共查询到20条相似文献,搜索用时 31 毫秒
1.
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
2.
Background, aim, and scope The adverse environmental impacts of chlorinated hydrocarbons on the Earth’s ozone layer have focused attention on the effort
to replace these compounds by nonchlorinated substitutes with environmental acceptability. Hydrofluoroethers (HFEs) and fluorinated
alcohols are currently being introduced in many applications for this purpose. Nevertheless, the presence of a great number
of C–F bonds drives to atmospheric long-lived compounds with infrared absorption features. Thus, it is necessary to improve
our knowledge about lifetimes and global warming potentials (GWP) for these compounds in order to get a complete evaluation
of their environmental impact. Tropospheric degradation is expected to be initiated mainly by OH reactions in the gas phase.
Nevertheless, Cl atoms reaction may also be important since rate constants are generally larger than those of OH. In the present
work, we report the results obtained in the study of the reactions of Cl radicals with HFE-7000 (CF 3CF 2CF 2OCH 3) (1) and its isomer CF 3CF 2CF 2CH 2OH (2).
Materials and methods Kinetic rate coefficients with Cl atoms have been measured using the discharge flow tube–mass spectrometric technique at 1 Torr
of total pressure. The reactions of these chlorofluorocarbons (CFCs) substitutes have been studied under pseudo-first-order
kinetic conditions in excess of the fluorinated compounds over Cl atoms. The temperature ranges were 266–333 and 298–353 K
for reactions of HFE-7000 and CF 3CF 2CF 2CH 2OH, respectively.
Results The measured room temperature rate constants were k(Cl+CF 3CF 2CF 2OCH 3) = (1.24 ± 0.28) × 10 −13 cm 3 molecule −1 s −1and k(Cl+CF 3CF 2CF 2CH 2OH) = (8.35 ± 1.63) × 10 −13 cm 3 molecule −1 s −1 (errors are 2 σ + 10% to cover systematic errors). The Arrhenius expression for reaction 1 was k
1(266–333 K) = (6.1 ± 3.8) × 10 −13exp[−(445 ± 186)/ T] cm 3 molecule −1 s −1 and k
2(298–353 K) = (1.9 ± 0.7) × 10 −12exp[−(244 ± 125)/ T] cm 3 molecule −1 s −1 (errors are 2 σ). The reactions are reported to proceed through the abstraction of an H atom to form HCl and the corresponding halo-alkyl
radical. At 298 K and 1 Torr, yields on HCl of 0.95 ± 0.38 and 0.97 ± 0.16 (errors are 2 σ) were obtained for CF 3CF 2CF 2OCH 3 and CF 3CF 2CF 2CH 2OH, respectively.
Discussion The obtained kinetic rate constants are related to the previous data in the literature, showing a good agreement taking into
account the error limits. Comparing the obtained results at room temperature, k
1 and k
2, HFE-7000 is significantly less reactive than its isomer C 3F 7CH 2OH. A similar behavior has been reported for the reactions of other fluorinated alcohols and their isomeric fluorinated ethers
with Cl atoms. Literature data, together with the results reported in this work, show that, for both fluorinated ethers and
alcohols, the kinetic rate constant may be considered as not dependent on the number of –CF 2– in the perfluorinated chain. This result may be useful since it is possible to obtain the required physicochemical properties
for a given application by changing the number of –CF 2– without changes in the atmospheric reactivity. Furthermore, lifetimes estimations for these CFCs substitutes are calculated
and discussed. The average estimated Cl lifetimes are 256 and 38 years for HFE-7000 and C 3H 7CH 2OH, respectively.
Conclusions The studied CFCs’ substitutes are relatively short-lived and OH reaction constitutes their main reactive sink. The average
contribution of Cl reactions to global lifetime is about 2% in both cases. Nevertheless, under local conditions as in the
marine boundary layer, τ
Cl values as low as 2.5 and 0.4 years for HFE-7000 and C 3H 7CH 2OH, respectively, are expected, showing that the contribution of Cl to the atmospheric degradation of these CFCs substitutes
under such conditions may constitute a relevant sink. In the case of CF 3CF 2CF 2OCH 3, significant activation energy has been measured, thus the use of kinetic rate coefficient only at room temperature would
result in underestimations of lifetimes and GWPs.
