Geochemical evidences of the anthropogenic alteration of trace metal composition of the sediments of Chiricahueto marsh (SE Gulf of California)

Seven sediment cores (60-80 cm) were collected at Chiricahueto marsh, a salt marsh influenced by agrochemical, domestic and industrial effluents. The concentrations of Ag, Al, Cd, Co, Cu, Fe, Li, Mn, Pb, V and Zn were studied in the solid phase at each 1-cm section. The profiles of Ag, Cd, Cu, Mn, Ni, Pb and Zn showed a slight recent pollution in the site with enrichment and anthropogenic factors higher than unity; and correlation analysis indicated a direct association with organic carbon. Al, Co, Cr, Fe, Li, and V concentration profiles displayed a negative correlation with organic C and positive with mud content and no consistent enrichment at surface. Based on the principal component analysis and correlation analysis, two principal groups of metals were identified. The first group includes Al, Co, Cr, Fe and Li, that are derived predominantly from the weathering of parent materials in the local bedrock; and the second group include most of the metals, which were relatively enriched at surficial sediments, that are produced mainly by anthropogenic activities such as agriculture (Cd, Cu and Zn), sewage effluents (Ag, Cd, Cu, Ni, Pb and Zn) and in lesser extent atmospheric deposition (Cd and Pb).     

Zingiberene and curcumene in wild tomato

Composition of ginger oil prepared from fresh ginger rhizomes, Zingiber officinale Roscoe (Zingiberaceae) was determined by gas chromatography (GC) and GC-mass spectrometric techniques. The main sesquiterpene hydrocarbons identified were alpha-zingiberene (27-30%), alpha-curcumene (8-9%), beta-sesquiphellandrene (4.8%). and bisabolene (3.2%). The function of zingiberene and curcumene as insecticides, repellents, and insect feeding deterrents has been previously reported. Other plant species having similar constituents might be found. Leaves of six wild tomato accessions of Lycopersicon hirsutum f. glabratum (Mull); three accessions of L. hirsutum f. typicum (Humb & Bonpl.); two accessions of L. pennellii Corr. (D'Arcy); one accession of L. pimpinellifolium; and one commercial tomato L. esculentumm cv. Fabulous were analyzed. Analysis of L. hirsutum f. typicum (Solanaceae) accessions indicated the presence of zingiberene, curcumene, and other lipophilic secondary metabolites in the leaves of two accessions (PI-127826 and PI-127827). An average three month old wild tomato plant of accessions PI-127826 and PI-127827 provided 1.93 and 1.30 kg fresh leaves (averaging about 38,307 and 28,130 cm2 exposed leaf surface area, respectively) and produced 19.3 and 10.1 g of zingiberene and curcumene (PI-127826) and 17.2 and 1.8 g of zingiberene and curcumene (PI-127827), respectively. Leaf extracts of the wild tomato L. hirsutum f. typicum (accessions PI-127826 and PI-127827) can be used as a biorational source of zingiberene and curcumene.     

Boreal bog plants: nitrogen sources and uptake of recently deposited nitrogen

The main goals of this study were to determine the delta15N signature of quantitatively important boreal bog plants as basis for discussing their N sources, and to assess the effects of five different 3 year N treatments (i.e. 0, 5, 10, 20 and 40 kg N ha(-1) year(-1)) on the bog plants and surface peat at different depths (i.e. 0, 5, 10, 20 and 40 cm) by using 15N as tracer. Plants and peat were analyzed for N concentration, 15N natural abundance and 15N at.%. From the results we draw three main conclusions: First, the relative importance of different N sources is species-specific among bog plants. Second, an annual addition of 5 kg N ha(-1) year(-1) was sufficient to significantly increase the N concentration in Sphagnum mosses, liverworts and shallow rooted vascular plants, and an annual addition of 40 kg N ha(-1) year(-1) during 3 years was not sufficient to increase the N concentration in deep rooted plants, although the 15N content increased continuously, indicating a possible longer term effect. Third, an annual addition of 40 kg N ha(-1) year(-1) during 3 years increased the N content in surface peat at depths of 5 and 10 cm, but not at depths of 20 and 40 cm, indicating the capacity of the living Sphagnum mosses and the surface peat to take up deposited N, and thereby function as a filter.     

