Bioaccumulation and critical body residue of PAHs in the amphipod,Diporeia spp: additional evidence to support toxicity additivity for PAH mixtures

Polycyclic aromatic hydrocarbons (PAHs) are considered to act additively when exposed as congener mixtures. Additive internal concentrations at the site of toxic action is the basis for recent efforts to establish a sum PAH guideline for sediment-associated PAH toxicity. This study determined the toxicity of several PAH congeners on a body residue basis in Diporeia spp. These values were compared to the previously established LR(50) value for a PAH mixture based on the molar sum of PAH congeners and demonstrated similar LR(50) values for individual PAH. These results support the contention that the PAH act at the same molar concentration whether present as individual compounds or in mixture. Aqueous exposures were conducted for 28 d, and the water was exchanged daily to maintain the exposure concentration. The concentration in the exposures declined by an average of 22% between water exchanges across all compounds, and ranged from 11% to 32%. The toxicokinetics were determined using both time-weighted-average (TWA) and time-variable water concentrations and were not statistically different between the two source functions. Toxicity was determined for both mortality and immobility (failure to swim on prodding) and on both a TWA water concentration and a body residue basis. The LC(50) values ranged from 1757 microg l(-1) for naphthalene after 10 d exposure to 79.1 microg l(-1) for pyrene after 28 d exposure, and the EC(50) ranged from 1587 microg l(-1) for naphthalene after 10 d exposure to 38.2 microg l(-1) for pyrene after 28 d exposure. The LR(50) values for all congeners at all lengths of exposure were essentially constant and averaged 7.5+/-2.6 micromol g(-1), while the ER(50) for immobility averaged 2.6+/-0.6 micromol g(-1). The bioconcentration factor declined with increasing exposure concentration and was driven primarily by a lower uptake rate with increasing dose, while the elimination remained essentially constant for each compound.     

Evidence for a seasonal fluctuation of arsenic in New Zealand's longest river and the effect of treatment on concentrations in drinking water

A year-long survey, with samples collected weekly, was conducted to estimate long-term average concentrations of arsenic in treated and untreated drinking water for the city of Hamilton, New Zealand. The average concentration of arsenic in Waikato River water at Hamilton before processing was found to be (32.1 +/- 3.7) microg litre(-1), about three times above the new WHO limit of 10 microg litre(-1). However, full conventional water treatment effects a five-fold reduction in arsenic concentrations in drinking water to a level which meets the new standards of (6.2 +/- 0.8) microg litre(-1). The results of both this study and retrospective analysis of archived data suggest that total arsenic concentrations in the Waikato River are likely to follow a regular seasonal variation, being about 10-25 microg litre(-1) higher in the summer months. Changes in river flow rates have an almost negligible effect on the summer peak and winter trough; it is proposed that most of the variation in total arsenic concentrations may be due to the seasonal conversion of arsenic in the river sediments to more soluble forms.     

Arsenic species and chemistry in groundwater of southeast Michigan

Groundwater samples, taken from 73 wells in 10 counties of southeast Michigan in 1997 had arsenic concentrations in the range of 0.5 to 278 microg/L the average being 29 microg/l. About 12% of these wells had arsenic concentrations that exceeded the current USEPA's maximum contaminant level of 50 microg/l. Most (53-98%) of the arsenic detected was arsenite [As(III)] and other observations supported the arsenic species distribution (low redox potential and DO). In shallow groundwater (< 15 m), arsenic concentrations are low likely due to the formation of insoluble ferrosoferric hydroxide complex. In deep groundwater (> 15 m), the concentration of arsenic is possibly controlled by reductive dissolution of arsenic-rich iron hydroxide/oxyhydroxide and dissolution of arsenic sulfide minerals.     

