Contribution of Streptomyces in sediment to earthy odor in the overlying water in Xionghe Reservoir, China

Musty and earthy odors frequently characterize the source water and fish of the Xionghe Reservoir in China. Although odorous compounds and odor-producing cyanobacteria have been analyzed in surface water, potential odorants in sediments and their contribution to the water body have remained uninvestigated. In this study, we examined the odorous compounds and possible odor-producers in the sediments and overlying water of Xionghe Reservoir from November 2007 to October 2008. High concentrations of geosmin (up to 5280.1 ng kg⁻¹ dw⁻¹) were detected in sediments, and eight strains of Streptomyces isolated from sediments were verified as producers of geosmin and/or 2-MIB in M liquid medium by HSPME-GC-MS. Geosmin concentrations in the overlying water were correlated with those in the sediments (r = 0.838, p < 0.05). In vitro studies showed that geosmin in the overlying water was released from the sediment, and that within 12 days the amount released from the sediment was 21.4–51.4%. Concentrations of geosmin in sediments were positively correlated with organic matter (r = 0.642, p < 0.01), total nitrogen (r = 0.606, p < 0.01) and Chl a (r = 0.674, p < 0.01), and were negatively associated with temperature (r = −0.425, p < 0.05). This study indicates that odorous compounds that are released from sediments should be taken into account when assessing the sources of these odorants in waters.     

Reevaluation of health risk benchmark for sustainable water practice through risk analysis of rooftop-harvested rainwater

Health risk concerns associated with household use of rooftop-harvested rainwater (HRW) constitute one of the main impediments to exploit the benefits of rainwater harvesting in the United States. However, the benchmark based on the U.S. EPA acceptable annual infection risk level of ≤1 case per 10,000 persons per year (≤10⁻⁴ pppy) developed to aid drinking water regulations may be unnecessarily stringent for sustainable water practice. In this study, we challenge the current risk benchmark by quantifying the potential microbial risk associated with consumption of HRW-irrigated home produce and comparing it against the current risk benchmark. Microbial pathogen data for HRW and exposure rates reported in literature are applied to assess the potential microbial risk posed to household consumers of their homegrown produce. A Quantitative Microbial Risk Assessment (QMRA) model based on worst-case scenario (e.g. overhead irrigation, no pathogen inactivation) is applied to three crops that are most popular among home gardeners (lettuce, cucumbers, and tomatoes) and commonly consumed raw. The infection risks of household consumers attributed to consumption of these home produce vary with the type of produce. The lettuce presents the highest risk, which is followed by tomato and cucumber, respectively. Results show that the 95th percentile values of infection risk per intake event of home produce are one to three orders of magnitude (10⁻⁷ to 10⁻⁵) lower than U.S. EPA risk benchmark (≤10⁻⁴ pppy). However, annual infection risks under the same scenario (multiple intake events in a year) are very likely to exceed the risk benchmark by one order of magnitude in some cases. Estimated 95th percentile values of the annual risk are in the 10⁻⁴ to 10⁻³ pppy range, which are still lower than the 10⁻³ to 10⁻¹ pppy risk range of reclaimed water irrigated produce estimated in comparable studies. We further discuss the desirability of HRW for irrigating home produce based on the relative risk of HRW to reclaimed wastewater for irrigation of food crops. The appropriateness of the ≤10⁻⁴ pppy risk benchmark for assessing safety level of HRW-irrigated fresh produce is questioned by considering the assumptions made for the QMRA model. Consequently, the need of an updated approach to assess appropriateness of sustainable water practice for making guidelines and policies is proposed.     

Mercury contamination in the vicinity of a chlor-alkali plant and potential risks to local population

