Aerobic degradation of tetrabromobisphenol-A by microbes in river sediment

This study investigated the aerobic degradation of tetrabromobisphenol-A (TBBPA) and changes in the microbial community in river sediment from southern Taiwan. Aerobic degradation rate constants (k₁) and half-lives (t_1/2) for TBBPA (50 μg g⁻¹) ranged from 0.053 to 0.077 d⁻¹ and 9.0 to 13.1 d, respectively. The degradation of TBBPA (50 μg g⁻¹) was enhanced by adding yeast extract (5 mg L⁻¹), sodium chloride (10 ppt), cellulose (0.96 mg L⁻¹), humic acid (0.5 g L⁻¹), brij 30 (55 μM), brij 35 (91 μM), rhamnolipid (130 mg L⁻¹), or surfactin (43 mg L⁻¹), with rhamnolipid yielding a higher TBBPA degradation than the other additives. For different toxic chemicals in the sediment, the results showed the high-to-low order of degradation rates were bisphenol-A (BPA) (50 μg g⁻¹) > nonylphenol (NP) (50 μg g⁻¹) > 4,4′-dibrominated diphenyl ether (BDE-15) (50 μg g⁻¹) > TBBPA (50 μg g⁻¹) > 2,2′,3,3′,4,4′,5,5′,6,6′-decabromodiphenyl ether (BDE-209) (50 μg g⁻¹). The addition of various treatments changed the microbial community in river sediments. The results also showed that Bacillus pumilus and Rhodococcus ruber were the dominant bacteria in the process of TBBPA degradation in the river sediments.     

Effects of salinity, DOM and metals on the fate and microbial toxicology of propetamphos formulations in river and estuarine sediment

Toxicity studies tend to use pure pesticides with single organisms. However, natural systems are complex and biological communities diverse. The organophosphate pesticide propetamphos (PPT) has been found exceeding regulatory limits (100 ng L⁻¹) in rivers. We address whether solution properties affect the fate of Analar (Analar-PPT) or industrial PPT (PPT-Ind) propetamphos formulations and whether propetamphos and metal toxicant effects are additive, antagonistic or synergistic? The sorption, desorption, biodegradation and microbial toxicology of Analar-PPT and PPT-Ind were investigated in Conwy River and estuary sediment. Results showed elevated salinity enhanced PPT sorption, while higher salinities increased PPT-Ind retention. Higher dissolved organic matter (DOM) and low salinity slowed Analar-PPT biodegradation (1.9 × 10⁻³ h⁻¹). Analar-PPT and PPT-Ind biodegradation was further reduced by low salinity, high DOM and dissolved Zn and Pb (6.3 × 10⁻⁴ h⁻¹, 1100 h t_½ for Analar-PPT; 7.5 × 10⁻⁴ h⁻¹, 924 h t_½ for PPT-Ind). Toxicity effects of PPT, Zn and Pb in equitoxic ratio were higher for PPT-Ind (4.7 μg PPT-Ind g⁻¹; 581 μg Zn g⁻¹; 395 μg Pb g⁻¹) than for Analar-PPT (34.6 μg PPT g⁻¹; 312 μg Zn g⁻¹; 212 μg Pb g⁻¹) whilst a toxicant ratio 1:100:10 suggested small quantities of Analar-PPT (EC₁₀ = 0.06 μg g⁻¹) affected microbial communities. The combined toxicity effect was more than additive. Thus, industrial formulations and pollutant mixtures should be considered when assessing environmental toxicity.     

Production and sedimentation of peptide toxins nodularin-R and microcystin-LR in the northern Baltic Sea

This seven-year survey was primarily targeted to quantification of production of nodularin-R (NOD-R), a cyclic pentapeptide hepatotoxin, in Baltic Sea cyanobacteria waterblooms. Additionally, NOD-R and microcystin-LR (MC-LR; a cyclic heptapeptide toxin) sedimentation rates and NOD-R sediment storage were estimated. NOD-R production (70-2450 μg m⁻³; ∼1 kg km⁻² per season) and sedimentation rates (particles; 0.03-5.7 μg m⁻² d⁻¹; ∼0.3 kg km⁻² per season) were highly variable over space and time. Cell numbers of Nodularia spumigena did not correlate with NOD-R quantities. Dissolved NOD-R comprised 57-100% of total NOD-R in the predominantly senescent, low-intensity phytoplankton blooms and seston. Unprecedentedly intensive MC-LR sedimentation (0.56 μg m⁻² d⁻¹) occurred in 2004. Hepatotoxin sedimentation rates highly exceeded those of anthropogenic xenobiotics. NOD-R storage in surficial sediments was 0.4-20 μg kg⁻¹ (∼0.1 kg km⁻²). Loss of NOD-R within the chain consisting of phytoplankton, seston and soft sediments seemed very effective.     

