Characterization of particulate emissions from occupant activities in offices

This paper characterizes the relationship between occupant activities and indoor air particulate levels in a non-smoking office building. Occupant activities were recorded on video. Particulate concentrations were monitored by three optical particle counters (OPCs) in five size ranges at three heights. Particulate mass concentrations were measured gravimetrically and bioaerosol concentrations were determined by impaction methods. Occupant activities and number concentrations were determined with 1-min resolution over a 1-week period. Occupant activities such as walking past or visiting the monitoring site explained 24-55% of the variation of 1- to 25-micron diameter particle number concentrations. Statistical models associating particulate concentrations with occupant activities depended on the size fraction and included an autocorrelative term. Occupant activities are estimated to contribute up to 10 micrograms m-3 in particulate concentrations per person. Number concentrations of particles smaller than 1 micron had little correlation with indoor activities other than cigarette smoking and were highly correlated with outdoor levels. The method can be used to characterize emissions from activities if rapid measurements can be made and if activities can be coded from the video record.     

Uptake of cadmium, zinc, copper, lead and chromium in the pacific oyster. Crassostrea gigas. Grown in the tamar river. Tasmania

Hundreds of oysters and mud samples from 15 sites along the Tamar River were analysed for cadmium, copper, zinc, lead and chromium. The widely accepted concept of enrichment factors of up to several hundred thousand, describing accumulation by oysters of cadmium, zinc and copper from seawater has been found to be grossly misleading. Concentrations found for these three metals in oysters were only 10–40 times the concentrations in inhabited muds. Concentrations of metals in muds may be used to indicate whether a potential oyster bed would produce oysters that were grossly contaminated. Approximately 1 ppm cadmium in mud could result in oysters containing at least 25 ppm, i.e. 4–5 ppm wet wt. Similarly. 100 ppm zinc in mud could produce oysters containing at least 4000 ppm. i.e. 800–1000 ppm wet wt. Three heavy metal accumulation processes were discernible. Copper and chromium appeared to be absorbed up to a maximum weight that was limited by the size of the oyster and was independent of the amount of metal in the mud. Lead was not absorbed through any physiological demand, but was randomly incorporated at sites containing high concentrations in the mud. Zinc and cadmium were accumulated by a process that depended primarily on the concentrations of these metals in the mud at each site. Mean dry wt concentrations of metals in oysters and mud samples ranged from: 4.2–134 ppm and 0·4 to 5·7 ppm cadmium; 200–1700 ppm and 3–224 ppm copper: 0 135 ppm and 4–1500 ppm lead: 1–37 ppm and 2–88 ppm chromium; 1700 14.000 ppm and 20–500 ppm zinc. respectively.     

Contact flocculation-filtration of humic substances

Contact flocculation-filtration of humic dispersions with alum in medium grain (0.62 mm) sand gave short runs to breakthrough, while in coarse (1.2 mm) media clarification was inefficient. Alum with cationic polymer gave in coarse media acceptable runs, but shorter then for mineral dispersions. Analysis of results by parameters of existing filtration models showed that using the Ives-Iwasaki model and plotting filtration coefficient λ vs specific deposit σ gave different λ_max for different polymer dose, plot of λ_max vs dose goes through maximum at optimum dose.Plotting the cube root of headloss vs square root of specific deposit gave a straight line corresponding to Shektman formula.Analysis by Adin-Rebhun model showed that for contact flocculation-filtration humic dispersions attachment coefficient k₁ was similar to, detachment k₂ was many fold higher then and theoretical maximum mass capacity much lower then in case of mineral dispersions.Calculations showed that the solid content and the density of alumo-organic deposits in bed are much lower than of alumo-mineral deposits. Polymers and minerals increase the solid content, the density of deposits and the mass capacity of filter beds.     

Effect of agitation, turbidity, aluminium foil reflectors and container volume on the inactivation efficiency of batch-process solar disinfectors

We report the results of experiments designed to improve the efficacy of the solar disinfection of drinking water, inactivation process. The effects of periodic agitation, covering the rear surface of the container with aluminium foil, container volume and turbidity on the solar inactivation kinetics of Escherichia coli (starting population = 10(6) CFU ml(-1)) were investigated. It was shown that agitation promoted the release of dissolved oxygen from water with subsequent decrease in the inactivation rates of E. coli. In contrast, covering the rear surface of the solar disinfection container with aluminium foil improved the inactivation efficiency of the system. The mean decay constant for bacterial populations in foil-backed bottles was found to be a factor of 1.85 (std. dev. = 0.43) higher than that of non-foil-backed bottles. Inactivation rates decrease as turbidity increases. However, total inactivation was achievable in 300 NTU samples within 8 h exposure to strong sunshine. Inactivation kinetics was not dependent on the volume of the water container for volumes in the range 500-1500 ml.     