Recommendations and perspectives The results obtained in this work may be helpful within the database used in the modeling studies of coastal areas. The knowledge
of the atmospheric behavior and the structure–reactivity relationship discussed in this work may also contribute to the development
of new environmentally acceptable chemicals. New volatile materials susceptible of emission to the troposphere should be subject
to the study of their reactions with OH and Cl in the range of temperature of the troposphere. The knowledge of the temperature
dependence of the kinetic rate constants, as it is now reported for the case of reactions 1 and 2, will allow more accurate
lifetimes and related magnitudes like GWPs. Nevertheless, a better knowledge of the vertical Cl tropospheric distribution
is still required. 相似文献
3.
Background, aim, and scope The paper describes the spatial contamination of the River Kymijoki, South-Eastern Finland, and the coastal region of the
Gulf of Finland with PCDD/Fs and mercury. The findings of ecotoxicologial and human health studies are also reported, including
environmental and human risk assessments. Sediments from the River Kymijoki, draining into the Gulf of Finland, have been
heavily polluted by the pulp and paper industry and by chemical industries. A wood preservative, known as Ky-5, was manufactured
in the upper reaches of the river between 1940 and 1984 causing severe pollution of river sediments with polychlorinated dibenzo- p-dioxins (PCDD) and dibenzofurans (PCDF). Moreover, the sediments have been polluted with mercury (Hg) from chlor-alkali production
and the use of Hg as a slimicide in pulp and paper manufacturing.
Materials and methods An extensive sediment survey was conducted as well as sediment transport modeling, toxicity screening of sediment invertebrates,
and a survey of contaminant bioaccumulation in invertebrates and fish. Studies on human exposure to PCDD/Fs and the possible
effects on hypermineralization of teeth as well as an epidemiological study to reveal increased cancer risk were also conducted.
An assessment of the ecological and human health risks with a null hypothesis (no remediation) was undertaken.
Results The sediment survey revealed severe contamination of river and coastal sediments with PCDD/Fs and Hg. The total volume of
contaminated sediments was estimated to reach 5 × 10 6 m 3 and hot spots with extremely high concentrations (max 292,000 ng g −1 or 1,060 ng I-TEQ g −1 d.w.) were located immediately downstream from the pollution source (approximately 90,000 m 3). Sediment contamination was accompanied by changes in benthic assemblages, but direct effects were masked by many factors.
The fish showed only slightly elevated PCDD/F levels in muscle, but orders of magnitude higher in the liver compared with
reference freshwater sites and the Baltic Sea. The concentrations in human fat did not reveal high human exposure in the Kymijoki
area in general and was lower than in sea fishermen. The relative risk for total cancer among farmers was marginally higher
(RR = 1.13) among those living close to the river, compared with farmers living further away, and the possibility of increased
cancer risk cannot be ruled out. A conservative risk assessment revealed that the present probability of exceeding the WHO
upper exposure limit of 4 pg WHO-TEQ kg −1 d −1 for PCDD/Fs and DL-PCBs was 6%. The probability of exceeding the WHO limit value of 0.23 μg kg −1 d −1 for methyl mercury was estimated to be notably higher at 62%. Based on these studies and the estimated risks connected with
different remediation techniques a general remediation plan with cost benefit analysis was generated for several sub-regions
in the river. Dredging, on-site treatment, and a close disposal of the most contaminated sediments (90,000 m 3) was suggested as the first phase of the remediation. The decision regarding the start of remediation will be made during
autumn 2008.
Conclusions The sediments in the River Kymijoki are heavily polluted with PCDD/Fs and mercury from earlier chlorophenol, chlor-alkali,
and pulp and paper manufacturing. A continuous transport of contaminants is taking place to the Gulf of Finland in the Baltic
Sea. The highly increased PCDD/F and Hg levels in river sediments pose an ecotoxicological risk to benthic fauna, to fish-eating
predators and probably to human health. The risks posed by mercury exceed those from PCDD/Fs and need to be evaluated for
(former) chlor-alkali sites and other mercury releasing industries as one basis for remediation decision making.