A mercury-cell chlor-alkali plant operated in Estarreja (North-western Portugal) for 50 years causing widespread environmental contamination. Although production by this process ceased in 2002, mercury contamination from the plant remains significant. The main objective of this study was to investigate mercury impact on the nearby environment and potential risks to local population. To assess the level of contamination soil samples were collected from agricultural fields in the vicinity of the plant, extending the study by taking samples of the predominant vegetation suitable for animal and human consumption, water samples, and fish species from a nearby coastal lagoon, to gain a preliminary insight into the potential for contamination of the terrestrial and aquatic food web. To determine population exposure to mercury, hair samples were collected from local residents. Total mercury concentration in the 0-15 cm layer of soil was found to be highly variable, ranging between 0.010 and 91 mg kg^− 1, although mercury contamination of soils was found to be restricted to a confined area. Lolium perenne roots contained between 0.0070 and 2.0 mg kg^− 1, and there is evidence that root systems uptake mercury from the soil. Levels of mercury in the aerial parts of plants ranged between 0.018 and 0.98 mg kg^− 1. It appears that plants with higher mercury concentration in soils and roots also display higher mercury concentration in leaves.Total mercury concentration in water samples ranged between 12 and 846 ng L^− 1, all samples presenting concentrations below the maximum level allowable for drinking water defined in the Portuguese law (1.0 μg L^− 1).Mercury levels in fish samples were below the maximum limit defined in the Portuguese law (0.5 mg kg^− 1), ranging from 0.0040 to 0.24 mg kg^− 1. Vegetables collected presented maximum mercury concentration of 0.17 mg kg^− 1. In general, food is not contaminated and should not be responsible for major human exposure to the metal.Mercury determined in human hair samples (0.090-4.2 mg kg^− 1; mean 1.5 mg kg^− 1) can be considered within normal limits, according to WHO guidelines suggesting that it is not affecting the local population. Despite being subject to decades of mercury emissions, nowadays this pollutant is only found in limited small areas and must not constitute a risk for human health, should these areas be restricted and monitored.Considering the present data, it appears that the population from Estarreja is currently not being affected by mercury levels that still remain in the environment.     

Spatial variations on methane emissions from Zoige alpine wetlands of Southwest China

This study was aimed to understand the spatial variation of CH₄ emissions from alpine wetlands in Southwest China on a field-scale in two phenological seasons, namely the peak growing season and the spring thaw. Methane emission rates were measured at 30 plots, which included three kinds of environmental types: dry hummock, Carex muliensis and Eleocharis valleculosa sites. There were highly spatial variations of methane emissions among and within different environmental types in both phenological seasons. Mean methane emission rates ranged from 1.1 to 37.0 mg CH₄ m^− 2 h^− 1 in the peak growing season and from 0.004 to 0.691 mg CH₄ m^− 2 h^− 1 in the spring thaw. In the peak growing season, coefficients of variation (CV) averaged 38% among environmental types and 64% within environmental types; while in the spring thaw, CV were on the average 61% among environmental types and 96% within environmental types. The key influencing factors were the standing water table and the plant community height in the peak growing season, while in the spring thaw, no significant correlations between factors and methane emissions were found.     

Frequency of use controls chemical leaching from drinking-water containers subject to disinfection

Microbial-, and chemical-based burden of disease associated with lack of access to safe water continues to primarily impact developing countries. Cost-effective health risk-mitigating measures, such as of solar disinfection applied to microbial-contaminated water stored in plastic bottles have been increasingly tested in developing countries adversely impacted by epidemic water-borne diseases. Public health concerns associated with chemical leaching from water packaging materials led us to investigate the magnitude and variability of antimony (Sb) and bromine (Br) leaching from reused plastic containers (polyethylene terephthalate, PET; and polycarbonate, PC) subject to UV and/or temperature-driven disinfection. The overall objective of this study was to determine the main and interactive effects of temperature, UV exposure duration, and frequency of bottle reuse on the extent of leaching of Sb and Br from plastic bottles into water. Regardless of UV exposure duration, frequency of reuse (up to 27 times) was the major factor that linearly increased Sb leaching from PET bottles at all temperatures tested (13-47 °C). Leached Sb concentrations (∼360 ng L⁻¹) from the highly reused (27 times) PET bottles (minimal Sb leaching from PC bottles, <15 ng L⁻¹) did not pose a serious risk to human health according to current daily Sb acceptable intake estimates. Leached Br concentrations from both PET and PC containers (up to ∼15 μg L⁻¹) did not pose a consumer health risk either, however, no acceptable daily dose estimates exist for oral ingestion of organo-brominated, or other plasticizers/additives compounds if they were to be found in bottled water at much lower concentrations. Additional research on potential leaching of organic chemicals from water packaging materials is deemed necessary under relevant environmental conditions.     

