Occurrence of dissolved and particle-bound taste and odor compounds in Swiss lake waters

The occurrence of algal taste and odor (T&O) compounds was investigated in three Swiss lakes which exhibit different nutrient levels from eutrophic to oligotrophic (Lake Greifensee, Lake Zurich and Lake Lucerne). Apart from dissolved T&O compounds, the study also encompassed particle-bound compounds, i.e., compounds that can be released from damaged algal cells during drinking water treatment. A combined instrumental (SPME-GC-MS) and sensory method was applied that allowed to detect and quantify T&O compounds in natural waters in the sub ppt to low ppt-range.In addition to the prominent T&O compounds geosmin and 2-methyl-isoborneol (MIB), four other T&O compounds could be detected in the lake waters, though all at relatively low concentrations (maximum concentrations of geosmin 19 ng L⁻¹, MIB 3 ng L⁻¹, β-ionone 27 ng L⁻¹, β-cyclocitral 7 ng L⁻¹, 2-isobutyl-3-methoxypyrazine 2 ng L⁻¹, 2-isopropyl-3-methoxypyrazine 16 ng L⁻¹). The concentration peaks typically occurred in the epilimnion during summer concurrent with a high phytoplankton biomass. Consistently, the concentration levels for most of the compounds varied substantially between the three lakes and generally decreased in the order eutrophic Lake Greifensee > mesotrophic Lake Zurich > oligotrophic Lake Lucerne. Furthermore, our data revealed that the occurrence of β-ionone was largely influenced by Planktothrix rubescens. This is the first time that a correlation between β-ionone and this cyanobacterium has been reported for natural waters.     

Evidences of non-reactive mercury-selenium compounds generated from cultures of Pseudomonas fluorescens

This work was designed to determine chemically inert mercury-selenium (Hg-Se) compounds formed in a culture of Pseudomonas fluorescens exposed to Hg²⁺ and Se^IV (selenite). To isolate these compounds, different digestion methods were studied and sodium dodecyl sulfate (SDS) lysis was selected. The Hg⁰ and non-reactive Hg were determined in two series of cultures containing 0.0-6.00 μg L⁻¹ Se^IV (0.0-76.0 μmol L⁻¹) in combination with low 5.00 μg L⁻¹ (0.025 μmol L⁻¹) or high 100 μg L⁻¹ (0.500 μmol L⁻¹) Hg²⁺. It was found that Hg⁰ formed in the culture decreased with the increase of initial Se^IV, while the non-reactive Hg increased with the Se^IV. In cultures with low initial [Hg²⁺], a median Se^IV (2.0 μg L⁻¹ or 25.3 μmol L⁻¹) resulted in about 70% of the added Hg²⁺ sequestered as non-reactive Hg, and in culture with high initial Hg²⁺, about 40% was sequestered. P. fluorescens was proved to be indispensible for the formation of the non-reactive Hg-Se compounds. The Hg:Se molar ratio in the non-reactive Hg-Se compounds was close to 1, suggesting the existence of mercuric selenide in cells. Mechanisms for the formation of the non-reactive Hg-Se compounds are proposed.     

Plant tolerance to diesel minimizes its impact on soil microbial characteristics during rhizoremediation of diesel-contaminated soils