A human health risk assessment of rare earth elements in soil and vegetables from a mining area in Fujian Province,Southeast China

Contaminated food through dietary intake has become the main potential risk impacts on human health. This study investigated concentrations of rare earth elements (REEs) in soil, vegetables, human hair and blood, and assessed human health risk through vegetables consumption in the vicinity of a large-scale mining area located in Hetian Town of Changting County, Fujian Province, Southeast China. The results of the study included the following mean concentrations for total and bio-available REEs of 242.92 ± 68.98 (135.85–327.56) μg g⁻¹ and 118.59 ± 38.49 (57.89–158.96) μg g⁻¹ dry weight (dw) in agricultural soil, respectively, and total REEs of 3.58 ± 5.28 (0.07–64.42) μg g⁻¹ dw in vegetable samples. Concentrations of total REEs in blood and hair collected from the local residents ranged from 424.76 to 1274.80 μg L⁻¹ with an average of 689.74 ± 254.25 μg L⁻¹ and from 0.06 to 1.59 μg g⁻¹ with an average of 0.48 ± 0.59 μg g⁻¹ of the study, respectively. In addition, a significant correlation was observed between REEs in blood and corresponding soil samples (R² = 0.6556, p < 0.05), however there was no correlation between REEs in hair and corresponding soils (p > 0.05). Mean concentrations of REEs of 2.85 (0.59–10.24) μg L⁻¹ in well water from the local households was 53-fold than that in the drinking water of Fuzhou city (0.054 μg L⁻¹). The health risk assessment indicated that vegetable consumption would not result in exceeding the safe values of estimate daily intake (EDI) REEs (100−110 μg kg⁻¹ d⁻¹) for adults and children, but attention should be paid to monitoring human beings health in such rare earth mining areas due to long-term exposure to high dose REEs from food consumptions.     

Evaluation of the possible adverse effects of legacy persistent organic pollutants (POPs) on the brown booby (Sula leucogaster) along the Brazilian coast

This study aimed to investigate the impact of contamination by persistent organic pollutants (POPs) on Brazilian wildlife. The concentrations of certain POPs, including dichlorodiphenyltrichloroethane (DDT) and polychlorinated biphenyls (PCBs), in the eggs of the brown booby (Sula leucogaster) were measured. The eggs were collected from breeding colonies located on three archipelagos (Saint Peter and Saint Paul, Abrolhos and Cagarras Islands) in the Atlantic Ocean, which are located at different distances from the Brazilian coast (range 4-1010 km). In addition, possible alterations in eggshell characteristics were evaluated. The average values of POPs found in eggs from the archipelago of Saint Peter and Saint Paul (0.05 μg g⁻¹ of ΣPCBs and 0.01 μg g⁻¹ of ΣDDT) and the archipelago of Abrolhos (0.19 μg g⁻¹ of ΣPCBs and 0.03 μg g⁻¹ of ΣDDT) were low compared to the reference values reported in the literature. In contrast, the concentrations measured in eggs from Cagarras (8.4 μg g⁻¹ of ΣPCBs and 1.8 μg g⁻¹ of ΣDDT) were the highest, and this total PCB level is close to the threshold values considered to be harmful to birds. Our findings indicate that the brown booby colony closest to the Rio de Janeiro coast has recently been exposed to DDT. Despite the high pollution levels found on the Cagarras Islands, no alterations in the eggshell weight or the thickness of the analyzed eggs were detected. Hence, more detailed studies are recommended to determine the actual effects of the selected POPs on the Cagarras breeding colony.     

