PBDEs and PCBs in sediments of the Thi Nai Lagoon (Central Vietnam) and soils from its mainland

Concentration and distribution of PCBs, PCB 11, and PBDEs in both surficial sediment and soil samples, taken from a zone subject to recent accelerated development, were investigated to assess the environmental quality and understand both natural and anthropogenic processes that influence contaminant behaviors. Values of PCB and PBDE are in the lower range of those reported in literature, typical of low impacted coastal zones. This could be due to efficient processes of resuspension and removal. Contaminants in the lagoon showed higher concentrations in sediments from sites close to the city and the outfalls of the industrial area, while soils showed maximum values in the northern samples. In addition, congener patterns and statistical analyses suggest the presence of effective degradation processes, especially for PBDEs, with the exception of the most concentrated samples that may indicate a direct input. PCB 11 is a significant component (up to 18%) in most lagoon sediments. Its presence is strongly associated with fine particles, thus the distribution seems to be driven mainly by the system hydrodynamic and does not trace the sources. Due to evaporation, only flooded agricultural soils show a similar relative abundance of this congener.     

Influence of large-spectrum environmental contamination on the micro-meiobenthic assemblages in harbour sediments of the ligurian sea (W Mediterranean)

The concentration of a large spectrum of environmental contaminants (PCBs, PAHs, pesticides and metals) was assessed in surface sediments of two Ligurian harbours (Sanremo and Alassio, NW Mediterranean Sea, Italy) and their relative impact on micro-meiobenthic assemblages was analysed. Concentration, distribution and relative importance of the different contaminants varied considerably between harbours in relation to the different anthropic activities and contamination sources. Results from Principal Component Analysis indicated that high levels of contaminants were typically correlated with low micro-meiobenthic abundance in the sediment. Heavy metals and the organic enrichment were the main factors affecting the distribution and abundance of the bacterial and meiofaunal assemblages in Alassio harbour, whereas hydrocarbons and pesticides played a major role in Sanremo sediments. Neither the bacteria density nor the meiofauna abundance were dependent on sediment grain size, suggesting that micro-meiobenthic parameters may be under the influence of other variables. Our results suggest that high concentrations of contaminants independently from their source or typology are responsible for the impact observed on micro-meiobenthic assemblages in these harbours.     

Little Egrets (Egretta Garzetta) and Trace-Metal Contamination in Wetlands of China

The rapidly developing Asian countries may face threatening environmental contamination, that however remains largely unassessed. We studied persistent trace elements in three wetlands, Poyang Lake, relatively unpolluted, and Tai Lake, and Pearl River Delta, selected as hotspots of pollution in Central China. We adopted as indicator the Little Egret, a widespread colonial waterbird, and during 1999 and 2000 we collected and analysed the same samples as for a parallel study we conducted in Pakistan, e.g. eggs, body feathers of chicks, prey spontaneously regurgitated by the chicks, and sediments at the areas most used by foraging egrets. The levels of trace-metals at our three study areas were similar, or within the range, of those found in the few other studies for East Asia, with few exceptions. The concentrations of the various elements were below the threshold that may affect the survival or reproduction of the birds, and even the highest concentrations relative to background, i.e. Se in eggs, and Hg in feathers at Pearl Delta, do not pose toxic hazards. In sediments, the levels of trace elements were lower than the critical levels assumed for contaminated soil, except for alarming high levels of As at Poyang. These results do not confirm our expectation, that Poyang was relatively uncontaminated, while Tai and Pearl were polluted. Although trace metal concentration differed significantly among the three study areas, these differences were minor and were not consistent among elements and samples. The bioaccumulation ratios from sediments through prey, feather and egg, were consistent with our previous findings for Pakistan. Only Hg exhibited high bioaccumulation, while Se and Zn had low accumulation, and the other elements no accumulation. This reasserts that feathers of predators such as egrets, may be more sensitive indicators of environmental contamination for the elements subject to bioaccumulation, whereas the sediments or the organisms low in the food chain are better indicators for the other elements.     

