Quantitative relationships between molecular structures,environmental temperatures and octanol-air partition coefficients of PCDD/Fs

In Thailand, human excreta might be recycled into agricultural soils as a supplement to commercial fertiliser and thereby enrich the general fertility of the soils. However, for Thailand an adequate knowledge of the quality of human excreta, in order to assess its fertiliser potential, is not available. A literature survey revealed only very limited information of the chemical composition and generation rate of human excreta in South East Asia. Data from other parts of the world also lacked specific information on collection and analytical methods, or the studies were typically 20-30 years old. In the present study the composition of human excreta has been studied in three case study areas in Southern Thailand: Kuan Lang, Phattalung and Prik. The inhabitants of the three areas represent people of Southern Thailand by age, sex, occupation, religion and type of residence. Human excreta was collected and stored for 1 week from five persons in each area, who each had their own toilet and collection bucket. In parallel, a septic tank at the Observation and Protection (O&P) Centre of Songkhla (a boys prison institution) adjacent to the three study areas was used as a daily sampling point, to obtain data on average amounts of human excreta and chemical composition. Information on average values of generation rate and chemical composition was obtained as well as inter-human variation. However, no significant variation was found between the results for human excreta at the O&P Centre or from the 15 individuals. Furthermore, there was no significant influence of age, sex, occupation or religion on the chemical composition. The only significant variation was that the older people excreted larger amounts of total wet matter than the younger, which could be due to a higher water intake, in order to reduce the risk of constipation. The generation rate found was 0.6-1.2 1 urine/cap/day and 120-400 g wet faeces/cap/day. The generation rate of the elements in the excreta was 7.6-7.9 g N/cap/day, 1.6-1.7 g P/cap/day, 1.8-2.7 g K/cap/day, 1.0-1.1 g S/cap/day, 0.75-1.5 g Ca/cap/day, 0.25-0.4 g Mg/cap/day, 9-16 mg Zn/cap/day, 1.4-1.5 mg Cu/cap/day, 0.3 mg Ni/cap/day, 0.02-0.03 mg Cd/cap/day, 0.07-0.14 mg Pb/cap/day, 0.01 mg Hg/cap/day and 0.8-1.1 mg B/cap/day. The metals (Ca, Mg, Zn, Cu, Ni, Cd, Pb, Hg) are mainly excreted via the faeces and the remaining elements (N, P, K, S, B) are mainly excreted via the urine. It can be concluded that human excreta constitutes a large fertiliser resource, which presently is not utilised in Thailand.     

Characterization of dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in the atmosphere of different workplaces of a sinter plant

This study investigated concentrations, contents and congener profiles of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in the workplaces of a sintering plant. Air samples were collected from the charging zone, the sintering zones of the sintering grate and the rough roll shredder, and the control room. The charging zone was found to have a higher total suspended particulate (TSP) but lower PCDD/F concentrations (=4969 microg nm(-3) and 7.61 pg nm(-3), respectively) than the sintering zone (=1422-1448 microg nm(-3) and 19.16-23.17 pg nm(-3), respectively). The TSP and PCDD/F concentrations were lowest in the control room (=98 microg nm(-3) and 1.75 pg nm(-3), respectively). However, the above concentrations were within the range of a typical urban-industrial area. Quite similar PCDD/F contents were found in particles in the sintering zones and control room (=11.72-14.30 and 15.85 ng g(-1), respectively) suggesting that the sintering zone and the control room are very similar. In both charging and sintering zones, 2,3,4,7,8-PeCDF contributed 40-60% to the total I-TEQ in both the gas phase and particle phase. However, in control room, both congeners 2,3,4,7,8-PeCDF and 2,3,7,8-TCDD were the main contributors; the later contributed 30% of the total I-TEQ in gas phase. In control room, the contribution of 2,3,7,8-TCDD to the total PCDD/F concentration in the gas phase greatly exceeded that in particle phase (=5.5% and 0.8%, respectively). Therefore, solutions must be sought to avoid the transfer of not only the particle-phase but also the gas-phase PCDD/Fs from the sintering zone to the control room in the future.     