Removal of heavy metals from a metaliferous water solution by Typha latifolia plants and sewage sludge compost

Typha latifolia plants, commonly known as cattails, were grown in a mixture of mature sewage sludge compost, commercial compost and perlite (2:1:1 by volume). Four Groups (A, B, C and D) were irrigated (once every two weeks) with a solution containing different concentrations of Cu, Ni, and Zn, where in the fifth (group M) tap water was used. At the end of the 10 weeks experimental period substrate and plants were dried, weighed and analysed for heavy metals. The amounts of all three metals removed from the irrigation solution, were substantial. In the roots and leaves/stems of T. latifolia the mean concentration of Zn reached values of 391.7 and 60.8 mg/kg of dry weight (d.w.), respectively. In the substrate of Group D all three metals recorded their highest mean concentrations of 1156.7 mg/kg d.w. for Cu, 296.7 mg/kg d.w. for Ni and 1231.7 mg/kg d.w. for Zn. Linear correlation analyses suggested that there was a linear relationship between the concentration of metals in the solutions and the concentration of metals in the substrates at the end of the experiment. The percentage removal of the metals in the substrate was large, reaching 100% for Cu and Zn in some groups and almost 96% for Ni in group D. The total amount of metals removed by the plants was considerably smaller than that of the substrate, due mainly to the small biomass development. A single factor ANOVA test (5% level) indicated that the build up in the concentration of metals in the roots and the leaves/stems was due to the use of metaliferous water solution and not from the metals pre-existing in the substrate. The contribution of the plants (both roots and leaves/stems) in the removing ability of the system was less than 1%.     

Optimizing electron spin resonance detection of hydroxyl radical in water

The parameters affecting the electron spin resonance (ESR) detection of hydroxyl free radical in water are studied and optimized. The hydroxyl radical is generated by the Fenton reaction with iron (II) ammonium sulfate and hydrogen peroxide reacting in a phosphate buffer using N-tert-butyl-alpha-phenylnitron as the spin trap. The concentrations of Fe²⁺, H₂O₂, and phosphate buffer are the parameters studied. The Taguchi method and the orthogonal experiment design were used to evaluate the effects of these parameters on the ESR signal intensity. By the analysis of the signal-to-noise ratio and the analysis of variance, the order of importance of the various parameters on the hydroxyl radical formation is determined for optimal ESR detection of hydroxyl radical. The results will help the development of water purification technologies using hydroxyl free radical as a green oxidant.     

Effects of EDTA and low molecular weight organic acids on soil solution properties of a heavy metal polluted soil

A pot experiment was conducted to study the effects of EDTA and low molecular weight organic acids (LMWOA) on the pH, total organic carbon (TOC) and heavy metals in the soil solution in the rhizosphere of Brassica juncea grown in a paddy soil contaminated with Cu, Zn, Pb and Cd. The results show that EDTA and LMWOA have no effect on the soil solution pH. EDTA addition significantly increased the TOC concentrations in the soil solution. The TOC concentrations in treatments with EDTA were significantly higher than those in treatments with LMWOA. Adding 3 mmol kg(-1) EDTA to the soil markedly increased the total concentrations of Cu, Zn, Pb and Cd in the soil solution. Compared to EDTA, LMWOA had a very small effect on the metal concentrations. Total concentrations in the soil solution followed the sequence: EDTA > citric acid (CA) approximately oxalic acid (OA) approximately malic acid (MA) for Cu and Pb; EDTA > MA > CA approximately OA for Zn; and EDTA > MA > CA > OA for Cd. The labile concentrations of Cu, Zn, Pb and Cd showed similar trends to the total concentrations.     

Spatial distribution of heavy metals in urban soils of Naples city (Italy)

Concentrations of surface and sub-surface soil Cu, Cr, Pb and Zn in the Naples city urban area were measured in 1999. Contourmaps were constructed to describe the metals spatial distribution. In the most contaminated soil samples, metals were speciated by means of the European Commission sequential extraction procedure. At twelve sites, Cu, Pb and Zn levels in soil were compared with those from a 1974 sampling. Many surface soils from the urban area as well as from the eastern industrial district contained levels of Cu, Pb and Zn that largely exceeded the limits (120, 100 and 150 mg kg(-l) for Cu, Pb and Zn, respectively) set for soils of public, residential and private areas by the Italian Ministry of Environment. Chromium values were never above regulatory limits(120 mg kg(-1)). Copper apparently accumulates in soils contiguous to railway lines and tramway. Cu and Cr existed in soil mainly inorganic forms (-68%), whereas Pb occurs essentially as residual mineral phases (77%). The considerable presence of Zn in the soluble, exchangeable and carbonate bound fraction (23%) suggests this element has high potential bioavailability and leachability through the soil. Concentrations of Cu, Pb and Zn have greatly increased since the 1974 sampling, with higher accumulation in soils from roadside fields.     

Effects of fenoxycarb exposure on complete larval development of the xanthid crab,Rhithropanopeus harrisii

Pest control agents, such as juvenile hormone analogues (JHA), have been developed to limit effects on non-target organisms that co-inhabit insect pest habitats. Rhithropanopeus harrisii, an estuarine xanthid crab, was used to observe the impacts of the JHA, fenoxycarb, on the pattern of complete larval development as well as survival of larvae and successful metamorphosis to first crab stage. Significant mortality occurred in the first of four zoeal stages (after 2-3 days of exposure) at the highest treatment of 240 microg fenoxycarb/l and in megalopae exposed to 48 microg fenoxycarb/l. The time required to metamorphose to the first crab stage was significantly increased for megalopae in all treatments 48 microg/l. This delay in development was sufficient to significantly prolong the entire developmental period from zoea to crabs. Unexposed larvae developed to crabs in an average of 16 days; larvae exposed to >/=48 microg/l required 19-20 days. Reduced survival and extended duration of developing larval stages in the life history of a benthic invertebrate may alter the population dynamics of these organisms in the estuary.     

