珠江三角洲河网区水体及鱼体内重金属含量分析与评价

采用原子吸收及原子荧光法,对珠江三角洲河网区水体及鱼体中重金属Cr、Cu、Pb、Fe、Zn、Mn、Ni、Cd、As和Hg含量进行了检测,并以国家地表水环境质量标准（Ⅲ类）及水产品中有毒有害物质限量进行了评价。结果表明,水体中Cr、Pb和Hg为主要污染元素,超标率分别为22.2%、11.1%和5.6%,水体中不同季节Pb和Cr含量变化基本特征为丰水期〉平水期〉枯水期,河网不同江段变化特征不同,这与重金属在水体中的存在形态及受水动力条件影响有关;鱼体中残留的重金属元素有Cr、Pb和As,超标率分别为36.7%、27.1%和6.3%,超标鱼类主要分布于肇庆-富湾及大塘-三水江段。不同鱼类重金属元素残留特征为底层鱼大于中上层鱼,肉食性鱼大于植食性鱼和杂食性鱼。Pb和Cr为珠江三角洲河网区水体及鱼体中重金属污染的主要元素。     

Trace metal concentrations in selected biological,sediment, and water column samples in a Northern New England river

A baseline ecosystem study was undertaken in a relatively non-industrialized New England river to determine trace metal levels of Cr, Cu, Pb and Zn concentrations in water column, sediment, fish, mollusks and aquatic macrophytes. Additional analyses were completed on fish and mollusks for Hg. Results showed metal concentrations in the study area were in general agreement with literature values. Both mollusks and aquatic macrophytes exhibited the highest levels of accumulated metals.     

Evaluation of Different Approaches for Respiratory Quotient Calculation and Effects of Nitrogen Sources on Respiratory Quotient Values of Hydrocarbon Bioremediation

Blechnum orientale L. is a traditional, medicinal fern found in China. To assess the characteristics of heavy metals and As accumulation, the fronds, roots, and the rooting soils of this fern were sampled from urban, suburban, and rural woodlands across Guangdong Province in southern China. The concentrations of As, Cd, Cr, Cu, Hg, Mn, Ni, Pb, and Zn in both the fern and its rooting soils were separately detected by ICP-MS. Contamination levels of woodland rooting soils were also assessed using both a single pollution index and the Nemerow pollution index. Both the metal concentrations and the pollution index showed that soils from urban, suburban, and even rural woodlands were adversely contaminated by As, Cd, Hg, and Pb. Based on transfer factor, B. orientale had good translocation of As, Hg, and Mn, but poor translocation of Cd, Cr, Ni, Cu, Ni, Pb, and Zn from the roots to the fronds. This result suggests that this fern could be an excluder to latter metals. Despite the significantly higher levels of metals in the roots as compared with the fronds, the low bioaccumulation factor suggests that this fern has a weak capacity for metal accumulation.

     

Metal concentrations in muscle of fish from aquatic systems in east Tennessee,U.S.A.

Heavy metal residues (i.e., As, Cd, Cu, Pb, Mn, Hg, and Zn) were determined in striated muscle of 268 fish specimens harvested during a 5-yr period (1980–1984) from several aquatic systems in east Tennessee (U.S.A.). Elevated concentrations of Hg, Mn, and Cd were found in the muscle of fish from several of the aquatic systems studied; concentrations of Hg exceeded the U.S. Food and Drug Administration action level of 1.0 ppm for food intended for human consumption. In general, the concentrations of the other metals in fish muscle were low. Moreover, muscle metal content did not vary among the three fish groups (i.e., game fish, catfish, and rough fish) investigated at any one of the nine sampling stations established. The results of this study are in agreement with the 1978–1979 pilot survey of Young and Blevins (1981) conducted at the same sampling stations. It appears that, in this region of Tennessee, heavy metal contamination of fish tissues has neither improved nor deteriorated during the last 5 yr.     

