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1.
Century old mine tailings in the Cobalt and Silver Center areas are widely dispersed throughout the terrestrial and aquatic environments and contain high concentrations of arsenic. Arsenic concentrations were found to be as high as 972 μg/L in surface waters and 10,800 mg/kg in lake sediment. The mean values for arsenic in surface waters and sediment from 9 lakes directly influenced by mining activity were 431 μg/L and 1704 mg/kg, respectively, whereas in the 12 control lakes with no mining activity in their catchment had mean values of 2.2 μg/L and 11 mg/kg in their water and sediment, respectively. Lakes impacted by downstream tailing migration (n?=?4) were also assessed and had intermediate concentrations of arsenic. Principal component analysis identified contaminated lakes as having different geochemical signatures than control lakes but lake sediment that was sampled below tailings in contaminated lakes, deposited pre-mining, can resemble the geochemistry of those found in control lakes. Arsenic concentrations in these samples ranged from 4.4 to 185 mg/kg, which can be considered reasonable background as these areas contained abundant mineral deposits that could naturally elevate background concentrations. Even though background concentrations are naturally elevated, the presence of arsenic-rich tailings in these lakes has prevented any natural recovery from occurring. Fe-Mn oxides at the water-sediment interface perpetually scavenge arsenic from buried tailings below and from contaminated surface waters that cause arsenic concentrations to remain enriched in the upper sediments even after tailings have been buried by lake sediment. This process has prevented recovery of the lake ecosystems even after nearly a century without mining.  相似文献   

2.
One of the aims of the Water Framework Directive 2000/60/CE is to assess the ecological status of water bodies in Europe in relation to priority contaminants, including some persistent organic pollutants (POPs). Recognizing the benefits of measuring hydrophobic compounds in biota tissues rather than in water, we used the European eel Anguilla anguilla in the present study as a bioindicator species for monitoring POPs in freshwater/brackish environments. We present the results of a contamination analysis of eels carried out in three Italian sites representative of different pollution levels: the last part of Tevere River, which flows through a very urbanized and industrialized area, Caprolace Lake and Lesina Lagoon, inside two different protected national parks. A very high pollution variability was recorded within each group of eels, in particular for those caught at Caprolace Lake. Due to this high variability, inter-population comparisons were carried out only between eels collected in Tevere River and Lesina Lagoon. PCBs values in Lesina Lagoon were two orders of magnitude lower than those measured in Tevere River, while no significant differences were found for levels of DDT compounds. Our results confirm the suitability of the eel as an indicator of persistent bioaccumulative pollutants in brackish environments and rivers where it can be easily caught, but we are sceptical of its use in deep lakes where its capture might be problematic considering standard operation procedures for fish sampling.  相似文献   

3.
The introduction of exotic fishes to naturally fishless waters is often associated with declines in species native to those waters. Mosquitofish, Gambusia affinis, have been introduced to waters worldwide for mosquito control. Taxa negatively affected by mosquitofish potentially include fairy shrimp (Crustacea: Anostraca) that often show high rates of endemism, and which are characteristic of naturally fishless wetlands on every continent. We tested the effects of mosquitofish on a fairy shrimp, Linderiella occidentalis, in experimental ponds that included a community of native aquatic invertebrates. We supplemented field experiments with lab trials to test whether mosquitofish preferred L. occidentalis to other prey. Survival of the fairy shrimp was significantly reduced in ponds with mosquitofish. Only 16.9% of fairy shrimp survived in ponds with mosquitofish, while 64.0% survived in control ponds. Fish presence also reduced abundance and biomass of other invertebrates. Results from feeding trials demonstrated that mosquitofish frequently prefer L. occidentalis to alternative prey. Our results suggest that introduction of mosquitofish into naturally fishless wetlands may lead to loss of diversity of their highly specialized aquatic fauna.  相似文献   

