The effect of solvents on metal ion adsorption by the alga Chlorella vulgaris

The dead dried alga, Chlorella vulgaris, was used for metal ion sequestering. The uptake of each of Cu(II), Cd(II), Fe(III), and Sn(IV) from their aqueous solutions decreased upon reuse of the biomass. Introducing mixed ethanol/water (50% v/v) metal ion solutions in batch systems enhanced the metal uptake of the exhausted biomass by 90% for iron, 40% for tin and only 14% for cadmium. In the column system, 20% v/v ethanol/water proved to be superior to acetone/water and isopropanol/water metal solutions in enhancing metal uptake. This increase in uptake offers a new method for regeneration of the algal capacity to remove metal ions from their solutions. Mossbauer results of iron and tin loaded algae from aqueous and mixed ethanol water solutions exhibited the characteristic doublet for (FeCl4-) at 0.350-0.565 mms(-1) respectively and the major doublet for inorganic Sn(IV) moieties at -0.217 to -0.365 mms(-1) respectively, excluding the possibility of microprecipitation of iron and tin, which is expected at such high concentrations of metals in the alga.     

Acceleration of catalase and peroxidase activities in Lemna minor L. and Allium cepa L. in response to low levels of aquatic mercury

The purpose of this study was to assess certain physiological responses of Lemna minor L. (duckweed) and Allium cepa L. (onion) to aquatic mercury at low concentrations. Following a 96-h exposure of plants to nutrient medium contaminated with known levels of mercuric chloride (HgCl(2)), 0.001 to 4 mg litre(-1) (0.0007 to 2.95 mg Hg litre(-1)) or methyl mercuric chloride (MeHgCl(2)), 0.0001 to 0.1 mg litre(-1) (0.0007 to 0.07 mg Hg litre(-1)), the physiological endpoints measured were the growth of fronds (Lemna minor) or roots (Allium cepa), and catalase and peroxidase activities in both plant assays. The EC(50) for HgCl(2) on the basis of the growth curve of Lemna minor was found to be 2.1 mg litre(-1). HgCl(2) and MeHgCl(2) were lethal to L. minor at concentrations of 4 and 0.01 mg litre(-1), respectively. The range of low concentrations that accelerated growth as well as enzymic activities in L. minor was 0.004 to 0.04 mg litre(-1) for HgCl(2) and 0.001 mg litre(-1) for MeHgCl(2). HgCl(2) and MeHgCl(2) induced maximum enzymic activity in Lemna fronds at concentrations of 0.008 and 0.0005 mg litre(-1), respectively. In Allium roots, catalase activity was accelerated at all the concentrations of HgCl(2) (0.001-2 mg litre(-1)) and MeHgCl(2) (0.0001-0.1 mg litre(-1)) tested. The activity of peroxidase was, however, accelerated by HgCl(2) at concentration range 0.01-1.0 mg litre(-1), or by MeHgCl(2) at 0.001 mg litre(-1). The concentrations of HgCl(2) and MeHgCl(2) that induced the highest enzymic activity in Allium roots were 0.05 mg litre(-1) and 0.001 mg litre(-1), respectively.     

Waste Fe(III)/Cr(III) hydroxide as adsorbent for the removal of Cr(VI) from aqueous solution and chromium plating industry wastewater

Fe(III)/Cr(III) hydroxide, a waste material from the fertilizer industry, has been used for the adsorption of Cr(VI) from aqueous solution, over a range of initial metal ion concentrations (5-30 mg litre(-1)), agitation times (1-180 min), adsorbent dosages (100-1200 mg per 50 ml), temperatures (24, 29 and 38 degrees C) and pH values (4.5-10). The adsorption of Cr(VI) increased with the initial concentration of Cr(VI) and with temperature. The process of uptake follows both the Langmuir and the Freundlich isotherm models. The applicability of Lagergren and empirical kinetic models has also been investigated. Almost quantitative removal of Cr(VI) at 10 mg litre(-1) in a 50-ml solution by 500 mg of adsorbent was found at an equilibrium pH of 5.6. The efficiency of chromium removal was also tested using wastewater from the chromium plating industry.     