Recommendations and perspectives The studies form the basis of a risk management strategy and a plan for possible remediation of contaminated sediments currently
under consideration in the Southeast Finland Regional Environment Centre. It is recommended that a detailed restoration plan
for the most seriously contaminated areas should be undertaken. Based on current knowledge, the restoration of the whole river
is not feasible, considering the current risk caused by the contaminated sediment in the river and the costs of an extensive
restoration project. The experiences gained in the present case should be utilized in the evaluation of PCDD/F- and mercury-contaminated
sites in other countries. The case demonstrates that the historic reservoirs are of contemporary relevance and should be addressed,
e.g., in the national implementation plans of the Stockholm Convention.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
4.
Mercury is a trace element that is potentially dangerous due its high toxicity and tendency to bioaccumulate in organisms. Currently, high mercury concentrations are seen in the environment especially due climate changes. Studies regarding mercury bioavailability in the southwestern Atlantic Ocean using tuna and tuna-like species are rare. The aim of the present study was to use tuna and tuna-like species (Thunnus atlanticus, Thunnus albacares, Katsuwonus pelamis, Euthynnus alletteratus, Coryphaena hippurus and Sarda sarda) as indicators of the availability of total mercury (THg) in oceanic food webs of the southwestern Atlantic Ocean. THg concentrations varied significantly among species for both muscle and liver (Kruskal–Wallis test; H5,130 = 52.7; p < 0.05; H5,130 = 50.1; p < 0.05, respectively). The lowest concentrations were found in C. hippurus (0.008 mg kg−1 wet weight in the muscle and 0.003 mg kg−1 wet weight in the liver), and the highest concentrations were reported in the muscle of T. atlanticus (1.3 mg kg−1 wet weight) and in the liver of S. sarda (2.5 mg kg−1 wet weight). The continued monitoring of tuna and tuna-like species is necessary to assist in their conservation since tuna can be sentinels of mercury pollution. 相似文献
5.
The main objective of the present study was to investigate possible links between biomarkers and swimming performance in the estuarine fish Pomatoschistus microps acutely exposed to metals (copper and mercury). In independent bioassays, P. microps juveniles were individually exposed for 96 h to sub-lethal concentrations of copper or mercury. At the end of the assays, swimming performance of fish was measured using a device specially developed for epibenthic fish (SPEDE). Furthermore, the following biomarkers were measured: lipid peroxidation (LPO) and the activity of the enzymes acetylcholinesterase (AChE), lactate dehydrogenase (LDH), glutathione S-transferases (GST), 7-ethoxyresorufin- O-deethylase (EROD), superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GR) and glutathione peroxidase (GPx). LC 50s of copper and mercury (dissolved throughout metal concentrations) at 96 h were 568 μg L −1 and 62 μg L −1, respectively. Significant and concentration-dependent effects of both metals on swimming resistance and covered distance against water flow were found at concentrations equal or higher than 50 μg L −1 for copper and 3 μg L −1 for mercury (dissolved throughout metal concentrations). These results indicate that SPEDE was efficacious to quantify behavioural alterations in the epibenthic fish P. microps at ecologically relevant concentrations. Significant alterations by both metals on biomarkers were found including: inhibition of AChE and EROD activities, induction of LDH, GST and anti-oxidant enzymes, and increased LPO levels, with LOEC values ranging from 25 to 200 μg L −1 for copper and from 3 to 25 μg L −1 for mercury (dissolved throughout metal concentrations). Furthermore, significant and positive correlations were found between some biomarkers (AChE and EROD) and behavioural parameters, while negative correlations were found for others (LPO, anti-oxidant enzymes and LDH) suggesting that disruption of cholinergic function through AChE inhibition, decreased detoxification capability due to EROD inhibition, additional energetic demands to face chemical stress, and oxidative stress and damage may contribute to decrease the swimming performance of fish. Since a reduced swimming capability of fish may reduce their ability to capture preys, avoid predators, and interfere with social and reproductive behaviour, the exposure of P. microps to copper and/or mercury concentrations similar to those tested here may decrease the fitness of wild populations of this species. 相似文献
6.