4.
脉冲强光对烤鳗的杀菌效果及感官品质的影响   总被引：7，自引：0，他引：7  
为了在烤鳗加工中应用脉冲强光杀菌技术，试验分析了脉冲强光杀灭烤鳗表面染菌的效果，以及杀菌对烤鳗感官品质影响的情况。结果表明：脉冲强光可以有效的杀灭烤鳗表面染菌，闪照15 s，烤鳗表面大肠杆菌的杀菌率为99.99%；经过25 s的处理，烤鳗的感官品质（颜色、气味、质地、味道）没有显著变化；过氧化值、 酸价变化率都不超过0.35%。脉冲强光对烤鳗贮藏品质影响也较小，经过30 s的闪照，贮藏期间烤鳗感官品质没有显著影响，过氧化值、 酸价变化率不超过0.80%，变化幅度均低于0.50%。杀菌的工艺因素中，闪照时间对烤鳗杀菌效果和过氧化值、酸价变化率的影响最显著。  相似文献   

5.
Recently, there has been increasing concern about perfluorinated compounds, especially perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) due to their biotic and abiotic persistence and chronic toxicity. To characterize the spatial distribution and seasonal variation of PFOS and PFOA in the aquatic and oceanic environment of Singapore, more than 100 water samples from reservoirs, rivers/canals, coastal waters, and treated effluents of wastewater treatment plants (WWTPs) were collected and analyzed in this study. Solid-phase extraction followed by high-performance liquid chromatography (HPLC) coupled with tandem MS (HPLC/MS/MS) was applied to quantitatively identify PFOS and PFOA. PFOS concentrations in surface waters, wastewaters and coastal waters were in the range of 2.2?C87.3 ng/L, 5.8?C532 ng/L, and 1.9?C8.9 ng/L, respectively, while those of PFOA were 5.7?C91.5 ng/L, 7.9?C1,060 ng/L, 2.4?C17.8 ng/L, respectively. Compared with surface waters and wastewaters, coastal waters had lower concentrations of PFOS and PFOA. Highest concentration of PFOA (532 ng/L) and PFOA (1,060 ng/L) were observed in treated effluents of two WWTPs. Our results suggest that coastal waters in the western area of Singapore are more heavily contaminated than those in the middle and eastern areas. The release of effluents from WWTPs is an important pathway by which perfluorinated compounds enter the oceanic environment. Between dry season and wet season, significant seasonal differences (p?=?0.025) were observed in surface waters for PFOS only, while no discernable seasonal differences were found for both PFOS and PFOA in coastal waters and wastewaters.  相似文献   

6.
Several types of pollutants are currently entering the territorial waters of Kuwait from a variety of sources. Some pollutants, especially petrochemicals, are known to be potentially mutagenic and/or carcinogenic. Some of these chemical pollutants may enter the tissues of aquatic organisms and eventually the human body. The presence of such chemicals in the marine environment might create a serious health hazard. The marine environment of Kuwait was monitored for the presence of mutagenic chemicals using living organisms such as shrimp, clams and algae as bioindicators. These organisms were collected from selected sites within Kuwait territorial waters. Their tissues were extracted in ethanol and screened for genetically active chemicals by two standard bacterial assays, the Fluctuation Test and the Ames Test. Salmonella typhimurium TA98 was used as a tester strain. The data obtained from this study indicated that the shrimp, algae and clam samples were polluted with low concentration of frameshift mutagens. Due to the limited scope and nature of this study it was impossible to determine the source(s) of input or the chemical nature of these pollutants.  相似文献   

7.
A reconnaissance survey was made of trace metals in surface waters and three aquatic bryophytes (Scapania undulata,Hygrohypnum luridum andPolytrichum commune) in the mid-Wales Ag-Pb mining district. This area is contaminated by heavy metals from past mining. Elevated levels of Ag, Cd, Cu, Pb, and Zn were found in water and plant tissue. All the plants accumulated Ag and the other metals butScapania appears the most suitable as a plant monitor of Ag-polluted waters.  相似文献   

