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671.
H.C. Agarwal D.K. Singh V.B. Sharma 《Journal of environmental science and health. Part. B》2013,48(1):189-194
Abstract Persistence, metabolism and binding of 14C‐parathion in alkaline sandy loam soil under sub‐tropical conditions of Delhi were studied for 545 days. After 3 days of treatment, 14C‐residues declined to 41% of the amount applied. The dissipation curve was biphasic; an initial rapid phase (up to 7 days) followed by slow dissipation. The half life of dissipation was only 3.36 days for the first phase and 84 days for the slow phase. The overall half life was 64.5 days. The total residues at zero‐time were 10.65 μg/g dry soil and were almost totally extractable. The extracts consisted of parathion, 4‐aminophenol, 4‐nitrophenol and paraoxon. The bound residues gradually increased and accounted for the total residue at the end of one year (0.7 μg/g). 相似文献
672.
Robert V. Hendriks Paul S. Nolan 《Journal of the Air & Waste Management Association (1995)》2013,63(4):432-438
This paper describes and discusses key design features of the retrofit of EPA’s Limestone Injection Multistage Burner (LIMB) system to an operating, wall-fired utility boiler at Ohio Edison’s Edgewater Station, based on the preliminary engineering design. It further describes results of pertinent projects in EPA's LIMB program and shows how these results were used as the basis for the design of the system. The full-scale demonstration is expected to prove the effectiveness and cost of the LIMB concept for use on large-scale utility boilers. To date, a preliminary engineering design for the Edgewater unit has been prepared incorporating the technology developed in smaller-scale studies. The schedule calls for system start-up by March 1987. EPA is engaged in a multiyear program to develop an improved control technology for emission of sulfur and nitrogen oxides from the combustion of fossil fuels. The technology involves staged-flow coal burners and injection of a reactive sorbeht into the furnace to reduce emissions. The program includes fundamental studies of reaction chemistry and kinetics, bench and pilot scale experimental studies, a full-scale demonstration, and economic and applicability studies. It is structured to establish a basis for future public sector commercialization, as well as help in understanding the technology’s controlling factors. 相似文献
673.
M. V. Maya Melena A. Soares Rajesh Agnihotri A. K. Pratihary Supriya Karapurkar Hema Naik S. W. A. Naqvi 《Environmental monitoring and assessment》2011,175(1-4):501-517
Chemical and isotopic (??13C and ??15N) investigation of the Mandovi estuary along the Indian west coast affected strongly by the seasonal monsoon cycle was carried out. The Mandovi estuary is a major waterway for Goa and extensively used for transportation of iron and manganese ore. In addition, with large population centers as well as agricultural fields located on its shores, the estuary is assumed to have been influenced by human activities. Measurements of chemical and isotopic parameters made in the lower part of the estuary during the southwest (SW) monsoon and post-monsoon seasons reveal distinct changes, and it is observed that despite considerable enrichment of macronutrients during the SW monsoon, productivity of the estuary (phytoplankton biomass), as inferred from the chlorophyll-a content, is not as high as expected. This is due to occurrences of high turbidity and cloud cover that limits photosynthetic productivity. The isotopic characterization (C and N isotopes) of suspended organic matter produced/transported during the monsoon and post-monsoon seasons of year 2007 provides a baseline dataset for future isotopic studies in such type of tropical estuaries. 相似文献
674.
Rainfall trends in twentieth century over Kerala,India 总被引:1,自引:0,他引:1
K.N. Krishnakumar G.S.L.H.V. Prasada Rao C.S. Gopakumar 《Atmospheric environment (Oxford, England : 1994)》2009,43(11):1940-1944
Attempts were made to study temporal variation in monthly, seasonal and annual rainfall over Kerala, India, during the period from 1871 to 2005. Longterm changes in rainfall determined by Man-Kendall rank statistics and linear trend. The analysis revealed significant decrease in southwest monsoon rainfall while increase in post-monsoon season over the State of Kerala which is popularly known as the “Gateway of summer monsoon”. Rainfall during winter and summer seasons showed insignificant increasing trend. Rainfall during June and July showed significant decreasing trend while increasing trend in January, February and April. Hydel power generation and water availability during summer months are the concern in the State due to rainfall decline in June and July, which are the rainiest months. At the same time, majority of plantation crops are likely to benefit due to increase in rainfall during the post-monsoon season if they are stable and prolonged. 相似文献
675.
676.
