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1.
Liu J Yan C Macnair MR Hu J Li Y 《Environmental science and pollution research international》2007,14(5):345-349
Background Acid-volatile sulfide (AVS) is operationally defined as sulfides in sediment, which are soluble in cold acid, and is reported
as the most active part of the total sulfur in aquatic sediments. It is a key partitioning phase controlling the activities
of divalent cationic heavy metals in sediment.
Methods In order to examine this in mangrove environments, six sites were selected along the Jiulong River Estuary in Fujian, China,
which had previously been reported to be polluted by heavy metals. Sediments were sampled from 0–60 cm depth at each site,
and the spatial distribution of AVS and SEM (simultaneously extracted metals: copper, cadmium, zinc, and lead) were determined.
Results and Discussion The results indicate that the AVS concentrations had a spatial variation, ranging from 0.24 to 16.10 μmol g−1 sediment dry weight. The AVS concentration in the surface layer is lower than that of the deeper sediment, with peak values
in the 15–30 cm horizon. There was no correlation between the AVS value and organic matter content or total dissolved salts,
but a significant positive correlation of AVS with surface sediment (0–5 cm) moisture content was found. This indicates that
water logged sediments tend to have a high AVS value. The amount of SEM was within the range of 0.33–2.80 μmol g−1 sediment dry weight and decreased with sediment depth.
Conclusions There was a marked variation in AVS and SEM among different sites studied. AVS concentrations were generally lower in the
surface sediments, while SEM concentrations slightly decreased with the depth. Higher concentrations of SEM found in the upper
layers of the sediments confirm the earlier suggestions that this study area may suffer from increasing heavy metal pollution.
Recommendations and Perspectives When monitoring environmental impacts by using AVS, the micro and large-scale spatial variation as well as vertical distribution
need to be estimated to avoid misleading results. Both AVS and SEM concentrations in different sediment layers should be taken
into account in assessing the potential impact of heavy metals on the biotic environment. 相似文献
2.
Hartmut Frank Harald Scholl Dirk Renschen Benoît Rether Abdelkrim Laouedj Yrjö Norokorpi 《Environmental science and pollution research international》1994,1(1):4-14
Haloacetic acids are atmospheric oxidation products of airborne C2-halocarbons which are important solvents and propellants. Levels of trichloroacetate (TCA) in conifer needles from mountain
ranges in Germany (Black Forest, Erzgebirge) and from two sites in Finland are compared; TCA is present in conifer needles
at concentrations up to 0.7 μmol/kg, MCA up to 0.2 μmol/kg. At the Finnish sites, TCA-concentrations and branch degeneration
symptoms of Scots pine are correlated. Monochloroacetate (MCA) has been determined in needle samples from Southern Germany
in concentrations exceeding its phytotoxicity threshold towards photoautotrophic organisms. Data on atmospheric chloroacetate
levels in Germany are also given; ambient air levels of chloroacetic acids range from about 2 pmol/m3 (TCA) to 390 pmol/m3 (MCA). TCA and dichloroacetic acid (DCA) arise from atmospheric oxidation of airborne C2-chlorocarbons, while the source of MCA is not yet known; several tentative pathways are suggested. 相似文献
3.
Edeltrauda Helios Rybicka Michael Jefferson Wilson 《Environmental science and pollution research international》2000,7(1):7-13
The examinations of selected wastes and stream sediments from the vicinity of a chemical plant by sequential extraction procedures
and direct methods, SEM/EDX and XRD, were carried out in order to identify the different forms of chromium, particularly as
they are released to potential mobility. The results show that the top and bottom waste samples contain 37,756 and 53,650
μg g1 Cr, respectively, but about 7% and 2% of the total chromium type Cr(VI). The chemical extraction results show that the mobility
of Cr in the upper part of the waste pile is significantly higher than in the bottom section; the exchangeable form of Cr
accounts for 25% and < 1%, respectively, the last one irrespective of redox conditions. About 50% of Cr is associated with
the reducible fraction of the top waste, and similar with the residual fraction in the bottom waste. Oxidation of the bottom
waste shift some portion of Cr from residual to the moderately reducible fraction. The major Cr-forms in the river sediments
are compounded with Fe-oxides. The < 2 μm size fraction of the selected sediment sample, particular enriched in chromium contained
up to 73,000 μg g1 Cr with about 95% of this in the moderately reducible fraction, predominantly bound with oxyhydroxides. SEM/EDX and XRD analysis
of wastes and river sediment indicate that the main insoluble Cr-phase is ferroan — (Mg, Fe) (Cr, Al)2O4 which would be dissolved mainly in the residual fraction. 相似文献
4.