Soil contamination due to petroleum-derived products is an important environmental problem. We assessed the impacts of diesel oil on plants (Trifolium repens and Lolium perenne) and soil microbial community characteristics within the context of the rhizoremediation of contaminated soils. For this purpose, a diesel fuel spill on a grassland soil was simulated under pot conditions at a dose of 12,000 mg diesel kg^− 1 DW soil. Thirty days after diesel addition, T. repens (white clover) and L. perenne (perennial ryegrass) were sown in the pots and grown under greenhouse conditions (temperature 25/18 °C day/night, relative humidity 60/80% day/night and a photosynthetic photon flux density of 400 μmol photon m^− 2 s^− 1) for 5 months. A parallel set of unplanted pots was also included. Concentrations of n-alkanes in soil were determined as an indicator of diesel degradation. Seedling germination, plant growth, maximal photochemical efficiency of photosystem II (F_v/F_m), pigment composition and lipophylic antioxidant content were determined to assess the impacts of diesel on the studied plants. Soil microbial community characteristics, such as enzyme and community-level physiological profiles, were also determined and used to calculate the soil quality index (SQI). The presence of plants had a stimulatory effect on soil microbial activity. L. perenne was far more tolerant to diesel contamination than T. repens. Diesel contamination affected soil microbial characteristics, although its impact was less pronounced in the rhizosphere of L. perenne. Rhizoremediation with T. repens and L. perenne resulted in a similar reduction of total n-alkanes concentration. However, values of the soil microbial parameters and the SQI showed that the more tolerant species (L. perenne) was able to better maintain its rhizosphere characteristics when growing in diesel-contaminated soil, suggesting a better soil health. We concluded that plant tolerance is of crucial importance for the recovery of soil health during rhizoremediation of contaminated soils.     

Water, vegetation and sediment gradients in submerged aquatic vegetation mesocosms used for low-level phosphorus removal

Gradients in phosphorus (P) removal and storage were investigated over 6 years using mesocosms (each consisting of three tanks in series) containing submerged aquatic vegetation (SAV) grown on muck and limerock (LR) substrates. Mean inflow total P concentrations (TP) of 32 μg L⁻¹ were reduced to 15 and 17 μg L⁻¹ in the muck and LR mesocosms, respectively. Mesocosm P loading rates (mean = 1.75 g m⁻² year⁻¹) varied widely during the study and were not correlated with outflow TP, which instead varied seasonally with lowest monthly mean values in December and January.The mesocosms initially were stocked with Najas guadalupensis, Ceratophyllum demersum, and Chara zeylanica, but became dominated by C. zeylanica. At the end of the study, highest vegetative biomass (1.1 and 1.4 kg m⁻² for muck and LR substrates) and tissue P content (1775 and 1160 mg kg⁻¹) occurred in the first tank in series, and lowest biomass (1.0 and 0.2 kg m⁻²) and tissue P (147 and 120 mg kg⁻¹) in the third tank. Sediment accretion rates (2.5, 1.9 and 0.9 cm yr⁻¹ on muck substrates), accrued sediment TP (378, 309 and 272 mg kg⁻¹), and porewater soluble reactive P (SRP) concentrations (40, 6 and 4 μg L⁻¹) in the first, second and third tanks, respectively, exhibited a similar decreasing spatial trend. Plant tissue calcium (Ca) near mesocosm inflow (19-30% dry weight) and outflow (23-26%) were not significantly different, and sediment Ca was also similar (range of 24 to 28%) among sequential tanks.Well-defined vegetation and sediment enrichment gradients developed in SAV wetlands operated under low TP conditions. While the mesocosm data did not reflect deterioration in treatment performance over 6 years, accumulation of P-enriched sediments near the inflow could eventually compromise hydraulic storage and P removal effectiveness of these shallow systems.     

Degradation of diclofenac by TiO2 photocatalysis: UV absorbance kinetics and process evaluation through a set of toxicity bioassays

In the present study the degradation kinetics and mineralization of diclofenac (DCF) by the TiO₂ photocatalysis were investigated in terms of UV absorbance and COD measurements for a wide range of initial DCF concentrations (5-80 mg L⁻¹) and photocatalyst loadings (0.2-1.6 g TiO₂ L⁻¹) in a batch reactor system. A set of bioassays (Daphnia magna, Pseudokirchneriella subcapitata and Artemia salina) was performed to evaluate the potential detoxification of DCF. A pseudo-first-order kinetic model was found to fit well most of the experimental data, while at high initial DCF concentrations (40 and 80 mg L⁻¹) and at 1.6 g TiO₂ L⁻¹ photocatalyst loading a second-order kinetic model was found to fit the data better. The toxicity of the treated DCF samples on D. magna and P. subcapitata varied during the oxidation, probably due to the formation of some intermediate products more toxic than DCF. Unicellular freshwater algae was found to be very sensitive to the treated samples as well as the results from D. magna test were consistent to those of algae tests. A. salina was not found to be sensitive under the investigated conditions. Finally, UV absorbance analysis were found to be an useful tool for a fast and easy to perform measurement to get preliminary information on the organic intermediates that are formed during oxidation and also on their disappearance rate.     