Determination of rate constants and half-lives for the simultaneous biodegradation of several cyanobacterial metabolites in Australian source waters

The fate of five cyanobacterial metabolites was assessed in water sourced from Lake Burragorang (Warragamba Dam) in New South Wales, Australia. All of the studied metabolites were shown to be biodegradable in this water source. For some metabolites, biodegradation was influenced by factors, including temperature, location (within the water body) and seasonal variations. The biodegradation of the metabolites was shown to follow pseudo-first-order kinetics with rate constants ranging from 8.0 × 10⁻⁴ to 1.3 × 10⁻² h⁻¹. Half-lives of the metabolites were also estimated and ranged from 2.2 to 36.1 d. The order of ease of biodegradability in this water source followed the trend: microcystin-LR ≥ cylindrospermopsin > saxitoxins > geosmin ≥ 2-methylisoborneol. The lack of detection of the mlrA gene during microcystin biodegradation suggests that these toxins may be degraded via a different pathway. While no metabolite-degrading organisms were isolated in this study, the inoculation of previously isolated geosmin- and microcystin-degrading bacteria into Lake Burragorang water resulted in efficient biodegradation of the respective metabolites. For example, microcystin-degrading isolate TT25 was able to degrade three microcystin variants to concentrations below analytical detection within 24 h, suggesting that inoculation of such bacteria has the potential to enhance biodegradation in Lake Burragorang.     

Solid phase extraction coupled to liquid chromatography-tandem mass spectrometry analysis of sulfonamides, tetracyclines, analgesics and hormones in surface water and wastewater in Luxembourg

In the early 1990s different studies highlighted the relationship between pharmaceuticals, human health and the environment. Among the emerging contaminants, antibiotics are obviously of high concern, because of their potential for inducing antibiotic resistance. In addition, natural and synthetic hormones are relevant because of their potential endocrine-disrupting effects on wildlife. This investigation focuses on the analysis of four classes of veterinary and human pharmaceuticals (sulfonamides, tetracyclines, analgesics and hormones) in surface water and wastewater in Luxembourg. The selected eleven pharmaceuticals include four sulfonamides (sulfathiazole, sulfamethoxazole, sulfadimethoxine and sulfamethazine), two tetracyclines (tetracycline and oxytetracycline), two analgesics (ibuprofen and diclofenac), and three hormones (2 naturals, estrone and β-estradiol, and a synthetic one, 17-α-ethinyl estradiol). The most innovative parts of this study are the simultaneous extraction of the above-mentioned pharmaceuticals as well as tracking their behaviour during flood events in a small river catchment. The method includes pre-concentration by solid phase extraction using Oasis® HLB (Hydrophilic Lipophilic Balance) which gave superior results compared to Chromabond® C-18EC, Chromabond® EASY and Bond Elut® PLEXA cartridges, also evaluated in this investigation. The analysis of the investigated pharmaceutical compounds is carried out by high performance liquid chromatography coupled to a triple quadrupole mass spectrometer. The limits of quantification were 1 ng L^− 1, except for β-estradiol (2 ng L^− 1) and 17-α-ethinyl estradiol (6 ng L^− 1). Recovery rates range from 70 to 94%, with relative standard deviations between 4 and 19%. Application of this method to river concentration and flood events revealed high concentrations of ibuprofen (10-4000 ng L^− 1), with highest levels during flood events, while concentrations of estrogens (1-240 ng L^− 1) and sulfonamides (1-20 ng L^− 1) were comparatively low.     

Behavior, mass inventories and modeling evaluation of xenobiotic endocrine-disrupting chemicals along an urban receiving wastewater river in Henan Province, China