Metals in stocked Lake Trout (Salvelinus namaycush) in lakes near Sudbury,Canada

Muscle tissue from stocked lake trout (Salvelinus namaycush) from lakes near the smelters at Sudbury, Canada was analyzed for Al, Cu, Fe, Hg, Mn, Ni, and Zn. Metals in tissue were not abnormally high compared with fish from lakes farther away from the smelters. Tissue concentrations of Al, Fe, Mn, and Zn declined significantly after stocking. Because metal concentrations were lower in hatchery water than the study lakes, this decline in tissue metal suggests that diet plays a prominent role in the uptake of these metals in lake trout. Only Hg showed evidence of accumulation to levels that might be harmful for human consumption, and then only in a few older, larger trout. In contrast, tissue Mn and Zn were inversely correlated with trout weight. Fluctuations, independent of age, body weight or time of year, were observed in tissue concentrations of Al, Cu, and Zn. Annual cycles, independent of pH and alkalinity were observed in tissue concentrations of Fe, Hg, Mn, and Ni. Bioaccumulation of metal proved to be an unfounded concern for the rehabilitation of fish populations in lakes near Sudbury.     

Distribution of mercury in the aquatic food web of Onondaga Lake,New York

Historical discharges of mercury (Hg) to Onondaga Lake, New York, have resulted in elevated Hg concentrations in lake fishes. In 1990, a remedial investigation and feasibility study (RI/FS) was initiated to evaluate problems related to Hg and other hazardous substances in the lake. As part of the RI/FS, the distribution of Hg in the aquatic food web was determined to provide input to a site-specific model of Hg cycling and to evaluate potential ecological risks of Hg in the lake. Mercury concentrations were measured in surficial sediments, sediment interstitial water, lake water, phytoplankton, Zooplankton, benthic macroinvertebrates, and fishes (including planktivores, benthivores, and piscivores). The percentage of total Hg accounted for by methyl-Hg (CH₃Hg) generally increased with higher trophic levels, confirming that CH₃Hg is more efficiently transferred to higher trophic levels than is inorganic Hg. Concentrations of total Hg in amphipods and chironomids were closely related to concentrations of total Hg in sediments, suggesting that sediments are a likely source of Hg for benthic macroinvertebrates. Mercury concentrations in edible muscle tissue (fillets) of lake fishes have declined substantially from values found in the early 1970s, reflecting the large reductions in Hg discharges to the lake that have occurred since that time. The CH₃Hg concentrations in fillets and whole bodies of fishes generally were similar, indicating that concentrations in fillets often can provide estimates of concentrations in whole bodies. Methyl-Hg concentrations and bioaccumulation factors increased with higher trophic levels in both the pelagic and benthic components of the lake food web.     

Effects of various cooking processes on the concentrations of arsenic, cadmium, mercury, and lead in foods

The effects of cooking processes commonly used by the population of Catalonia (Spain) on total arsenic (As), cadmium (Cd), mercury (Hg), and lead (Pb) concentrations in various foodstuffs were investigated. All food samples were randomly acquired in local markets, big supermarkets, and grocery stores of Reus (Catalonia). Foods included fish (sardine, hake, and tuna), meat (veal steak, loin of pork, breast and thigh of chicken, and steak and rib of lamb), string bean, potato, rice, and olive oil. For each food item, two composite samples were prepared for metal analyses, whose levels in raw and cooked (fried, grilled, roasted, and boiled) samples were determined by inductively coupled plasma-mass spectrometry (ICP-MS). The highest concentrations of As, Hg, and Pb (raw and cooked samples) were mainly found in fish, with a clear tendency, in general, to increase metal concentrations after cooking. However, in these samples, Cd levels were very close to their detection limit. In turn, the concentrations of metals in raw and cooked meat samples were detected in all samples (As) or only in a very few samples (Cd, Hg, and Pb). A similar finding corresponded to string beans, rice, and olive oil, while in potatoes, Hg could not be detected and Pb only was detected in the raw samples. In summary, the results of the present study show that, in general terms, the cooking process is only of a very limited value as a means of reducing metal concentrations. This hypothetical reduction depends upon cooking conditions (time, temperature, and medium of cooking).     