Water Quality of Medium Size Watercourse Under Baseflow Conditions: The Case Study of River Sutla in Croatia

The study on medium size river Sutla in Croatia indicated considerable water contamination at specific sites during the baseflow period, probably associated to low flow-rate (0.73-68.8 m3 s(-1)), and consequently low dilution capacity of this river. Various aspects of contamination were observed: increased conductivity to 1,000 microS cm(-1), decreased dissolved oxygen level to 50%, 4-5 degrees C increased water temperature, increased concentrations of several dissolved trace elements (e.g., maximal values of Li: 45.4 microg l(-1); Rb: 10.4 microg l(-1); Mo: 20.1 microg l(-1); Cd: 0.31 microg l(-1); Sn: 30.2 microg l(-1); Sb: 11.8 microg l(-1); Pb: 1.18 microg l(-1); Ti: 1.03 microg l(-1); Mn: 261.1 microg l(-1); and Fe: 80.5 microg l(-1)) and macro elements (e.g., maximal values of Na: 107.5 mg l(-1); and K: 17.3 mg l(-1)), as well as moderate or even critical fecal (E. coli: 4,888 MPN/100 ml; total coliforms: 45,307 MPN/100 ml; enterococci: 1,303 MPN/100 ml) and organic pollution (heterotrophic bacteria: 94,000 cfu/ml). Although metal concentrations still have not exceeded the limits considered as hazardous for aquatic life or eventually for human health, the observed prominent increases of both metal concentrations and bacterial counts in the river water should be considered as a warning and incentive to protect the small and medium size rivers from the future deterioration, as recommended by EU Water Framework Directive.     

Nonylphenolic compounds in drinking and surface waters downstream of treated textile and pulp and paper effluents: a survey and preliminary assessment of their potential effects on public health and aquatic life

Eleven drinking water treatment plants, located downstream of textile plants or pulp and paper mills, have been sampled monthly during a year for the analysis of 17 nonylphenol ethoxylates (NP1-17EO) and two nonylphenoxycarboxylic acids (NP1-2EC). At all but one plant, results in the drinking water, for the sum of these 19 substances, range between below detection levels and 6.7 microg/l. Annual means are between 0.02 and 2.8 microg/l. At the other plant, the yearly average concentration is 10.4 microg/l and the monthly maximum is 43.3 microg/l. In the surface (pre-treatment) water, the annual mean concentrations of the 11 plants range between 0.14 and 17.8 microg/l and the recorded instantaneous maximum is 55.3 microg/l. According to Canadian health authorities, drinking water is a negligible route of human exposure to nonylphenolic compounds, even at the highest concentrations found in this study. After transformation of the data into nonylphenol equivalents, about 20% of the surface water samples exceed the Canadian 1 microg/l nonylphenol water quality guideline for the protection of aquatic life. Some results also exceed Québec's 6 microg/l nonylphenol guideline. The efficiency of the plants in removing nonylphenolic compounds from drinking water is highly variable, ranging from 11% to 99%.     

Evaluation and standardisation of a simple HG-AAS method for rapid speciation of As(III) and As(V) in some contaminated groundwater samples of West Bengal, India

A simple HG-AAS technique has been evaluated and standardised for rapid speciation of As(III) and As(V) in a number of contaminated groundwater samples of West Bengal, India. Citric acid has been used for selective hydride formation of As(III). The sensitivity of the evaluated HG-AAS method is 7.91 mg(-1)l, standard deviation, 0.001 and detection limit, 0.4 microg l(-1). As(III) sensitivity remains constant in the sample pH range of 2.3-10.6. Concomitant mineral matrix of the water samples did not interfere with arsenic determination. Eight out of ten groundwater samples analysed for As(IlI)and As(V) contain more As(III), which lies in the range of 54-350 ppb. As(III) estimation in drinking water along with total arsenic should be invoked as a policy for a realistic risk assessment of the contaminated water.     