Heavy metal contamination from mining sites in South Morocco: 1. Use of a biotest to assess metal toxicity of tailings and soils

Our work was conducted to investigate the heavy metal toxicity of tailings and soils collected from five metal mines located in the south of Morocco. We used the MetPAD biotest Kit which detects the toxicity specifically due to the heavy metals in environmental samples. This biotest initially developed to assess the toxicity of aquatic samples was adapted to the heterogeneous physico-chemical conditions of anthropogenic soils. Contrasted industrial soils were collected from four abandoned mines (A, B, C and E) and one mine (D) still active. The toxicity test was run concurrently with chemical analyses on the aqueous extracts of tailings materials and soils in order to assess the potential availability of heavy metals. Soil pH was variable, ranging from very acidic (pH 2.6) to alkaline values (pH 8.0-8.8). The tailings from polymetallic mines (B and D) contained very high concentrations of Zn (38,000-108,000 mg kg(-1)), Pb (20,412-30,100 mg kg(-1)), Cu (2,019-8,635 mg kg(-1)) and Cd (148-228 mg kg(-1)). Water-extractable metal concentrations (i.e., soil extracts) were much lower but were highly toxic as shown by the MetPAD test, except for soils from mines A, E and site C3 from mine C. The soil extracts from mine D were the most toxic amongst all the soils tested. On this site, the toxicity of soil water extracts was mainly due to high concentrations of Zn (785-1,753 mg l(-1)), Cu (1.8-82 mg l(-1)) and Cd (2.0-2.7 mg l(-1)). The general trend observed was an increase in metal toxicity measured by the biotest with increasing available metal contents in tailings materials and soils. Therefore, the MetPAD test can be used as a rapid and sensitive predictive tool to assess the heavy metal availability in soils highly contaminated by mining activities.     

Unavailability of polynuclear aromatic hydrocarbons from coal particles to the eastern oyster

The accumulation by oysters of polycyclic aromatic hydrocarbons (PAH) from coal dust entering the estuarine environment has been postulated in the vicinity of coal transfer operations. Oysters Crassostrea virginica were exposed to coal dust plus 15 day leachate at concentrations of 10 mg litre(-1) and 1 mg litre(-1) coal dust for 28 days in a flow-through test system. Potential effects of the exposures were measured by comparing the uptake of PAH and the growth of the exposed animals versus control groups. Oysters sampled at 7, 14 and 28 days did not exhibit an increase in PAH body burden over control animals provided the guts were first purged of particulates. Even at the high test concentrations (10 mg litre(-1)), no effect of the exposure on shell growth was observed.     

Benthic macroinvertebrate community structure in 20 streams of varying pH and humic content

The structure of stream benthic macroinvertebrate communities in relation to pH and humic content was studied in 20 second and third-order forest streams in southern Sweden. Streams varied in pH from 4.2 to 8.0, and in humic content from a colour of 5 to 1200 mg Pt litre(-1). There was a positive relationship between pH and species richness, with a discontinuity occurring at pH approximately 5.7. At pH > 5.7, species richness decreased with increasing colour. At pH < 5.7 there was a positive correlation between species richness and humic concentration up to a colour of about 200-300 mg Pt litre(-1). this may be explained by high concentrations, 0.4-0.9 mg litre(-1), of labile monomeric Al occurring in the low coloured acid streams. In streams with a colour > 200 mg Pt litre(-1) labile monomeric Al was less than 0.2 mg litre(-1). There was no significant change in species richness above this threshold, but a shift in species composition towards a dominance of Plecoptera and Chironomidae. This threshold model seems to explain the observed differences in stream benthic community structure better than a simple linear relationship with pH or humic content.     

Lethal and sublethal toxicity of 4-nonylphenol to the common mussel (Mytilus edulis L.)