Environmental occurrence and degradation of the herbicide n-chloridazon

A sampling campaign was carried out for n-chloridazon (n-CLZ) and its degradation product desphenyl-chloridazon (DPC) in the Hesse region (Germany) during the year 2007: a total of 548 environmental samples including groundwater, surface water and wastewater treatment plant (WWTP) effluent were analysed. Furthermore, aerobic degradation of n-CLZ has been studied utilising a fixed bed bioreactor (FBBR).In surface water, n-CLZ was detected at low concentrations (average 0.01 ± 0.06 μg L⁻¹; maximum 0.89 μg L⁻¹) with a seasonal peak, whereas DPC was present throughout the year at much higher concentrations (average 0.72 ± 0.81 μg L⁻¹; maximum 7.4 μg L⁻¹). Higher n-CLZ concentrations were observed in the North compared with South Hesse, which is ascribed to a higher density of agricultural areas. Furthermore, methylated DPC (Me-DPC), another degradation product, was detected in surface water.In the degradation test, n-CLZ was completely converted to DPC at all concentrations tested (Me-DPC was not formed under the test conditions). DPC was resistant to further degradation during the whole experimental period of 98 days. The results obtained suggest persistence and high dispersion of DPC in the aquatic environment.     

Evaluation and validation of a novel Arxula adeninivorans estrogen screen (nAES) assay and its application in analysis of wastewater, seawater, brackish water and urine

A novel Arxula adeninivorans yeast estrogen screen (nAES) assay has been developed for detection of estrogenic activity in various liquid samples such as wastewater, seawater, brackish water and swine urine. Two bio-components were engineered to co-express the human estrogen receptor α (hERα) and an inducible reporter gene; either the non-conventional phytase gene (phyK, derived from Klebsiella sp. ASR1) or the non-conventional tannase gene (ATAN1, derived from Arxula). Both reporters were put under the control of an Arxula derived glucoamylase (GAA) promoter, which was modified by the insertion of two estrogen-responsive elements (EREs). The Arxula transformation/expression platform Xplor® 2, which lacks resistance markers and E. coli elements, was used to select stable mitotic transformants. They were then analyzed for robustness and suitability as the bio-component for the nAES assay. Two types of the nAES assay based on the reporter proteins phytase and tannase (nAES-P, nAES-T) were used in this work. The nAES-P type is more suitable for the analysis of seawater, brackish water and urine whereas the nAES-T type exhibited higher robustness to NaCl. Both assay types have similar characteristics for the determination of estrogen in sewage and urine samples e.g. 6-25 h assay period with detection and determination limits and EC₅₀ values for 17β-estradiol of 2.8 ng L^− 1, 5.9 ng L^− 1, 33.2 ng L^− 1 (nAES-P) and 3.1 ng L^− 1, 6.7 ng L^− 1 and 39.4 ng L^− 1 (nAES-T). Substrate specificity and analytical measurement range (AMR) for both assay types are also similar. These characteristics show that the nAES assay based on non-conventional salt tolerant yeast is applicable for a high throughput estrogen analysis in the environmental and regulatory control sectors.     

Effects of salinities on the gene expression of a (NAD+)-dependent glycerol-3-phosphate dehydrogenase in Dunaliella salina