The association between total urinary arsenic concentration and renal dysfunction in a community-based population from central Taiwan

Arsenic (As) is an important environmental toxicant that can cause cancer and cardiovascular disease, but the relationship between As exposure and renal dysfunction is not clear. The aim of this study is to examine the association between As exposure and renal dysfunction in a community-based population in central Taiwan. One thousand and forty-three subjects were recruited between 2002 and 2005. The risk for type 2 diabetes was increased by 2-fold (p < 0.05) in subjects with total urinary As (U-As) > 75 μg g⁻¹ creatinine as compared with subjects whose U-As was ?35 μg g⁻¹ creatinine after the adjustment for potential confounders. The adjusted odds ratio for an abnormal β2 microglobulin (B2MG > 0.154 mg L⁻¹) was significantly higher in subjects with U-As > 35 μg g⁻¹ creatinine as compared with the reference group adjusted for age, sex, living area, cigarette smoking, diabetes, and hypertension. The risk for abnormal B2MG and estimated glomerular filtration rate (eGFR < 90 mL min⁻¹ (1.73 m²)⁻¹) was both increased around 2-fold (p < 0.05) in subjects with U-As > 75 μg g⁻¹ creatinine as compared with those with U-As ? 35 μg g⁻¹ creatinine adjusted for all the risk factors plus lead (Pb), cadmium and nickel. The prevalence of abnormal B2MG was 4.82 times higher in subjects with both over the median levels of U-As (85.1 μg L⁻¹) and urinary Pb (18.9 μg L⁻¹) as compared to both lower than the median (p < 0.001). These results indicate that U-As might relate to renal dysfunction even other important risk factors were taken into account. Follow-up studies for causal inference are warranted.     

Distribution of Se and its species in Myriophyllum spicatum and Ceratophyllum demersum growing in water containing Se (VI)

The uptake of Se (VI) by two aquatic plants, Myriophyllum spicatum L. and Ceratophyllum demersum L., and its effects on their physiological characteristics have been studied. Plants were cultivated outdoors under semi-controlled conditions and in two concentrations of Na selenate solution (20 μg Se L⁻¹ and 10 mg Se L⁻¹). The higher dose of Se reduced the photochemical efficiency of PSII in both species, while the lower dose had no effect on PSII. Addition of Se had no effect on the amounts of chlorophyll a and b. The concentration of Se in plants grown in 10 mg Se L⁻¹, averaged 212 ± 12 μg Se g⁻¹ DM in M. spicatum (grown from 8-13 d), and 492 ± 85 μg Se g⁻¹ DM in C. demersum (grown for 31 d). Both species could take up a large amount of Se. The amount of soluble Se compounds in enzyme extracts ranged from 16% to 26% in control, and in high Se solution from 48% to 36% in M. spicatum and C. demersum, respectively. Se-species were determined using HPLC-ICP-MS. The main soluble species in both plants was selenate (∼37%), while SeMet and SeMeSeCys were detected at trace levels.     

Comparative embryotoxicity of a pentabrominated diphenyl ether mixture to common terns (Sterna hirundo) and American kestrels (Falco sparverius)

Concentrations of polybrominated diphenyl ethers (PBDEs) in Forster’s tern (Sterna forsteri) eggs from San Francisco Bay have been reported to range up to 63 μg g⁻¹ lipid weight. This value exceeds the lowest-observed-adverse-effect level (1.8 μg g⁻¹ egg wet weight; ∼32 μg⁻¹ lipid weight) reported in an embryotoxicity study with American kestrels (Falco sparverius). As a surrogate for Forster’s terns, common tern (Sterna hirundo) eggs were treated by air cell injection with corn oil vehicle (control) or a commercial penta-BDE formulation (DE-71) at nominal concentrations of 0.2, 2, and 20 μg g⁻¹ egg. As a positive control, kestrel eggs received vehicle or 20 μg DE-71 g⁻¹ egg. In terns, there were no effects of DE-71 on embryonic survival, and pipping or hatching success; however, treated eggs hatched later (0.44 d) than controls. Organ weights, organ-to-body weight ratios, and bone lengths did not differ, and histopathological observations were unremarkable. Several measures of hepatic oxidative stress in hatchling terns were not affected by DE-71, although there was some evidence of oxidative DNA damage (8-hydroxy-deoxyguanosine; 8-OH-dG). Although DE-71 did not impair pipping and hatching of kestrels, it did result in a delay in hatch, shorter humerus length, and reduced total thyroid weight. Concentrations of oxidized glutathione, reduced glutathione, thiobarbituric acid reactive substances, and 8-OH-dG in liver were greater in DE-71-treated kestrels compared to controls. Our findings suggest common tern embryos, and perhaps other tern species, are less sensitive to PBDEs than kestrel embryos.     