Diel cycles of arsenic speciation due to photooxidation in acid mine drainage from the Iberian Pyrite Belt (Sw Spain)

Twenty four hours diel cycles of arsenic speciation in Acid Mine Drainage (AMD) due to photooxidation have been reported for the first time. AMD samples were taken during 48 h (31st March and 1st April, 2005) at 6 h intervals from the effluent of a massive abandoned polymetallic sulphide mine of the Iberian Pyrite Belt (Sw Spain). Samples were preserved in situ using cationic exchange prior to analysis by coupled high performance liquid chromatography, hydride generation and atomic fluorescence spectrometry (HPLC-HG-AFS) for arsenic speciation. The results indicated the presence of inorganic arsenic species with daily means of 262mugl(-1) for As(V) and 107 microg l(-1) for As(III). No marked diel trend was observed for As(V). However, a marked diel trend was observed for As(III) in the two studied days, with maximum concentrations during nighttime (141-143 microg l(-1)) and minimum concentrations at daytime (72-77 microg l(-1)). This difference in concentration during daytime and nighttime is ca. 100%. A similar diel cycle was observed for iron. An explanation for the arsenic diel cycles observed is the light induced photooxidation of As(III) and the elimination of As(V) due to its adsorption onto Fe precipitates during the daytime. Furthermore, the diel changes in arsenic speciation emphasize the importance of designing suitable sampling strategies in AMD systems.     

Environmental fate and bioavailability of wood preservatives in freshwater sediments near an old sawmill site.

Impacts of an old contaminated sawmill site located in Eastern Finland were studied, with emphasis on transportation and bioaccumulation of wood preservatives in the surrounding water system. To assess the transportation of chlorophenols and chromated copper arsenate (CCA) from the sawmill to the nearby lake, the concentrations of these compounds in selected sediment samples were analyzed. To assess the contribution of a pulp mill further upstream, the concentration of extractable organic halogens (EOX) was analyzed. Bioaccumulation of wood preservatives from sediments was examined using Lumbriculus variegatus as test organism. In sediments collected from the sawmill area, concentrations of chlorophenols, arsenic, chromium and copper were high. In the surrounding area the concentrations of these compounds were slightly elevated at some sampling points but were mostly within the natural range of variation. Thus, it can be concluded that transportation of wood preservatives from the sawmill area to its surroundings is fairly low. However, 60 microg/l of arsenic and 50 microg/l of copper were found in water taken from a brook that runs through a landfill area of the sawmill to the nearby river, and the concentration of arsenic in the surface sediment at one sampling point in the lake was slightly elevated. The total amount of organohalogens in sediment was higher in the river and the lake than in the sawmill area. Of all the wood preservatives studied, only arsenic was found to bioaccumulate in present conditions, reaching a tissue concentration of 362 microg/g dw in organisms exposed for 28 days to sediment from the brook. High concentration of arsenic in oligochaeta tissue was related to high concentration of arsenic in the pore water.     

Heavy-metal pollution and arseniasis in Hetao region, China

In the Hetao region in northern China drinking water has become toxic due to the presence of arsenic (As) and other heavy metals in soil and water. The 7 counties in this region cover approx. 6100 km2, and in all 180,000 people are suffering from the toxic effects of contaminated drinking water. However, very few studies have been carried out in the region on the possible source of this arsenic. This paper is based on studies of the distribution of heavy metals in soil and groundwater. Results show that the average content of As is 0.483 microg g(-1) in groundwater and 13.74 microg g(-1) in soil. These levels are higher than the drinking water standard of 0.05 microg g(-1) recommended by the World Health Organization in 1984, and for the local background level in soil (5.20 microg g(-1)). This heavy-metal content in water and soil decreases gradually with increasing distance from the contaminated area, which fronts the Yin Mountains. The ratios of the Pb and Sr isotope contents in water are closely related to the ratios found in the water of the regions' mining area, and the ratios in soil correspond to the content of As in groundwater and soil in the area where pathological changes have been detected. Results suggest that the contaminants originate in the ore deposit zone fronting Yin mountains in the upper reaches of the Hetao Region.     