Modelling the long-term fate of polychlorinated dibenzo-p-dioxins and furans (PCDD/Fs) in the Grenland Fjords, Norway

The development and application of a predictive fate model (DIG--Dioxins in Grenland) for polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/F) in the marine environment of the Norwegian Grenland Fjords are described. The objective of the modelling study was to predict long-term future changes in PCDD/F concentrations in the fjord following the cessation of point source emissions. To assess the reliability of the model, the model performance was evaluated by comparing model results to field measurements collected between 1989 and 2001. Model bias (defined as the ratio of median predicted concentration and median observed concentration) for prediction of concentrations for three different PCDD/F congeners (2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), 1,2,3,6,7,8-hexadibenzofuran (HxCDF) and octachlorodibenzofuran (OCDF)) in the fjord was between 0.53 and 24, which was deemed a satisfactory result for models of this type. The model was run to determine the dynamic change in concentrations between 1950 and 2050 and to examine the key fluxes of PCDD/Fs in the fjord. Between 1990 and 2050 sediment concentrations of TCDD, HxCDF and OCDF were predicted to fall at fairly constant but gradually slowing rates to concentrations 52, 98 and 88 times lower, respectively, of their 1990 values. Losses of PCDD/Fs from the bottom sediments in the Frierfjord were predicted to be a combination of sediment burial and net resuspension to the water column. Sediment burial was shown to be relatively more important in the fjord's deep-water sediments, whereas resuspension was relatively more important in the shallow sediments. For the shallower sediments, a net water-to-sediment flux was predicted for all three congeners up until the mid-1970s, when emission reductions were initiated, and thereafter a net sediment-to-water flux was predicted. The shallow sediments acted as net sources to the deeper sediments and to the fishing areas in the outer fjord.     

Effects of forest fire on the level and distribution of PCDD/Fs and PAHs in soil

Forest fires are believed to produce polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs); however, there is no firm evidence supporting this conjecture. To address this issue, we investigated whether PCDD/Fs and polycyclic aromatic hydrocarbons (PAHs) are formed by forest fires. The present work takes the indirect approach of measuring the levels of PCDD/Fs and PAHs in soil and ash samples 1, 5 and 9 months after forest fires. To determine if PCDD/Fs or PAHs were formed during forest fires, the levels of PCDD/Fs and PAHs measured in the burnt soil samples were compared with those in the corresponding unburnt soil samples. One month after forest fires, the concentrations of PCDD/Fs and PAHs in burnt soils were higher than in the corresponding unburnt soils. In addition, the homologue profiles differed between the burnt and unburnt soils. Five months after forest fires, however, the concentrations of PCDD/Fs and PAHs in the burnt soils were similar to those in unburnt soils. The data presented here strongly suggest that PCDD/Fs and PAHs form during forest fires and are then introduced into the soil. The results further suggest that the ash resulting from the combustion of wood and other organic matter is the main agent influencing the concentration of PCDD/Fs and PAHs in the soil.     

Lipid peroxidation and antioxidant status in workers exposed to PCDD/Fs of metal recovery plants

Secondary copper smelters, which primarily utilize the waste materials that contain organic impurities, and the zinc recovery plant, which handles mostly fly ash and slag from the iron and steel industry, are major emission sources of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs) in Taiwan. In this study, we compared the levels of erythrocyte glutathione (GSH), erythrocyte superoxide dismutase (SOD) and plasma malondialdehyde (MDA) in workers at a secondary copper smelting plant and a zinc recovery plant who may have been exposed to PCDD/Fs. Though the PCDD/F levels were higher in workers of zinc recovery plant than those of secondary copper smelting plant, no significant difference was found for serum PCDD/F levels between the two kinds of plants. We observed a significant difference in plasma MDA levels between workers at the zinc recovery plant (2.54 microM) and those at the copper smelting plant (1.79 microM). There was and a significant positive correlation between plasma MDA levels and the PCDD/Fs levels. In addition, we observed that the MDA levels were not affected by smoking and exercise status. Therefore, the data suggest that the MDA levels of the metal recovery workers are influenced by their PCDD/F exposure. The erythrocyte SOD activity in workers from the zinc recovery plant was marginally higher than that from the secondary copper plant (196 vs. 146 units/ml, p<0.06). In both plants, large variations in the MDA and SOD levels were found, especially in the high-PCDD/Fs-exposure group, which may be attributed, at least partially, to the differences in smoking status and the number of cigarettes smoked. Overall, our results indicate a higher oxidative stress in workers of the zinc recovery plant than in workers of the secondary copper smelting plant in Taiwan.     

