Refine search
Results 941-950 of 2,513
Spatio-temporal pattern of community development in dredged material used for habitat enhancement: A study case in a brackish lagoon Full text
2014
Munari, C. | Mistri, M.
Dredged material is a potential resource for beneficial use for create/improve subtidal habitats. In a northwestern Adriatic lagoon, dredged sand was placed in inner areas with the management objective of improving the characteristics of the muddy areas being recharged. With this study we investigated the recolonization dynamics of benthic communities following the placement of dredged sand in a microtidal lagoon. The disposal of dredged sand had an immediate and negative effect on resident fauna. After an initial reduction, benthic communities followed different recovery pathways. One year after disposal, we recorded an almost complete recovery of the benthic invertebrates in terms of univariate parameters. Despite multivariate analyses still showed significantly different community structures, the trajectories of recovery for disposal areas converged towards the same basin of attraction of control areas. The ecological quality of sites, assessed with benthic indices, did not improve, thus no new beneficial habitat was created for macrobenthos.
Show more [+] Less [-]Relationship between sources and patterns of VOCs in indoor air Full text
2014
Rösch, Carolin | Kohajda, Tibor | Röder, Stefan | Bergen, Martin von | Schlink, Uwe
People spend most of their daytime in indoor environments. Their activities influence the composition of the indoor air by emitting volatile organic compounds (VOCs). The increasing number of different VOCs became the focus of attention in recent years as the question arises from the relationship between exposure to air pollutants and diseases. The present study of flats in Leipzig (Germany) is based on measurements of 60 different VOCs and is unique in the field of indoor air quality due to its enormous size of samples (n=2 242) and questionnaire data. The main purpose of our analysis was to identify the sources and patterns that characterize airborne VOCs in occupied flats. We combined two methods, principal components analysis (PCA) and non–negative matrix factorization (NMF), to assign compounds to their origin and to understand the coinstantaneous existence of several VOCs. PCA clustering provided a source apportionment and yielded 10 principal components (PCs) with an explained variance of 72%. However, real indoor air quality is often affected by combined sources. NMF reveals characteristic compositions of VOCs in indoor environments and emphasizes that constantly recurring structures are not single sources, but rather fusions of them, so called patterns. Interpreting these sources, we realized that homes were strongly influenced by ventilation, human activities, furnishings, natural processes (such as solar radiation) or their combinations. The very large set of samples and the combination with questionnaires applied on this comprehensive assessment of VOCs allows generalizing the results to homes in middle–scale cities with minor industrial pollution. As a conclusion, single VOC–dose–response relationships are inopportune for situations when indoor sources occur in combination. Further studies are necessary to assess associated health risks.
Show more [+] Less [-]Health–risk assessment of workers exposed to flour dust: A cross–sectional study of random samples of bakeries workers Full text
2014
Moghaddasi, Yousef | Mirmohammadi, Seyedtaghi | Ahmad, Anees | Etemadi Nejad, Syavash | Yazdani, Jamshid
The objectives of this study were to measure exposure to dust in the small bakery shops, to define the determinants of occupational asthma, and to propose control measures for this. The study included bakery workers of one hundred bakeries (the cases; n=200, the controls; n=20). Their individual information was obtained by a simple questionnaire based on “Ear–Nose–Throat” (ENT) work–related symptoms such as coughing, wheezing, chest tightness and irritations. Subjects were considered as “possible occupational asthma cases”. Medical visit was carried out to complete clinical and lung function investigations for these subjects. The mean flour dust concentration in the current study was 28mg/m3. Fifty six of bakery workers had work related symptoms significantly higher than those in controls. The spirometric results illustrated that the workers with experience of less than five years are not affected as there was no significant difference between exposed cases and controls in mean forced expiratory volume in one second (FEV1) or forced vital capacity (FVC) percent determined. But workers with experience of five years or more showed significantly lower mean FEV1 and FVC percent predicted when compared with controls. The results of lung function test for subjects demonstrated that the flour dust pollution adversely affects on main lung function parameters, such as FVC and FEV1. This study confirms that the risk of pulmonary disease among flour dust exposed workers is higher than the unexposed control subjects.