Epibrassinolide ameliorates Cr (VI) stress via influencing the levels of indole-3-acetic acid, abscisic acid, polyamines and antioxidant system of radish seedlings

The present investigation determined the effects of epibrassinolide (EBL) on the levels of indole-3-acetic acid (IAA), abscisic acid (ABA), and polyamine (PA) and antioxidant potential of 7-d old Raphanus sativus L. cv. ‘Pusa chetki’ seedlings grown under Cr (VI) metal stress. Reduced titers of free (0.767 μg g⁻¹ FW) and bound (0.545 μg g⁻¹ FW) IAA in Cr (VI) stressed seedlings were observed over untreated control. Supplementations of EBL to Cr (VI) stressed seedlings were able to enhance both free (2.14-5.68 μg g⁻¹ FW) and bound IAA (2.45-7.78 μg g⁻¹ FW) concentrations in comparison to Cr (VI) metal treatment alone. Significant rise in free (13.49 μg g⁻¹ FW) and bound (12.17 μg g⁻¹ FW) ABA contents were noticed for Cr (VI) stressed seedlings when compared to untreated control. No significant increase in ABA contents were recorded for Cr (VI) stressed seedlings upon supplementation with EBL over Cr (VI) treatment alone. A significant increase in Put (18.40 μg g⁻¹ FW) and Cad (9.08 μg g⁻¹ FW) contents were found for 10⁻⁹ M EBL plus Cr (VI) metal treatments when compared to Cr (VI) treatment alone. Spermidine (Spd) contents were found to decline significantly for EBL treatment alone or when supplemented with Cr (VI) treatments over untreated controls and Cr (VI) treatment alone. Antioxidant levels were found to enhance, with glutathione (57.98 mg g⁻¹ FW), proline (4.97 mg g⁻¹ FW), glycinebetaine (39.01 μmol mL⁻¹), ascorbic acid (3.17 mg g⁻¹ FW) and phytochelatins (65.69 μmol g⁻¹ FW) contents noted for EBL supplemented to Cr (VI) metal solution over Cr (VI) treatment alone. Reduced activities of guaiacol peroxidase (0.391 U mg⁻¹ protein) and catalase (0.221 U mg⁻¹ protein) and enhanced activities of glutathione reductase (7.14 U mg⁻¹ protein), superoxide dismutase (15.20 U mg⁻¹ protein) and ascorbate peroxidase (4.31 U mg⁻¹ protein) were observed in seedlings treated with EBL plus Cr (VI) over Cr metal treatment alone. Reduced MDA (2.55 μmol g⁻¹ FW) and H₂O₂ (33.24 μmol g⁻¹ FW) contents were recorded for 10⁻⁹ M EBL supplemented to Cr (VI) stress over Cr (VI) treatment alone. Enhancement in free radical scavenging potential as indicated by higher values of 1,1-diphenylpicrylhydrazyl, deoxyribose and reducing power activity assays, and increased levels of phenols and soluble sugars also showed significant influence of EBL in alleviating Cr (VI) stress in radish seedlings.     

Evaluation of recycling the effluent of hydrogen fermentation for biobutanol production: Kinetic study with butyrate and sucrose concentrations

Butyrate in the effluent of hydrogen-producing bioreactor is a potential feed for biobutanol production. For recycling butyrate, this study investigated the kinetics of biobutanol production by Clostridium beijerinckii NRRL B592 from different paired concentrations of butyrate and sucrose in a series of batch reactors. Results show that the lag time of butanol production increased with higher concentration of either sucrose or butyrate. In regression analyses, the maximum specific butanol production potential of 6.49 g g⁻¹ of dry cell was projected for 31.9 g L⁻¹ sucrose and 1.3 g L⁻¹ butyrate, and the maximum specific butanol production rate of 0.87 g d⁻¹ g⁻¹ of dry cell was predicted for 25.0 g L⁻¹ sucrose and 2.6 g L⁻¹ butyrate. The specific butanol production potential will decrease if more butyrate is added to the reactor. However, both sucrose and butyrate concentrations are weighted equally on the specific butanol production rate. This observation also is true on butanol yield. The maximum butanol yield of 0.49 mol mol⁻¹ was projected for 25.0 g L⁻¹ sucrose and 2.3 g L⁻¹ butyrate. In addition, a confirmation study found butanol yield increased from 0.2 to 0.3 mol mol⁻¹ when butyrate addition increased from 0 to 1 g L⁻¹ under low sugar concentration (3.8 g L⁻¹ sucrose). The existence of butyrate increases the activity of biobutanol production and reduces the fermentable sugar concentration needed for acetone–butanol–ethanol fermentation.     