Background, aim, and scope The widespread use of some platinum group elements as catalysts to minimize emission of pollutants from combustion engines
produced a constantly growing increase of the concentration of these elements in the environment; their potential toxicological
properties explain the increasing interest in routine easy monitoring. We have found that leaves of Prunus laurus cerasus are efficient collectors of particulate with a dimension <60–80 μm, and a simple and reliable procedure was developed to
reveal traces of platinum, palladium, and rhodium released from automotive catalysts. The analysis of the dust deposited on
the foliage is a direct indicator of traffic pollution. 相似文献
7.
Purpose This study aims to examine whether addition of immobilising agents to a sandy, alkaline (pH = 8.1) soil, which had been contaminated
with Pb and Zn by airborne particles from a Pb/Zn smelter, would substantially reduce metal bioavailability. 相似文献
8.
In this study an attempt is made to estimate nitrogen and phosphorus discharged to the environment from the striped catfish
( Pangasianodon hypophthalmus) farming sector in the Mekong Delta (8°33′–10°55′N, 104°30′–106°50′E), South Vietnam. The sector accounted for 687,000 t
production in 2007 and 1,094,879 t in 2008, with over 95% of the produce destined for export to over 100 countries. Commercial
and farm-made feeds are used in catfish farming, currently the former being more predominant. Nitrogen discharge levels were
similar for commercial feeds (median 46.0 kg/t fish) and farm-made feeds (median 46.8 kg/t fish); whilst, phosphorus discharge
levels for commercial feeds (median 14.4 kg/t fish) were considerably lower than for farm-made feeds (median 18.4 kg/t fish).
Based on the median nutrient discharge levels for commercial feeds, striped catfish production in the Mekong Delta discharged
31,602 t N and 9,893 t P, and 50,364 t N and 15,766 t P in 2007 and 2008, respectively. However, the amount of nutrients returned
directly to the Mekong River may be substantially less than this as a significant proportion of the water used for catfish
farming as well as the sludge is diverted to other agricultural farming systems. Striped catfish farming in the Mekong Delta
compared favourably with other cultured species, irrespective of the type of feed used, when the total amounts of N and P
discharged in the production of a tonne of production was estimated. 相似文献
9.
In this study, we investigated the combined effects of temperatures fluencies and mercury (Hg) on glutathione-dependent antioxidant system in fish, by measuring the oxidative stress indicator (LPO, lipid peroxidation) and the parameters involved in the glutathione-related antioxidant defense system (GPx, glutathione peroxidase; GR, glutathione reductase; GST, glutathione S-transferase; GSH, reduced glutathione), as well as the expression of related genes in grass carp, Ctenopharyngodon idella. Fish (45.37?±?3.58 g) were exposed to 10 test groups, e.g., 15 °C with/without Hg, 20 °C with/without Hg, 25 °C with/without Hg, 30 °C with/without Hg, 35 °C with/without Hg for 4 weeks. Three-way ANOVA was used to analyze the correlation between the measured parameters and experimental conditions (water temperature, Hg exposure, exposure time, and their interactions.). Our results show that there is no interaction between mercury and low temperature, but the combined effect at high temperature has been confirmed, which indicated the glutathione-dependent enzyme system in grass carp has a complex regulatory mechanism with temperature fluctuations. In the actual field monitoring, it is necessary to consider the impact of extreme temperature on the toxicity of pollutants in the aquatic ecosystem. 相似文献
10.
Mercury is a ubiquitous, persistent toxicant found in the environment. In water, mercury bioaccumulates up the food chain and leads to high concentrations in fish. Consumption of contaminated fish is the major source of exposure to mercury in the US. The objective of this study was to enroll persons living in areas selected by the Environmental Protection Agency (EPA) to have high mercury concentrations and who consume at least 6 oz of locally caught fish per week to determine the feasibility of monitoring future trends among a population identified as highly exposed. Blood samples were collected at time of interview and analyzed for mercury. Participants ( n = 287) were enrolled from North Carolina, Maryland, and South Dakota. Participants reported eating an average of five servings of fish per week. The overall geometric mean for total mercury was 0.75 μg L −1, with North Carolina having the highest mean level (2.02 μg L −1). Overall, 42% of the study population had levels greater than the US geometric mean 0.83 μg L −1. The number of servings of fish consumed was not found to be associated with blood mercury levels. We were able to identify some persons with elevated mercury concentrations living in areas identified by EPA; however, identifying and monitoring a highly exposed population over time would be challenging. 相似文献
11.