Show more [+] Less [-]Baseline survey of trace metals in ambient PM10 at Tummalapalle uranium mining site Full text
2014
Trace metals (Ag, Al, As, Cd, Co, Cr, Cs, Cu, Fe, Mn, Ni, Pb, Se, Sr, Tl, U, V and Zn) in PM10 were measured at 10 different sites in the surrounding areas of Tummalapalle Uranium Mining (India). The PM10 samples were collected on glass fiber/EPM 2000 filter using high volume air samplers in 10 different sampling sites during November–2010 to February–2012. Trace metals in PM10 were analyzed using Inductively Coupled Plasma Mass Spectrometer (ICP–MS). The observed trace metal concentrations varied from 0.01 to 2 640ng/m3. It was found that metals associated with crustal sources like Al and Fe were in higher concentrations. The elements Tl, U, Cs and Co were found to be in very low concentrations. Obtained trace metal data in PM10 were subjected to statistical analyses using correlation matrices and factor analysis to examine the interrelationship between the investigated trace elements and possible source identification of the elements. Enrichment factors of trace metals were also determined to determine the anthropogenic contribution to ambient PM10. The daily intake of analyzed trace metals by the adult population in the surrounding of Tummalapalle Uranium mining (30km radial distance) was estimated and it was found to be in the range of 1 to 13 401ng/day through the inhalation route.
Show more [+] Less [-]Temporal patterns and potential sources of polycyclic aromatic hydrocarbons in xylem of Pinus kwangtungensis Full text
2014
The temporal patterns and the possible sources of polycyclic aromatic hydrocarbons (PAHs) in the xylem formed from 1883 to 2007 of Kwangtung pine (Pinus kwangtungensis), growing in the Nanling Mountains of Southern China, were detected whether dendrochemistry was sufficient to monitor historical changes in regional airborne PAHs. The total concentrations of 17 PAHs (ΣPAHs) distributed in the xylem of P. kwangtungensis did not progressively increase over time. Temporal patterns of high molecular weight PAHs (HMW–PAHs) coincided to a certain extent with the historical–socioeconomic changes in China. Based on the compositional analysis, PAHs absorbed by and accumulated in the xylem of P. kwangtungensis in the Nanling Mountains might be of pyrogenic origin. Although the possible sources of xylem PAHs were diverse over the studied period, principal component analysis could not convincingly distinguish the main contributors to xylem PAHs. Using only xylem of P. kwangtungensis was not adequate for retrospective monitoring of airborne PAHs in the atmosphere of the Nanling Mountains. Sampling other trees along a gradient and combining other meteorological and socioeconomic index data might provide more reliable information on historical changes in regional airborne PAHs.
Show more [+] Less [-]Measurement of PCDD/Fs emissions from a coal–fired power plant in Malaysia and establishment of emission factors Full text
2014
This paper presents the PCDD/Fs emissions measured from a coal–fired power plant in Malaysia. The study discusses partitioning of PCDD/Fs in particle and gas phase, effects of coal quality to PCDD/Fs formation, effects of air pollution control device (APCD) configuration to PCDD/Fs formation and establishment of emission factors of PCDD/Fs from the studied coal–fired power plant. The results presented in this study were mostly in good agreement with the previous works on PCDD/Fs emissions conducted in other countries. Laboratory analysis results showed that PCDFs were the dominant congeners. The emissions of PCDD/Fs were low which most probably due to the high combustion efficiency. The PCDFs/PCDDs ratio was more than 1 and PCDD/Fs were detected in fly ash, hence speculating that the formation of PCDD/Fs during coal combustion was mainly through de novo synthesis. Analysis on partitioning of PCDD/Fs showed that the compounds were mainly emitted in gas phase. This study also indicated that type of coal influenced the formation of PCDD/Fs during coal combustion where bituminous coal with high sulfur (S) content resulted in slightly lower PCDD/Fs emissions compared to sub–bituminous coal. It was also found that operation of flue gas desulfurization (FGD) reduced the emission of PCDD/Fs. The established emission factors for PCDD/Fs were in the range of 0.08 to 0.11ng I–TEQ/kg.
Show more [+] Less [-]Source speciation resolving hydrochemical complexity of coastal aquifers Full text
2014
Sonkamble, Sahebrao | Chandra, Subash | Ahmed, Shakeel | Rangarajan, R.