8.
Irrigation of crops with treated wastewater has the potential to introduce effluent-derived organic microcontaminants into surface waters through agricultural runoff. To determine whether compounds indicative of the presence of treated effluent in irrigation water could be identified in agricultural runoff, surface runoff samples collected from effluent-irrigated and rain-fed cultivated fields were analyzed for a broad spectrum of organic compounds. A variety of compounds was identified that appeared to be associated with irrigation with treated wastewater. These compounds included human pharmaceuticals (e.g., carbamazepine, gemfibrozil, carisoprodol), personal care product ingredients (e.g., insect repellent, polycyclic musks), and alkyl phosphate flame retardant chemicals. Most of these compounds appear not to have been previously reported in agricultural runoff. These compounds were present at concentrations below the few published aquatic toxicology data available; however, their potential to elicit more subtle effects in aquatic organisms cannot be excluded. None of these compounds were detected by broad-spectrum analysis in samples from the same fields during runoff-producing rain events.  相似文献   

9.
In order to understand the present status of heavy metal contamination and the risk associated with human consumption, commercial freshwater eels in Vietnam were examined. The concentration of eight elements (Cr, Mn, Co, Cu, Zn, Sr, Cd, and Pb) was determined in muscle tissue of tropical eel Anguilla marmorata collected in four provinces, Quang Tri, Quang Ngai, Binh Dinh, and Phu Yen, from the central part of Vietnam. Concentrations of Cu, Zn, Cd, and Sr were found to be highest, whereas Co concentration showed the lowest at Quang Tri. Cr was recorded to be lowest in Quang Ngai, while the amounts of Mn and Pb did not vary among locations. Although the metal concentrations in the muscle of A. marmorata did not represent a risk for human consumption, elevated Cd concentrations in Quang Tri related to agriculture activities suggest that further investigations should be undertaken to clarify the potential risk to the eel population.  相似文献   

10.
Among the many anthropogenic abiotic stresses, manganese (Mn) toxicity has been recognized for its impact on aquatic ecosystems as well as on the biological components of these ecosystems, including aquatic plants. The objective of this study was to determine the Mn accumulation ability of aquatic macrophytes (Azolla caroliniana, Salvinia minima and Spirodela polyrhiza) and evaluate the morphophysiological responses of the species that gather the highest amount of Mn when exposed to a supra-optimal supply of manganese. The experiments were conducted in the laboratory, and the effects of Mn were evaluated based on plant growth; the concentration of total chlorophyll, carotenoids, and anthocyanins; the enzymatic activity of catalase and peroxidase; and leaf anatomy. All of the studied species accumulated Mn in their tissues. Moreover, it was observed that this accumulation was dependent on the concentration of the metal in solution. S. polyrhiza showed higher concentrations of Mn in its tissues (17.062?mg?g?1 dry weight (DW)), followed by S. minima (4.283?mg?g?1 DW) and A. caroliniana (1.341?mg?g?1 DW). Despite the Mn accumulation in all species, S. polyrhiza was the only one selected for further analyses because of its greater ability to accumulate Mn. The high Mn concentration found in tissues of S. polyrhiza suggests that this species has the potential to sequester and accumulate this metal. However, a sensitive response in the plants exposed to higher Mn concentrations (0.4?mM) was observed. The phytotoxicity effects of this accumulation were responsible for a decrease in the plant growth, a reduction in the pigment content (total chlorophyll, carotenoids, and anthocyanins), a low activity of catalase, and the disarrangement of the leaf aerenchyma.  相似文献   