Glycerol-3-phosphate dehydrogenase (G3pdh) is a key enzyme in the pathway of glycerol synthesis, which converts dihydroxyacetone phosphate (DHAP) to glycerol-3-phosphate. In this study, the effects of salinity changes on variation of cell shape and single cell glycerol content of Dunaliella salina were observed, and the effects of salinity changes on the gene expressions of a (NAD⁺)-dependent G3pdh (EC1.1.1.8) among G3pdh isozymes in D. salina were detected by real-time quantitative PCR. Results showed that the changes of shape and volume of D. salina cell cultured chronically at various salinities were minor, but when the salinity was changed rapidly, the variations of cell shape and cell volume of D. salina were significant, which were recovered basically after 2 h except treating by high salinity. Also, it was found some lipid globules in the surface of D. salina cells when the salinity increased from 2.0 to 4.0-5.0 M NaCl rapidly. When D. salina was cultured chronically at various salinities, the accumulation of single cell glycerol increased with increased salinity, and D. salina also could rapidly decrease or increase single cell glycerol contents to adapt to hypoosmotic or hyperosmotic shock. The expression level of G3pdh in D. salina grown at various salinities was significantly inversely correlated to the salinity, but there was no significant correlation between the expression level of G3pdh and salinity after 2 h of treatment by hyperosmotic or hypoosmotic shock.     

Responses of streams in central Appalachian Mountain region to reduced acidic deposition—Comparisons with other regions in North America and Europe

Data from 5 wet deposition stations and 21 streams during 1980-2006 were analyzed to investigate chemical responses of streams to reduced acidic deposition in the central Appalachian Mountain region of West Virginia, USA. Wet deposition of acidic anions (i.e., sulfate, nitrate, and chloride) and hydrogen ions decreased significantly during the studied time period. Stream sulfate showed a delayed response to the reduced acidic deposition, and showed a decrease in the 2000s (− 5.54 µeq L^− 1 yr^− 1) and the whole period (− 0.49 µeq L^− 1 yr^− 1). No significant trend of stream nitrate + nitrite and chloride was observed. Stream alkalinity increased in the 1990s (+ 23.33 µeq L^− 1 yr^− 1) and the whole period (+ 7.26 µeq L^− 1 yr^− 1). Stream hydrogen ions decreased in the 1990s (− 0.002 µeq L^− 1 yr^− 1), 2000s (− 0.001 µeq L^− 1 yr^− 1), and the whole period (− 0.001 µeq L^− 1 yr^− 1). Compared with most acidic streams and lakes in the United States and Europe, a lower decreasing rate of hydrogen ions and higher increasing rate of alkalinity were observed in the alkaline West Virginian streams in the 1990s. However, due to their initial negative or zero alkalinity values, those acidic streams showed a higher percent increase in alkalinity than that in the alkaline West Virginian streams (from 800 µeq L^− 1 yr^− 1 to 1200 µeq L^− 1 yr^− 1). Total aluminum in the West Virginian streams decreased in the 1990s (− 0.67 µmol L^− 1 yr^− 1) and the whole period (− 0.22 µmol L^− 1 yr^− 1). The current study advanced our understanding of streams' responses to the reduced acidic deposition in the Mid-Appalachians since the passage of the 1970 and 1990 Amendments to the United States Clean Air Act (US CAAA).     

Rhizosphere acidification of faba bean, soybean and maize

Interspecific facilitation on phosphorus uptake was observed in faba bean/maize intercropping systems in previous studies. The mechanism behind this, however, remained unknown. Under nitrate supply, the difference in rhizosphere acidification potential was studied by directly measuring pH of the solution and by visualizing and quantifying proton efflux of roots between faba bean (Vicia faba L. cv. Lincan No.5), soybean (Glycine max L. cv. Zhonghuang No. 17) and maize (Zea mays L. cv. Zhongdan No.2) in monoculture and intercrop, supplied without or with 0.2 mmol L^− 1 P as KH₂PO₄. The pH of the nutrient solution grown faba bean was lower than initial pH of 6.0 from day 1 to day 22 under P deficiency, whereas the pH of the solution with maize was declined from day 13 after treatment. Growing soybean increased solution pH irrespective of P supply. Under P deficiency, the proton efflux of faba bean both total (315.25 nmol h^− 1 plant^− 1) and specific proton efflux (0.47 nmol h^− 1 cm^− 1) was greater than that those of soybean (21.80 nmol h^− 1 plant^− 1 and 0.05 nmol h^− 1 cm^− 1, respectively). Faba bean had much more ability of rhizosphere acidification than soybean and maize. The result can explain partly why faba bean utilizes sparingly soluble P more effectively than soybean and maize do, and has an important implication in understanding the mechanism behind interspecific facilitation on P uptake by intercropped species.     