Seasonal variation of heavy metals in ambient air and precipitation at a single site in Washington, DC

Atmospheric samples of precipitation and ambient air were collected at a single site in Washington, DC, for 7 months (for ambient air samples) and 1 year (for wet deposition samples) and analyzed for arsenic, cadmium, chromium and lead. The ranges of heavy metal concentrations for 6-day wet deposition samples collected over the 1-year period were 0.20-1.3 microg/l, 0.060-5.1 microg/l, 0.062-4.6 microg/l and 0.11-3.2 microg/l for arsenic, cadmium, chromium and lead, respectively, with a precision better than 5% for more than 95% of the measurements. The ranges of heavy metal concentrations for the 6-day ambient air samples were 0.800-15.7 ng/m(3), 1.50-30.0 ng/m(3), 16.8-112 ng/m(3), and 2.90-137 ng/m(3) for arsenic, cadmium, chromium and lead, respectively, with a precision better than 10%. The spread in the heavy metal concentration over the observation period suggests a high seasonal variability for heavy metal content in both ambient air and wet deposition samples.     

Organo-chlorine pesticide (DDT and HCH) residues in the Taihu Lake Region and its movement in soil-water system I. Field survey of DDT and HCH residues in ecosystem of the region

The use of organo-chlorine (DDT and HCH) has been banned in China for 20 years. A field survey was carried out during 1999-2000 in the Taihu Lake Region. Organo-chlorine pesticide (OCP) residues in soil, water, fish and sediment samples were investigated. DDT was detected in 5 out of 10 samples with concentration ranging from 0.3 to 5.3 microg/kg in the surface (0-15 cm) layer, 6 out of 10 with 0.5 to 4.0 microg/kg in the subsoil layer (16-30 cm), and 4 of 10 with 0 to 2.7 microg/ kg in the deep soil layer (31-50 cm). Results for HCH residues in soil samples were similar to those of DDT. These results indicate that OCP residues in 0-50 cm profile had been leached out or degraded to safe level. In river water DDT was detected in 10 out of 13 samples ranging from 0.2 to 9.3 microg/l, with an average of 1.0 microg/l. While HCH was detected in 12 out of 13 samples ranging from 0.02 to 36.1 microg/l, with an average 5.6 microg/l. DDT residues in sediment ranged from 0.1 to 8.8 microg/kg, while HCH ranged from 0.3 to 66.5 microg/kg. DDT residues in fish body ranged from 3.7 to 23.5 microg/kg and HCH ranged from 3.7 to 132 microg/kg. These results demonstrate an accumulation through food chain (from soil-water-sediment-microbes-crop-fish-... etc.), also that HCH residues are generally more persistent than DDT residues. However, all these data are well below than the state warning standard limit.     

Fluoride levels in well-water from a chronic arsenicism area of Northern Mexico

This paper reports on the concentrations and geographical relationships between fluoride and total arsenic in 129 water wells of the Región Lagunera, Mexico, where arsenic has caused severe health effects. Fluoride concentrations ranged from less than 0.5 to 3.7 mg liter(-1); 25 samples (19.4%) had levels above 1.5mg liter(-1), the current WHO and Mexican drinking water standard, whereas 45 (34.9%) had levels below 0.5 mg liter(-1). The range of total arsenic concentrations was 0.008-0.624 mg liter(-1) and 64 (50%) had levels above 0.050 mg liter(-1), the current WHO standard. A linear regression analysis of arsenic and fluoride concentrations showed a highly positive correlation (r = 0.774), consistent with their geographical distribution. The highest concentrations of both elements were found in the northeastern part of the Región, mostly corresponding to rural areas, whereas the lowest concentrations were found in the southwestern part of the Región, as well as in the cities of Torreón in the state of Coahuila, and Gómez Palacio and Lerdo in the state of Durango. In consequence, people exposed to high arsenic concentrations are also exposed to fluoride at levels above the drinking water standard. The possibility of interactions between both elements is also discussed.     