The toxicity of nonylphenol to the common mussel (Mytilus edulis L.) has been determined in both semistatic and continuous flow test systems. The LC50 values obtained were for 96 h, 30 mg litre(-1); 360 h, 0.5 mg litre(-1); and 850 h, 0.14 mg litre(-1). Sublethal effects, manifested as decreased byssus strength and change of scope for growth, were obtained at a concentration as low as 0.056 mg litre(-1). Fertilization and early developmental success were not affected at the highest concentration tested (0.2 mg litre(-1)).     

An investigation of the impact of afforestation on stream-water chemistry in the Loch Dee catchment, SW Scotland

The impact of conifer afforestation on stream-water chemistry was investigated in the acidified catchment of Loch Dee, SW Scotland. Long-term trends in stream-water chemistry were evaluated during a period of forest growth from age 6 to 17 years. A significant increase was observed for pH (0.2 units) and a significant decline for aluminium (0.05 mg litre(-1)), sulphate (1.2 mg litre(-1)) and nitrate (0.02 mg litre(-1)) concentrations. The long-term decrease in stream-water acidity was ascribed to the marked reductions in sulphur depositions during the 1970s and early 1980s. There was no evidence that this response had been attenuated by afforestation, the improvements in stream-water chemistry being of a similar magnitude to those recorded in nearby moorland lochs and exceeding that in an adjacent moorland-catchment stream. The lack of a clear forest acidification effect is consistent with deposition-model estimates which show the increased scavenging of occult and dry deposition by the growing forest to be small at this site (相似文献   

Abundance and population structure of perch (Perca fluviatilis L.) in some acidic Norwegian lakes

Abundance (catch per unit effort, n=3752) and population structure of perch Perca fluviatilis were studied in 30 acidic Norwegian lakes with relation to pH (4.3-5.9), calcium (0.41-2.44 mg litre(-1)), labile aluminium (24-255 microg litre(-1)) and total organic carbon (TOC, 1.7-13.8 mg C litre(-1)). Standard series of bottom gill-nets were used to sample fish populations. A multiple regression analysis showed that abundance was significantly correlated to TOC (P<0.05) and, to a smaller extent, to the Ca in lakes with concentrations between 0.41 and 1.70 mg litre(-1) (P=0.07). The lakes which were inhabited by pike were excluded from the analysis. Recruitment failure seems to be the main cause of reductions in perch numbers in the lakes studied. However, high mortality among adult individuals was also evident, and an episode of fish kill was observed in one of the lakes.     

Effects of ammonia on periphytic communities

Laboratory tests were conducted to evaluate the chronic effects of ammonia on periphytic communities. Species richness of the protozoan component of these communities was affected at un-ionized ammonia concentrations of 相似文献   

Effects of metals on life cycle parameters of the earthworm Eisenia fetida exposed to field-contaminated, metal-polluted soils

Two control and eight field-contaminated, metal-polluted soils were inoculated with Eisenia fetida (Savigny, 1826). Three, 7, 14, 21, 28 and 42 days after inoculation, earthworm survival, body weight, cocoon production and hatching rate were measured. Seventeen metals were analysed in E. fetida tissue, bulk soil and soil solution. Soil organic carbon content, texture, pH and cation exchange capacity were also measured. Cocoon production and hatching rate were more sensitive to adverse conditions than survival or weight change. Soil properties other than metal concentration impacted toxicity. The most toxic soils were organic-poor (1-10 g C kg(-1)), sandy soils (c. 74% sand), with intermediate metal concentrations (e.g. 7150-13,100 mg Pb kg(-1), 2970-53,400 mg Zn kg(-1)). Significant relationships between soil properties and the life cycle parameters were determined. The best coefficients of correlation were generally found for texture, pH, Ag, Cd, Mg, Pb, Tl, and Zn both singularly and in multivariate regressions. Studies that use metal-amended artificial soils are not useful to predict toxicity of field multi-contaminated soils.     

