya P Chakrabarti K Chakraborty A Nayak DC Tripathy S Powell MA 《Chemosphere》2007,66(9):1789-1793
The importance of the use of potassium in agriculture is increasing in South Asia for making most productive use of the nutrient in terms of economic returns. Nutrient supply traditionally by cattle manure is constrained by its insufficient availability. Municipal waste compost may be an alternative source of nutrient supplements. Field experiments were conducted at the Experimental Farm of Calcutta University, West Bengal, India during the wet seasons of 1997, 1998 and 1999 on flooded lowland rice. Potassium fractions in municipal waste compost and cattle manure were determined by sequential extraction and also the potassium uptake by rice to compare the effectiveness of municipal waste compost with traditional manure. Potassium was significantly bound to the organic matter in municipal waste compost. Potassium uptake by rice grain and straw increased significantly with the combined application of organics and fertilizers and it was higher in grain than in straw. Water-soluble and non-exchangeable potassium contents of municipal waste compost and cattle manure were highly correlated with the uptake of potassium by straw and grain. Exchangeable and residual potassium were also significantly correlated with the uptake of potassium by straw and grain of rice. Much higher uptake of K in rice straw and rain resulted from applying the manures in conjunction with fertilizers than when applied singly. 相似文献
95.
Volunteer monitoring of natural resources is promoted for its ability to increase public awareness, to provide valuable knowledge, and to encourage policy change that promotes ecosystem health. We used the case of volunteer macroinvertebrate monitoring (VMM) in streams to investigate whether the quality of data collected is correlated with data use and organizers' perception of whether they have achieved these outcomes. We examined the relation between site and group characteristics, data quality, data use, and perceived outcomes (education, social capital, and policy change). We found that group size and the degree to which citizen groups perform tasks on their own (rather than aided by professionals) positively correlated with the quality of data collected. Group size and number of years monitoring positively influenced whether a group used their data. While one might expect that groups committed to collecting good-quality data would be more likely to use it, there was no relation between data quality and data use, and no relation between data quality and perceived outcomes. More data use was, however, correlated with a group's feeling of connection to a network of engaged citizens and professionals. While VMM may hold promise for bringing citizens and scientists together to work on joint conservation agendas, our data illustrate that data quality does not correlate with a volunteer group's desire to use their data to promote regulatory change. Therefore, we encourage scientists and citizens alike to recognize this potential disconnect and strive to be explicit about the role of data in conservation efforts. 相似文献
96.
Denitrification of synthetic high nitrate waste containing 9032 ppm NO(3)-N (40,000 ppm NO(3)) in a time period of only 6h has been achieved in our previous study using activated sludge. The activated sludge culture was acclimatized by a stepwise increase in the nitrate concentration of synthetic waste. In the present work, studies were carried out on the changing microbial population of the sludge and the physiology of nitrate metabolism during the various stages of adaptation process to high strength synthetic nitrate waste. During the course of adaptation, with an increase in the nitrate concentration, a sharp increase in the number of denitrifiers was found with an equally rapid decrease in the nitrifying community. Two key enzymes involved in the first two steps of the denitrification process were also studied during this period. The results of the study suggest that specific enzyme levels increase as the activated sludge adapts itself to higher nitrate concentrations. Biological denitrification of high nitrate waste is a slow process and to increase the rate of denitrification, parameters such as pH, temperature, C:N and biomass concentration of the process were optimized using orthogonal array method. Optimized conditions increased the specific nitrate reduction rate by 54% and specific nitrite reduction rate by 45%. 相似文献
97.
Krogh KA Søeborg T Brodin B Halling-Sørensen B 《Journal of environmental quality》2008,37(6):2202-2211
Avermectins are widely used to treat livestock for parasite infections. Ivermectin, which belongs to the group of avermectins, is particularly hazardous to the environment, especially to crustaceans and to soil-dwelling organisms. Sorption is one of the key factors controlling transport and bioavailability. Therefore, batch studies have been conducted to characterize the sorption and desorption behavior of ivermectin in three European soils (Madrid, York, and artificial soil). The solid-water distribution coefficient (K(d)) for ivermectin sorption to the tested soils were between 57 and 396 L kg(-1) (determined at 0.1 microg g(-1)), while the organic carbon-normalized sorption coefficients (K(oc)) ranged from 4.00 x 10(3) to 2.58 x 10(4) L kg(-1). The Freundlich sorption coefficient (K(F)) was 396 (after 48 h) for the artificial soil over a concentration range of 0.1 to 50 microg g(-1), with regression constants indicating a concentration-dependent sorption. The obtained data and data in the literature are inconclusive with regard to whether hydrophobic partitioning or more specific interactions are involved in sorption of avermectins. For abamectin, hydrophobic partitioning seems to be one of the dominant types of binding, while hydrophobicity is less important for ivermectin, which is probably due to the lower lipophilicity of the molecule. Furthermore, the presence of cations such as Ca(2+) leads to decreasing sorption. Thus, it is presumed that ivermectin binds to soil by formation of complexes with immobile, inorganic soil matter. In contrast to abamectin, hysteresis could be excluded for ivermectin in the studied soils for the evaluation of sorption and desorption. The sorption mechanism is highly dependent on physicochemical properties of the avermectin. 相似文献
98.