Permeable reactive barriers (PRBs) are an alternative technology to treat mine drainage containing sulfate and heavy metals. Two column experiments were conducted to assess the suitability of an organic carbon (OC) based reactive mixture and an Fe0-bearing organic carbon (FeOC) based reactive mixture, under controlled groundwater flow conditions. The organic carbon mixture contains about 30% (volume) organic carbon (composted leaf mulch) and 70% (volume) sand and gravel. The Fe0-bearing organic carbon mixture contains 10% (volume) zero-valent iron, 20% (volume) organic carbon, 10% (volume) limestone, and 60% (volume) sand and gravel. Simulated groundwater containing 380 ppm sulfate, 5 ppm As, and 0.5 ppm Sb was passed through the columns at flow rates of 64 (the OC column) and 62 (the FeOC column) ml d− 1, which are equivalent to 0.79 (the OC column) and 0.78 (the FeOC column) pore volumes (PVs) per week or 0.046 m d− 1 for both columns. The OC column showed an initial sulfate reduction rate of 0.4 µmol g (OC)− 1 d− 1 and exhausted its capacity to promote sulfate reduction after 30 PVs, or 9 months of flow. The FeOC column sustained a relatively constant sulfate reduction rate of 0.9 µmol g (OC)− 1 d− 1 for at least 65 PVs (17 months). In the FeOC column, the δ34S values increase with the decreasing sulfate concentration. The δ34S fractionation follows a Rayleigh fractionation model with an enrichment factor of 21.6‰. The performance decline of the OC column was caused by the depletion of substrate or electron donor. The cathodic production of H2 by anaerobic corrosion of Fe probably sustained a higher level of SRB activity in the FeOC column. These results suggest that zero-valent iron can be used to provide an electron donor in sulfate reducing PRBs. A sharp increase in the δ13C value of the dissolved inorganic carbon and a decrease in the concentration of HCO3− indicate that hydrogenotrophic methanogenesis is occurring in the first 15 cm of the FeOC column. 相似文献
5.
The paper presents the application of the hyphenated technique - high-performance liquid chromatography with atomic absorption spectrometry detection with hydride generation (HPLC-HG-AAS) - in the determinations of inorganic forms of arsenic: As(III) and As(V) in the exchangeable fraction of flood deposits. The separation of analytical signals of the determined arsenic forms was obtained using an ion-exchange column in a chromatographic system with the atomic absorption spectrometer as a detector, at the determination limits of 5 ng g−1 for As(III) and 10 ng g−1 for As(V). Flood deposits were collected after big flood event in valley of the Warta river which took place in summer 2010. Samples of overbank deposits were taken in Poznań agglomeration and vicinity (NW Poland). The results of determinations of arsenic forms in the exchangeable fraction of flood deposits allowed indication of a hypothetical path of deposits migration transported by a river during flood and environmental threats posed by their deposition by flood. 相似文献
6.
7.
Robin D. Calfee Edward E. Little Laverne Cleveland Mace G. Barron 《Environmental science and pollution research international》1999,6(4):207-212
Traditionally, the toxic effects of petroleum have been investigated by conducting studies in the absence of ultraviolet radiation
(UV). Photomediated toxicity is often not considered, and the toxic effects of an oil spill can be grossly underestimated.