Changes in the Biochemical Composition of Tetraselmis Suecia and Isochrysis Galbana During Growth and Decay

The variations of the biochemical composition of Tetraselmis suecica and Isochrysis galbana during growth and decay were determined. the content of chlorophyll a (Chl-a) of the cultures, as expected, slowly degraded into phaeopigments during decay, confirming that chlorophyll measurements do not always provide an accurate estimate of phytoplanktonic biomass and, consequently, may fail if used to measure the food availability of particulate matter for consumers. Measurements of total amounts of proteins, carbohydrates and lipids, related to the nutritional value of particles in terms of caloric content, are shown to provide information on the readily available food for consumers, particularly during the blooms. the protein/carbohydrate, C/N and POC/Chl-a ratios were used to evaluate the differences between these two species during the growth and the decomposition processes. A comparison between experimental and field conditions was undertaken to implement our understanding of the growth and degradation processes of particulate organic matter of phytoplanktonic origin in the sea and its role on natural systems, during and after phytoplankton blooms.     

Pollution historical trends as recorded by sediments at selected sites of the Venice Lagoon

Polychlorinated biphenyls (PCBs), dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs) and hexaclorobenzene (HCB) were determined in three sediment cores of the Venice Lagoon: I1, from the San Giuliano Canal that is likely the main source of pollutants for the study area; E, representing the lagoon sediment of the zone of Campalto; and M3, typical of a salt marsh environment and mostly subject to atmospheric inputs. Maximum concentrations were found in core I1: 25-1858 ngI-TE kg(-1) (PCDD/Fs), 1.7-13 microg kg(-1) (HCB), and 107-717 microg kg(-1) (PCBs) are surficial and peak values, respectively. The lagoon sediment (E), is much less contaminated: 24-47 ngI-TE kg(-1) for PCDD/Fs, 2.3-3.6 microg kg(-1) for HCB, and 56-203 microg kg(-1) for PCBs, whereas M3 shows the lowest values: 1.6-6.0 ngI-TE kg(-1) for PCDD/Fs, 0.3-0.6 microg kg(-1) for HCB, and 7.1-39 microg kg(-1) for PCBs. In any case, the recent trend is toward a decrease of pollutant concentration. The chronology of cores E and M3 is based on both 210Pb and 137Cs activity-depth profiles. The maximum concentrations of PCDD/Fs, HCB, and PCBs correspond to the years 1949, 1980, and 1968, respectively. The homologue profiles of PCDD/Fs confirm that I1 has been subject to an industrial source while the other sites also recorded significant contributions, changing over time, of octachlorinated dioxin from combustion. A comparison of the pollutant inventories, all normalised to 210Pb inventories, suggests that the atmospheric contribution to the contamination of the area of Campalto is low: the upper limits range from 6% (PCDD/Fs) to 17% (HCB).     

Effects of site-specific climatic conditions on the radial growth of the lichen biomonitor <Emphasis Type="Italic">Xanthoria parietina</Emphasis>

The protocols commonly applied in surveys with lichens as biomonitors of airborne trace elements require analyses of samples derived from thalli or parts of thalli grown in the last year before sampling, under the postulation that samples of the same size are of the same age. Unfortunately, the influence of ecological site-specific factors on lichen growth is still largely ignored, so that samples of the same size collected in environmentally and climatically diverse sites might actually differ in age. This work aims at quantifying the influence of climatic conditions on the radial growth rates (RaGRs) of Xanthoria parietina, one of the most popular lichen biomonitors. RaGR was monitored in seven populations distributed along an altitudinal transect of 30 km in the Classical Karst (NE Italy), from 20 to 500 m above sea level. For c. 17 months, lobe growth was measured seasonally with a digital calliper, and site-specific climatic variables were monitored by means of thermo-hygrometric sensors and implemented by meteorological data. Finally, the lobe growth of X. parietina was modelled as a function of 18 environmental variables. Results revealed that thalli of relatively dry sites had significantly lower seasonal RaGR with respect to moister ones. Considering that cumulative precipitations were equally distributed along the transect, it was concluded that RaGR of X. parietina is affected negatively by high air temperatures and positively by high relative humidity. The importance of RaGR variation in lichen bioaccumulation studies is critically discussed.     

Characterization of the bioaerosol in a natural thermal cave and assessment of the risk of transmission of SARS-CoV-2 virus

Environmental Geochemistry and Health - Thermal caves represent an environment characterized by unique chemical/physical properties, often used for treatment and care of musculoskeletal,...     