Risk ranking of multiple-POPs in detritivorous fish from the Río de la Plata

To evaluate the bioaccumulation and the risk associated to consumption of lipid-rich detritivorous fish, a comprehensive set of organic pollutants (n = 213) including polychlorinated biphenyls (PCBs), dioxin like PCBs (dlPCBs), chlorinated pesticides (CHLPs), chlorobenzenes (CBzs), polybrominated diphenyl ethers (PBDEs), polychlorinated dibenzo dioxins and furans (PCDD/F), resolved (ALI) and unresolved aliphatic hydrocarbons (UCM) and linear alkyl benzenes (LABs) were analyzed in Sábalo fish (Prochilodus lineatus) collected in the polluted Metropolitan Buenos Aires coast and in migrating specimens. Fatty fish muscles (lipids: 74 ± 9.3% dry weight) contained homogeneous (24-51% variability) and very high-concentrations of organic pollutants ranging from 60 to 1300 μg g⁻¹ fresh weight (fw) ALI + UCM; 10-40 μg g⁻¹ fw LABs and PCBs; 0.1-1 μg g⁻¹ fw dlPCBs, DDTs, chlordanes, CBzs and PBDEs; 0.01-0.1 μg g⁻¹ fw mirex, endosulfans, aldrin, dieldrin, endrin and 0.07-0.2 ng g⁻¹ PCDD/F. Total toxicity equivalents (TEQs) ranged from 60 to 395 pg g⁻¹ fw (34 ± 17 and 213 ± 124 pg g⁻¹ TEQs for PCDD/F and dlPCBs respectively). These are among the highest concentrations reported for fish and point out the remarkable ability of Sábalo to feed on anthropogenic organic-enriched particles and tolerate a high pollutant load. Contaminant signatures show partial alteration with still abundant lower molecular weight components indicating that fish feeds directly in the outfalls. Consumption limits based on reference doses ranged from 0.1 (PCBs) to >12 000 g d⁻¹ (endosulfan) allowing a comprehensive risk-based ranking of contaminants in this long-range migrating, detritivorous fish.     

Nano-TiO2 enhances the toxicity of copper in natural water to Daphnia magna

The acute toxicity of engineered nanoparticles (NPs) in aquatic environments at high concentrations has been well-established. This study demonstrates that, at a concentration generally considered to be safe in the environment, nano-TiO₂ remarkably enhanced the toxicity of copper to Daphnia magna by increasing the copper bioaccumulation. Specifically, at 2 mg L⁻¹ nano-TiO₂, the (LC₅₀) of Cu²⁺ concentration observed to kill half the population, decreased from 111 μg L⁻¹ to 42 μg L⁻¹. Correspondingly, the level of metallothionein decreased from 135 μg g⁻¹ wet weight to 99 μg g⁻¹ wet weight at a Cu²⁺ level of 100 μg L⁻¹. The copper was found to be adsorbed onto the nano-TiO₂, and ingested and accumulated in the animals, thereby causing toxic injury. The nano-TiO₂ may compete for free copper ions with sulfhydryl groups, causing the inhibition of the detoxification by metallothioneins.     

Risk assessment of xenoestrogens in a typical domestic sewage-holding lake in China

Release of domestic sewage leads to accumulation of xenoestrogens in holding waters, especially in closed or semi-enclosed waters such as lakes. In the study, the occurrence, distribution, estrogenic activity and risk of eight xenoestreogens were evaluated in Lake Donghu, China. Nonylphenol (NP), octylphenol (OP), and bisphenol A (BPA) were identified as the main xenoestrogens ranging from tens of ng L⁻¹ (in the surface water) or ng g⁻¹ dw (in the suspended particles and sediment) to tens of μg L⁻¹ or μg g⁻¹ dw. The sum of 17β-estradiol equivalents (∑EEQs) ranged from 0.32 to 45.02 ng L⁻¹ in the surface water, 0.53 to 71.86 ng g⁻¹ dw in the suspended particles, and 0.09 to 24.73 ng g⁻¹ dw in the sediment. Diethylstilbestrol (DES) was determined as the main contributor to ∑EEQs followed by NP. The risk assessment showed a higher risk in the surface water than in the suspended particles and sediment in such domestic sewage-holding lake.     