The toxicity of a weathered oil collected from a monitoring well at an abandoned oil field toCeriodaphnia dubia was examined in the presence of UV. A solar simulator equipped with UVB, UVA, and cool white lamps was used to generate environmentally
comparable solar radiation intensities.C. dubia were exposed to six concentrations of water accommodated fractions (WAF) of weathered oil in conjunction with three levels
of laboratory simulated UV (Reference = < 0.002 μW/cm2UVB; 3.0 μW/cm2 UVA; Low = 0.30 μW/cm2 UVB; 75.0 μW/cm2 UVA; High = 2.0 μW/cm2 UVB; 340.0 μW/cm2 UVA) and visible light. Seven day static renewal bioassays were used to characterize WAF/UV toxicity. WAF toxicity significantly
(p < 0.05) increased when the organisms were exposed to WAF in the presence of UV. The photoenhanced toxicity of the WAF increased
with WAF concentration within each UV regime. Relative to the reference light regime, the average number of neonates from
adults exposed to 1.6 mg TPH/L decreased significantly by 20% within the low light regime, and by 60% within the high light
regime. These results indicate that organisms exposed to dissolved-phase weathered oil in the presence of environmentally
realistic solar radiation, exhibit 1.3–2.5 times greater sensitivity, relative to organisms exposed under traditional laboratory
fluorescent lighting. 相似文献
8.
Mature Lumbricus terrestris were host soils and leaf litter were collected from a former arsenic mine in Devon, UK (Devon Great Consols), a former gold mine in Ontario, Canada (Deloro), and an uncontaminated residential garden in Nottingham, UK. Arsenic concentrations determined by inductively coupled plasma-mass spectrometry (ICP-MS) in soils were 16-348 mg kg−1, 6.0-239 mg kg−1 in the earthworms and 8.6 mg kg−1 in leaf litter sampled at Deloro (all dry weight). High performance liquid chromatography (HPLC-ICP-MS) analysis revealed arsenite (AsIII), arsenate (AsV) and five organoarsenic species; arsenobetaine (AB), methylarsonate (MAV), dimethylarsinate (DMAV), arsenosugar 1 (glycerol sugar), arsenosugar 2 (phosphate sugar), and trimethylarsineoxide (TMAO) in field-collected L. terrestris. Differences were observed in the variety of organoarsenic species present between field sites. Several organoarsenic species were observed in the leaf litter (DMAV, arsenosugar 2 and TMAO) but not AB. Depuration resulted in higher concentrations of inorganic As being detected in the earthworm whereas the concentration or variety of organoarsenic species was unchanged. Commercially sourced L. terrestris were exposed to As contaminated soil in laboratory mesocosms (1.0, 98, 183, 236, 324 and 436 mg kg−1) without leaf litter and were additionally analyzed using X-ray absorption near edge structure (XANES). Only inorganic AsIII and AsV was observed. It is proposed that ingestion of leaf litter and symbiotic processes in the natural soil environment are likely sources of organoarsenic compounds in field-collected L. terrestris. 相似文献
9.
Kurunthachalam Senthilkumar Carolyn A. Duda Daniel L. Villeneuve Kurunthachalam Kannan Jerzy Falandysz John P. Giesy 《Environmental science and pollution research international》1999,6(4):200-206
Concentrations of mono- (MBT), di- (DBT), and tri-(TBT) butyltin compounds were measured in eggs, liver, and muscle of nine
species of fish from four regions of the Baltic Sea - the Firth of Vistula, the Gulf of Gdańsk, Puck Bay, and the mouth of
the Vistula River. The overall concentration ranges among all the fish sampled from the four sites were: < 7 to 79 ng/g for
MBT, 6 to 1100 ng/g for DBT, 7 to 3600 ng/g for TBT, and 16 to 4800 ng/g for total BTs, on a wet wt basis. The highest concentration
of total BTs was found in herring liver from the Firth of Vistula (4800 ng/g, wet wt) and in roach muscle from Puck Bay (3300
ng/g, wet wt), while the least concentration was found in burbot eggs and liver from the Vistula River (39 and 32 ng/g, wet
wt, respectively). TBT was the major form of BTs present in most samples analyzed. Sediment samples collected from shipyards
in the Gulf of Gdańsk contained butyltin concentrations ranging from 1.2 to 46 μg/g (dry wt) for MBT, 2.0 to 42 μg/g for DBT,
and 2.6 to 40 μg/g for TBT. As with the fish, the majority of the BTs in sediment were present as TBT, which suggested recent
exposure of the aquatic environment of the region to TBT. 相似文献
10.