Formation of PCDD/Fs from heating polyethylene with metal chlorides in the presence of air

This paper investigated the effect of inorganic chlorine on the formation of PCDD/Fs from heating polyethylene (PE) in the presence of air. There was an increase in the formation of PCDD/Fs with an increasing amount of metal chlorides except NaCl, which was not observed to have any effects on the formation of PCDD/Fs without the presence of catalysts. Although the levels of PCDD/Fs formation in this study have no relevance to full scale municipal solid waste incineration, the results of the present experiments can aid understanding of the mechanisms of the formation of PCDD/Fs from heating PE in the presence of metal chlorides.     

Emissions of metals and polychlorinated dibenzo(p)dioxins and furans (PCDD/Fs) from Portland cement manufacturing plants: inter-kiln variability and dependence on fuel-types

Emissions from Portland cement manufacturing facilities may increase health risks in nearby populations and are thus subject to stringent regulations. Direct testing of pollutant concentrations in exhaust gases provides the best basis for assessing the extent of these risks. However, these tests (i) are often conducted under stressed, rather than typical, operating conditions, (ii) may be limited in number and duration, and (iii) may be influenced by specific fuel-types and attributes of individual kilns. We report here on the results of more than 150 emissions-tests conducted of two kilns at a Portland cement manufacturing plant in Portugal. The tests measured various regulated metals and polychlorinated dibenzo(p)dioxins and furans (PCDD/Fs). Stack-gas concentrations of pollutants were found to be highly variable, with standard deviations on the order of mean values. Emission rates of many pollutants were higher when coal was used as the main kiln fuel (instead of petroleum coke). Use of various supplemental fuels, however, had little effect on stack emissions, and few statistically significant differences were observed when hazardous waste was included in the fuel mix. Significant differences in emissions for some pollutants were observed between the two kilns despite their similar designs and uses of similar fuels. All measured values were found to be within applicable regulatory limits.     

Ratio variation of congener profiles of PCDD/Fs and dioxin-like PCBs in human milk during lactation

This study investigates the compositional variations, changes in concentrations and contribution of particular congeners of PCDDs, PCDFs, non-ortho PCBs and mono-ortho PCBs in human milk from two mothers sampled during the 12-month lactation period. Total PCDD/F and dioxin-like PCB concentration in milk sampled from the primiparous mother on day 5 after delivery was 37 pg TEQ/g fat, and this value decreased significantly by 43% at 12 months. In milk sampled from the multiparous mother nursing her second child on day 5 after delivery was 12 pg TEQ/g fat, and this value decreased by 40% at 12 months. The decrease was statistically significant not for PCDD/Fs, but for dioxin-like PCBs. The ratio variance of the congener profiles of PCDD/Fs and dioxin-like PCBs in the milk remained similar during lactation. Moreover, the congener profiles of PCDD/Fs and dioxin-like PCBs in the milk showed similar percentages for both mothers independent of the lactation event and the number of previous births. The mean daily intake of dioxins by the infant nursed by the primiparous mother and the infant nursed by the multiparous mother up to six months of age was 140 and 46 pg TEQ/kg body weight, respectively. From seven to twelve months of age, the mean daily intake was 37 and 13 pg TEQ/kg body weight, respectively. Both values decreased by approximately 70%. The reasons why the mothers' body burden of dioxins decreased by breastfeeding and why the infants' daily intake of human milk per body weight decreased as the infant grows older consequently decreased were considered.     