Use of the mercury cycling model (MCM) to predict the fate of mercury in the Great Lakes

In response to U.S. EPA's proposed Great Lakes water quality criteria for mercury (Hg), a fieldvalidated Hg cycling model (MCM) was used to predict Hg levels in the abiotic and biotic components of Lake Superior and Lake Erie. The U.S. EPA criteria are based on water column Hg concentrations and simple trophic level transfer and, thus, do not consider sediment interactions and water chemistry factors. The model, using data from published reports, was run to simulate a 25 year steady state period. For these simulations, methylmercury (MeHg) represented 5% of total Hg in Lake Erie and 8% of total Hg in Lake Superior. These proportions are roughly 3–5 times lower than U.S. EPA's estimate that MeHg contributes about 25% of total Hg in the water column of the Great Lakes. The predicted median concentrations of total Hg in top-carnivore fish were 0.13 mg/kg in Lake Superior and 0.16 mg/kg in Lake Erie. Predicted median MeHg concentrations in Lake Superior and Lake Erie (water column) were 0.019 and 0.075 ng/L, respectively. For both lakes, most (>55%) of the Hg was partitioned to sediments. Although the MCM simulation does have practical limitations (e.g., lakes are treated as fully-mixed open systems), the results demonstrate that generic assumptions of Hg behavior in all Great Lakes waterbodies are too simplistic.     

Trace Elements in Plankton, Benthic Organisms, and Forage Fish of Lake Moreno, Northern Patagonia, Argentina

The Northern Patagonian Andean range shared by Chile and Argentina has numerous glacial oligotrophic lakes protected in a series of National Parks. Recent baseline surveys indicated that concentrations in muscle and liver tissues from various fish species from across Nahuel Huapi and Los Alerces National Parks in Argentina were comparable or higher than similar fish species from other parts of the world. As a result, Lake Moreno, in Nahuel Huapi National Park, was chosen to investigate multiple element sinks, trends, and transfer in a representative Patagonia aquatic food web. The metals and metalloids Ag, As, Ba, Br, Cs, Co, Cr, Fe, Hg, K, Na, Rb, Se, and Zn were analyzed in three size plankton fractions, submerged macrophytes, biofilm, insect larvae, amphipods, decapods, gastropods (snails), annelids (earthworms), and forage fish. Except for nanoplankton (10–53 μm; small-celled algae, rotifers) and microplankton (53–200 μm; larger algae, ciliates, zooplankton nauplii), which share elemental compositional similarities, each taxon category had its own distinctive compositional pattern, revealed by principal component analysis. Nano- and microplankton tend to be relatively elevated in some metals, including As, Co, Cr, Fe, Hg, Zn, and Rb, followed by biofilm. Shredder-scrapper Trichoptera (caddisflies) have higher concentration of most of the studied elements than other insect larvae taxa, especially carnivorous Odonata (Anisoptera, dragonflies), which were associated with lower elemental contents. Those trends point to an overall tendency for biodiminishing element concentrations with trophic level in the benthos of Lake Moreno.     

Chemical Investigation of Water Resources Around the Yatagan Thermal Power Plant of Turkey

In this work, trace metals such as Hg, Pb, As, Cd, Cu, Fe, Mn and Zn in underground water samples obtained from three wells, an ash-pond and drinking water located near the Yatagan Thermal Power Plant were measured. As, Hg, Cu and Zn contents of the underground water were lower than those reported in the EEC (European Economic Community) and WHO (World Health Organization) guidelines. In contrast, the levels of Fe, Pb, Cd and Mn in some groundwater samples were higher than EEC and WHO guideline values. The trace metal concentrations in coal ash-pond water were observed to be lower than water quality standards with the exception of Pb. The obtained results indicated that the trace metal concentration in the sampled drinking water site did not exceed WHO limits.     

Trace metal composition and speciation in street sediment: Sault Ste. Marie,Canada