Historically, the locations of cities mainly depend on the available water source and the urban river not only supplies the fresh water to city but also receives its wastewaters. To analyze the influences of urban zone on its receiving water river, the Jialu River in Henan Province, China, a typical urban river was chosen. Water and sediment samples were collected along the river in 2007 to analyze the concentrations of xenobiotic endocrine-disrupting chemicals (XEDCs) including nonylphenol (NP), octylphenol (OP) and bisphenol A (BPA) in surface water and sediment. The results showed that the concentrations of OP, NP and BPA in surface water were 20.9-63.2 ng L⁻¹ (mean 39.8 ng L⁻¹), 75.2-1520 ng L⁻¹ (mean 645 ng L⁻¹), 410-2990 ng L⁻¹ (mean 1535 ng L⁻¹), respectively. The lowest and highest concentrations of XEDCs in surface water were found in the upper stream and downstream of Zhengzhou urban zone, which was regarded as the major discharge source of these chemicals to this river. The concentrations of OP, NP and BPA in the sediment were 15.9-31.1 ng g⁻¹, 145-349 ng g⁻¹ and 626-3584 ng g⁻¹ with the average concentrations of 21.4 ng g⁻¹, 257 ng g⁻¹ and 2291 ng g⁻¹, respectively. The results of in situ sediment-water partition of XEDCs showed that the partition coefficients (log K_oc′) in the downstream were higher than that in the upstream, which was mainly caused by the retransfer of surface sediment from the upper stream to the downstream. Comparison of measured and theoretical inventories of XEDCs in sediment indicated that the residual time of XEDCs in sediment in the river was about 5 years, which was in the same order of magnitude with its big flood frequency. In order to predict concentration variances of XEDCs in surface water, a fugacity-hydrodynamic model was developed according to the concept of in series completely stirred tank reactors (CSTR). The model results showed that about 29-65% of XEDCs derived from the urban zone (about 2.0 t yr⁻¹) would finally dissipate from aqueous phase in the 170 km downstream of the river. Assuming the discharge amount of XEDCs from the urban zone remaining constant, the predicted concentrations of the total XEDCs in the over 90% river reach would be higher than 1.0 μg L⁻¹ under all normal, high water and low water season in 2007.     

Halophyte filter beds for treatment of saline wastewater from aquaculture

The expansion of aquaculture and the recent development of more intensive land-based marine farms require efficient and cost-effective systems for treatment of highly nutrient-rich saline wastewater. Constructed wetlands with halophytic plants offer the potential for waste-stream treatment combined with production of valuable secondary plant crops. Pilot wetland filter beds, constructed in triplicate and planted with the saltmarsh plant Salicornia europaea, were evaluated over 88 days under commercial operating conditions on a marine fish and shrimp farm. Nitrogen waste was primarily in the form of dissolved inorganic nitrogen (TDIN) and was removed by 98.2 ± 2.2% under ambient loadings of 109-383 μmol l⁻¹. There was a linear relationship between TDIN uptake and loading over the range of inputs tested. At peak loadings of up to 8185 ± 590 μmol l⁻¹ (equivalent to 600 mmol N m⁻² d⁻¹), the filter beds removed between 30 and 58% (250 mmol N m⁻² d⁻¹) of influent TDIN. Influent dissolved inorganic phosphorus levels ranged from 34 to 90 μmol l⁻¹, with 36-89% reduction under routine operations. Dissolved organic nitrogen (DON) loadings were lower (11-144 μmol l⁻¹), and between 23 and 69% of influent DON was removed during routine operation, with no significant removal of DON under high TDIN loading. Over the 88-day study, cumulative nitrogen removal was 1.28 mol m⁻², of which 1.09 mol m⁻² was retained in plant tissue, with plant uptake ranging from 2.4 to 27.0 mmol N g⁻¹ dry weight d⁻¹. The results demonstrate the effectiveness of N and P removal from wastewater from land-based intensive marine aquaculture farms by constructed wetlands planted with S. europaea.     

Removal of micropollutants from aerobically treated grey water via ozone and activated carbon