Historical trends of PCDD/Fs and CO-PCBs in a sediment core collected in Sendai Bay, Japan

The vertical distribution of dioxins in a sediment core was investigated to elucidate historical trends of dioxins discharged into Sendai Bay, Japan. The dioxin concentration was 410 pg/g dry weight (dw) in sediments deposited in the mid-1930s and 3870 pg/g dw in those deposited in the mid-1980s. Dioxin fluxes increased from the mid-1930s and then reached a maximum in the mid-1980s. 1,3,6,8-TeCDD+1,3,7,9-TeCDD, OCDD, and Co-PCB concentrations were 110, 140, and 26 pg/g dw, respectively, in mid-1930s sediments, and reached maximums of 1800, 1100, and 200 pg/g dw, respectively, in mid-1980s sediments. Shipments to Miyagi Prefecture of CNP and PCP products, the major sources of 1,3,6,8-TeCDD+1,3,7,9-TeCDD and OCDD, were highest in 1975 (4700t) and 1970 (3100t), respectively; and in Japan, the amount of PCBs, the major source of Co-PCB congeners, used was highest (11,100t) in 1970. Thus, the period for which the maximum concentrations of 1,3,6,8+1,3,7,9-TeCDD, OCDD, and Co-PCBs were measured in the sediment core (mid-1980s) did not correspond to the time of maximum use of CNP, PCP, or PCB products, but lagged behind by more than 10 years. We attributed this time lag to the time required for the movement of dioxins from Miyagi Prefecture to Sendai Bay.     

The role of UV-B on the degradation of PCDD/Fs and PAHs sorbed on surfaces of spruce (Picea abies (L.) Karst.) needles

Photodegradation of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) and polycyclic aromatic hydrocarbons (PAHs) sorbed on surfaces of spruce (Picea abies (L.) Karst.) needles was investigated. The role of sunlight and, in particular, the role of short wavelength UV-B radiation were studied in a sun simulator under controlled environmental conditions. The photodegradation of PCDD/Fs and PAHs follows first-order kinetics. Simulated sunlight containing UV-B induced two phases of photodegradation kinetics for PCDD/Fs, whereas no distinct phases of the kinetics were observed for PAHs. UV-B radiation plays a much more important role on the photodegradation for PCDD/Fs than that for PAHs. Direct photolysis dominates the photodegradation of PCDD/Fs and PAHs.     

Contamination of the alluvial plain, feeding-stuffs and foodstuffs with polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans (PCDD/Fs), dioxin-like polychlorinated biphenyls (DL-PCBs) and mercury from the River Elbe in the light of the flood event in August 2002

Meadow soils, feeding-stuffs and foodstuffs from the alluvial plain of the river Elbe were analyzed in respect of PCDD/Fs, DL-PCBs and mercury with a view to assessing the consequences of the extreme flood of August 2002. The PCDD/F concentrations in the soils range from 3 to 2100 ng WHO-TEQ/kg dm, and for the DL-PCBs the range was 0.32 to 28 ng WHO-TEQ/kg dm. On the basis of established threshold values >40% of the areas are only fit for restricted usage. Mercury concentrations range from 0.11 to 17 mg/kg dm, whereby the action value of 2 mg/kg dm is exceeded in about 50% of the soil samples. A cumulative memory effect from past floods rather than a recent contamination from August 2002 is documented. Soils taken from behind broken dykes showed significantly lower concentrations. Grass, hay and grass silage originating from pasture land in Lower Saxony were taken before and immediately after the flooding. PCDD/Fs range from 0.29 to 16 ng WHO-TEQ/kg, the maximum permitted value of 0.75 ng WHO-TEQ/kg was exceeded in about 50% of the samples. Muscle-tissue from cattle, sheep, lamb and a roe deer as well as untreated milk from individual cows returned values ranging from 0.76 to 5.9 pg WHO-PCDD/F-TEQ/g fat, and 10% of the samples returned values higher than the permitted maximum of 3 pg WHO-PCDD/F-TEQ/g fat. The action value of 2 pg WHO-PCDD/F-TEQ/g fat was exceeded in 33% of the samples. No direct connection between these results and the effects of the flood could be established. A major input path for PCDD/Fs is the tributary Mulde, which discharges contaminated sediments from its catchment area into the Elbe.     

