Search

Smoked cigarettes are the most prevalent form of litter worldwide, often finding their way into oceans and inland waterways. Cigarette smoke contains more than 4000 individual chemicals, some of them carcinogenic or otherwise toxic. We examined the cytotoxicity, genotoxicity, aryl hydrocarbon receptor (AhR), estrogen receptor (ER), and p53 response pathways of smoked cigarette leachate in vitro. Both seawater and freshwater leachates of smoked cigarettes were tested. Cytotoxicity and genotoxicity were negligible at 100 smoked cigarettes/L, while statistically significant AhR, ER, and p53 responses were observed in the extracts of both leachates, suggesting a potential risk to human health through exposure to cigarette litter in the environment. To identify responsible chemicals for the AhR response, an effect directed analysis approach was coupled with nontargeted chemical analysis based on comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometry (GC × GC/TOF-MS). Eleve...

Levels of amphetamine, methamphetamine, cocaine, and benzoylecgonine (BE), the metabolite of cocaine, were quantitated by solid phase extraction and liquid chromatography with tandem mass spectrometry (LC/MS/MS) in Forester Creek in San Diego County, CA, and in raw wastewater from the region’s sewage treatment plant. Drug residues in these surface waters were detected with 100% frequency. Mean concentrations were 0.022 ± 0.016, 0.450 ± 0.398, 0.024 ± 0.014, and 0.019 ± 0.012 μg/L for amphetamine, methamphetamine, BE, and cocaine respectively. Nonparametric testing by Spearman rank correlation showed significant (p

A 16S rRNA gene multiplex 454 pyrosequencing approach was used to characterize the structure of the bacterial community in subsurface flow constructed wetlands planted with Typha angustifolia and unplanted wetland mesocosms receiving ibuprofen-enriched wastewater at a concentration of 250 μg L −1 . The removal efficiency of ibuprofen (IBP) in the planted beds (78.5%) was significantly higher than that in the unplanted beds (57.9%) ( P ≤ 0.05). The presence of ibuprofen significantly ( P ≤ 0.05) reduced the diversity of the bacterial community. In total, 20 phyla comprising 265 genera were identified. The most predominant phyla were Firmicutes (27.6%), Actinobacteria (26.0%) and Proteobacteria (24.9%), making up 57–95% of the 16S rDNA sequences. Other dominating phyla in wetland soils were Chloroflexi (7.3%), Bacteroidetes (2.7%), Synergistetes (2.1%), and Acidobacteria (2.0%). A distinct profile of bacterial community in the wetland mesocosms was observed after IBP enrichment. IBP-enrichment enhanced the relative abundance of Actinobacteria, Bacilli and γ-Proteobacteria at class level. The efficient ibuprofen removal observed in this study suggested that the IBP-enriched wetland systems may have selected a restricted group of bacteria that was able to survive best in the disturbed condition and participate in the IBP biodegradation. Our findings also indicated that the presence of macrophytes may have a vital impact on the microbial community and planted wetlands may be more robust and buffered against significant shifts in microbial composition in response to IBP-disturbance.

The rapid development of nanotechnology will inevitably result in an increasing release of engineered nanoparticles (NPs) to wastewaters. In this study we investigated the fate and toxicity of ZnO NPs in aquatic plant mesocosms, as well as the potential for root accumulation and root-to-shoot translocation of these Zn NPs in the wetland plant Schoenoplectus tabernaemontani exposed to ZnO NPs. The growth of S. tabernaemontani in these hydroponic mesocosms was significantly inhibited by ZnO NPs (1000 mg L(-1)) compared to a control. Levels of Zn in the plant roots for the ZnO NP treatment ranged from 402 to 36513 μg g(-1), while values ranged from 256 to 9429 μg g(-)(1) (dry weight) for Zn(2+) treatment, implying that the uptake of Zn from ZnO NPs was substantially greater than that for Zn(2+). The root uptake (of the initial mass of Zn in the solution) for ZnO NP treatment ranged from 8.6% to 43.5%, while for Zn(2+) treatment they were 1.66% to 17.44%. The low values of the translocation factor for both ZnO NP (0.001-0.05) and Zn(2+) (0.05-0.27) treatments implied that the potential for translocation of Zn NPs from roots to shoots was limited. ZnO NP distribution in the root tissues of S. tabernaemontani was confirmed by scanning electron microscopy (SEM). Transmission electron microscopy (TEM) demonstrated that ZnO NPs could pass through plant cell walls, and were present within the plant cells of S. tabernaemontani.

Rapid growth in production and use of nanoparticles (NPs) will inevitably result in the introduction of NPs deliberately or unintentionally into industrial and urban wastewater streams. Efficient removal of NPs from wastewater is particularly important in view of increasing concerns over potential ecotoxicity and hazards of NP exposure to humans and the environment over the long term. For the first time, we report the fate of copper oxide (CuO) NPs and cadmium sulphide/zinc sulphide (CdS/ZnS) quantum dots (QDs) in aquatic mesocosms planted with Schoenoplectus tabernaemontani . S. tabernaemontani was more sensitive to toxic effects of CdS QDs than CuO NPs and the reduction in plant biomass was significant ( p −1 after exposure period of 21 d. Levels of Cu 2+ under CuO NP treatment in the root ranged from 14 μg g −1 (0.5 mg L −1 treatment) to 4,057 μg g −1 (50 mg L −1 treatment), while the values for Cd 2+ under CdS QDs treatment were 9 to 1518 μg g −1 , respectively. Root uptake percentage (of the total initial NP mass) for CuO NP treatment ranged from 40.6 to 68.4%, while the values were 8.7 to 21.3% for CdS QDs. The low value ( S. tabernaemontani roots. To our knowledge, this is the first evidence of NP uptake and accumulation by the higher aquatic plant S. tabernaemontani. These findings provide impetus for future investigation on NP behaviour and removal, as well as the complex interaction between NPs and plants in aquatic plant-based treatment systems.