Comparison of toxicity and release rates of Cu and Zn from anti-fouling paints leached in natural and artificial brackish seawater

Biocide-containing anti-fouling paints are regulated and approved according to the added active ingredients, such as Cu. Biocide-free paints are considered to be less environmentally damaging and do not need an approval. Zn, a common ingredient in paints with the potential of causing adverse effects has received only minor attention. Laboratory experiments were conducted in artificial brackish seawater (ASW) and natural brackish seawater (NSW) to quantify release rates of Cu and Zn from biocide-containing and biocide-free labeled eroding anti-fouling paints used on commercial vessels as well as leisure boats. In addition, organisms from three trophic levels, the crustacean Nitocra spinipes, the macroalga Ceramium tenuicorne and the bacteria Vibrio fischeri, were exposed to Cu and Zn to determine the toxicity of these metals. The release rate of Cu in NSW was higher from the paints for professional use (3.2-3.6 µg cm⁻² d^− 1) than from the biocide leaching leisure boat paint (1.1 µg cm⁻² d^− 1). Biocide-free paints did leach considerably more Zn (4.4-8.2 µg cm⁻² d^− 1) than biocide-containing leisure boat paint (3.0 µg cm⁻² d^− 1) and ship paints (0.7-2.0 µg cm⁻² d^− 1). In ASW the release rates of both metals were notably higher than in NSW for most tested paints. The macroalga was the most sensitive species to both Cu (EC₅₀ = 6.4 µg l^− 1) and Zn (EC₅₀ = 25 µg l^− 1) compared to the crustacean (Cu, LC₅₀ = 2000 µg l^− 1 Zn, LC₅₀ = 890 µg l^− 1), and the bacteria (Cu, EC₅₀ = 800 µg l^− 1 and Zn, EC₅₀ = 2000 µg l^− 1). The results suggest that the amounts of Zn and Cu leached from anti-fouling paints may attain toxic concentrations in areas with high boat density. To fully account for potential ecological risk associated with anti-fouling paints, Zn as well as active ingredients should be considered in the regulatory process.     

Precipitation of arsenic sulphide from acidic water in a fixed-film bioreactor

Arsenic (As) is a toxic element frequently present in acid mine waters and effluents. Precipitation of trivalent arsenic sulphide in sulphate-reducing conditions at low pH has been studied with the aim of removing this hazardous element in a waste product with high As content. To achieve this, a 400 mL fixed-film column bioreactor was fed continuously with a synthetic solution containing 100 mg L⁻¹ As(V), glycerol and/or hydrogen, at pH values between 2.7 and 5. The highest global As removal rate obtained during these experiments was close to 2.5 mg L⁻¹ h⁻¹. A switch from glycerol to hydrogen when the biofilm was mature induced an abrupt increase in the sulphate-reducing activity, resulting in a dramatic mobilisation of arsenic due to the formation of soluble thioarsenic complexes. A new analytical method, based on ionic chromatography, was used to evaluate the proportion of As present as thioarsenic complexes in the bioreactor. Profiles of pH, total As and sulphate concentrations suggest that As removal efficiency was linked to solubility of orpiment (As₂S₃) depending on pH conditions. Molecular fingerprints revealed fairly homogeneous bacterial colonisation throughout the reactor. The bacterial community was diverse and included fermenting bacteria and Desulfosporosinus-like sulphate-reducing bacteria. arrA genes, involved in dissimilatory reduction of As(V), were found and the retrieved sequences suggested that As(V) was reduced by a Desulfosporosinus-like organism. This study was the first to show that As can be removed by bioprecipitation of orpiment from acidic solution containing up to 100 mg L⁻¹ As(V) in a bioreactor.     