Street sediment collected in Sault Ste. Marie, Ontario was examined for trace element composition (As, Cd, Cr, Cu, Fe, Pb, Hg, Ni and Zn) and the metal partitioning to various sediment properties was determined by sequential extraction. Total Ni, Cu, Zn and Pb concentrations exceeded the lowest effect levels specified in the Ontario Provincial Sediment Quality Guidelines for Metals (Environment Ontario, 1992) and derived from bioassay studies. According to these Guidelines, the disposal of such sediment has to be guided by environmental considerations. A significant fraction of these metals was extractable in 0.5 N HCl over a 12-hour period and considered as potentially bioavailable. The major accumulative phases of toxic metals in this sediment are exchangeable, carbonate, Fe/Mn oxides and organic matter but the relative importance of each phase varied for individual metals. Approximately 20% of the total extractable Cd is found in each of these four fractions. Pb, Zn and Mn are predominantly bound to carbonates, Fe/Mn oxides and organic matter. Cu shows a high affinity for organic matter and to a lesser extent for carbonates. Elevated levels of Cd, Pb, Cu, Zn, Mn and Cr in the exchangeable and/or soluble phase suggest that sediment associated metals, mobilised from streets in Sault Ste. Marie during runoff and snowmelt, would adversely impact water quality in the receiving waters. However, large fractions of the total metal load are associated with coarser particles which are unlikely to be transported through the drainage system into receiving waters.     

Facts and fallacies concerning mercury uptake by fish in acid stressed lakes

Concerns about Hg contamination of fish have changed in emphasis from Hg-contaminated systems to more remote and apparently unpolluted systems. For remote lakes, a negative relationship between lake pH and Hg in fish has been demonstrated, implying an effect on Hg uptake from lake acidification. Though this relationship was discussed, and hypotheses put forward concerning the possible mechanisms 8 yr ago, the factors regulating Hg uptake by aquatic biota are still poorly understood. Several recent studies have prompted workers to observe that frequently cited concepts about processes affecting Hg accumulation and cycling are in fact over-simplifications. This review attempts to synthesize and clarify the present state of knowledge. We critically evaluate evidence for a number of controlling factors in the context of the concentrations, the chemical species and the biological uptake processes for Hg. The factors include: trophic status and organic content of water, food chain transfer and biomagnification of Hg, organism age and size effects, feeding strategies, biological and chemical methylation, concentration of cations including H⁺ and Ca²⁺ and the immediate source of Hg.     

Bioaccumulation of mercury and methylmercury

The factors controlling the accumulation of mercury in fish are poorly understood. The oft invoked lipid solubility of MMHg is an inadequate explanation because inorganic Hg complexes, which are not bioaccumulated, are as lipid soluble as their MMHg analogs and, unlike other hydrophobic compounds, MMHg in fish resides in protein rather than fat tissue. We show that passive uptake of the lipophilic complexes (primarily HgCl₂ and CH₃HgCl) results in high concentrations of both inorganic and MMHg in phytoplankton. However, differences in partitioning within phytoplankton cells between inorganic mercury — which is principally membrane bound — and MMHg — which accumulates in the cytoplasm — lead to a greater assimilation of MMHg during Zooplankton grazing. Most of the discrimination between inorganic and MMHg thus occurs during trophic transfer while the major enrichment factor is between water and phytoplankton. As a result, MMHg concentrations in fish are ultimately determined by water chemistry which controls MMHg speciation and uptake at the base of the food chain.     

Effect of submerged macrophytes on metal and metalloid concentrations in sediments and water of the Yunnan Plateau lakes in China

Purpose

Submerged macrophytes have an ability to absorb metals and metalloids either from the sediments via the roots, from the water by the leaves, or from both sources. The objectives of this study were (1) to test the hypothesis that metal and metalloid concentrations in water and sediments from sampling sites with submerged macrophytes are significantly lower than those from sampling sites without submerged macrophytes, (2) to explore the accumulation potential for metals and metalloids of different submerged macrophyte species, and (3) to discuss the relationships among submerged macrophytes, water, and sediments in the Yunnan Plateau lakes.

Materials and methods

Twenty Yunnan Plateau lakes with different trophic levels were selected. Concentrations of 16 metals and metalloids (Al, As, Ba, Cd, Co, Cr, Cu, Fe, Li, Mn, Mo, Ni, Pb, Se, Sr, and Zn) in submerged macrophytes, water, and sediments were determined by using ICP-AES. Relationships among metal and metalloid concentrations in water, sediments, and submerged macrophytes were carried out by Pearson correlation analysis. The enrichment factor was calculated as the ratio between the concentration of metals and metalloids in a sediment sample and the soil background value.