Elimination of beta-blockers in sewage treatment plants

beta-Blockers are used to treat high blood pressure as well as patients recovering from heart attacks. In several studies, they were detected in surface water, thus indicating incomplete degradability of these substances in sewage treatment plants (STPs). In this study, we determined the sorption coefficients (K(D)) and degradation rates of the four beta-blockers sotalol, atenolol, metoprolol and propranolol in sludge from an STP operating with municipal wastewater. The sorption coefficients (K(D), standard deviations in brackets) were determined as 0.04(+/-0.035), 0.04(+/-0.033), 0.00(+/-0.023) and 0.32(+/-0.058) Lg(-1)(COD), and the pseudo-first-order degradation rate constants were estimated to be 0.29(+/-0.02), 0.69(+/-0.05), 0.58(+/-0.05) and 0.39(+/-0.07) Ld(-1)g(-1)(COD) for sotalol, atenolol, metoprolol and propranolol, respectively. These values translate into a typical elimination in STPs (sludge concentrations of 4g(COD)L(-1) and a hydraulic retention time of 6h) of 25%, 37%, 44% and 50% for sotalol, propranolol, metoprolol and atenolol, respectively. These results are also confirmed by measurements in two municipal STPs for atenolol, sotalol and propranolol. The estimated eliminations are slightly too high for metoprolol.     

Environmental Implications of Treatment of Coastal Sewage Discharges

The environmental implications of implementing the requirement for treatment of coastal sewage prior to discharge, which were put forward in an EC draft Directive on municipal waste-water treatment, are examined. In order to establish the current situation, the results of a national survey of coastal and estuarine sewage discharges are presented. A review of the impact of sewage discharges on the marine environment is presented in conjunction with an assessment of the impact of sewage-treatment processes on the land and in the air. These aspects are integrated into overall conclusions about net environmental impact. Finally, a decision-tree approach to the assignment of priority to additional action required at individual locations is developed.     

Mobilization of lead from human bone tissue during pregnancy and lactation--a summary of long-term research

The skeleton is potential endogenous source of lead during pregnancy and lactation. We have undertaken a longitudinal investigation into the mobilization of lead from the human maternal skeleton to determine whether lead is mobilized from the maternal skeleton during pregnancy and lactation, and if so, when and how much is released. Subjects in the study were migrants to Australia (n=15) whose skeletal lead isotopic composition (endogenous lead) was different to that prevailing in the Australian environment (exogenous lead). This migrant cohort was compared with 6 multi-generational Australian controls. Biological and environmental samples were taken pre-pregnancy where possible, throughout pregnancy and postpartum for at least 6 months. Newly-born infants of the migrant and Australian mothers were monitored for 6 months. Blood lead concentrations for the migrant mothers ranged from 1.5 to 20 microg/dl (geometric mean 2.8) and for Australian mothers ranged from 1.9 to 4.3 microg/dl (geometric mean 2.9). There was minimal change in lead isotopic composition of the Australian pregnant controls although there were increases of approximately 40% in blood lead concentration in 3 of 6 cases during the postpartum period and from 0 to 12% in the other 3. In the migrant pregnant subjects, the geometric mean skeletal lead contribution to blood lead using the isotopic composition was approximately 33% (range 10-88%) for 14 subjects using a revised estimate for exogenous lead. Skeletal contribution to blood lead during the postpartum period was significantly greater than during pregnancy (P<0.001). The skeletal contributions to blood lead are higher and the changes are more consistent in those subjects who conceived within 100 days of arrival in Australia compared with those who conceived longer than 100 days. In the migrant subjects, changes in blood lead concentration during pregnancy and postpartum varied from subject to subject with an overall 20% increase; the increases during the postpartum period were greater than during pregnancy (P<0.001). It was estimated that the amount of maternal skeletal lead mobilized during pregnancy and transferred to the infant via cord blood averaged approximately 79%. The increased skeletal contribution to blood lead is attributed to a low daily calcium intake of approximately 500 mgCa/day, a condition which was present in both migrant and Australian subjects. An ongoing clinical trial is providing a new cohort with calcium supplements. A summary of other aspects of the study is included and covers: additional flux released from the skeleton during pregnancy and postpartum; XRF bone lead results; urinary excretion of lead during pregnancy and postpartum; dietary contribution to blood lead in female adults and children; comparison of rates of exchange of lead in blood of newly-born infants and mothers; relationships of lead in breast milk to lead in blood, urine and diet of the infant and mother; changes in blood lead after cessation of breastfeeding; urinary lead isotopes during pregnancy and postpartum indicate no preferential partitioning of endogenous lead into plasma; a comparison of some aspects of the nonhuman primate and human pregnancy studies.     

Compensation for extra preliminary and general (P & G) cost arising from delays, variations and disruptions: the palmiet pumped storage scheme

Underground construction is notorious for high cost and time overruns. This is probably inherent in the nature of the work, which usually involves high risks on the part of both the employer and the contractor, in view of the extent of the uncertainties with regard to such factors as geology, appropriate design and performance. The main civil works constructed for South Africa's Palmiet Pumped Storage Scheme between 1983 and 1987 have demonstrated that with early identification and proper management of the risks and costs, the value of cost and time overruns can be curtailed to a very large extent. This paper describes broadly the process adopted on the project, focusing in particular on the successful management at Palmiet of the financial risks pertaining to the cost of the contractor's overheads, establishment, supervision and plant in a contract that was known to be subject to variations, extensions and delays. This was achieved by appropriate scheduling, provisions for payment and on-site management of these cost items, usually described broadly as the Preliminary and General (P & G) Items. These items accounted for 34% of the value of the contract.     

县（市）级城市建设档案的管理工作

根据国家“十一五”规划，到2010年全国城市建设水平将达到一个新台阶。城市的快速发展，特别是东西部中小城市的步伐必须跟上城市建设的发展。因而，加快县（市）级城市建设档案管理工作迫在眉睫。