11.
Electrochemistry can be a valuable instrument to preserve the aquatic environment, first, by elucidating the oxidation-reduction mechanisms of substances having toxicological potential at laboratory scale; second, by aiding through extrapolation to comprise the evolution and fate in the environment of these pollutants and, finally, by establishing the basis of some electrochemical deactivation processes at industrial scale. In this way, this paper deals on studies of a type of highly pollutant substances for the aquatic media such as the S-triazines. The first part of the paper is focused to show the electrochemical reduction behavior of some S-triazines (eleven compounds have been studied). Later, the probable consequences at natural scale of these electroreductive processes are evaluated. Thus, the electrochemical reduction of diluted solutions of s-triazine herbicides and parent compounds takes place at potentials of ?0.90 to ?1.20 V, at very acidic pH values. The electroreduction products generated in all cases have loss the aromaticity and, depending on the compound, the chlorine atom or the –SCH3 group. So, the resulting molecules present lower toxicity than the original compounds. For this reason, the electroreductive way can be an efficient option for the detoxification of S-triazine polluted waters. On the other hand, the natural deactivation of the s-triazines present in natural waters, in addition to the conventional photooxidative route taking place in well illuminated and oxygenated waters, could take place through the reductive process when the waters are essentially anoxic, acidic, and rich in suspended materials. This natural reduction, moreover, could favour the later oxidation or metabolization of the byproducts emanating of the original plaguicides. Finally, the reduction of S-triazines, both forced (industrial water depuration via electrochemical reduction) and no forced (natural aquatic media) requires more negative redox potentials, that is, more reductive environments as the molecules become more complex.  相似文献   

12.
The objective of the present study was to investigate the short-term effects of benzo(a)pyrene (BaP) on juvenile sea bass (Dicentrarchus labrax L.) using a multiparameter approach. At the end of the 96?h of exposure to a range of BaP concentrations (2?C256???g?l?1) in laboratorial conditions, a suite of biomarkers involved in biotransformation pathways, oxidative stress and damage, neurotransmission and energetic metabolism were analysed. Levels of BaP metabolites in bile and BaP-type compounds in tissues were also included as biomarkers of exposure, and the post-exposure swimming velocity was used as a toxicity endpoint at a higher level of biological organisation. In addition, a time-series experiment on the levels of bile BaP metabolites was also performed. Increased levels of BaP metabolites in bile and BaP-type compounds in liver and brain of exposed fish were found, indicating BaP uptake, metabolisation and distribution by different tissues. BaP induced oxidative stress and damage, but no significant effects on the post-exposure swimming velocity, neurotransmission and energetic pathways were found. An increase in the levels of BaP metabolites in bile over time was also observed, reaching a threshold similar at all the concentrations tested. Overall, this integrative multiparameter study reflecting different biological responses of D. labrax was suitable to assess the effects caused by the short-term exposure to BaP and may be useful in the marine environmental risk assessment of polycyclic aromatic hydrocarbons pollution. The observed toxic effects also highlight the relevance of short-term exposure to relatively high concentrations of chemicals, as can occur in the case of punctual heavy chemical releases, such as oil spills in the marine environment.  相似文献   

13.
N-alkanes were measured both in dissolved and particulate-adsorbed phases of water samples collected from five stations located along Shatt al-Arab River in Iraq. The aim of this study was to provide a background information on the presence, origin, and distribution of n-alkanes in the waters of Shatt al-Arab River. Total concentrations of n-alkanes were lower in the dissolved phase (29.37 (μg L?1) than in the particulate-adsorbed fraction (17.62 μg g?1 dw). Distribution of n-alkanes in both fractions is characterized by two distinct patterns. First, for C compounds numbered C14 to C22, the ‘odd’ numbered hydrocarbons were slightly more abundant with C17 being the most concentrated. The second is shown within n-alkanes greater than C22. In these the ‘odd’ numbered hydrocarbons show even greater predominance indicating that much of the n-alkanes in the waters of Shatt al-Arab, may have originated from aquatic biogenic sources; i.e., diatoms, algal forms, bacterial activities, and higher plants. The CPI values were found to be from 0.99 to 1.98 in the dissolved fraction and from 0.70 to 2.10 in the particulate fraction. Petroleum hydrocarbon inputs and urban related oil discharges (anthropogenic pollution) may also have contributed to the input of n-alkanes in Shatt al-Arab, particularly near the city of Basrah (St. IV). Total concentrations at station IV were much higher (8.40 μg L?1 and 5.80 μg g?1) than that for the most upstream station, # I, (3.20 μg L?1 and 1.48 μg g?1) and decreased again further downstream at station V (7.10 μg L?1 and 4.32 μg g?1). The CPI values were around 1.0 in station IV. In a conclusion, results obtained in this study indicate that the n-alkanes in the waters of Shatt al-Arab River are of aquatic biogenic and anthropogenic (petroleum related) origins.  相似文献   