Ozonation and adsorption onto activated carbon were tested for the removal micropollutants of personal care products from aerobically treated grey water. MilliQ water spiked with micropollutants (100-1600 μgL⁻¹) was ozonated at a dosing rate of 1.22. In 45 min, this effectively removed (>99%): Four parabens, bisphenol-A, hexylcinnamic aldehyde, 4-methylbenzylidene-camphor (4MBC), benzophenone-3 (BP3), triclosan, galaxolide and ethylhexyl methoxycinnamate. After 60 min, the removal efficiency of benzalkonium chloride was 98%, tonalide and nonylphenol 95%, octocrylene 92% and 2-phenyl-5-benzimidazolesulfonic acid (PBSA) 84%. Ozonation of aerobically treated grey water at an applied ozone dose of 15 mgL⁻¹, reduced the concentrations of octocrylene, nonylphenol, triclosan, galaxolide, tonalide and 4-methylbenzylidene-camphor to below limits of quantification, with removal efficiencies of at least 79%. Complete adsorption of all studied micropollutants onto powdered activated carbon (PAC) was observed in batch tests with milliQ water spiked with 100-1600 μgL⁻¹ at a PAC dose of 1.25 gL⁻¹ and a contact time of 5 min. Three granular activated carbon (GAC) column experiments were operated to treat aerobically treated grey water. The operation of a GAC column with aerobically treated grey water spiked with micropollutants in the range of 0.1-10 μgL⁻¹ at a flow of 0.5 bed volumes (BV)h⁻¹ showed micropollutant removal efficiencies higher than 72%. During the operation time of 1728 BV, no breakthrough of TOC or micropollutants was observed. Removal of micropollutants from aerobically treated grey water was tested in a GAC column at a flow of 2 BVh⁻¹. Bisphenol-A, triclosan, tonalide, BP3, galaxolide, nonylphenol and PBSA were effectively removed even after a stable TOC breakthrough of 65% had been reached. After spiking the aerobically treated effluent with micropollutants to concentrations of 10-100 μgL⁻¹, efficient removal to below limits of quantification continued for at least 1440 BV. Both ozonation and adsorption are suitable techniques for the removal of micropollutants from aerobically treated grey water.     

Runoff of pharmaceuticals and personal care products following application of biosolids to an agricultural field

Municipal biosolids are a source of nutrients for crop production. Beneficial Management Practices (BMPs) can be used to minimize the risk of contamination of adjacent water resources with chemical or microbial agents that are of public or environmental health concern. In this field study, we applied biosolids slurry at a commercial rate using either subsurface injection or broadcast application followed by incorporation. Precipitation was simulated at 1, 3, 7, 22, 36 and 266 days post-application on 2 m² microplots to evaluate surface runoff of 9 model pharmaceuticals and personal care products (PPCPs), atenolol, carbamazepine, cotinine, gemfibrozil, naproxen, ibuprofen, acetaminophen, sulfamethoxazole and triclosan. In runoff from the injected plots, concentrations of the model PPCPs were generally below the limits of quantitation. In contrast, in the broadcast application treatment, the concentrations of atenolol, carbamazepine, cotinine, gemfibrozil, naproxen, sulfamethoxazole and triclosan on the day following application ranged from 70-1477 ng L^− 1 in runoff and generally declined thereafter with first order kinetics. The total mass of PPCPs mobilized in surface runoff per m² of the field ranged from 0.63 µg for atenolol to 21.1 µg for ibuprofen. For ibuprofen and acetaminophen, concentrations in runoff first decreased and then increased, suggesting that these drugs were initially chemically or physically sequestered in the biosolids slurry, and subsequently released in the soil. Carbamazepine and triclosan were detected at low concentrations in a runoff event 266 days after broadcast application. Overall, this study showed that injection of biosolids slurry below the soil surface could effectively eliminate surface runoff of PPCPs.     

Pesticide contamination and phytotoxicity of sediment interstitial water to tropical benthic microalgae

Many organic compounds including some herbicides concentrate in sediment, thus it may be expected that interstitial waters contain higher concentrations of these contaminants than the water column. To estimate benthic microalgal exposure to pesticides, sediment and interstitial water sampled in the dry season from four major rivers in north Queensland, Australia, were analysed for these contaminants. Interstitial water extracts from the sediments were tested for acute phytotoxicity to benthic microalgae using PAM fluorometry and the results were compared with chemical analyses of the same water samples. A range of pesticides were detected in both sediment and interstitial waters from all sites, notably the herbicide diuron at concentrations ranging from 0.3 to 11 μg kg⁻¹ dry weight sediment, and up to 68 ng L⁻¹ in interstitial waters. Herbicide concentrations estimated from partition coefficients and the sediment concentrations typically overestimated analytically determined concentrations present in interstitial water by an order of magnitude. The analytically determined herbicide concentrations in the interstitial water explained most of the phytotoxicity measured with the bioassay; however, photoinhibition was slightly higher than expected based on analytical results, indicating the presence of unidentified phytotoxins. These results demonstrate the presence of pesticides in interstitial waters in the Tropical dry season, sometimes at concentrations that may affect sensitive benthic organisms, and supports the use of the I-PAM bioassay as a valuable tool in exposure- and environmental risk- and impact-assessments.     