Spatial isolation favours the divergence in microcystin net production by Microcystis in Ugandan freshwater lakes

It is generally agreed that the hepatotoxic microcystins (MCs) are the most abundant toxins produced by cyanobacteria in freshwater. In various freshwater lakes in East Africa MC-producing Microcystis has been reported to dominate the phytoplankton, however the regulation of MC production is poorly understood. From May 2007 to April 2008 the Microcystis abundance, the absolute and relative abundance of the mcyB genotype indicative of MC production and the MC concentrations were recorded monthly in five freshwater lakes in Uganda: (1) in a crater lake (Lake Saka), (2) in three shallow lakes (Lake Mburo, George, Edward), (3) in Lake Victoria (Murchison Bay, Napoleon Gulf). During the whole study period Microcystis was abundant or dominated the phytoplankton. In all samples mcyB-containing cells of Microcystis were found and on average comprised 20 ± 2% (SE) of the total population. The proportion of the mcyB genotype differed significantly between the sampling sites, and while the highest mcyB proportions were recorded in Lake Saka (37 ± 3%), the lowest proportion was recorded in Lake George (1.4 ± 0.2%). Consequently Microcystis from Lake George had the lowest MC cell quotas (0.03-1.24 fg MC cell⁻¹) and resulted in the lowest MC concentrations (0-0.5 μg L⁻¹) while Microcystis from Lake Saka consistently showed maximum MC cell quotas (14-144 fg cell⁻¹) and the highest MC concentrations (0.5-10.2 μg L⁻¹). Over the whole study period the average MC content per Microcystis cell depended linearly on the proportion of the mcyB genotype of Microcystis. It is concluded that Microcystis populations differ consistently and independently of the season in mcyB genotype proportion between lakes resulting in population-specific differences in the average MC content per cell.     

Heterogenous photocatalytic degradation kinetics and detoxification of an urban wastewater treatment plant effluent contaminated with pharmaceuticals

Degradation kinetics and mineralization of an urban wastewater treatment plant effluent contaminated with a mixture of pharmaceutical compounds composed of amoxicillin (10 mg L⁻¹), carbamazepine (5 mg L⁻¹) and diclofenac (2.5 mg L⁻¹) by TiO₂ photocatalysis were investigated. The photocatalytic effect was investigated using both spiked distilled water and actual wastewater solutions. The process efficiency was evaluated through UV absorbance and TOC measurements. A set of bioassays (Daphnia magna, Pseudokirchneriella subcapitata and Lepidium sativum) was performed to evaluate the potential toxicity of the oxidation intermediates. A pseudo-first order kinetic model was found to fit well the experimental data. The mineralization rate (TOC) of the wastewater contaminated with the pharmaceuticals was found to be really slow (t_1/2 = 86.6 min) compared to that of the same pharmaceuticals spiked in distilled water (t_1/2 = 46.5 min). The results from the toxicity tests of single pharmaceuticals, their mixture and the wastewater matrix spiked with the pharmaceuticals displayed a general accordance between the responses of the freshwater aquatic species (P. subscapitata > D. magna). In general the photocatalytic treatment did not completely reduce the toxicity under the investigated conditions (maximum catalyst loading and irradiation time 0.8 g TiO₂ L⁻¹ and 120 min respectively).     

Heavy metals: confounding factors in the response of New Zealand freshwater fish assemblages to natural and anthropogenic acidity