Chemically chlorinated organic matter as well as natural background humic acids contain significant amounts of organically bound halogens that must be determined for assessment of environmental pollution. In this work the use of ion chromatography (IC) and inductively coupled plasma mass spectrometry (ICP-MS) is proposed for the determination of total organic Cl, Br and I concentration in humic acids extracted from various forest soil horizons after a single digestion by microwave-induced combustion (MIC). Samples were pressed as pellets and combusted using 20 bar of oxygen and ammonium nitrate solution as igniter. Analytes were absorbed in diluted alkaline solution (50 mM (NH4)2CO3) and a reflux step was applied after combustion to improve analyte recoveries (5 min, microwave power of 1400 W). The accuracy was evaluated using certified reference materials (CRM) and spiked samples. Using MIC the agreement with CRM values and spike recoveries was higher than 97% for all analytes. As an advantage over conventional procedures, using MIC it was possible to digest up to eight samples in only 25 min, obtaining a single solution suitable for all halogens determination in humic acids samples by different techniques (IC and ICP-MS). The limit of detection (3σ) for Cl, Br and I obtained by IC was 1.2, 2.5 and 4.3 μg g−1 and by ICP-MS it was 1.4, 0.03 and 0.002 μg g−1, respectively. 相似文献
11.
A wide range of fluorinated alkyl compounds (FACs) has been reported in wildlife in various locations in the world. However, such information regarding Japanese wildlife is rarely found. In the present study, we investigated the occurrence of 21 FACs, including perfluorinated alkyl sulfonates (PFASs), perfluorinated carboxylates (PFCAs), and fluorotelomer acids, in the livers of 10 wild bird species from two regions in northern Japan. To avoid interferences, FACs were quantified by a recently developed method using acetonitrile and solid-phase extraction followed by an ion exchange HPLC column separation. Apart from perfluorooctane sulfonate (PFOS), which was found at the highest levels of all the compounds detected, several long chain perfluorinated carboxylates (PFCAs) from C8 to C16, particularly perfluorotetradecanoic acid (PFTeDA) and perfluorohexadecanoic acid (PFHxDA), were detected for the first time. Additionally, 7:3 FTCA, a fluorotelomer acid, was also detected in most swan livers from Miyagi prefecture and all the birds from Tochigi prefecture. However, none of the sulfonamides and unsaturated telomer acids were detected in any species. Swans seem to be the least exposed wild birds to FACs among the investigated birds, signifying that feeding habits may reflect FAC accumulation in wild birds. The highest total concentration of detected FACs was 405 ng g−1 wet wt., which was found in a Japanese sparrowhawk, indicating that the top predatory wild birds can accumulate several long chain carboxylic acids. However, the current FAC concentrations found in livers may suggest that these compounds alone would not cause a severe toxic effect in these species. 相似文献
12.
Martin Pichler Georg Guggenberger Robert Hartmann Wolfgang Zech 《Environmental science and pollution research international》1996,3(1):24-31
The behavior of 20 PAH in the organic layers of a L mull, an Of mull and a mor was assessed by a combined approach of a soil
profile study, and the analysis of particle-size separates. Increasing PAH concentrations with depth in the mor profile (L,
866 μg kg−3; Of, 2902 μg kg−1; Oh, 10489 ug kg−1) were assigned to selective enrichment during organic matter decomposition. PAH were further highly enriched within the finer
separates. For the L horizons, significant positive correlations were established between the enrichment of individual PAH
(as observed from the decomposition gradient between the >2-mm fraction and the < 0.05-mm fraction), and the KOW for each compound. The slope of the regression line, m, described the degree of differentiation between low- and high-molecular
PAH during litter decomposition. Since m was greatest in the most biologically active humus type (L mull, 0.33) and smallest
in the most inactive (mor, 0.20), microbial breakdown was assumed as the dominating process for this differentiation. The
results also indicated that decomposition processes had already taken place in the L horizons, leading to morphological and
chemical changes of organic matter, and to an enrichment of high molecular PAH. 相似文献
13.