Alteration of shell nacre micromorphology in blue mussel Mytilus edulis after exposure to free-ionic silver and silver nanoparticles

This study describes the morphology of inner shell surface (ISS) of the blue mussel Mytilus edulis Linnaeus after short-term exposures to radiolabeled silver in free-ionic (^110mAg⁺) and engineered nanoparticulate (^110mAgNPs, <40 nm) phases. Radiolabeled silver in starting solutions was used in a similar low concentration (∼15 Bq mL⁻¹) for both treatments. After exposure experiments radiolabeled silver was leached from the ISS using HCl. It concentration for shells from both treatments was ∼0.5 Bq mL⁻¹. Whole ISS of young individuals and prismatic layer of adults showed no evidence of any major alteration process after silver uptake. However, the nacre portion of adult mussels exposed to both treatments revealed distinct doughnut shape structures (DSS) formed by calcium carbonate micrograins that covered the surface of aragonite tablets. Scanning electron microscope (SEM) imaging revealed the existence of only minor differences in DSS morphology between mussels exposed to Ag⁺ and AgNPs. From literature survey, DSS were also found in bivalves exposed to Cd²⁺. The DSS occurring in a specimen of a field-collected bivalve is also shown. Formation of distinctive DSS can be explained by a disturbance of the shell calcification mechanism. Although the occurrence of DSS is not exclusively associated with metal bioavailability to the mussels, the morphology of DSS seems to be linked to the speciation of the metal used in the uptake experiments.     

Identification of two new cytochrome P450 genes and RNA interference to evaluate their roles in detoxification of commonly used insecticides in Locusta migratoria

Composite samples of Australian farmed Yellowtail Kingfish (Seriola lalandi) (YTKF) (n = 27), Mulloway (Argyrosomus hololepidotus) (n = 6) and manufactured feed (n = 5) were analysed to benchmark levels of a broad range of residues and contaminants of potential public health and trade significance. A subset of these samples [YTKF (n = 5), Mulloway (n = 2) and feed (n = 5)] was analysed for dioxins and polychlorinated biphenyls (PCBs). The mean concentration of dioxins in YTKF was 0.6 pg TEQ g⁻¹ (range 0.22-0.8) and in Mulloway was 0.16 pg TEQ g⁻¹ (range 0.16-0.16). The mean concentration of dioxins and dioxin-like PCBs in YTKF was 2.6 pg TEQ g⁻¹ (range 1.4-3.5), while Mulloway had a mean concentration of 0.67 pg TEQ g⁻¹ (range 0.57-0.76). The mean concentration of PCBs in YTKF was 21 μg kg⁻¹ (range 8.6-29) and in Mulloway was 5.4 μg kg⁻¹ (mean 4.7-6). The mean concentration of dioxin-like PCBs in YTKF was 2.1 pg TEQ g⁻¹ (range 1.2-2.8) and in Mulloway was 0.51 pg TEQ g⁻¹ (range 0.41-0.61). The mean mercury concentration in YTKF was 0.03 mg kg⁻¹ (range 0.02-0.05) and in Mulloway it was 0.02 mg kg⁻¹ (range 0.02-0.04). There were no detectable levels of any pesticide or antimicrobial compounds in any sample of YTKF or Mulloway. Attention is drawn to technical differences in port of entry testing programs such as sampling strategies, portion tested, laboratory methodology, residue definitions and reporting conventions that exporters’ products may be subject to. All residues and contaminants were either undetectable or present at very low levels when judged against Australian, Japanese and European Union regulatory standards (where set).     

Effects of the pharmaceuticals gemfibrozil and diclofenac on biomarker expression in the zebra mussel (Dreissena polymorpha) and their comparison with standardised toxicity tests