Acidification of freshwaters is a global phenomenon, occurring both through natural leaching of organic acids and through human activities from industrial emissions and mining. The West Coast of the South Island, New Zealand, has both naturally acidic and acid mine drainage (AMD) streams enabling us to investigate the response of fish communities to a gradient of acidity in the presence and absence of additional stressors such as elevated concentrations of heavy metals. We surveyed a total of 42 streams ranging from highly acidic (pH 3.1) and high in heavy metals (10 mg L⁻¹ Fe; 38 mg L⁻¹ Al) to circum-neutral (pH 8.1) and low in metals (0.02 mg L⁻¹ Fe; 0.05 mg L⁻¹ Al). Marked differences in pH and metal tolerances were observed among the 15 species that we recorded. Five Galaxias species, Anguilla dieffenbachii and Anguillaaustralis were found in more acidic waters (pH< 5), while bluegill bullies (Gobiomorphus hubbsi) and torrentfish (Cheimarrichthys fosteri) were least tolerant of low pH (minimum pH 6.2 and 5.5, respectively). Surprisingly, the strongest physicochemical predictor of fish diversity, density and biomass was dissolved metal concentrations (Fe, Al, Zn, Mn and Ni) rather than pH. No fish were detected in streams with dissolved metal concentrations > 2.7 mg L⁻¹ and nine taxa were only found in streams with metal concentrations < 1 mg L⁻¹. The importance of heavy metals as critical drivers of fish communities has not been previously reported in New Zealand, although the mechanism of the metal effects warrants further study. Our findings indicate that any remediation of AMD streams which seeks to enable fish recolonisation should aim to improve water quality by raising pH above ≈ 4.5 and reducing concentrations of dissolved Al and Fe to < 1.0 mg L⁻¹.     

Characterization of copper bioreduction and biosorption by a highly copper resistant bacterium isolated from copper-contaminated vineyard soil

Copper is an essential but toxic heavy metal that negatively impacts living systems at high concentration. This study presents factors affecting copper bioremoval (bioreduction and biosorption) by a highly copper resistant monoculture of Pseudomonas sp. NA and copper bioremoval from soil. Seven bacteria resistant to high concentration of Cu(II) were isolated from enrichment cultures of vineyard soils and mining wastes. Culture parameters influencing copper bioreduction and biosorption by one monoculture isolate were studied. The isolate was identified by 16S rRNA gene sequence analysis as a Pseudomonas sp. NA (98% similarity to Pseudomonas putida, Pseudomonas plecoglossicida and other Pseudomonas sp.). The optimal temperature for growth was 30 °C and bioremoval of Cu(II) was maximal at 35 °C. Considerable growth of the isolate was observed between pH 5.0 and 8.0 with the highest growth and biosorption recorded at pH 6.0. Maximal bioreduction was observed at pH 5.0. Cu(II) bioremoval was directly proportional to Cu(II) concentration in media. Pseudomonas sp. NA removed more than 110 mg L^− 1 Cu(II) in water within 24 h through bioreduction and biosorption at initial concentration of 300 mg L^− 1. In cultures amended with 100 mg L^− 1, 20.7 mg L^− 1 of Cu(II) was biologically reduced and more than 23 mg L^− 1 of Cu(II) was biologically removed in 12 h. The isolate strongly promoted copper bioleaching in soil. Results indicate that Pseudomonas sp. NA has good potential as an agent for removing copper from water and soil.     

Effect of COD/SO4ratio and Fe(II) under the variable hydraulic retention time (HRT) on fermentative hydrogen production

The effect of chemical oxygen demand/sulfate (COD/SO₄²⁻) ratio on fermentative hydrogen production using enriched mixed microflora has been studied. The chemostat system maintained with a substrate (glucose) concentration of 15 g COD L⁻¹ exhibited stable H₂ production at inlet sulfate concentrations of 0-20 g L⁻¹ during 282 days. The tested COD/SO₄²⁻ ratios ranged from 150 to 0.75 (with control) at pH 5.5 with hydraulic retention time (HRT) of 24, 12 and 6 h. The hydrogen production at HRT 6 h and pH 5.5 was not influenced by decreasing the COD/SO₄²⁻ ratio from 150 to 15 (with control) followed by noticeable increase at COD/SO₄²⁻ ratios of 5 and 3, but it was slightly decreased when the COD/SO₄²⁻ ratio further decreased to 1.5 and 0.75. These results indicate that high sulfate concentrations (up to 20,000 mg L⁻¹) would not interfere with hydrogen production under the investigated experimental conditions. Maximum hydrogen production was 2.95, 4.60 and 9.40 L day⁻¹ with hydrogen yields of 2.0, 1.8 and 1.6 mol H₂ mol⁻¹ glucose at HRTs of 24, 12 and 6 h, respectively. The volatile fatty acid (VFA) fraction produced during the reaction was in the order of butyrate > acetate > ethanol > propionate in all experiments. Fluorescence In Situ Hybridization (FISH) analysis indicated the presence of Clostridium spp., Clostridium butyricum, Clostridium perfringens and Ruminococcus flavefaciens as hydrogen producing bacteria (HPB) and absence of sulfate reducing bacteria (SRB) in our study.     