Fate of N-nitrosodimethylamine in recycled water after recharge into anaerobic aquifer

Laboratory and field experiments were undertaken to assess the fate of N-nitrosodimethylamine (NDMA) in aerobic recycled water that was recharged into a deep anaerobic pyritic aquifer, as part of a managed aquifer recharge (MAR) strategy. Laboratory studies demonstrated a high mobility of NDMA in the Leederville aquifer system with a retardation coefficient of 1.1. Anaerobic degradation column and ¹⁴C-NDMA microcosm studies showed that anaerobic conditions of the aquifer provided a suitable environment for the biodegradation of NDMA with first-order kinetics. At microgram per litre concentrations, inhibition of biodegradation was observed with degradation half-lives (260 ± 20 days) up to an order of magnitude greater than at nanogram per litre concentrations (25-150 days), which are more typical of environmental concentrations. No threshold effects were observed at the lower ng L⁻¹ concentrations with NDMA concentrations reduced from 560 ng L⁻¹ to <6 ng L⁻¹ over a 42 day ¹⁴C-NDMA aerobic microcosm experiment.Aerobic ¹⁴C-NDMA microcosm studies were also undertaken to assess potential aerobic degradation, likely to occur close to the recharge bore. These microcosm experiments showed a faster degradation rate than anaerobic microcosms, with a degradation half-life of 8 ± 2 days, after a lag period of approximately 10 days.Results from a MAR field trial recharging the Leederville aquifer with aerobic recycled water showed that NDMA concentrations reduced from 2.5 ± 1.0 ng L⁻¹ to 1.3 ± 0.4 ng L⁻¹ between the recharge bore and a monitoring location 20 m down gradient (an estimated aquifer residence time of 10 days), consistent with data from the aerobic microcosm experiment. Further down gradient, in the anaerobic zone of the aquifer, NDMA degradation could not be assessed, as NDMA concentrations were too close to their analytical detection limit (<1 ng L⁻¹).     

On-farm treatment of dairy soiled water using aerobic woodchip filters

Dairy soiled water (DSW) is produced on dairy farms through the washing-down of milking parlours and holding areas, and is generally applied to land. However, there is a risk of nutrient loss to surface and ground waters from land application. The aim of this study was to use aerobic woodchip filters to remove organic matter, suspended solids (SS) and nutrients from DSW. This novel treatment method would allow the re-use of the final effluent from the woodchip filters to wash down yards, thereby reducing water usage and environmental risks associated with land spreading. Three replicate 100 m² farm-scale woodchip filters, each 1 m deep, were constructed and operated to treat DSW from 300 cows over an 11-month study duration. The filters were loaded at a hydraulic loading rate of 30 L m⁻² d⁻¹, applied in four doses through a network of pipes on the filter surface. Average influent concentrations of chemical oxygen demand (COD), SS and total nitrogen (TN) of 5750 ± 1441 mg L⁻¹, 602 ± 303 mg L⁻¹ and 357 ± 100 mg L⁻¹, respectively, were reduced by 66, 86 and 57% in the filters. Effluent nutrient concentrations remained relatively stable over the study period, indicating the effectiveness of the filter despite increasing and/or fluctuating influent concentrations. Woodchip filters are a low cost, minimal maintenance treatment system, using a renewable resource that can be easily integrated into existing farm infrastructure.     