Lovreglio P D'Errico MN Gilberti ME Drago I Basso A Apostoli P Soleo L 《Chemosphere》2012,86(9):898-905
To study the effect of eating foods with a high arsenic (As) content on the intra and inter-individual variability of urinary concentrations of the As species, daily urine samples were collected for 10 consecutive days from 12 healthy male subjects. A daily food diary was kept throughout the study period. Personal exposure to airborne As was measured once during the study. As3, As5, monomethylarsonic acid (MMA), dimethylarsinic acid (DMA) and arsenobetaine were determined in all urine samples by inductive coupled plasma mass spectrometry, and the sum of As3 + As5 + MMA + DMA (iAs) by hydride generation-atomic absorption spectrophotometry. Exposure to airborne As was below the limit of detection in all samplings. As3 was found in only 19.2% and As5 in only 3.3% of the urine samples, whereas high urinary concentrations of arsenobetaine were observed. With the exception of arsenobetaine, expressed as a percentage, a significant inter-individual variability was observed for all species of As, for iAs and for the MMA/DMA ratio (p < 0.001). Instead, the intra-individual variability was significant only for the MMA/DMA ratio (p < 0.001). Among foods with a high As content, only a heavy consumption of seafood was shown to influence inter-individual variability of DMA%, arsenobetaine expressed as μg g−1 creatinine and iAs. In conclusion, even in populations with a high intake of organic As through foods, the finding of a significant inter-individual but no significant intra-individual variability of urinary species confirms the usefulness of urinary As speciation for biological monitoring of exposure to As. 相似文献
14.
Abdol-Samad Abedi Esmat Nasseri Fatemeh Esfarjani Fatemeh Mohammadi-Nasrabadi Motahareh Hashemi Moosavi Hedayat Hoseini 《Environmental science and pollution research international》2020,27(10):10147-10159
The aim of the current research was to systematically review and summarize the studies that evaluated the concentration of lead (Pb) and cadmium (Cd) in cow milk in different regions of Iran and to perform a meta-analysis of the findings. Moreover, the non-carcinogenic and carcinogenic risks of Pb and Cd through milk consumption in adult and child consumers were assessed. As a result of a systematic search in the international and national databases between January 2008 and October 2018, 17 reports involving 1874 samples were incorporated in our study for meta-analysis. The pooled concentrations of Pb and Cd were estimated to be 13.95 μg mL−1 (95% CI 9.72–18.11 μg mL−1) and 3.55 μg mL−1 (95% CI − 2.38–9.48 μg mL−1), respectively, which were lower than the WHO/FAO and national standard limits. The estimated weekly intake (EWI) of Pb and Cd through consuming milk was 16.65 and 7 μg day−1 for adults of 70 kg and 45 and 34 μg day−1 for children of 26 kg, respectively, which was well below the risk values set by Joint FAO/WHO Expert Committee on Food Additives (JECFA). The maximum target hazard quotient values (THQs) of Pb and Cd were 5.55E−5 and 5.55E−5 for adults and 5.55E−5 and 5.55E−5 for children, respectively, which were lower than 1 value, suggesting that Iranian consumers are not exposed to non-carcinogenic risk through consuming milk. Moreover, the incremental lifetime cancer risk (ILCR) of Pb estimated to be 2.96E−04 in adults and 1.0E−03 in children, indicating that consumers in Iran are at threshold carcinogenic risk of Pb through consuming milk (ILCR > 10−4). Therefore, planning and policy making for the sustainable reduction of these toxic metals in milk, particularly in industrial regions of Iran, are crucial. 相似文献
15.
do A Kehrig H Seixas TG Palermo EA Baêta AP Castelo-Branco CW Malm O Moreira I 《Environmental science and pollution research international》2009,16(1):10-24
Background, aim, and scope Selenium (Se) has been shown to reduce mercury (Hg) bioavailability and trophic transfer in aquatic ecosystems. The study
of methylmercury (MeHg) and Se bioaccumulation by plankton is therefore of great significance in order to obtain a better
understanding of the estuarine processes concerning Hg and Se accumulation and biomagnification throughout the food web. In
the western South Atlantic, few studies have documented trace element and MeHg in fish tissues. No previous study about trace
elements and MeHg in plankton has been conducted concerning tropical marine food webs. Se, Hg, and MeHg were determined in
two size classes of plankton, microplankton (70–290 μm) and mesoplankton (≥290 μm), and also in muscle tissues and livers
of four fish species of different trophic levels (Mugil liza, a planktivorous fish; Bagre spp., an omnivorous fish; Micropogonias furnieri, a benthic carnivorous fish; and Centropomus undecimalis, a pelagic carnivorous fish) from a polluted estuary in the Brazilian Southeast coast, Guanabara Bay. Biological and ecological
factors such as body length, feeding habits, and trophic transfer were considered in order to outline the relationships between
these two elements. The differences in trace element levels among the different trophic levels were investigated.