Environmental impact of mining activities in the Lousal area (Portugal): chemical and diatom characterization of metal-contaminated stream sediments and surface water of Corona stream

Lousal mine is a typical “abandoned mine” with all sorts of problems as consequence of the cessation of the mining activity and lack of infrastructure maintenance. The mine is closed at present, but the heavy metal enriched tailings remain at the surface in oxidizing conditions. Surface water and stream sediments revealed much higher concentrations than the local geochemical background values, which the “Contaminated Sediment Standing Team” classifies as very toxic. High concentrations of Cu, Pb, Zn, As, Cd and Hg occurred within the stream sediments downstream of the tailings sites (up to: 817 mg kg⁻¹ As, 6.7 mg kg⁻¹ Cd, 1568 mg kg⁻¹ Cu, 1059 mg kg⁻¹ Pb, 82.4 mg kg⁻¹ Sb, 4373 mg kg⁻¹ Zn). The AMD waters showed values of pH ranging from 1.9 to 2.9 and concentrations of 9249 to 20,700 mg L⁻¹ SO₄⁻², 959 to 4830 mg L⁻¹ Fe and 136 to 624 mg L⁻¹ Al. Meanwhile, the acid effluents and mixed stream waters also carried high contents of SO₄^2−, Fe, Al, Cu, Pb, Zn, Cd, and As, generally exceeding the Fresh Water Aquatic Life Acute Criteria. Negative impacts in the diatom communities growing at different sites along a strong metal pollution gradient were shown through Canonical Correspondence Analysis: in the sites influenced by Acid Mine Drainage (AMD), the dominant taxon was Achnanthidium minutissimum. However, Pinnularia acoricola was the dominant species when the environmental conditions were extremely adverse: very low pH and high metal concentrations (sites 2 and 3). Teratological forms of Achnanthidium minutissimum (Kützing) Czarnecki, Brachysira vitrea (Grunow) Ross in Hartley, Fragilaria rumpens (Kützing) G. W. F. Carlson and Nitzschia hantzschiana Rabenhorst were found. A morphometric study of B. vitrea showed that a decrease in size was evident at the most contaminated sites. These results are evidence of metal and acidic pollution.     

Occurrence and fate of organophosphorus flame retardants and plasticizers in urban and remote surface waters in Germany

Within this study, concentration levels and distribution of the organophosphates tris(2-chloroethyl) phosphate (TCEP), tris(2-chloro-1-methylethyl) phosphate (TCPP), tris(2-butoxyethyl) phosphate (TBEP), tri-iso-butyl phosphate (TiBP), and tri-n-butyl phosphate (TnBP) were investigated at nine lentic surface waters under different anthropogenic impact between June 2007 and October 2009. Furthermore, the possibility of in-lake photochemical degradation of the analytes was studied in laboratory experiments using spiked ultrapure water and lake water samples incubated in Teflon bottles (which transmit sunlight). TBEP, TiBP, and TnBP were photochemically degraded in spiked lake water samples upon exposure to sunlight. Organophosphate concentrations in the more remote lakes were often below or close to the limits of quantification (LOQ). TCPP was the substance with the highest median concentration in rural volcanic lakes (7-18 ng L⁻¹) indicating an atmospheric transport of the compound. At urban lakes their median concentrations were in the range of 23-61 ng L⁻¹ (TCEP), 85-126 ng L⁻¹ (TCPP), <LOQ-53 ng L⁻¹ (TBEP), 8-10 ng L⁻¹ (TiBP), and 17-32 ng L⁻¹ (TnBP). High variability but no significant seasonal trends were observed for all five organophosphates in urban lake water samples.