Simultaneous determination of microcystin contaminations in various vertebrates (fish, turtle, duck and water bird) from a large eutrophic Chinese lake, Lake Taihu, with toxic Microcystis blooms

This is the first to conduct simultaneous determination of microcystin (MC) contaminations in multi-groups of vertebrates (fish, turtle, duck and water bird) from Lake Taihu with Microcystis blooms. MCs (-RR, -YR, -LR) in Microcystis scum was 328 μg g^− 1 DW. MCs reached 235 μg g^− 1 DW in intestinal contents of phytoplanktivorous silver carp, but never exceeded 0.1 μg g^− 1 DW in intestinal contents of other animals. The highest MC content in liver of fish was in Carassius auratus (150 ng g^− 1 DW), followed by silver carp and Culter ilishaeformis, whereas the lowest was in common carp (3 ng g^− 1 DW). In livers of turtle, duck and water bird, MC content ranged from 18 to 30 ng g^− 1 DW. High MC level was found in the gonad, egg yolk and egg white of Nycticorax nycticorax and Anas platyrhynchos, suggesting the potential effect of MCs on water bird and duck embryos. High MC contents were identified for the first time in the spleens of N. nycticorax and A. platyrhynchos (6.850 and 9.462 ng g^− 1 DW, respectively), indicating a different organotropism of MCs in birds. Lakes with deaths of turtles or water birds in the literatures had a considerably higher MC content in both cyanobacteria and wildlife than Lake Taihu, indicating that toxicity of cyanobacteria may determine accumulation level of MCs and consequently fates of aquatic wildlife.     

Analysis of dissolved microcystins in surface water samples from Kovada Lake, Turkey

Dissolved (extracellular) microcystin (MC) concentrations were determined at 3 sampling stations on Lake Kovada, Turkey. The dominant species of cyanobacteria found in August and September of 2006 were Microcystis aeruginosa, Synechococcus sp., Phormidium limosum, Phormidium formosa and Planktothrix limnetica. MC concentrations in water were measured by ELISA and MC variants were examined by HPLC-PDA. Quantitative analysis by HPLC indicated that five MC variants (MC-LR, -RR, -LA, -LW, -LF) were identified in water samples from Kovada Lake. The maximum concentration of dissolved MC-LW was 98.9 µg l^− 1 in October. MC-LR was only detected in May at a concentration of 0.5 µg l^− 1. The cross reactivity of the antibody (MC10E7) to variants such as MC-LA MC-LW & MC-LF was low. Hence the results determined by ELISA were lower than those determined by HPLC in September and October samples due to differences in the specificity of the antibody to MC variants. Total extraceullar MCs was quantified by ELISA and ranged from 0.73 to 48.5 µg MC-LR equivalents l^− 1, which in some cases exceeded the WHO provisional Guideline Value for MC-LR in drinking water. This study confirms that the lakes of Turkey should be monitored for toxic cyanobacteria and for MCs to avoid or reduce the potential exposure of people to these health hazards.     

Variability of invertebrate abundance in drinking water distribution systems in the Netherlands in relation to biostability and sediment volumes

A survey of invertebrates in drinking water from treatment works, internal taps and hydrants on mains was carried out by almost all water companies in the Netherlands from September 1993 to August 1995. Aquatic sow bugs (Asellidae, 1-12 mm) and oligochaeta worms (Oligochaeta, 1-100 mm), both known to have caused rare though embarrassing consumer complaints, were found to form 98% of the mean biomass in water flushed from mains. Their numbers in the mains water ranged up to 1500 (mean 37) Asellidae m⁻³ and up to 9900 (mean 135) Oligochaeta m⁻³. Smaller crustaceans (0.5-2 mm) dominated the numbers in water from mains. e.g. water fleas (Cladocera and Copepoda up to 14,000 m⁻³). Common invertebrates in treated water and in tap water were Rotifera (<1 mm) and nematode worms (Nematoda, <2 mm). No Asellidae, large Oligochaeta (>5 mm) or other large invertebrates were found in 1560 samples of 200 l treated water or tap water.Large variations in invertebrate abundance were found within and between distribution systems. Of the variability of mean biomass in mains per system, 55%, 60% and 63% could statistically be explained by differences in the Biofilm Formation Rate, non-particulate organic matter and the permanganate index of the treated water of the treatment works respectively. A similar correlation was found between mean invertebrate biomass and mean sediment volumes in the distribution systems (R² = 52%).     