Materials and methods Fish were collected from July 2004 to August 2005 at Guanabara Bay. Plankton was collected from six locations within the bay
in August 2005. Total mercury (THg) was determined by cold vapor atomic absorption spectrometry (CV-AAS) with sodium borohydride
as a reducing agent. MeHg analysis was conducted by digesting samples with an alcoholic potassium hydroxide solution followed
by dithizone-toluene extraction. MeHg was then identified and quantified in the toluene layer by gas chromatography with an
electron capture detector (GC-ECD). Se was determined by AAS using graphite tube with Pin platform and Zeeman background correction.
Results and discussion Total mercury, MeHg, and Se increased with plankton size class. THg and Se values were below 2.0 and 4.8 μg g−1 dry wt in microplankton and mesoplankton, respectively. A large excess of molar concentrations of Se in relation to THg was
observed in both plankton size class and both fish tissues. Plankton presented the lowest concentrations of this element.
In fish, the liver showed the highest THg and Se concentrations. THg and Se in muscle were higher in Centropomus undecimalis (3.4 and 25.5 nmol g−1) than in Micropogonias furnieri (2.9 and 15.3 nmol g−1), Bagre spp (1.3 and 3.4 nmol g−1) and Mugil liza (0.3 and 5.1 nmol g−1), respectively. The trophic transfer of THg and Se was observed between trophic levels from prey (considering microplankton
and mesoplankton) to top predator (fish). The top predators in this ecosystem, Centropomus undecimalis and Micropogonias furnieri, presented similar MeHg concentrations in muscles and liver. Microplankton presented lower ratios of methylmercury to total
mercury concentration (MeHg/THg) (34%) than those found in mesoplankton (69%) and in the muscle of planktivorous fish, Mugil liza (56%). The other fish species presented similar MeHg/THg in muscle tissue (of around 100%). M. liza showed lower MeHg/THg in the liver than C. undecimalis (35%), M. furnieri (31%) and Bagre spp. (22%). Significant positive linear relationships were observed between the molar concentrations of THg and Se in the
muscle tissue of M. furnieri and M. liza. These fish species also showed significant inverse linear relationships between hepatic MeHg and Se, suggesting a strong
antagonistic effect of Se on MeHg assimilation and accumulation.
Conclusions Differences found among the concentrations THg, MeHg, and Se in microplankton, mesozooplankton, and fishes were probably related
to the preferred prey and bioavailability of these elements in the marine environment. The increasing concentration of MeHg
and Se at successively higher trophic levels of the food web of Guanabara Bay corresponds to a transfer between trophic levels
from the lower trophic level to the top-level predator, suggesting that MeHg and Se were biomagnified throughout the food
web. Hg and Se were positively correlated with the fish standard length, suggesting that larger and older fish bioaccumulated
more of these trace elements. THg, MeHg, and Se were a function of the plankton size.
Recommendations and perspectives There is a need to assess the role of selenium in mercury accumulation in tropical ecosystems. Without further studies of
the speciation of selenium in livers of fishes from this region, the precise role of this element, if any, cannot be verified
in positively affecting mercury accumulation. Further studies of this element in the study of marine species should include
liver samples containing relatively high concentrations of mercury. A basin-wide survey of selenium in fishes is also recommended. 相似文献
16.
《国际环境与污染杂志》2011,36(4):350-366
Mn in street dust and soil from selected roads was studied to assess the contribution of combustion of vehicular methylcyclopentadienyl manganese tricarbonyl (MMT) to Mn levels and distribution in Pretoria, South Africa. Total Mn concentrations ranged from (329.1-863.9 μg g−1) for dust and (215.8-450.6 μg g−1) for soil. These values were significantly higher than the mean value (278.9 μg g−1) found on soil from a rural environment in Pretoria. The lowest value for the dust sample (329.1 μg g−1) was close to the mean background level of 330 μg g−1 for Mn in soil. Mn distribution in the samples was most in the residual fraction (178.18-487.50 μg g−1) and (140.76-293.40 μg g−1) for dust and soil respectively. Mn in the other fractions were 56.45-202.60 μg g−1 oxides, 90.71-45.34 μg g−1 organic, 45.36-12.65 μg g−1 carbonates and 1.98-6.72 μg g−1 exchangeable for dust and 32.54–167.31 μg g−1 oxides, 34.23–70.45 μg g−1 organic, 10.98-30.45 μg g−1 carbonate and 1.0-4.87 μg g−1 exchangeable for soil. Major source of Mn determined was mainly from the combustion of vehicular MMT. 相似文献
17.