Pharmaceuticals, including the lipid regulator gemfibrozil and the non-steroidal anti-inflammatory drug diclofenac have been identified in waste water treatment plant effluents and receiving waters throughout the western world. The acute and chronic toxicity of these compounds was assessed for three freshwater species (Daphnia magna,Pseudokirchneriella subcapitata, Lemna minor) using standardised toxicity tests with toxicity found in the non-environmentally relevant mid mg L⁻¹ concentration range. For the acute endpoints (IC₅₀ and EC₅₀) gemfibrozil showed higher toxicity ranging from 29 to 59 mg L⁻¹ (diclofenac 47-67 mg L⁻¹), while diclofenac was more toxic for the chronic D. magna 21 d endpoints ranging from 10 to 56 mg L⁻¹ (gemfibrozil 32-100 mg L⁻¹). These results were compared with the expression of several biomarkers in the zebra mussel (Dreissena polymorpha) 24 and 96 h after exposure by injection to concentrations of 21 and 21,000 μg L⁻¹ corresponding to nominal concentrations of 1 and 1000 μg L⁻¹. Exposure to gemfibrozil and diclofenac at both concentrations significantly increased the level of lipid peroxidation, a biomarker of damage. At the elevated nominal concentration of 1000 μg L⁻¹ the biomarkers of defence glutathione transferase and metallothionein were significantly elevated for gemfibrozil and diclofenac respectively, as was DNA damage after 96 h exposure to gemfibrozil. No evidence of endocrine disruption was observed using the alkali-labile phosphate technique. Results from this suite of biomarkers indicate these compounds can cause significant stress at environmentally relevant concentrations acting primarily through oxidation pathways with significant destabilization of the lysosomal membrane and that biomarker expression is a more sensitive endpoint than standardised toxicity tests.     

Use of whole-body and subcellular Cu residues of Lumbriculus variegatus to predict waterborne Cu toxicity to both L. variegatus and Chironomus riparius in fresh water

We tested the use of whole-body and subcellular Cu residues (biologically-active (BAM) and inactive compartments (BIM)), of the oligochaete Lumbriculus variegatus to predict Cu toxicity in fresh water. The critical whole-body residue associated with 50% mortality (CBR₅₀) was constant (38.2-55.6 μg g⁻¹ fresh wt.) across water hardness (38-117 mg L⁻¹ as CaCO₃) and exposure times during the chronic exposure. The critical subcellular residue (CSR₅₀) in metal-rich granules (part of BIM) associated with 50% mortality was approximately 5 μg g⁻¹ fresh wt., indicating that Cu bioavailability is correlated with toxicity:subcellular residue is a better predictor of Cu toxicity than whole-body residue. There was a strong correlation between the whole-body residue of L. variegatus (biomonitor) and survival of Chironomus riparius (relatively sensitive species) in a hard water Cu co-exposure. The CBR₅₀ in L. variegatus for predicting mortality of C. riparius was 29.1-45.7 μg g⁻¹ fresh wt., which was consistent within the experimental period; therefore use of Cu residue in an accumulator species to predict bioavailability of Cu to a sensitive species is a promising approach.     

Mercury in the biotic compartments of Northwest Patagonia lakes, Argentina

We report on total mercury (THg) concentrations in the principal components of food webs of selected Northern Patagonia Andean Range ultraoligotrophic lakes, Argentina. The THg contents were determined using Instrumental Neutron Activation Analysis in muscle and liver of four fish species occupying the higher trophic positions (the introduced Salmo trutta, Oncorhynchus mykiss and Salvelinus fontinalis, and the native Percichthys trucha) accounted for eight lakes belonging to Nahuel Huapi and Los Alerces National Parks. We studied the food web components of both the West and East branches of Lake Moreno, including benthic primary producers such as biofilm, mosses, and macrophytes, three plankton fractions, fish, riparian tree leaves, and benthic invertebrates, namely decapods, molluscs, insect larvae, leeches, oligochaetes, and amphipods.Mercury concentrations in fish muscle varied in a wide range, from less than 0.05 to 4 μg g⁻¹ dry weight (DW), without a distribution pattern among species but showing higher values for P. trucha and S. fontinalis, particularly in Lake Moreno.The THg contents of the food web components of Lake Moreno varied within 4 orders of magnitude, with the lower values ranging from 0.01 to 0.5 μg g⁻¹ DW in tree leaves, some macrophytes, juvenile salmonids or benthic macroinvertebrates, and reaching concentrations over 200 μg g⁻¹ DW in the plankton. Juvenile Galaxias maculatus caught in the pelagic area presented the highest THg contents of all fish sampled, reaching 10 μg g⁻¹ DW, contents that could be associated with the high THg concentrations in plankton since it is their main food source. Although Lake Moreno is a system without local point sources of contamination, situated in a protected area, some benthic organisms presented high THg contents when compared with those from polluted ecosystems.     