Results and discussion

No significant differences were found in metal and metalloid concentrations in water and sediments between sampling sites with submerged macrophytes and sampling sites without submerged macrophytes. Moreover, lake water and sediments were mainly contaminated by As, Cr, and Pb. Potamogeton distinctus is a hyperaccumulator of Fe according to the threshold value for Fe hyperaccumulation. Many significantly positive correlations were found among metals and metalloids in submerged macrophytes due to co-accumulation. We found significant correlation between Cr in submerged macrophytes and Cr in water, and strong positive correlations between As, Cd, and Cu in submerged macrophytes and As, Cd, and Cu in corresponding sediments in the Yunnan Plateau lakes.

Conclusions

Submerged macrophytes have no significant effects on metal and metalloid concentrations in sediments and water in all the 20 Yunnan Plateau lakes in the study. However, further studies are necessary to understand the interactions of metals and metalloids in submerged macrophytes, water, and sediments.

     

A mercury model used for assessment of dredging impacts

The effects of dredging of contaminated sediments on the mercury (Hg) concentrations of prey and predatory fish were calculated for the Kokemäenjoki River and its estuary in Western Finland. The accumulation of Hg in fish is controlled by the Hg concentrations in water, zooplankton, zoobenthos and by suspended solids. Hg is accumulated into fish mainly through food web, eg. from perch (Perca fluviatilis) as prey and to pike (Esox lucius) as predator. In addition to dredging, temperature and flood situations have also increased the Hg accumulation and release from the bottom sediments. The validity of the model has been tested with data recorded from earlier dredgings. Thereafter the model has been used to predict the Hg levels caused by dredging planned upstream in the river. The predictions are supported by the concentrations of total mercury (Tot.Hg) and methyl mercury (MeHg) measured in water and in sediments under several flow conditions. As a result, 30 % increase of Hg in pike — from 0.8 to 1.05 mg/kg —was expected. This was too high, and therefore dredging was not included in the final plan for flood protection.     

5种重金属暴露对斑马鱼呼吸运动的影响

为了探讨外源性重金属暴露对鱼类呼吸反应的影响,利用鱼类的呼吸参数的变化来预警水体污染。尝试以斑马鱼为实验生物,进行了5种重金属离子对斑马鱼的急性毒性实验;应用生物早期预警系统（BIO-SENSOR 7008）,研究了斑马鱼在不同重金属浓度暴露1 h后的呼吸反应变化情况及预警结果。结果表明,Hg^2＋、Cu^2＋、Cd^2＋、Zn^2＋、Pb^2＋等重金属对斑马鱼的96 hLC50分别为0.14、0.174、6.497、44.48、116.432 mg.L-1;安全浓度分别为0.014、0.017、0.65、4.5、11.6 mg.L^-1;应用呼吸参数的预警浓度分别为0.08、0.08、4.8、7.5、105 mg.L^-1。其中系列浓度Hg2＋暴露下斑马鱼呼吸频率和呼吸强度都显著升高（F=2.75,P〈0.05;F=28.95,P〈0.01）;Cu^2＋、Cd^2＋等暴露对斑马鱼呼吸频率和呼吸强度先升高再降低（P〈0.01）;Zn^2＋暴露则对斑马鱼呼吸运动具有显著抑制作用（P〈0.01）;而Pb2＋对斑马鱼呼吸强度影响较小（P〉0.05）。斑马鱼呼吸参数作为生物监测指标来预警水体Hg^2＋、Cu^2＋、Zn^2＋等重金属污染较为敏感。     

Anthropogenic heavy metal inputs to lowland river systems,a case study. The River Stour,U.K.

Surface waters, sediments and interstitial waters were collected from 9 sites of the River Stour, UK, during June 1987. The aim was to identify the sources of EC List I (Hg, Cd) and List II (As, Cr, Cu, Ni, Pb, Zn) metals and metalloids to this lowland river system and to assess the magnitude of metal enrichment. The study reach spanned some 60 km, traversing rural and urban landscapes. Results indicate that the larger municipal sewage treatment works (STW), which receive industrial effluents, were the major source of metals, but smaller rural works also exerted some contaminative influences. Metal concentrations in bottom sediments, displayed 2–11 fold increases over catchment background levels with maximum loadings coinciding with discharges from the Great Cornard and Sudbury STWs. Elevations in water column metal concentrations were also apparent downstream of point source inputs, but concentrations were consistently below designated ‘Water Quality Standards’. Distance from the point source, sediment texture and hydrology appeared to be the main factors responsible for the observed distribution of metals within this river system.     