Monica Ferreira Costa Scheyla C. T. Barbosa Mário Barletta David V. Dantas Helena A. Kehrig Tércia G. Seixas Olaf Malm 《Environmental science and pollution research international》2009,16(4):423-430
Background, aim, and scope At tropical latitudes, and especially on the semi-arid coasts of the Brazilian Northeast, the rainfall regime governs the
water quality of estuaries due to the pronounced difference between the rainy and dry seasons. These changes may be responsible
for seasonal changes in bioavailability of mercury (Hg) and other pollutants to the estuarine and coastal biota. Mercury bioaccumulates
along estuarine–marine food chains usually result in higher concentrations in tissues of top predators and posing a risk to
both marine mammals and humans alike. The Goiana River Estuary (7.5° S) is a typical estuary of the semi-arid tropical regions
and supports traditional communities with fisheries (mollusks, fish, and crustacean). It is also responsible for an important
part of the biological production of the adjacent coastal waters.
Materials and methods
Trichiurus lepturus (Actinopterygii: Perciformes) is a pscivorous marine straggler. Fish from this species (n = 104) were captured in a trapping barrier used by the local traditional population and using an otter trawl net along the
main channel of the low estuary during two dry seasons (D1 = November, December 2005, January 2006; D2 = November, December
2006, January 2007) and the end of a rainy season (R = August, September, October 2006). Fish muscle samples were preserved
cold and then freeze-dried prior to analysis of its total mercury (Hg-T) contents. Total mercury was determined by cold vapor
atomic absorption spectrometry (CV-AAS) with sodium borohydride as a reducing agent.
Results The studied individuals (n = 104) were sub-adult (30–70 cm, 71 ind.) and adult fish (>70 cm, 33 ind.). Weight (W) (204.1 ± 97.9 g, total biomass = 21,229.7 g)
and total length (TL) (63.1 ± 10.1 cm, range 29.5–89.0 cm) presented a significant (p < 0.05) correlation. Two-way ANOVA (n = 81) showed that TL and W had significant differences (p < 0.05) among seasons, being higher in D1 than in D2 and R, respectively. Moreover, season vs. month interaction were detected
for the variables length and weight. For the variable weight was detected significant difference for the factor month (p < 0.05). It suggests that the fish enter the estuary at the end of the rainy season and increase in length and weight during
the time they spend in the estuary. Fish from this estuary are shown to be fit for human consumption (125.3 ± 61.9 μgHg-T
kg–1 w.wt.; n = 104). Fish mercury contents increased with size and weight. Correlations between TL and Hg-T (r = 0.37286) and between W and Hg-T (r = 0.38212) were significant (p < 0.05). Dryer months showed higher mercury concentrations in fish (D1 773.4 ± 207.5 μgHg-T kg–1 d.wt., n = 27; D2 370.1 ± 78.8 μgHg-T kg–1 d.wt., n = 27; R 331.2 ± 138.5 μgHg-T kg–1 d.wt., n = 27). The variable mercury concentration showed differences in relation to the factor season (p < 0.05), where fish captured during the first dry season showed the highest concentration of mercury. The correlation between
Hg-T and rainfall (Rf) showed a negative correlation (r = –0.56; p < 0.05).
Discussion The main likely source of mercury to this estuary is diffuse continental run off, including urban and industrial effluents.
Since concentration of mercury in fish tissue is negatively correlated to rainfall, but positively correlated with fish length
and weight, it suggests that fish growth in this estuary results in mercury uptake and concentration on the fish tissue. In
the dry season of 2005–2006, when rainfall remained below the historic average, fish bioaccumulated significantly more mercury
than in the dry season 2006–2007, when rainfall was within the predictable historic average. It is suggested that less rainfall,
and consequently less particulate matter and less primary production in the estuary, make mercury more available to the higher
levels of the estuarine food chain. In the case of higher rainfall, when river flow increases and water quality in the estuary
is reduced, mercury probably is quickly exported associated to the particulate matter to the adjacent coastal waters where
it then disperses. This species is a potential routine bioindicator for mercury contamination of the biota, but so far was
used only with a limited number of individuals and contexts.