The acute toxicity of phenol and unionized ammonia, separately and together, to the ephemeropteran Baetis rhodani (Pictet)

The acute toxicity of phenol and ammonia, singly and in combination, to larvae of the ephemeropteran, Baetis rhodani, was examined using a computerized continuous flow system in the laboratory. The 24 h LC50 values (with 95% confidence intervals) were calculated to be 29.9 (17.3-51.5) mg phenol litre(-1) and 8.2 (2.0-33.0) mg un-ionized ammonia litre(-1). When phenol and ammonia were together in low concentration (< 20 mg litre(-1) and < 3 mg litre(-1) [un-ionized], respectively), they expressed their toxicity additively, but at higher concentrations they behaved in a greater-than-additive manner. When the 24 h LC50 values were used to predict the toxicity of a coking plant effluent, containing principally ammonia and phenol, it was found that the B. rhodani larvae died quicker than expected indicating the presence of other toxic chemicals. This exemplifies the value of using direct toxicity assessments to detect the presence of unknown toxicants.     

The impact of aluminium on green algae isolated from two hydrochemically different headwater streams, Bavaria, Germany

Two strains of green algae (Scenedesmus sp. and Chlorella sp.) have been isolated from two headwater streams differing in stream chemistry (Eger river: acidic, low alkalinity; Püttlach river: slightly alkaline, high alkalinity). In this study the growth response of these indigenous algae to increased concentrations of aluminium (Al) is investigated. A semi-continuous culture technique was used for Al-toxicity studies. Algal response was determined by calculating growth rates from turbidity and cell counts. Those Al-species which are well known to be toxic were estimated by equilibrium calculations using the WATEQ computer program (Truesdall & Jones, 1973). The pH-value of the culture media was usually pH=5, except for one of the test series. Tested concentrations ranged from c=4 to 220 micromol litre(-1). The isolated strains of green algae were highly sensitive to increased Al-concentrations. The strain isolated from the Püttlach river was more sensitive than the Eger river algae. A total growth inhibition occurs at Al-concentrations of c=4 micromol litre(-1) if the whole Al was added at once. If Al was added gradually into the growth media the response of the algae was delayed. This is due to Al-enrichment in cells. In our long term toxicity studies, growth inhibition occurs even at nearly neutral pH-conditions (pH=6.5) although Al toxicity is expected at pH-values less than pH=5.5. This new result confirms the need of long-term studies in continuous cultures under simulated natural conditions. This might be the only way to achieve valid conclusions about the fate and the toxicity of environmental pollutants.     

The effect of chronic toxicity of copper on the activity of Balbiani rings and nucleolar organizing region in the salivary gland chromosomes of Chironomus ninevah larvae

The effect of copper on the activity of Balbiani rings (BR1 and BR2) and nucleolar organizing region (NOR) in chromosome IV of the salivary gland of the 4th instar larvae of Chironomus ninevah has been investigated. Sublethal concentrations, i.e. 0.02, 0.1, 0.15 and 0.2 mg litre(-1) suppress the activity of BR1, and are statistically significant. The same concentrations reduced the activity of BR2 and NOR, but without significant differences, except 0.1 mg litre(-1) which was significant. The purpose of this work was to evaluate the effect of chronic toxicity of Cu(2+) on the expression of gene activity of midge salivary gland chromosomes Although there may be many more aquatic organisms that are more sensitive to copper, this midge was selected as a biological indicator species because of its association with benthic sediments.     