Aquatic mosses for the detection and follow-up of accidental discharges in surface waters

Aquatic mosses have been used to study four accidental discharges of the heavy metals Cd, Zn and Hg or the chlorinated hydrocarbons pentachlorophenol (PCP) and lindane in highly contrasting river types. Hg, PCP and lindane moss concentrations reached 880, 4500 and 350 ng g^?1, respectively. In the case of Cd and Zn, water samples and transferred bioindicators were taken simultaneously throughout an accidental discharge. The very high dissolved metal concentrations reached during this accident (9 mg L^?1 Zn, 90 μg L^?1 Cd) induced accumulation by the mosses of up to 28 mg g^?1 for Zn and 225 μg g^?1 for Cd. The increase in concentrations in the mosses was as rapid and substantial as in the water, the time lag due to accumulation kinetics being almost zero. On the other hand, the memory effect enabled mosses to retain marked evidence of Cd, Zn, Hg, PCP and lindane up to 13 days after the accident when difference from background levels can hardly be detected in the water. The four case studies, which killed fish, but not the mosses, show that the previously established scales of quality based on the analysis of aquatic mosses are well suited to estimating the potential damage to the aquatic ecosystem as a whole.     

Effects of iron-ore mining and processing on metal bioavailability in a tropical coastal lagoon

Background, aim, and scope

In water systems, water quality and geochemical properties of sediments determine the speciation of trace metals, metal transport, and sediment–water exchange, influencing metal availability and its potential effects on biota. Studies from temperate climates have shown that iron-ore mining and tailing wastewaters, besides being a source of trace metals, usually show high levels of dissolved ions and particulate suspended matter, thus having the potential of indirectly changing metal bioavailability. For the first time in the tropics, we identified the effects of iron-ore mining and processing on metal bioavailability in a coastal lagoon. With an extensive sampling scheme, we investigated the potential sources of metals; the links among metal levels in water, sediments, and invertebrates; and the contrasting effects on metal speciation and bioavailability.

Methodology

The metals Fe, Mn, Al, Cr, Zn, Cu, Ni, Pb, Cd, Hg, and As were measured in water, sediments (surface and profiles), and invertebrates from Mãe-Bá Lagoon and in the sites directly influenced by the mining operations (tailing dams and nearby rivers). In addition, samples from two other lagoons, considered pristine, were analyzed. The study area is located in the southeast of Brazil (Iron Quadrangle Region and a coastal area of Espírito Santo State). General water characteristics included pH, dissolved organic carbon, alkalinity, and anion composition. Water metal speciation was assessed by a speciation model (Chemical Equilibria in Aquatic Systems). Grain-size distribution, organic carbon, carbonate, and acid volatile sulfide (AVS) were determined in sediments. Statistical methods included comparison of means by Mann–Whitney test, ordination and correlation analyses, and analysis of regression for geochemical normalization of metals with grain size.

Results and discussion

The dissolved metal concentrations, the total metal levels in sediments, and the normalization based on the fine sediment fraction showed that the mining operations constitute potential sources of Fe, Mn, Cr, Cu, Ni, Pb, As, and Hg to Mãe-Bá Lagoon. However, trace metal availability was reduced because of increased pH, hardness, and sulfide content (356 μmol/g) in the sites influenced by the mining. The lagoon showed similar water chemistry as in the mining sites, with metal bioavailability further decreased by the presence of dissolved organic carbon and chloride. Although AVS levels in the lagoon were low (0.48–56 μmol/g), metal bioavailability was reduced because of the presence of organic matter. Metal levels in invertebrates confirmed the predicted low metal bioavailability in Mãe-Bá Lagoon. The lagoon was considered moderately contaminated only by Hg and As.

Conclusions

The iron-ore mining and processing studied here constitute potential sources of metal pollution into the tropical lagoon. Contrary to expectations, however, it also contributes to reducing the overall metal bioavailability in the lagoon.

Recommendations and perspectives

These findings are believed to be useful for evaluating metal exposure in a more integrated way, identifying not only the sources of pollution but also how they can affect the components involved in metal speciation and bioavailability in water systems, leading to new insights.