The Singrauli region in the southeastern part of Uttar Pradesh, India is one of the most polluted industrial sites of Asia.
It encompasses 11 open cast coalmines and six thermal power stations that generate about 7,500 MW (about 10% of India’s installed
generation capacity) electricity. Thermal power plants represent the main source of pollution in this region, emitting six
million tonnes of fly-ash per annum. Fly-ash is deposited on soils over a large area surrounding thermal power plants. Fly-ashes
have high surface concentrations of several toxic elements (heavy metals) and high atmospheric mobility. Fly ash is produced
through high-temperature combustion of fossil fuel rich in ferromagnetic minerals. These contaminants can be identified using
rock-magnetic methods. Magnetic susceptibility is directly linked to the concentration of ferromagnetic minerals, primarily
high values of magnetite. In this study, magnetic susceptibility of top soil samples collected from surrounding areas of a
bituminous-coal-fired power plant were measured to identify areas of high emission levels and to chart the spatial distribution
of airborne solid particles. Sites close to the power plant have shown higher values of susceptibility that decreases with
increasing distance from the source. A significant correlation between magnetic susceptibility and heavy metal content in
soils is found. A comparison of the spatial distribution of magnetic susceptibility with heavy-metal concentrations in soil
samples suggests that magnetic measurements can be used as a rapid and inexpensive method for proxy mapping of air borne pollution
due to industrial activity. 相似文献
99.
Acute toxic hazard evaluations of glyphosate herbicide on terrestrial vertebrates of the oregon coast range 总被引:2,自引:1,他引:1
McComb BC Curtis L Chambers CL Newton M Bentson K 《Environmental science and pollution research international》2008,15(3):266-272
GOAL, SCOPE AND BACKGROUND: The degree to which dose responses of model organisms (lab rodents) can adequately predict dose responses of free-ranging wild mammals or amphibians is unknown, and the relative sensitivity of such species to body loading of a toxicant such as glyphosate is seldom reported. For relative effects of dosage, we compare sensitivity of nine wild vertebrate species to effects of high doses of glyphosate in Swiss-Webster laboratory mice both by gavage and by intraperitoneal injection. We also evaluate sublethal effects of herbicide exposure on behavior and reproductive success of one mammal and one amphibian species. METHODS: Comparisons of acute toxicity of glyphosate were made with intraperitoneal dosings of technical glyphosate isopropylamine salt to nine species of terrestrial vertebrates (five amphibians, four mammals) and compared with responses in Swiss-Webster laboratory mice. Animals collected from sites that had no recent herbicide application were allowed 7-14 days to equilibrate in captivity before treatment. RESULTS: Median lethal dose ranged from 800 to 1,340 mg kg(-1) in mammals, and 1,170 to >2,000 mg kg(-1) in amphibians, with Oregon vole being the most sensitive. White lab mice were in the middle of the mammalian range. Tailed frog, at >2,000 mg kg(-1) was the least sensitive. Calibration of IP sensitivity to oral administration by gavage indicated that roughly four times as much glyphosate must be administered to obtain a comparable estimate of lethality. Administration by gavage in highly concentrated solutions tended to cause physical injury, hence may prove less useful as a relative indicator of toxicity. When sublethal dosages were given to roughskin newts or chipmunks, mobility and use of cover appeared largely unaffected. DISCUSSION: Direct toxic effects of spraying glyphosate under normal forest management seem unlikely for the nine species examined. Nor could we detect significant indirect effects of exposure on behavior and use of cover features in two species. There may be effects on other aspects of the field biology of these animals, such as reproductive rates, which we did not investigate. Recent field data indicate that changes in habitat quality following herbicide application can result in high reproductive activity in species associated with the grasses and forbs that proliferate following field applications. CONCLUSIONS: When compared to field data on body burdens of wild mammals exposed after aerial application of glyphosate at maximum rates in forests, there seems to be a large margin of safety between dosages encountered and those causing either death or limitation of movement, foraging or shelter. RECOMMENDATIONS AND PERSPECTIVES: Margins of safety for small mammals and amphibians appear to be large under any probable exposure scenarios, however our results indicate high variability in responses among species. Uncertainty introduced into field studies from unknown sources of mortality (e.g, likely predation) must be considered when interpreting our results. 相似文献
100.
Joseph C. Cooper Giovanni Signorello 《Journal of Environmental Planning and Management》2008,51(1):1-14
Programs that reimburse farmers for the cost of implementing more environmentally benign management practices are becoming increasingly popular in both the US and the EU. Utilizing the random utility and random profit difference approaches, the paper develops a theoretical model that explains why farmers may require a premium in excess of the decrease in profits to adopt a conservation plan, and may even require a premium in the case where adoption of the plan is associated with a mean increase in profits. This premium is estimated using a survey of farmers in conjunction with predictions of changes in production costs. 相似文献