The mixing zone between limed and acidic river waters: complex aluminium chemistry and extreme toxicity for salmonids

When liming running waters, dosers must compensate for different flow and water qualities and for the downstream inflow from acid tributaries which creates mixing zones. At a certain point in the mixing zone, a constant or fluctuating chemical disequilibrium will appear due to transformation processes. In laboratory assays, over-saturated solutions of aluminium with ongoing active precipitation of aluminium have been found to be especially toxic to fish. Recent experiments in a mixing zone in the limed River Audna, Norway, have confirmed this phenomenon. Atlantic salmon (Salmo salar L.) and sea trout (Salmo trutta L.) smolts were exposed to acid and limed waters and mixtures of the two waters downstream from the point of connection. In the acid tributary (mean values: pH=4.8, Ca=1.3 mg litre (-1)), Ali 236 microg litre(-1)=), LT5) was 22 and 40 h for Atlantic salmon and sea trout, respectively. In the mixing zone (pH=4.8-6.5, Ca=1.2-3.2 mg litre(-1), Ali=50-240 microg litre(-1)), LT50 was 7 h for both species, masking the normal species difference in tolerance. Osmoregulatory failure and rapid gill lesions occurred in the mixing zone as an effect of the transformation of Al into high molecular weight precipitating species. This is the first documentation of the existence of such highly toxic mixing zones in nature, and the results clearly show that the mixing zone is even more toxic to fish than acid aluminium-rich waters.     

Microbial transformation of thiocyanate

Thiocyanate is present in appreciable concentration in coal carbonization wastewater along with other toxicants like phenols, cyanide, sulphide and ammonia. This paper encompasses studies on biodegradation of thiocyanate by a microbial consortium obtained from a biological treatment plant receiving coal carbonization wastewater. Effects of secondary toxicants and growth stimulants on thiocyanate oxidation by the consortium, and thiocyanate transformation in actual and partially treated coal carbonization waste, have also been studied. Results indicate that the consortium can degrade thiocyanate up to 1400 mg litre(-1) in batch culture with 10 mg litre(-1) of initial inoculum within a period of 6 days. Phenol above 500 mg litre(-1) and cyanide at 10 mg litre(-1) completely inhibits thiocyanate oxidation. Sulphide at 32 mg litre(-1) and ammonia at 4000 mg litre(-1) at neutral pH prolongs thiocyanate oxidation from 3 to 6 days and from 4 to 7.5 days, respectively. These studies reveal that elimination of phenolics, their oxidized products, ammonia, cyanides and sulphides is a pre-requisite for effective thiocyanate removal from the waste by the consortium. Bacteria of the genera Pseudomonas and Bacillus dominate the consortium.     

The influence of plantation forestry on the pH and aluminium concentration of upland welsh streams: a re-examination

Previous studies relating forest presence to stream acidity and aluminium concentration were based on small numbers of catchments, often precluding the elimination of confounding influences on stream chemistry, such as geology or soil type. Spatial patterns in aluminium and pH data from 113 Welsh catchments of contrasting land use were therefore analysed in three different ranges of acid sensitivity (< 10, 10-15, 15-25 mg CaCO(3) litre(-1) total hardness). In each range, pH declined and aluminium increased significantly with increasing percentage forest cover. There was no evidence that the relationships reflected a spurious effect of forest location. Where aluminium concentrations were elevated under forest in a sub-set of 13 streams, aluminium was present predominantly in the labile form, most toxic to fish. Regressions of pH and aluminium on percentage forest cover provide a useful method of assessing the amount of forest in Welsh catchments which might give rise to given chemical conditions (e.g. pH <6, Al > 80 microg litre(-1)), though some difficulties are likely in accurately specifying the conditions desirable for fish or other biota.     

Effects of the insect growth regulator (S)-methoprene on survival and reproduction of the freshwater cladoceran Moina macrocopa

This study examines the acute and chronic effects of the insecticide (S)-methoprene on the survival and reproduction of the freshwater cladoceran Moina macrocopa. In laboratory toxicity tests, the 24- and 48-h LC50 values for (S)-methoprene were 0.51 and 0.34 mg litre(-1), respectively. Survival, longevity and fecundity were reduced at 0.05 mg litre(-1) and higher concentrations. At 0.005 and 0.01 mg litre(-1), longevity and fecundity increased slightly as compared to control animals. If environmental concentrations of methoprene do not exceed 0.05 mg litre(-1), as is generally the case, application of this insecticide is unlikely to induce detrimental effects on natural cladoceran populations. The stimulatory effect of very low levels of methoprene on reproductive performance is consistent with the hypothesis of a regulatory role of juvenile hormone-like compounds in crustacean reproduction.     