TiO2-catalyzed photooxidation of arsenite to arsenate in aqueous samples

The TiO2-catalyzed photooxidation of arsenite (As(III)) to arsenate (As(V)) was studied in aqueous TiO2 suspensions using a solar simulator which emitted ultraviolet and visible radiations. The concentration of As(III) was varied between 50 microg l(-1) and 10 mg l(-1), and the concentration of TiO2 between 1 mg l(-1) and 50 mg l(-1). Total oxidation of As(III) to As(V) occurred within minutes. The concentration of As(III) declined exponentially which indicates first-order kinetics. In the pH range between 5 and 9 there was no significant influence of the pH of the suspension on the reaction rate. Batch experiments without irradiation showed that part of the arsenic was adsorbed on the TiO2 surface. When using 100 microg l(-1) As and between 1 mg l(-1) and 50 mg l(-1) TiO2, 8-39% of As(III) and up to 73% of As(V) were adsorbed by TiO2. As(III) was also oxidized by UV radiation in the absence of TiO2, but the reaction was slower than in the presence of TiO2 resulting in an irradiation time too long for practical use. In addition, oxidation of As(III) in the presence of TiO2 was also observed under solar irradiation within a few minutes.     

Sensitivities of Australian and New Zealand amphipods to copper and zinc in waters and metal-spiked sediments

The sensitivities of eight benthic amphipods, Chaetocorophium cf. lucasi, Corophium colo, Grandidierella japonica, Hyale crassicornis, Hyale longicornis, Melita awa, Melita matilda and Melita plumulosa, to copper and zinc in water-only and whole-sediment toxicity tests were compared. Whole-sediment tests used copper- (1300 mg/kg) and zinc- (4000 mg/kg) spiked sediments after equilibration for sufficient time to produce pore water and overlying water concentrations below the lowest observable effect concentrations of water-only exposures. Survival of adults (after 10 d) and juveniles (after 96 h), and the metal concentrations in the body tissues of adults, were determined at the end of the tests. Two epibenthic amphipods from the genus Melita were the most sensitive species to aqueous copper and zinc, with a 96-h LC50 value of 120 microg Cu/l for both M. awa and M. plumulosa juveniles, and a 96-h LC50 value of 640 microg Zn/l for juveniles of M. plumulosa. Juvenile amphipods (7-d old) were more sensitive than adult amphipods (>30-d old) in both water-only and whole-sediment tests, with adult-LC50/juvenile-LC50 ratios in water-only tests ranging from 1.2 to l.5 for copper and 1 to 1.4 for zinc. All species except C. colo, C. cf. lucasi and M. matilda were sensitive to the copper-spiked sediment, with survival between 14% and 74% of controls. Similarly, all species except C. colo and G. japonica, showed a response to the zinc-spiked sediment (26-81% of control survival). The epibenthic amphipods were more sensitive than the infaunal tube-dwelling amphipods and are recommended as test species.     

Use of oxytetracycline and tylosin in intensive calf farming: evaluation of transfer to manure and soil

Antibiotics may enter soils with manure from treated animals. Because of their biological effects, antibiotics are regarded as potential micropollutants. The levels of oxytetracycline and tylosin over time were followed in faeces, bedding and manure, and then in the soil of a manured field and surrounding drainage courses, after oral treatment of calves. Fifty Simmental calves were treated for 5 days with 60 mg/kg/day of oxytetracycline. After 15 days the animals were treated for 5 days with 20 mg/kg/day of tylosin. Tylosin degraded rapidly, and was no longer detected in manure 45 days after cessation of treatment and no trace of the compound was detected in soil or surrounding water (detection limits 10 microg/l). The half-life of oxytetracycline in manure was 30 days and the compound was still detectable in this matrix (820 microg/kg) after 5 months maturation. In the manured soil oxytetracycline was detected at concentrations at least 10 times lower than the European Agency for the Evaluation of Medicinal Products threshold (100 microg/kg) requiring phase II environmental risk assessment. Oxytetracycline was not detected in the water courses (detection limit 1 microg/l). These results demonstrate that the processes occurring between faeces production and application of manure to the soil are very effective in reducing the load of TYL and OTC in the environment. For both drugs a toxicity test was performed using the alga Selenastrum capricornutum. The EC50 was 4.18 mg/l for oxytetracycline and 0.95 mg/l for tylosin. A worst-case hazard assessment for the aquatic environment was performed comparing the ratio between the measured concentrations (LOD) and effect data from previous work (OTC) or from this work (TYL). This showed ratio between toxicity levels (bacteria) (EC50=0.14 mg/l) and measured concentrations (LOD=1 microg/l) for OTC to be 140. The corresponding value for TYL (LOD=10 microg/l) was 95.     