Leaching of human pathogens in repacked soil lysimeters and contamination of potato tubers under subsurface drip irrigation in Denmark

The risk for contamination of potatoes and groundwater through subsurface drip irrigation with low quality water was explored in 30 large-scale lysimeters containing repacked coarse sand and sandy loam soils. The human pathogens, Salmonella Senftenberg, Campylobacter jejuni and Escherichia coli O157:H7, and the virus indicator Salmonella Typhimurium bacteriophage 28B, were added weekly through irrigation tubes for one month with low irrigation rates (8 mm per week). In the following six months lysimeters were irrigated with groundwater free of pathogens. Two weeks after irrigation was started, phage 28B was detected in low concentrations (2 pfu ml⁻¹) in leachate from both sandy loam soil and coarse sand lysimeters. After 27 days, phage 28B continued to be present in similar concentrations in leachate from lysimeters containing coarse sand, while no phage were found in lysimeters with sandy loam soil. The added bacterial pathogens were not found in any leachate samples during the entire study period of 212 days. Under the study conditions with repacked soil, limited macropores and low water velocity, bacterial pathogens seemed to be retained in the soil matrix and died-off before leaching to groundwater. However, viruses may leach to groundwater and represent a health risk as for some viruses only few virus particles are needed to cause human disease. The bacterial pathogens and the phage 28B were found on the potato samples harvested just after the application of microbial tracers was terminated. The findings of bacterial pathogens and phage 28 on all potato samples suggest that the main risk associated with subsurface drip irrigation with low quality water is faecal contamination of root crops, in particular those consumed raw.     

Evaluation of selected ubiquitous contaminants in the aquatic environment and their transformation products. A pilot study of their removal from a sewage treatment plant

A simple method using direct sample injection combined with liquid chromatography tandem mass spectrometry has been developed for the simultaneous analysis of six alkaloid compounds in environmental samples. The target list includes two psychostimulants (nicotine and caffeine), three metabolites (cotinine, nicotinic acid and paraxanthine) and a coffee chemical (trigonelline). The analytical method was evaluated in three different matrices (surface water, influent and effluent wastewater). The method developed showed an adequate sensitivity, below 0.6 μg L⁻¹ for wastewater and 0.1 μg L⁻¹ for river matrices, without any prior treatment of the samples. Finally, the methodology was applied to real samples for evaluation of their removal from a sewage treatment plant and their persistence/fate in the aquatic environment. All compounds studied in this work were detected at all sampling points collected along the Henares River. However, nicotinic acid was only detected three times in treated sewage samples at levels above its detection limit.     

Controlling eutrophication by combined bloom precipitation and sediment phosphorus inactivation

The hypothesis that the combination of the flocculent polyaluminium chloride (PAC) with the lanthanum-modified bentonite Phoslock^® (Flock & Lock) could sink effectively a water bloom of cyanobacteria and could shift a turbid, cyanobacteria infested lake to a clear water lake was tested in a controlled laboratory experiment and a whole lake experiment. In the laboratory, a relatively low dose of the flocculent PAC (2.2 and 4.4 mg Al l⁻¹) was insufficient to sediment positively buoyant cyanobacteria (Microcystis aeruginosa). Similarly, the lanthanum modified clay (dosed at 390 mg l⁻¹) was insufficient to sediment the positively buoyant cyanobacteria. However, the combination of PAC and Phoslock^® effectively sedimented cyanobacteria flocks. Likewise, a combined treatment of 2 tons PAC and 18 tons Phoslock^® in Lake Rauwbraken in April 2008 effectively sedimented a developing cyanobacteria bloom of Aphanizomenon flos-aquae. The average chlorophyll-a concentration in the two years prior to this Flock & Lock treatment was 19.5 (±36.5) μg l⁻¹, while it was as low as 3.7 (±4.5) μg l⁻¹ in the years following the treatment. The combined treatment effectively reduced the amount of total phosphorus (TP) in the water column from on average 169 (±126) μg P l⁻¹ before the application to 14 (±15) μg P l⁻¹ after the treatment. Based on mean summer chlorophyll-a and TP concentrations, the lake was shifted from a eutrophic/hypertrophic state to an oligo/mesotrophic state. From directly after treatment in April 2008 until and including 2013, Lake Rauwbraken remained in an oligo-mesotrophic clear water state with TP reduced to less than 10% of the pre-treatment. This result shows that eutrophication in relatively small, isolated, stratifying lakes can be restored by targeting both water column and sediment P using a combination of flocculent and solid phase P-sorbent.