Biological variation in sensitivity to N-heterocyclic PAHs; effects of acridine on seven species of micro-algae

The toxicity of the nitrogen (N) heterocyclic polyaromatic hydrocarbon (PAH) acridine was tested for seven species of microalgae: Scenedesmus acuminatus, Selenastrum capricornutum, Chlamydomonas eugametos, Staurastrum chaetoceras, Staurastrum manfeldtii, Navicula salinarum and Nitzschia sigma. The effect of acridine on the algae was studied in a 96-h growth test, in which growth rates were determined using cell numbers and biovolume. The obtained EC50 values (for growth rates based on cell numbers) ranged from 0.08 mg litre(-1) for N. sigma to 0.78 mg litre(-1) for C. eugametos and N. salinarum. Effect concentrations based on biovolume were slightly higher for most species. Metabolism of acridine was observed for one species (S. capricornutum), but this capacity did not result in a very different tolerance. Acridine toxicity was neither related to taxonomical background (green algae versus diatoms) nor to original habitat of the species (planktonic or benthic, eutrophic or oligo-mesotrophic). The presence of near-UV radiation during the incubation might explain the higher toxicity of acridine than is expected on basis of QSAR derived narcotic toxicity.     

Trout farm effluents: characterization and impact on the receiving streams

Effluents from three rainbow trout (Oncorhynchus mykiss) farms located in Northern Portugal were characterized and their impact on the receiving streams was evaluated. Mean fish productions in the studied fish farms were 15, 55 and 500 t of trout per year, respectively. The feeding water was abstracted from Fornelo, Inha and Coura Rivers, at flow rates ranging from 1.2 (15 t year(-1) fish farm) to 4.8 litre s(-1) per ton annual fish production (500 t year(-1) fish farm). As the water flows through the farms, net variations in the chemical characteristics were observed: a mean reduction in the dissolved oxygen (DO) concentration between 0.7 and 2.4 mg litre(-1); mean increases between 1.9 and 3.2 mg CaCO3 litre(-1) for total alkalinity, between 0.9 and 14 mg litre(-1) for BOD5, between 0.27 and 1.46 mg litre(-1) for ammonia nitrogen (NH4-N), between 0.060 and 0.579 mg litre(-1) for soluble phosphorus (PO4-P) and less than 16 mg litre(-1) for suspended solids; variations in the pH value and nitrate nitrogen concentration were not statistically significant (p<0.05). At the 500 t year(-1) fish farm it was also possible to detect net increases of total hardness (3.2 mg CaCO3 litre(-1)), electric conductivity (19 mS cm(-1)) and permanganate value (3.6 mgO2 litre(-1)). At the other farms net variations in these parameters were not significant. Net mass flow variations reported to the annual fish production are presented. The DO mass flow decreased, on average, between 255 and 549 g t(-1) of fish per day. The mean daily BOD5 increase ranged from 353 to 1510 g t(-1) of fish. The corresponding ranges for the other parameters were 105-157 g t(-1) for NH4-N, 24-62 g t(-1) for PO4-P, 348-1035 g CaCO3 t(-1) for total alkalinity and 224 x 10(6)-506 x 10(6) t(-1) for mesophilic bacteria. Daily net variations of suspended solids, total hardness, electric conductivity and permanganate value were below 1753 g t(-1), 342 g CaCO3 t(-1), 2081 mS cm t(-1) and 392 gO2 t(-1), respectively. Longitudinal concentration profiles for the most relevant parameters show the impact of the effluent discharges on the physico-chemical and bacteriological river water quality downstream from the trout farms. Analyzing the situations from a purely chemical point of view, the polluted stretches were 3, 5 and 12 km long downstream from the effluent discharges, respectively. The microbiological contamination extended over longer distances.