There is a growing concern of seawater intrusion to freshwater aquifers due to groundwater overexploitation in the eastern coastal belt of Southern India. The problem becomes complex in the regions where industrial effluents are also contaminating the freshwater aquifers. In order to understand the hydrochemical complexity of the system, topographic elevation, static water level measurements, major ion chemistry, ionic cross plots, water type contours and factor analysis were applied for 144 groundwater samples of shallow and deep sources from Quaternary and Tertiary coastal aquifers, located within the industrial zone of 25 km2 area near Cuddalore, Southern India. The ionic cross plots indicates dissolution of halite minerals from marine sources and seawater mixing into inland aquifers up to the level of 9.3%. The factor analysis explains three significant factors totaling 86.3% of cumulative sample variance which includes varying contribution from marine, industrial effluent and freshwater sources.
Show more [+] Less [-]Temporal trends and spatial distribution of DDT in bivalves from the coastal marine environments of the continental United States, 1986–2009 Full text
2014
Sericano, José L. | Wade, Terry L. | Sweet, Stephen T. | Ramírez, Juan | Lauenstein, Gunnar G.
Analysis of DDT isomers and breakdown products, DDD and DDE, in over 3500 bivalve samples collected from more than 300 locations along the continental United States indicates that concentrations are decreasing. Overall average concentrations for the East (45.8±24.6ng/gdw), Gulf (42.4±21.1ng/gdw), and West (90.9±43.3ng/gdw) coasts are declining with an environmental half-life between 10 and 14years and are predicted to decrease below 10% of today’s concentrations by 2050. Geographically, areas with high and low levels are well identified. Bivalves yielding the highest concentrations were collected in areas linked to areas of DDT production or heavy usage. These areas are clustered in the southern California and San Francisco area, on the West coast; Delaware and Hudson/Raritan Estuary, on the East coast; and in Alabama and northwestern Florida, on the Gulf of Mexico. Statistically significant decreasing trends in ΣDDT concentrations are apparent at most of these locations.
Show more [+] Less [-]Late Holocene evolution and increasing pollution in Guanabara Bay, Rio de Janeiro, SE Brazil Full text
2014
Vilela, Claudia Gutterres | Figueira, Brígida Orioli | Macedo, Mariana Cardoso | Baptista Neto, José Antonio
To detect changes during the Late Holocene and historical periods in Guanabara Bay, the paleoecological and ecological parameters from nine cores were analysed using foraminiferal assemblages and bioindicators. Using radiocarbon dates and sedimentation rates in the cores, it was possible to detect the first Europeans’ arrival in the 16th century. Foraminiferal bioindicators of organic matter and human pollution were correlated with radiocarbon dates from the bottom and middle of the cores in each region and revealed an increase in pollution along the cores. The foraminiferal results were compared with total organic carbon (TOC) values before, during and after European settlement and showed a historical increase in organic matter.Pristine mangrove ecosystems are characterised by agglutinated species such as Ammotium salsum, and the presence of this organism also confirmed the extent of historical mangrove forests. Ammonia tepida, Buliminella elegantissima and Elphidium excavatum were the dominant species, but they presented distinct patterns over time. B. elegantissima was dominant before the European influence in older sediments with high organic matter content that were found at deeper intervals. A. tepida is dominant in younger sediments at upper intervals, as a bioindicator of human pollution.
Show more [+] Less [-]Uptake of PCBs contained in marine sediments by the green macroalga Ulva rigida Full text
2014
The uptake of PCBs contained in marine sediments by the green macroalga Ulva rigida was investigated in both laboratory and field experiments. Under laboratory conditions, total PCBs (tPCBs) uptake was significantly greater in live vs dead plants. The concentration of tPCB taken up in live plants was greatest in the first 24h (1580μgkg−1 dry weight), and then increased at a lower rate from day 2 to 14. Dead plants had a significantly lower tPCB concentration after 24h (609μgkg−1 dry weight) and lower uptake rate through day 14. Lesser chlorinated PCB congeners (below 123) made up the majority of PCBs taken up. Congener composition in both laboratory and field experiments was correlated to congener logKow value and sediment content. Field experiments showed that Ulva plants could concentrate PCBs to 3.9mgkg−1 in 24h. Thus, U. rigida is capable of removing PCBs in sediments at a rapid rate.
Show more [+] Less [-]