Concentrations of cyclic volatile methylsiloxanes in biosolid amended soil,influent, effluent,receiving water,and sediment of wastewater treatment plants in Canada

A comprehensive surveillance program was conducted to determine the occurrence of three cyclic volatile methylsiloxanes (cVMS) octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5), and dodecamethylcyclohexasiloxane (D6) in environmental compartments impacted by wastewater effluent discharges. Eleven wastewater treatment plants (WWTPs), representative of those found in Southern Ontario and Southern Quebec, Canada, were investigated to determine levels of cVMS in their influents and effluents. In addition, receiving water and sediment impacted by WWTP effluents, and biosolid-amended soil from agricultural fields were also analyzed for a preliminary evaluation of the environmental exposure of cVMS in media impacted by wastewater effluent and solids. A newly-developed large volume injection (septumless head adapter and cooled injection system) gas chromatography – mass spectrometry method was used to avoid contamination originating from instrumental analysis. Concentrations of D4, D5, and D6 in influents to the 11 WWTPs were in the range 0.282–6.69 μg L⁻¹, 7.75–135 μg L⁻¹, and 1.53–26.9 μg L⁻¹, respectively. In general, wastewater treatment showed cVMS removal rates of greater than 92%, regardless of treatment type. The D4, D5, and D6 concentration ranges in effluent were <0.009–0.045 μg L⁻¹, <0.027–1.56 μg L⁻¹, and <0.022–0.093 μg L⁻¹, respectively. The concentrations in receiving water influenced by effluent, were lower compared to those in effluent in most cases, with the ranges <0.009–0.023 μg L⁻¹, <0.027–1.48 μg L⁻¹, and <0.022–0.151 μg L⁻¹ for D4, D5, and D6, respectively. Sediment concentrations ranged from <0.003–0.049 μg g⁻¹ dw, 0.011–5.84 μg g⁻¹ dw, and 0.004–0.371 μg g⁻¹ dw for D4, D5, and D6, respectively. The concentrations in biosolid-amended soil, having values of <0.008–0.017 μg g⁻¹ dw, <0.007–0.221 μg g⁻¹ dw, and <0.009–0.711 μg g⁻¹ dw for D4, D5, and D6, respectively, were lower than those in sediment impacted by wastewater effluent in most cases. In comparison with the no-observed-effected concentrations (NOEC) and IC50 (concentration that causes 50% inhibition of the response) values, the potential risks to aquatic, sediment-dwelling, and terrestrial organisms from these reported concentrations are low.     

Immunotoxicity in ascidians: antifouling compounds alternative to organotins: III--the case of copper(I) and Irgarol 1051

After the widespread ban of TBT, due to its severe impact on coastal biocoenoses, mainly related to its immunosuppressive effects on both invertebrates and vertebrates, alternative biocides such as Cu(I) salts and the triazine Irgarol 1051, the latter previously used in agriculture as a herbicide, have been massively introduced in combined formulations for antifouling paints against a wide spectrum of fouling organisms. Using short-term (60 min) haemocyte cultures of the colonial ascidian Botryllus schlosseri exposed to various sublethal concentrations of copper(I) chloride (LC₅₀ = 281 μM, i.e., 17.8 mg Cu L⁻¹) and Irgarol 1051 (LC₅₀ > 500 μM, i.e., >127 mg L⁻¹), we evaluated their immunotoxic effects through a series of cytochemical assays previously used for organotin compounds. Both compounds can induce dose-dependent immunosuppression, acting on different cellular targets and altering many activities of immunocytes but, unlike TBT, did not have significant effects on cell morphology. Generally, Cu(I) appeared to be more toxic than Irgarol 1051: it significantly (p < 0.05) inhibited yeast phagocytosis at 0.1 μM (∼10 μg L⁻¹), and affected calcium homeostasis and mitochondrial cytochrome-c oxidase activity at 0.01 μM (∼1 μg L⁻¹). Both substances were able to change membrane permeability, induce apoptosis from concentrations of 0.1 μM (∼10 μg L⁻¹) and 200 μM (∼50 mg L⁻¹) for Cu(I) and Irgarol 1051, respectively, and alter the activity of hydrolases. Both Cu(I) and Irgarol 1051 inhibited the activity of phenoloxidase, but did not show any interactive effect when co-present in the exposure medium, suggesting different mechanisms of action.