14.
Opencast coalmine effluent contains higher concentrations of Cd, Cr, Co, Ni and Pb. Biofiltration of these metals has been demonstrated successfully with the help of aquatic macrophytes i.e., E. crassipes, L. minor and A. pinnata. Experiments revealed E. crassipes reduced highest concentration of heavy metals followed by L. minor and A. pinnata on 20th days retention period. Plant tissue analysis revealed higher accumulation of metals in roots than leaves. Highly significant correlations have been noted between removal of heavy metals in effluent and their accumulation in roots and leaves of the experimental sets. Translocation factor also revealed lower transportation of metals from root to leaves. Reduction in chlorophyll and protein content was noted with the accumulation of heavy metals. N, P and K analysis in plant tissues indicated continuous decrease in their concentration with increasing metal concentration. Negative and significant correlations between metal accumulation and N, P and K concentrations in plant tissues showed adverse effects of heavy metals. Analysis of variance (Dunnett t-test) showed significant results (p?<?0.001) for all the metals in different durations.  相似文献   

15.
Temporal trends in acid-base chemistry are reported for surface waters in 6 regions of the United States. The lakes and streams are low ANC, dilute systems, selected to represent acid-sensitive aquatic resources in the 6 regions. The predominant trends observed were decreases in lake and stream SO4 2? concentrations in sites east of the Mississippi River, and increases in NO3 ? in the Adirondack lake and Catskill stream sites (both located in eastern New York State). Correlations of trend results from all sites with other factors indicated that trends in precipitation volume were highly correlated with the observed trend patterns. From the surface water trend results, three distinct clusters were identified that corresponded to three trend patterns: ‘dilution,’ ‘recovery,’ and ‘acidification.’ These were distributed across the LTM regions, with no particular geographic patterns.  相似文献   

16.
Phytotoxicity of Flumequine (F) on the aquatic duckweed, Lemna minor L., and plant drug uptake were evaluated by a simple ecotoxicological test. Flumequine, at all concentrations between 50 and 1000 μg L-1 tested, affected the plant growth: leaves and roots were damaged, but duckweed continued to grow on a five weeks period. Furthermore, increasing drug concentrations decreased the chlorophyll b content in plants. These effects depend on F uptake by plants, which is quite high (from 0.72 to 13.93 μg g-1 plant dry weight). Based on this activity, Lemna can be taken into consideration as a tool for in situ remediation of drug contaminated waters: the presence of Lemna significantly lower the F concentration in culture media on a five weeks period. Results strongly support its remediation capability.  相似文献   

17.
Erythromycin is one of the most widely used antibiotics globally and is considered an emerging contaminant in wastewaters and environmental waters. The egg, larval, and pupal stages of the dengue vector Aedes aegypti L. reside and develop in aquatic environments. These mosquito stages may be exposed to compounds in the water, such as erythromycin. Aquatic stages of Ae. aegypti were reared in different concentrations of erythromycin which resulted in significant delay and decrease in eclosion of eggs and pupation of larvae (P?<?0.05). Moreover, emergence of adults from pupae, larval survival, and adult female fecundity significantly decreased (P?<?0.05). A few occurrences of hypopigmentation in larvae and blisters in adult mosquitoes were also observed. Interestingly, second-generation eggs, which were laid by adult female mosquitoes exposed to erythromycin during their aquatic stages, did not exhibit decreased levels of eclosion in the presence of erythromycin. These results reveal that long-term erythromycin exposure disrupts the Ae. aegypti life cycle by decreasing survival and delaying progression throughout different life stages. However, this study demonstrates that Ae. aegypti can rapidly acquire significant tolerance to the emerging environmental contaminant erythromycin within two generations.  相似文献   