Mechanism of phenol photodegradation in the presence of pure and modified-TiO(2): A review

In recent years, the application of heterogeneous photocatalytic water purification processes has gained wide attention due to its effectiveness in degrading and mineralizing the recalcitrant organic compounds as well as the possibility of utilizing the solar UV and visible-light spectrum. By far, titania has played a much larger role in this scenario compared to other semiconductor photocatalysts due to its costly effectiveness, inert nature and photostability. A substantial amount of research has focused on the enhancement of TiO₂ photocatalysis by modification with metal, non-metal and ion doping.This paper aims to review and summarize the recent works on the titanium dioxide (TiO₂) photocatalytic oxidation of phenol and discusses various mechanisms of phenol photodegradation (indicating the intermediates products) and formation of OH radicals. Phenol degradation pathway in both systems, TiO₂/UV and doped-TiO₂/Vis, are described.     

Edge effects of roads on temperature, light, canopy cover, and canopy height in laurel and pine forests (Tenerife, Canary Islands)

The estimation of the road edge effect is useful to understand changes induced by the road network on ecosystems. Road networks on islands may break ecosystem integrity through microclimate edge effects, which are known to be associated with disturbances to animal and plant communities. Road edge effects have been scarcely studied on oceanic islands. In this paper we studied road edge effects on microclimate and canopy structure in laurel and pine forests in Tenerife (Canary Islands). We assessed depth of road edge effect for temperature at four vertical layers (soil, litter and air at 5 cm and 1.3 m above ground), light intensity, canopy cover and height, in transects running from narrow (6–7 m width) asphalt roads and dust trails to 100 m to the interior of both forests. We used an ANOVA procedure with Helmert difference contrasts to identify the distances along transects over which edge effects were significant. We detected significant gradients for most parameters but they were consistently narrow both within and between forests. In the laurel forest, we detected highly significant gradients for soil temperature, light, and canopy cover and height in both asphalt and unpaved roads. In the pine forest, we detected a highly significant gradient for soil temperature at asphalt roads, and a significant light gradient for both asphalt and unpaved roads. From the road edge to the forest interior, significant temperature changes persisted for only 3 m, light variation persisted for 6 m, and canopy cover and height changed significantly within the first 10 m. Asphalt roads and dust trails revealed different patterns of variation for temperature between edge and interior. No differences were found between the two types of roads in edge-interior trends for light or canopy structure. The abruptness of microclimate and canopy gradients was slightly higher in the laurel forest than in the pine forest, caused by a higher edge contrast in the former. The depth of the road edge effect found in laurel and pine forests was small, but it could have cumulative effects on forest microclimate and forest associated biota at the island scale. Such changes deserve attention by local road managers for planning and design purposes.     

Inverse relationships between selenium and mercury in tissues of young walleye (Stizosedion vitreum) from Canadian boreal lakes

The concentrations of total mercury (Hg), methylmercury (MeHg) and total selenium (Se) were determined in muscle, liver and brain tissues of young-of-the-year walleye (Stizosedion vitreum) specimens collected from 8 boreal lakes that are located within 107 km around the Sudbury smelters in Ontario, Canada. Dry weight basis concentrations of Hg were highest in muscle and lowest in brain (p < 0.05), those of MeHg were higher in muscle than in liver and brain but there was no significant difference between liver and brain (p < 0.05). The highest Se concentrations were found in liver and the lowest in brain (p < 0.05). Considering the biomass of the studied tissues, muscle was the part of the body where most of Hg, MeHg and Se were accumulated. In fish muscle, the percentage of MeHg over Hg was the highest and this percentage was the lowest in liver. The concentrations of Hg, MeHg and Se in the studied tissues were closely related to the concentrations of total dissolved Se in lake waters which vary with the distance of the lakes from the smelters. Thresholds of Se concentrations in tissues were revealed (6.2, 12.0 and 3.5 mg kg^− 1 dry wt., for muscle, liver and brain, respectively), above which a significant reduction of MeHg concentrations was observed in all studied tissues compared to lower Se levels in the same tissues. Based on the collected information and data analysis, possible mechanisms for the biological processes behind the observed inverse relationships between Se and Hg in fish tissues are discussed.     