Mobilization of arsenic from subsurface sediments by effect of bicarbonate ions in groundwater

Arsenic leaching by bicarbonate ions has been investigated in this study. Subsurface sediment samples from Bangladesh were treated with different carbonate and bicarbonate ions and the results demonstrate that the arsenic leaching efficiency of the carbonate solutions decreased in the order of Na2CO3>NaHCO3>BaCO3>MnCO3. Sodium carbonate and bicarbonate ions extracted arsenic most efficiently; Na2CO3 leached maximum 118.12 microg/l of arsenic, and NaHCO3, 94.56 microg/l of arsenic from the Ganges delta sediments after six days of incubation. The arsenic concentrations extracted in the batch experiments correlated very well with the bicarbonate concentrations. The kinetics study of arsenic release indicates that arsenic-leaching rate increased with reaction time in bicarbonate solutions. Bicarbonate ions can extract arsenic from sediment samples in both oxic and anoxic conditions. A linear relationship found between arsenic contents in core samples and those in leachates suggests that dissolved arsenic concentration in groundwater is related to the amount of arsenic in aquifer sediments. In batch experiment, bicarbonate solutions effectively extracted arsenic from arsenic adsorbed iron oxyhydroxide, reflecting that bicarbonate solutions may mobilize arsenic from iron and manganese oxyhydroxide in sediments that are ubiquitous in subsurface core samples. Carbonate ion may form complexes on the surface sites of iron hydroxide and substitute arsenic from the surface of minerals and sediments resulting in release of arsenic to groundwater. Like in the batch experiment, arsenic and bicarbonate concentrations in groundwater of Bangladesh correlated very well. Therefore, bicarbonate leaching is presumed to be one important mechanism to mobilize arsenic in bicarbonate dominated reducing aquifer of Bangladesh and other parts of the world as well.     

The long-term environmental behaviour of strontium and barium released from former mine workings in the granites of the Sunart region of Scotland, UK

The concentrations of strontium and barium have been measured in water, sediment and the shells of mussels (Mytilus edulis) from a river system in the Sunart region of Scotland, UK. The aim was to establish the fate and mobility of these elements, which are slowly being released from old mine workings on the Strontian granites. Enhanced strontium (1500-2000 microg l(-1) and 250-290 microg l(-1)) and barium concentrations (316 microg l(-1) and 83 microg l(-1)) were found in the waters originating from the two mine drains studied. Both element were also found at significant levels in the river sediments taken from the vicinity of each drainage site (Sr: 225 microg g(-1) and 120-125 microg g(-1); Ba: 1380 microg g(-1) and 126-170 microg g(-1)). The data suggests that the sediments are acting as a reservoir for these group II cations from where they become distributed throughout the river system. Strontium is found to be incorporated into the shells (3.16-3.46 microg g(-1)) and pearls (3.57 microg g(-1)) of the blue mussel, located at the estuarine margin some 10 km downstream, at values close to the maximum expected (3.3% by weight of the calcium content). The study presents a view of the fate of barium and strontium in a river system over a prolonged period of time. As such it provides valuable information for studies that seek to model the impact of the accidental release of barium and strontium (including the important radionuclide 90Sr) into the environment.     

Analysis of polycyclic aromatic hydrocarbons in wastewater treatment plant effluents using hollow fibre liquid-phase microextraction