Purpose Samples from the German Environmental Specimen Bank (ESB) covering particularly the years 1994–1996, 2000–2002, and 2006–2009
were analyzed for perfluorinated compounds (PFC; mainly C4–C13 carboxylic and sulfonic acids) to gain an overview on current
PFC levels and patterns in marine, limnetic, and terrestrial biota; to assess their concentrations in different trophic levels;
and to investigate whether risk management measures for PFC are successful. 相似文献
13.
Introduction A greenhouse experiment was conducted to determine if Cucurbita pepo ssp. pepo (pumpkin) root exudates could increase the uptake of polychlorinated biphenyls (PCBs) into plants. Contaminated soil was
pre-treated with pumpkin root exudates by first growing pumpkins in the soil. Plants (pumpkins and weeds) were grown in the
pre-treated (root exudate group) and non-treated (control group) contaminated soils. Seeds from five weed species collected
from two contaminated sites were germinated in sufficient quantities ( n ≥ 6) for three seedlings to be planted in two groups. 相似文献
14.
Background, aim, and scope It has been known that the pollutants of electronic wastes (E-wastes) can lead to severe pollution to the environment. It
has been reported that about 50% to 80% of E-wastes from developed countries are exported to Asia and Africa. It has become
a major global environmental problem to deal with ‘E-wastes’. E-waste recycling has remained primitive in Jinghai, China.
This not only produces enormous environmental pollution but also can bring about toxic or genotoxic effects on the human body,
threatening the health of both current residents and future generations living in the local environment. The concentration
of lead in the blood of children in the E-waste polluted area in China is higher than that of the control area. But little
is known about the cytogenetic effect to human beings caused by the pollution of E-wastes. In the present study, experiments
have been performed to investigate the genetics of permanent residents of three villages with numerous E-waste disposal sites
and to analyze the harmful effects of exposure to E-wastes.
Materials and methods In total, 171 villagers (exposed group) were randomly selected from permanent residents of three villages located in Jinghai
County of Tianjin, China, where there has been massive disposal of E-wastes. Thirty villagers were selected from the neighboring
towns without E-waste disposal sites to serve as controls. Chromosomal aberrations and cytokinesis blocking micronucleus were
performed to detect the cytogenetic effect, dic + r (dicentric and ring chromosome), monomer, fragments (acentric fragments,
minute chromosomes, and acentric rings), translocation, satellite, quadriradial, total aberrations, and micronuclear rate
were scored for each subject. DNA damage was detected using comet assay; the DNA percentage in the comet tail (TDNA%), tail
moment (TM), and Olive tail moment (OTM) were recorded to describe DNA damage to lymphocytes.
Results The total chromosome aberration rates (5.50%) and micronuclear rates (16.99%) of the exposure group were significantly higher
than in the control group ( P = 0.000). The percentage of DNA in the comet tail, tail moment, and Olive tail moment detected by comet assay showed that
there was a significant difference in DNA damage in the exposure group ( P = 0.000). The chromosome aberration, micronucleus rate, and DNA damage observed in women were significantly higher than those
in men. Chromosome aberration and micronuclear rates of both smokers and non-smokers in the exposure group are obviously higher
than that in the control group ( P = 0.000).
Discussion The use of outdated (and unsafe) ways to deal with E-wastes can lead to exposure to a variety of substances harmful to human
health. The components of pollution may enter the human body through the air, drinking water, and food chain to damage human
genetic material, resulting in genomic instability. The rates of chromosomal aberration, micronucleus formation, and the degree
of DNA damage in women in the group exposed to electronic waste were significantly higher than in men. The reason for this
may be concerned with the traditional lifestyle of the local residents or the difference of sensitivity to the exposure to
E-wastes or any others. Further investigations are needed to provide evidence to demonstrate this.
Conclusions Here, we report the obviously cytogenetic toxicity to the exposure population by the E-waste pollution for the first time.
E-waste pollution may be a potential agent of genetic mutation, and may induce cytogenetic damage within the general population
exposed to the pollution. These findings need to be considered, and steps should be taken to protect the current population
and future generations from the effects of pollution with E-wastes.