Spatial distribution of dental fluorosis in roe deer (Capreolus capreolus) from North Bohemia (Czech Republic) and its relationships with environmental factors

We assessed the spatial variation of fluoride load on the local ecosystem in the Czech part of the Ore Mountains region and its southern foothills - a heavily polluted part of Europe's "Black Triangle" region. Dental fluorosis in roe deer (Capreolus capreolus) served as a biomarker of fluoride exposure and thus as an indicator of environmental pollution by fluoride. The mean dental lesion index of fluorosis (DLI) calculated from the analyzed mandibles of wild roe deer (>or=2 years of age) was assigned to the hunting ground from which the specimens originated and classified into one of the eight fluorosis categories. Environmental factors potentially related to dental fluorosis (atmospheric deposition of sulfur, concentration of fluoride in and pH of surface waters, geomorphologic features, bedrock and soil type, and vegetation cover), which were represented in the study by GIS layers, were examined to explain the distribution pattern and severity of fluorosis in the roe deer. The study revealed that 75.5% of 616 analyzed mandibles showed dental fluorosis to different extent, with individual DLIs ranging from 0 to 21. The spatial pattern of marked fluorosis on the Czech side continues that found in a previous study on the German side of the Ore Mountains. Together they create a landscape island around several thermal power plants in the region. General Linear Model (GLM) analyses revealed significant relationships between degree of forest damage, soil type, and atmospheric sulfur deposition from air pollution and dental fluorosis, expressed as mean DLI in the roe deer.     

双极膜填充床电渗析技术应用试验

将双极膜（BPM）和填充床电渗析（EDI）技术相结合,组装成三隔室BPM－EDI装置,将其应用于复床离子交换树脂的电再生。试验结果表明：当再生电压为60V,再生时间为60min时,该装置的电再生效果接近化学再生的效果,显示了良好的技术可行性。     

Bioconcentration of linear alkylbenzene sulfonate (LAS) in bluegill (Lepomis macrochirus)

The potential of the surfactant linear alkylbenzene sulfonate (LAS) to be bioconcentrated in various tissues and organs of bluegill (Lepomis macrochirus) was determined during a 35 day continuous exposure to a mean measured water concentration of 0.5 (±0.05) mg l^{−1 14}C-ring labelled LAS and during a 14 day depuration study. Based on the assumption that all of the ¹⁴C-radioactivity was present as intact LAS, which represents the maximum amount of LAS that could be present, the steady state whole body bioconcentration factor (BCF) was 104 and the muscle BCF was 36. The site of greatest concentration was the gall bladder with a BCF of approx. 5000. The BCF for liver, gills and viscera, remaining carcass, and blood ranged from 64 to 283. Clearance of ¹⁴C-activity from the organs and tissues was rapid with half-lives of 2–5 days. These results on LAS were obtained by both the plateau and kinetic methods of data analysis and are similar to other published data on surfactant bioconcentration.     

Bioaccumulation profiles of 35S-labelled sodium alkylpoly(oxyethylene) sulfates in carp (Cyprinus carpio)

The uptake, distribution and elimination of two labelled surfactants, ³⁵S-labelled sodium dodecyltri(oxyethylene) sulfate (³⁵S-C12-AES(3)) and ³⁵S-labelled sodium dodecylpenta(oxyethylene) sulfate (³⁵S-C12-AES(5)) were investigated in carp (Cyprinus carpio) exposed to concentrations of 0.3–0.6 mg l^?1, using whole-body autoradiography and the liquid scintillation counting method. ³⁵S-Radioactivity was first rapidly absorbed by the gills and skin and transferred to other organs and tissues. After 24 h-exposure, there was a comparatively high accumulation of ³⁵S-radioactivity in the gills, hepatopancreas, gall bladder, intestinal content, and nasal and oral cavity. The distribution patterns of ³⁵S-radioactivity derived from ³⁵S-C12-AES(3) and ³⁵S-C12-AES(5) in tissues and organs were similar. The whole-body concentration factors of ³⁵S-radioactivity in fish exposed to ³⁵S-C12-AES(3) and ³⁵S-C12-AES(5) for 72 hr were 18 and 4.7, respectively. In surfactant-free water, the absorbed ³⁵S-radioactivity was eliminated more rapidly from the fish body exposed to ³⁵S-C12-AES(3) than ³⁵S-C12-AES(5). It was eliminated relatively fast from gills and hepatopancreas, but elimination from gall bladder was rather slow.