Trace elements and microbiological parameters in farmed Nile tilapia with emphasis on muscle,water, sediment and feed

Fish may bioaccumulate contaminants from the aquatic environment and extend them to the food chain provoking risks to human health. This study evaluated the microbiological parameters of the pond´s water and trace elements concentrations in samples of water, sediment, feed and muscle of farmed Nile tilapia used for human consumption in southern Brazil. A total of 240 fish were collected from 12 tilapia farms. Sediment, tank water and dry ration used in the animals' diet were collected for analysis. Analysis were performed by Energy Dispersion X-ray Fluorescence (EDXRF), Inductively Coupled Plasma Mass Spectrometer (ICP-MS), Induced Coupled Plasma Optical Emission Spectrometer (ICP-OES), and Atomic Absorption Spectrometer (AAS-VGA). In addition, the microbiological analysis of the water was carried out. The concentrations of Se, I, Fe, Cu and Zn in fish muscle were higher than the recommended by the Brazilian legislation, considering the advised daily intake for adults. The arsenic element had concentrations above the limit stipulated by the present Brazilian legislation, observed in all samples of muscle, sediment and tank water highlighting a possible environmental and fish contamination by the toxic element. Moreover, the arsenic concentration in the water presented a positive correlation (ρ?=?0.33) with arsenic in the muscle, suggesting that tilapia is a good environmental bioindicator, once they properly reflect the levels of arsenic in the water. It is suggested to perform an arsenic speciation for quantification of the inorganic form and accurate assessment of the degree of toxicity in the muscle samples and risks it can bring to human health. Regarding the other potentially toxic elements (Hg, Pb and Cd), and microbiological analysis of water it was verified that the consumption of the fish in question does not raise risks, since the values are within a quality benchmark established by law. The concentration of total and fecal coliforms in pond´s water in the facilities was in agreement with the microbiological indexes required by the legislation of CONAMA class II. Western region presented the lowest concentrations of fecal coliforms when compared to the other regions. There was no significant difference in the microbiological counts of total heterotrophic bacteria, Vibrio spp. and Pseudomonas spp. among the regions.     

Recent spatial gradients and time trends in Dhaka,Bangladesh, air pollution and their human health implications

Dhaka, the capital of Bangladesh, is among the most polluted cities in the world. This research evaluates seasonal patterns, day-of-week patterns, spatial gradients, and trends in PM_2.5 (<2.5 µm in aerodynamic diameter), PM₁₀ (<10 µm in aerodynamic diameter), and gaseous pollutants concentrations (SO₂, NO₂, CO, and O₃) monitored in Dhaka from 2013 to 2017. It expands on past work by considering multiple monitoring sites and air pollutants. Except for ozone, the average concentrations of these pollutants showed strong seasonal variation, with maximum during winter and minimum during monsoon, with the pollution concentration of PM_2.5 and PM₁₀ being roughly five- to sixfold higher during winter versus monsoon. Our comparisons of the pollutant concentrations with Bangladesh NAAQS and U.S. NAAQS limits analysis indicate particulate matter (PM_2.5 and PM₁₀) as the air pollutants of greatest concern, as they frequently exceeded the Bangladesh NAAQS and U.S. NAAQS, especially during nonmonsoon time. In contrast, gaseous pollutants reported far fewer exceedances throughout the study period. During the study period, the highest number of exceedances of NAAQS limits in Dhaka City (Darus-Salam site) were found for PM_2.5 (72% of total study days), followed by PM₁₀ (40% of total study days), O₃ (1.7% of total study days), SO₂ (0.38% of total study days), and CO (0.25% of total study days). The trend analyses results showed statistically significant positive slopes over time for SO₂ (5.6 ppb yr^?1, 95% confidence interval [CI]: 0.7, 10.5) and CO (0.32 ppm yr^?1, 95% CI: 0.01, 0.56), which suggest increase in brick kilns operation and high-sulfur diesel use. Though statistically nonsignificant annual decreasing slopes for PM_2.5 (?4.6 µg/m³ yr^?1, 95% CI: ?12.7, 3.6) and PM₁₀ (?2.7 µg/m³ yr^?1, 95% CI: ?7.9, 2.5) were observed during this study period, the PM_2.5 concentration is still too high (~ 82.0 µg/m³) and can cause severe impact on human health.

Implications: This study revealed key insights into air quality challenges across Dhaka, Bangladesh, indicating particulate matter (PM) as Dhaka’s most serious air pollutant threat to human health. The results of these analyses indicate that there is a need for immediate further investigations, and action based on those investigations, including the conduct local epidemiological PM exposure-human health effects studies for this city, in order to determine the most public health effective interventions.