X. Qu V.A. Vavilin L. Mazéas M. Lemunier C. Duquennoi P.-J. He T. Bouchez 《Waste management (New York, N.Y.)》2009,29(6):1828-1837
Utilizing stable carbon isotope data to account for aceticlastic and non-aceticlastic pathways of methane generation, a model was created to describe laboratory batch anaerobic decomposition of cellulosic materials (office paper and cardboard). The total organic and inorganic carbon concentrations, methane production volume, and methane and CO2 partial pressure values were used for the model calibration and validation. According to the fluorescent in situ hybridization observations, three groups of methanogens including strictly hydrogenotrophic methanogens, strictly aceticlastic methanogens (Methanosaeta sp.) and Methanosarcina sp., consuming both acetate and H2/H2CO3 as well as acetate-oxidizing syntrophs, were considered. It was shown that temporary inhibition of aceticlastic methanogens by non-ionized volatile fatty acids or acidic pH was responsible for two-step methane production from office paper at 35 °C where during the first and second steps methane was generated mostly from H2/H2CO3 and acetate, respectively. Water saturated and unsaturated cases were tested. According to the model, at the intermediate moisture (150%), much lower methane production occurred because of full-time inhibition of aceticlastic methanogens. At the lowest moisture, methane production was very low because most likely hydrolysis was seriously inhibited. Simulations showed that during cardboard and office paper biodegradation at 55 °C, non-aceticlastic syntrophic oxidation by acetate-oxidizing syntrophs and hydrogenotrophic methanogens were the dominant methanogenic pathways. 相似文献
677.
Assessing ecological risk on a regional scale 总被引:17,自引:0,他引:17
Carolyn T. Hunsaker Robin L. Graham Glenn W. Suter II Robert V. O'Neill Lawrence W. Barnthouse Robert H. Gardner 《Environmental management》1990,14(3):325-332
Society needs a quantitative and systematic way to estimate and compare the impacts of environmental problems that affect
large geographic areas. This paper presents an approach for regional risk assessment that combines regional assessment methods
and landscape ecology theory with an existing framework for ecological risk assessment. Risk assessment evaluates the effects
of an environmental change on a valued natural resource and interprets the significance of those effects in light of the uncertainties
identified in each component of the assessment process. Unique and important issues for regional risk assessment are emphasized;
these include the definition of the disturbance scenario, the assessment boundary definition, and the spatial heterogeneity
of the landscape.
Although the research described in this article has been funded wholly or in part by the United States Environmental Protection
Agency (EPA) through Interagency Agreement Number DW89932112-01-2 to the U.S. Department of Energy, it has not been subjected
to EPA review and therefore does not necessarily reflect the views of EPA and no official endorsement should be inferred. 相似文献
678.
D. L. DeAngelis P. J. Mulholland J. W. Elwood A. V. Palumbo A. D. Steinman 《Environmental management》1990,14(5):685-697
In systems where production is limited by the availability of a nutrient, nutrient input to and recycling within the system
is related to the resilience, or speed of recovery, of a system to its steady state following a disturbance. In particular,
it is shown that the return timeT
s
of the system to steady state, or the inverse of the resilience, is approximately equal to the mean turnover time of the
limiting nutrient in the system. From this relationship, it is possible to understand and predict how various properties of
food webs and their environments affect resilience. These properties include nutrient input rate, loss rate, size of the detritus
compartment, and trophic structure. The effects of these properties on resilience are described by using simple mathematical
models.
To test model predictions, experimental studies of the response of periphyton-dominated stream ecosystems to disturbance are
being conducted on a set of laboratory streams in which nutrient inputs and grazing intensity are regulated at different levels.
In streams without snail grazers (low-grazed streams), 90% recirculation of stream water to reduce nutrient inputs resulted
in longer turnover times (T
r
) of phosphorus within the stream compared with once-through flow. However, in streams with snail grazers (high-grazed streams),
there were no differences in phosphorus turnover time between once-through and partially recirculated treatments. Results
on the rate of recovery of periphyton from a flood/scour disturbance to each stream partially support the model prediction
of a positive relationship between ecosystem return time (T
s
) and nutrient turnover time (T
r
) within the streams. 相似文献
679.
V Hrissanthou 《Journal of the American Water Resources Association》1990,26(5):801-810
ABSTRACT: A simulation model that computes sediment yield due to sheet and rill erosion at the outlet of a large watershed requires daily precipitation and the soil, topographic, and vegetative characteristics of the watershed. An important problem, particularly in a large watershed, is the transport of sediment produced in the sub-watersheds to the outlet of the whole watershed. This problem is approached mathematically by a sediment routing model that is used as a component of the total model. 相似文献
680.
In this paper, a mechanical filtering system to treat pig slurry is proposed. The filter was made from the aerobic decomposition product of the organic fraction of municipal wastes and wheat straw was used as the support.Using a pilot plant to treat 2100 liters of swine slurry, an adequate reduction in BOD5; COD, and other parameters was obtained. The organic matter content of the material trapped in the filter was similar to that of compost and farmyard manure, but the nitrogen and phosphorous levels and the C/N ratio were more similar to farmyard manure. After passing through a filtering system, the treated liquid can be used for fertirrigation and as a feed for algae ponds. After a period of stabilization, the solid material can be mixed to produce manure. Although wheat straw was used as the support in this experiment, other agricultural wastes such as rice straw, corn stalks, millet stems, banana, cotton, and coconut trash can be used. Rather than municipal solid waste compost, other kinds of compost obtained from agricultural wastes such as leaves, bark, husks, etc., can be used as the filter. 相似文献