Recommendations and perspectives The above results remind us that the impact of E-waste recycling on environmental quality of Jinghai should be evaluated soon.
Moreover, it is urgent for the government to prohibit E-waste import and its processing by outdated ways. The future studies
such as pollutant details of drinking water, air, and soil in the area as well as epidemiological investigations on the harmful
effect to children must be performed eagerly. All the data available do provide a compelling case for immediate action in
both countries to address workplace health and safety and waste management.
Qiang Liu and Jia Cao contributed equally to this study and share the first authorship. 相似文献
15.
Current European Union regulation regarding polychlorinated dibenzo- p-dioxins, polychlorinated dibenzofurans (PCDD/Fs) and dioxin-like polychlorinated biphenyls (dl-PCBs) in food and feed is based on Toxic Equivalent Quotient (TEQ) concept. For confirmatory purpose, the isotope-dilution method associated to a measurement by gas chromatography coupled with high resolution mass spectrometry is usually the method of choice for precisely measuring the 29 target congeners in three separated fractions. Time and cost related to these analyses are very significant. Various kinds of screening concepts can be considered. In the present study, we elaborated and validated a prediction model for the 2005 World Health Organization TEQ in fish, based on the measurement of 4 PCDD/F and 2 non-ortho dl-PCB congeners, potentially analyzable in a single extracted fraction by gas chromatography coupled with mass spectrometry. Large independent datasets have been used for model elaboration ( n = 108) and validation ( n = 363, n = 357 and n = 6). 相似文献
16.
Caps and stipes of 141 fruiting bodies of Parasol Mushroom ( Macrolepiota procera) and surface layer of soils collected from 11 spatially distant and background (pristine) areas in Northern Poland were analyzed
for Ag, Al, Ba, Ca, Cd, Co, Cr, Cu, Fe, Hg, K, Mg, Mn, Na, Ni, P, Pb, Rb, Sr, and Zn by inductively coupled plasma optical
emission spectroscopy and cold vapor atomic absorption spectroscopy. In terms of bioconcentration and bioexclusion concept,
K, Ag, Cu, Rb, and P were highly bioconcentrated in caps, and their bioconcentration factor values varied for the 11 sites
between 120 and 500—67–420, 70–220, 10–170, and 45–100, respectively. Cd, Zn, Mg, and Na showed bioconcentration factors (BCFs)
between 3.3 and 36, 3.7–15, 0.92–6.3, and 1.4–44 while Al, Ba, Ca, Co, Cr, Mn, Ni, Pb, and Sr were excluded (BCF < 1). The
Parasol Mushroom is a species harvested in the wild, and its caps are of unique taste and can contain a spectrum of essential
and hazardous mineral compounds accumulated at elevated concentrations, even if collected at the background (pristine) areas.
These elevated mineral concentrations of the caps are due to the efficient bioconcentration potential of the species (K, Ag,
Cu, Rb, P, Cd, Zn, Mg, and Na) and abundance in the soil substrates (Al, Ca, Fe, Mn). The estimated intake rates of Cd, Hg,
and Pb contained in Parasol Mushroom’s caps show a cause for concern associated with these metals resulting from the consumption
of between 300- and 500-g caps daily, on a frequent basis in the mushrooming season. 相似文献
17.
Introduction Artisanal fisheries in tropical estuaries are an important economic activity worldwide. However, gear (e.g. ropes, nets, buoys,
crates) and vessels are often in use under dangerous conditions. Polyfilament nylon ropes are used until they are well beyond
human and environmental safety limits. Severe wear and tear results in the contamination of the environment with micro-fragments.
The spread of these fragments in the marine environment and their ingestion by the biota are documented in the scientific
literature and are increasing concerns. The aim of this study was to evaluate the ingestion of plastic fragments by two fish
(drum) species in relation to seasonal, habitat and fish size–class variation. 相似文献
18.
Background, aim, and scope As emerging contaminants, transformation products of the pollutants via various environmental processes are rather unknown,
and some may predominately contribute to the environmental risks of the parent compounds. Hence, studies on transformation
products complement the assessment of the environmental safety of the parent compounds. In this study, degradation experiments
and toxicity tests using diclofop-methyl (DM), a widely used herbicide, and selected major transformation products were carried
out in algal cultures to assess the time course of DM toxicity and its relevance in the formation of new breakdown products.