A simple and efficient method for the enrichment of low molecular weight polycyclic aromatic hydrocarbons (PAHs) in effluents originating from wastewater treatment plants is presented here. The proposed protocol couples the recently introduced hollow fibre liquid-phase microextraction (LPME) method with gas chromatography-mass spectrometry. Method parameters were controlled and the optimised experimental conditions were: 5 ml aqueous samples, containing 2.5% NaCl w/v, stirred at 1000 rpm, extracted with toluene for 15 min. The developed protocol yielded a linear calibration curve in the concentration range from 0.5 to 50 microg l(-1) for all target analytes (namely acenaphthene, phenanthrene, fluoranthene and pyrene) and limits of detection in the low microg l(-1) level (0.005-0.011 microg l(-1)). The repeatability and inter-day precision of the method varied between 2.7% and 11.3% and 7.9% and 14.4% respectively. The relative recoveries from different types of natural water samples revealed that matrix had a small effect on the hollow fibre LPME process. The developed method was then applied for the determination of PAHs contamination in effluent samples taken from two major municipal wastewater treatment plants. The results were compared with those obtained with solid-phase microextraction. The ability of both microextraction methods to concentrate organic analytes was demonstrated as both methods confirmed the presence of PAHs as well as of phthalates in the examined effluent samples.     

Determination of benzene, toluene, ethylbenzene, xylenes in water at sub-ng l-1 levels by solid-phase microextraction coupled to cryo-trap gas chromatography-mass spectrometry

A trace analytical method of benzene, toluene, ethylbenzene and xylenes (BTEX) in water has been developed by using headspace solid-phase microextraction (HS-SPME) coupled to cryo-trap gas chromatography-mass spectrometry (GC-MS). The chromatographic peak shape for BTEX was improved by using cryo-trap equipment. The HS-SPME experimental procedures to extract BTEX from water were optimized with a 75 microm carboxen/polydimethylsiloxane (CAR/PDMS)-coated fiber at a sodium chloride concentration of 267 g l(-1), extraction for 15 min at 25 degrees C and desorption at 290 degrees C for 2 min. Good linearity was verified in a range of 0.0001-50 microg l(-1) for each analyte (r(2)=0.996-0.999). The limits of detection (LODs) of BTEX in water reached at sub-ng l(-1) levels. LODs of benzene, toluene, ethylbenzene, m/p-xylene and o-xylene were 0.04, 0.02, 0.05, 0.01 and 0.02 ng l(-1), respectively. The proposed analytical method was successfully used for the quantification of trace BTEX in ground water. The results indicate that HS-SPME coupled to cryo-trap GC-MS is an effective tool for analysis of BTEX in water samples at the sub-ng l(-1) level.     

Water quality and fish size affect toxicity of endosulfan, an organochlorine pesticide, to rainbow trout

The acute toxicity of endosulfan in juvenile rainbow trout (Oncorhynchus mykiss, 10.61+/-1.69 g) was evaluated in glass aquaria under static conditions. Nominal concentrations of endosulfan in the toxicity test ranged from 1.3 microg l(-1) to 29 microg l(-1). The concentrations of endosulfan that killed 50% of the rainbow trout within 24-h (24-h LC50), 48-h LC50, 72-h LC50, and 96-h LC50 were 19.78, 8.89, 5.28, and 1.75 microg l(-1), respectively. None of the unexposed control fish died, and the first fish died 4 h after exposure to 26.3 microg l(-1) of endosulfan. Survival of fish was significantly increased with increasing fish size and decreased with decreased fish size at the same temperature (p<0.001). Temperature also had a significant effect on survival of fish. Alkalinity at levels above 20 mg l(-1) as CaCO3 significantly increased survival of fish at 19.78 microg l(-1) of endosulfan. Increasing alkalinity from 20 mg l(-1) as CaCO3 to 42 or higher concentrations tested in this study (121 mg l(-1) as CaCO3) significantly increased survival of fish (p<0.01). Total hardness ranging from 55 mg l(-1) as CaCO3 to 126 mg l(-1) as CaCO3 did not affect survival of fish exposed to endosulfan. Endosulfan toxicity was found to be irreversible when fish were exposed to minimum concentrations of endosulfan tested. Histologically, fish gills had lamellar edema, separation of epithelium from lamellae, lamellar fusion, and swelling of the epithelial cells. Melanomacrophage centers were scattered throughout the trunk kidney, head kidney, and spleen. The liver of endosulfan-exposed fish had severe focal necrosis. None of these lesions were seen in unexposed control fish. Results indicate that alkalinity, temperature, and fish size affect endosulfan toxicity of rainbow trout.