Conclusions Fish from the Goiana River estuary can still be safely consumed by the local population. However, any further contamination
of this resource might lead to total mercury levels above the recommended limits for pregnant women and small children. The
proposed heavy dependency of total mercury levels in fish on water quality indicates that land use and water quality standards
must be more closely watched in order to guarantee that best possible practices are in place to prevent bioaccumulation of
mercury and its transfer along the food chain. Human interventions and climatic events which affect river water flow are also
playing a role in the mercury cycle at tropical semi-arid estuaries.
Recommendations and perspectives
T. lepturus is largely consumed by coastal populations of tropical and sub-tropical countries all over the world. It is also consumed
by a number of marine mammals over which we have a strong conservation interest. This species is also a link among different
ecosystems along the estuarine ecocline. Therefore, knowledge of its degree of contamination might contribute to public health
issues as well as marine conservation actions. Studies on mercury and other contaminants using this species as bioindicator
(cosmopolitan, readily available) could help elucidating mechanisms through which pollutants are being transferred not only
through the food chain, but also from estuarine–coastal–open waters. In addition, using the same species in marine pollution
studies, especially as part of a mosaic of species, allows for wide range comparisons of marine food chain contamination. 相似文献
18.
Dimitrios Vassiliadis Kostas Kourtidis Olga Poulida 《Environmental science and pollution research international》1998,5(1):7-11
State space models for tropospheric urban ozone prediction are introduced and compared with linear regression models. The
linear and non-linear state space models make accurate short-term predictions of the ozone dynamics. The average prediction
error one hour in advance is 7 μg/m3 and increases logarithmically with time until it reaches 26 μg/m3 after 30 days. For a given sequence of solar radiation inputs, predictions converge exponentially with a time scale of 8
hours, so that the model is insensitive to perturbations of more than 150 μg/m3 O3. The slow increase of the prediction error in addition to the uniqueness of the prediction are encouraging for applications
of state space models in forecasting ozone levels when coupled with a model that predicts total radiation. Since a radiation
prediction model will be more accurate during cloud-free conditions, in addition to the fact that the state space models perform
better during the summer months, state space models are suitable for applications in sunny environments. 相似文献
19.
Long-term (1860–2010) catchment mass balance calculations rely on models and assumptions which are sources of uncertainty
in acidification assessments. In this article, we report on an application of MAGIC to model acidification at the four Swedish
IM forested catchments that have been subject to differing degrees of acidification stress. Uncertainties in the modeled mass
balances were mainly associated with the deposition scenario and assumptions about sulfate adsorption and soil mass. Estimated
base cation (BC) release rates (weathering) varied in a relatively narrow range of 47–62 or 42–47 meq m−2 year−1, depending on assumptions made about soil cation exchange capacity and base saturation. By varying aluminum solubility or
introducing a dynamic weathering feedback that allowed BC release to increase at more acidic pHs, a systematic effect on predicted
changes in acid neutralizing capacity (ΔANC ca. 10–41 μeq l−1) and pH (ca. ΔpH = 0.1–0.6) at all sites was observed. More robust projections of future changes in pH and ANC are dependent
on reducing uncertainties in BC release rates, the timing, and extent of natural acidification through BC uptake by plants,
temporal changes in soil element pools, and fluxes of Al between compartments. 相似文献
20.
Aqueous solubilities of four non-ortho and eight mono-ortho substituted PCBs were determined using a generator-column technique followed by subsequent off-line GC/ECD analysis of the aqueous solutions. The method is based on pumping water through a column containing glass beads coated with the congener being studied and has been used to measure solubilities at room temperature. The method circumvents many of the experimental difficulties encountered with the traditional shake-flask system. Aqueous solubility of 3,3′,4,4′-tetrachlorobiphenyl determined by this procedure is compared with data obtained from the shake-flask method and the computational method. The precision of replicate measurements is better than ±6.5%. Aqueous solubilities determined for 12 congeners ranged from 6.07 × 10−11 to 4.47 × −9 mol/L and generally decreased with molecular weight and increased with degree of ortho-chlorine substitution within a molecular-weight class. 相似文献