Methods The alga Chlorella vulgaris was maintained in the algal growth medium HB IV. The inhibition of algal growth was determined by measuring optical density
at 680 nm (OD 680). Initially, DM and two selected breakdown products were added to the algal cultures, and following degradation experiments
analyses were carried out by high performance liquid chromatography. In addition, the possible relationship between DM degradation
and toxicity was assessed, based on physico-chemical properties of the compounds and their toxicity.
Results DM was rapidly absorbed onto the surface of the algal cells where it was hydrolyzed to diclofop (DC). Further degradation
to 4-(2, 4-dichlorophenoxy) phenol (DP) occurred in the cells. However, only a minor amount of DC was degraded to DP under
the same conditions when DC was initially added to the algal culture. When C. vulgaris was exposed to these compounds for 96 h, the determined EC 50 showed that DC was about ten times less toxic than DM (EC 50 = 0.42 mg/L) and that DP (EC 50 = 0.20 mg/L) was the most toxic.
Discussion Due to strong hydrophobicity and rare dissociation, DM has tendency toward absorption as compared to DC. The higher average
degradation rates of DC initially treated by DM revealed the damage of the cell membranes caused by the DM and, thus, enhanced
movement of DC into the cells. Following occurrence of phenolic breakdown products, DP suggested that DC should be intracellularly
degraded to DP, which had a more potent mode of action and a higher acute toxicity. Moreover, the results for EC 50 at various intervals were in accordance with degradation processes of the initial compounds, in which rapid formation of
DP was attributed to an increasing toxicity of DM.
Conclusions The toxicity of DM in algal suspensions increased with time due to its degradation to DP, which contributed significantly
to the determined toxicity. These results indicate that the toxicity of the pesticide probably depends significantly on degradation.
It is thus important to consider the time-dependent environmental processes when evaluating the toxicological effects of pesticides
for proper risk assessment.
Recommendations and perspectives Increasing transformation products of these contaminants are identified in the environment, although they seem to be unknown
in terms of the lacking studies on environmental behavior and ecotoxicity concerning them. Certain breakdown products probably
greatly contribute to the apparent toxicity of the parent compounds, which is ascribed to the parent compounds in general
studies ignoring the dependence of their toxicity on various transformation pathways. These studies that identify new intermediates
and assess their toxicity via the environmental processes will be helpful to distinguish the nature of toxicity of the parent
contaminants. 相似文献
19.
Ongoing eutrophication is changing the Baltic Sea ecosystem. Aquaculture causes relatively small-scale nutrient emissions,
but local environmental impact may be considerable. We used substance flow analysis (SFA) to identify and quantify the most
significant flows and stocks of nitrogen (N) and phosphorus (P) related to rainbow trout aquaculture in Finland. In 2004–2007,
the input of nutrients to the system in the form of fish feed was 829 t N year −1 and 115 t P year −1. Around one-fifth of these nutrients ended up as food for human consumption. Of the primary input, 70% ended up in the Baltic
Sea, directly from aquaculture and indirectly through waste management. The nutrient cycle could be closed partially by using
local fish instead of imported fish in rainbow trout feed, thus reducing the net load of N and P to a fraction. 相似文献
20.
Research on the benefits of local ecological knowledge for conservation lacks empirical data on the pathways through which
local knowledge might affect natural resources management. We test whether ethnobotanical skills, a proxy for local ecological
knowledge, are associated to the clearance of forest through their interaction with agricultural labor. We collected information
from men in a society of gatherers–horticulturalist, the Tsimane’ (Bolivia). Data included a baseline survey, a survey of
ethnobotanical skills ( n = 190 men), and two surveys on agricultural labor inputs ( n = 466 plots). We find a direct effect of ethnobotanical skills in lowering the extent of forest cleared in fallow but not
in old-growth forest. We also find that the interaction between ethnobotanical skills and labor invested in shifting cultivation
has opposite effects depending on whether the clearing is done in old-growth or fallow forest. We explain the finding in the
context of Tsimane’ increasing integration to the market economy. 相似文献
|