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691.
S Keerthinarayana Y N Vijayashankar B Shivalingaiah K Visweswariah 《Journal of environmental science and health. Part. B》1990,25(4):493-509
Sorption is one among the many techniques available for the removal of organic materials from potable water and waste water. Use of locally available Wood Charcoal (WC) is essential in place of costly activated charcoal to make the process more economical and lucrative. The vital objective of this investigation was to assess the performance of WC for the removal of DDT from the aqueous phase. The influence of important factors like, particle size, pH, and time of contact, which affects the sorption process was studied in this investigation using batch experiments. The removal kinetics were carried out under the temperature 27 degrees +/- 1 degrees C (room temperature) and the sorption kinetics constants were evaluated. Sorption equilibria study has also been carried out to develop the Freudlich's sorption isotherm equation from which the ultimate sorption capacity of WC for sorption of DDT was calculated. 相似文献
692.
C. Y. Jim 《The Environmentalist》1992,12(1):29-46
Summary Environmental protection in Hong Kong traditionally has been neglected by the government and private sector, with citizens showing little interest. The overwhelming pre-occupation with economic growth and a plethora of pressing social needs are often cited as the main excuses for past apathy. Since the late 1970s, the government has taken positive steps to establish administrative structures and statutes to arrest environmental decline. Legislative processes, however, have often been delayed and the effectiveness of the laws trimmed by the strong industrial lobby. The erratic developments in the 1980s nevertheless allowed the enactment of four dedicated environmental laws and a complement of ancillary control measures. The current status of the environment in the fields of water, waste, air and noise has been assessed to highlight the pertinent maladies and shortcomings. The 1989 White Paper provided a clear package of official policies and programmes to correct past ills in a ten-year comprehensive plan. The ameliorative measures, both present and projected, are evaluated for their effectiveness and prospects. Some issues that deserve more attention and improvements are suggested. 相似文献
693.
Sediments collected from Tap Mun (within Tolo Harbour) and Yim Tin Tsai (outside Tolo Harbour) were extracted sequentially
and the copper, cadmium, and chromium contents were determined. Total contents of copper, cadmium, chromium, and arsenic were
also detected by acid digestion. The level of heavy metal extracted was higher in sequential extraction (which extracted all
forms of metal ions) than total acid digestion. Among the four heavy metals studied, only copper showed a significantly higher
(P<0.001) level in samples collected from Yim Tin Tsai (16.10 mg/kg) than that from Tap Mun (3.19 mg/kg). Such a difference
in copper level is mainly attributed to the significantly higher (P<0.05) levels of copper in the organic, carbonate, and sulfide forms, whereas there was no significant difference (P>0.05) in the exchangeable and sorbed forms.
Green-lipped mussel (Perna viridis) samples collected from the two sites were dissected into seven parts (gill, byssus, siphon, shell, digestive gland, soft
tissue, and adductor muscle) and the concentrations of copper, cadmium, chromium, and arsenic were measured. The highest concentration
of copper was obtained in the byssus. A higher concentration of copper was also noted in the mussels collected from Yim Tin
Tsai than those collected from Tap Mun. No specific trend was revealed for the other metals tested. Chromium and arsenic concentrations
were found to be independent of the body size of the mussels. Copper had a lower concentration in larger mussels and cadmium
level was found to decrease with size. In addition, the mussels collected from Tap Mun were much larger than those collected
from Yim Tin Tsai. 相似文献
694.
Yacov Y Haimes James H. Lambert Duan Li 《Journal of the American Water Resources Association》1992,28(1):201-209
ABSTRACT: This paper summarizes advances made in risk-based decisionmaking in water resources through use of the partitioned multiobjective risk method (PMRM). (Risk is a measure of the probability and severity of adverse effects.) In the PMRM, the risk of extreme events is differentiated from risk involving less extreme damage severity and is evaluated within a multiobjective framework. Study of the extreme-event risk function f4(*) has addressed the following issues: methods for calculating f4(*); the sensitivity of f4(*) to various parameters, particularly to the partitioning point of the extreme-event range and the selection of probability density functions; insight provided by the statistics of extremes; and the impact of f4(*) on risk management, for example, in the application of the PMRM to water resources problems. In particular, this paper shares with the reader recent research results on the PMRM, the relationship between the statistics of extremes and the conditional expected value, derived formulas for f4(*), distribution-free estimates of f4(*), documented case studies in dam safety, and future research directions. 相似文献
695.
Susanna T. Y. Tong 《Environmental management》1990,14(1):107-113
Roadside dusts and soils were collected from various nonindustrial districts in Cincinnati, Ohio, USA, and analyzed for lead
and copper contents. Results showed that the recent lead phase-down action has reduced the level of lead, but the concentrations
of both metals are still higher than the background levels for normal soil. Elevated concentrations of copper in heavily traveled
highways were noted, suggesting that much of the copper pollutants is probably of automotive origin. The concentration of
lead was found to vary with housing age, and higher levels of contamination in the older neighborhoods were observed. This
result is probably ascribable to the accumulation of residues from leaded gasoline and lead-based paint in the past and the
use of coal fire for space heating in older houses. 相似文献
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