Residues of organochlorinated pesticides in eggs of water birds from Tai Lake in China

The levels of organochlorine compounds in eggs of water birds from the colony on Tai Lake in China were studied. The eggs were collected in 2000 and belonged to the following species: 65 samples of black-crowned night heron (Nycticorax nycticorax), 36 samples of little egret (Egretta garzetta), 26 samples of cattle egret (Bubulcus ibis) from 13 clutches and 43 samples of Chinese pond heron (Ardeola bacchus) from 17 clutches. Dichlorodiphenyltrichloroethane (DDT) and its derivates (DDE and DDD), hexachlorocyclohexane (HCH) and its isomers (alpha-HCH, beta-HCH, gamma-HCH, delta-HCH), heptachlor, heptachlor epoxide, aldrin, dieldrin, endrin, endrin aldehyde, alpha-endosulfan, beta-endosulfan, and endosulfan sulfate were determined in the laboratory by gas chromatography. The data showed that DDE had the highest levels in all the samples, followed by beta-HCH. The mean levels of DDE among the water bird species were in the order as follows: black-crowned night heron (5464.26 ng/g, dry weight) > Chinese pond heron (2791.12 ng/g, dry weight) > little egret (1979.97 ng/g, dry weight) > cattle egret (660.11 ng/g, dry weight). DDT and its metabolites accounted for 90% of the total organochlorines, except that it was only 73% for cattle egret. The differences of the residue among the bird species were statistically significant and could be attributed to their variations in prey and habitat. Although the DDE burdens in Tai Lake were much lower than 8 microg/g (wet weight) which are thought to have significant adverse effects on black-crowned night herons, they would be expected to increase the risk of adverse effects on survival of chicks of herons and egrets, particularly black-crowned night heron, based on the critical value of 1 microg/g (wet weight) DDE. The burdens of HCHs in this study were higher and the cyclodienes were lower than those found elsewhere.     

Dioxins and furans formation in pilot incineration tests of sewage sludge spiked with organic chlorine

The factors affecting polychlorinated dibenzo-p-dioxins (PCDD) and polychlorinated dibenzofurans (PCDF) formation were studied in sewage sludge incineration tests carried out on a demonstrative plant. The plant includes a circulating fluidised bed furnace (FBF) and a rotary kiln furnace (RKF), operating alternatively. During the tests sewage sludge was spiked with chlorinated hydrocarbons and the operating parameters of the afterburning chamber were varied. PCDD/F were sampled in each test before the bag filter, thus collecting the above contaminants before abatement systems. From the tests it appeared that PCDD/F were always produced in more abundance in the tests carried out by FBF than by RKF. The higher PCDD/F concentrations in the tests by FBF were reached when sewage sludge was spiked with a high dosage of a surrogate organic mixture of chlorinated hydrocarbons and when the afterburning chamber was used only as transit equipment with the burner off. The distribution of the different PCDD/F homologues was compared. P5CDFs were generally the prevalent fraction, with very few exceptions for the tests by RKF at high temperature of the afterburning chamber. As for FBF tests, it was found that the PCDD/F homologue profile depends on the afterburning chamber temperature.     

Cellular damage of plant pathogenic fungi by antifungal compounds produced by Bacillus spp. isolates

The use of microorganisms as biological control agents (BCAs) has become an effective alternative to chemical means of controlling plant pathogens. The antagonistic and inhibitory activity of 71 Bacillus spp. strains, which were isolated from different Mexican sites, were tested against several phytopathogen fungi, Fusarium oxysporum, Fusarium equiseti, Fusarium avenaceum, Bipolaris spp. and Alternaria spp. From the antagonism study, the strain ELI149 showed a marked inhibition of growth against all tested fungi; therefore crude metabolites from this strain were extracted using ethyl acetate and amberlite resin and probed against the same fungi as well as strains of Mucor sp., Penicillium spp. and Paecilomyces spp. The results indicated that amberlite was more suitable for extraction of secondary metabolites with antifungal activity. Finally, observation of cell damage in the tested pathogenic fungi showed marked morphological changes on reproductive structures in all tested fungi indicating that antibiosis was the mechanism of the antagonistic effect. These results suggest that metabolites from the Bacillus strains have a wide spectrum of antibiotic activities, which can be used as biocontrol agents for controlling fungal plant diseases of agricultural importance.