18.
In the study area physical and chemical factors control the composition of surface and groundwaters, which in turn determine the water quality of the “Biviere di Gela” lake. These factors combine to create diverse water types which change their compositional character spatially as rainfall infiltrates the soil zone, moves down a topographically defined flow path, and interacts with bedrock minerals. Low-salinity waters, which represent the initial stage of underground circulation, start dissolving calcium carbonate from the local rocks. The progressive increase in salinity, characterized by substantially higher Ca, SO4, Na and Cl concentrations, suggests that dissolution of CaSO4 and NaCl is an important process during water–rock interactions. The “Biviere di Gela” lake is often separated into two units (Lago Grande and Lago Piccolo). “Lago Grande” water is generally of Na-SO4-Cl-type, whereas “Lago Piccolo” water is of Na-Cl-SO4-type. Their total content of dissolved salts varies with season, the amount of rainfall, and inflow of ground and drainage water. Over time, an increasing trend towards greater salinity and also sudden changes in the relative abundances of Cl and SO4 have been recorded for the “Lago Grande.” The isotope composition of the lake water appears to be affected by inflow of ground and surface waters and also by evaporative loss. The nitrate content of waters from the recharge basin is of particular concern because it contributes to lake eutrophication. The trace element contents do not evidence the presence of any significant metal contamination of lake waters, although a future potential hazard of metals bioaccumulation by the aquatic biota must be taken into consideration. Finally, a water balance for the basin shows that a drop in precipitation of about 20% might be critical for lake survival.  相似文献   

19.
An important consequence of acidification is the mobilization of Al from the edaphic to the aquatic environment. Elevated Al levels in acidic waters may be toxic to fish. Eggs, larvae, and postlarvae of white suckers (Catostomus commersoni) and brook trout (Salvelinus fontinalis) were exposed in laboratory bioassays to pH levels 4.2 to 5.6 and inorganic Al concentrations of 0 to 0.5 mg l?1. Aluminum toxicity varied with both pH and life history stage. At low pH levels (4.2 to 4.8), the presence of Al (up 0.2 mg l?1 for white suckers; 0.5 mg l?1 for brook trout) was beneficial to egg survival through the eyed stage. In contrast, Al concentrations of 0.1 mg l?1 (for white suckers) or 0.2 mg l?1 (for brook trout) and greater resulted in measurable reductions in survival and growth of larvae and postlarvae at all pH levels (4.2 to 5.6). Aluminum was most toxic in over-saturated solutions at pH levels 5.2 to 5.4. The simultaneous increase in Al concentration with elevated acidity must be considered to accurately assess the potential effect of acidification of surface waters on survival of fish populations.  相似文献   

20.
Phosphate from agricultural runoff is a major contributor to eutrophication in aquatic systems. Vegetated drainage ditches lining agricultural fields have been investigated for their potential to mitigate runoff, acting similarly to a wetland as they filter contaminants. It is hypothesized that some aquatic macrophytes will be more effective at removing phosphate than others. In a mesocosm study, three aquatic macrophyte species, cutgrass (Leersia oryzoides), cattail (Typha latifolia), and bur-reed (Sparganium americanum), were investigated for their ability to mitigate phosphate from water. Mesocosms were exposed to flowing phosphate-enriched water (10?mg?L?1) for 6?h, left stagnant for 42?h, and then flushed with non-nutrient enriched water for an additional 6?h to simulate flushing effects of a second storm event. Both L. oryzoides and T. latifolia decreased the load of dissolved phosphate (DP) in outflows by greater than 50?%, significantly more than S. americanum, which only decreased DP by 15?±?6?% (p????0.002). All treatments decreased concentrations inside mesocosms by 90?% or more after 1?week, though the decrease occurred more rapidly in T. latifolia and L. oryzoides mesocosms. By discovering which species are better at mitigating phosphate in agricultural runoff, planning the community composition of vegetation in drainage ditches and constructed wetlands can be improved for optimal remediation results.  相似文献   

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