Uptake, accumulation and translocation of caffeine by Scirpus validus grown in hydroponic condition were investigated. The plants were cultivated in Hoagland's nutrient solution spiked with caffeine at concentrations of 0.5-2.0 mg L(-1). The effect of photodegradation on caffeine elimination was determined in dark controls and proved to be negligible. Removal of caffeine in mesocosms without plants showed however that biodegradation could account for about 15-19% of the caffeine lost from solutions after 3 and 7 d. Plant uptake played a significant role in caffeine elimination. Caffeine was detected in both roots and shoots of S. validus. Root concentrations of caffeine were 0.1-6.1 μg g(-1), while the concentrations for shoots were 6.4-13.7 μg g(-1). A significant (p0.05) positive correlation between the concentration in the root and the initial concentrations in the nutrient solution was observed. The bioaccumulation factors (BAFs) of caffeine for roots ranged from 0.2 to 3.1, while BAFs for shoots ranged from 3.2 to 16.9. Translocation from roots to shoots was the major pathway of shoot accumulation. The fraction of caffeine in the roots as a percentage of the total caffeine mass in solution was limited to 0.2-4.4% throughout the whole experiment, while shoot uptake percentage ranged from 12% to 25% for caffeine at the initial concentration of 2.0 mg L(-1) to 50-62% for caffeine at the initial concentration of 0.5 mg L(-1). However, a marked decrease in the concentration of caffeine in the shoots between d-14 and d-21 suggests that caffeine may have been catabolized in the plant tissues subsequent to plant uptake and translocation.

A 454 high-throughput pyrosequencing approach was used to characterize the structures of microbial communities in wetland mesocosms receiving caffeine-enriched wastewater at a concentration of 250 μg L(-1). The removal efficiencies of caffeine in the planted beds (93.0 %) were significantly (p

Pharmaceutical compounds are now considered as emerging contaminants of environmental concern. The overall objective of this study was to evaluate the uptake and translocation of clofibric acid (CA) by the macrophyte Scirpus validus growing hydroponically. A set of the three replicates was established for each exposure time and for each CA concentration. Plants were grown in 4 L vessels (four plants per vessel corresponding to the three exposure period studies, i.e., 7, 14, 18, and 21 days) which contained an aerated modified Hoagland nutrient solution that was spiked with CA at concentrations of 0.5, 1.0, and 2.0 mg L(-1). At each exposure period, CA concentration was measured in the nutrient solutions. A sea sand disruption method was employed for the extraction of CA from plant tissues. The determination of the pharmaceutical concentration was carried out using solid phase extraction (SPE) followed by chromatographic analysis. The quantification of CA concentrations in both nutrient solutions (after SPE) and plant tissues (after extraction) was conducted by chromatographic analysis. CA concentrations of 5.4-26.8 μg g(-1) (fresh weight) were detected in the roots and 7.2-34.6 μg g(-1) (fresh weight) in the shoots after 21 days. Mass balance calculations showed that S. validus uptake alone accounted for a significant contribution (6-13% for the roots and 22-49% for the shoots) of the total loss of CA. The bioaccumulation factors (BAFs) based on fresh weight for the roots ranged from 6.6 to 23.2, while values for the shoots ranged from 9.5 to 32.1. All the BAFs for the shoots were greater than those in the roots, implying that CA has greater tendency to be translocated to the shoots, rather than the roots of S. validus. All the shoot-to-root concentration ratios were more than 1, denoting that the shoots of S. validus do preferentially accumulate CA. We demonstrated that CA can be actively taken up, subsequently translocated and accumulated by aboveground tissues of S. validus. Since S. validus could account for the removal of 28-62% of the total mass loss of CA from the system, such phytoremediation technology has great potential for the removal of pharmaceuticals such as CA from inflowing waters.

The ability of tropical horizontal subsurface constructed wetlands (HSSF CWs) planted with Typha angustifolia to remove four widely used pharmaceutical compounds (carbamazepine, declofenac, ibuprofen and naproxen) at the relatively short hydraulic residence time of 2–4 days was documented. For both ibuprofen and naproxen, pharmaceutical compounds with low Dow values, the planted beds showed significant (p 0.05) in their removal efficiencies between planted as compared to unplanted beds. No statistical significant differences (p > 0.05) were observed for the removal efficiencies of any of the pharmaceuticals tested for the 2-day HRT as compared to that corresponding to 4-day HRT. The rather efficient removal shown by the wetlands in this study (with HRTs of 2–4 days), indicates that such a CW system may be more practically used (with less land requirements) in tropical regions for removing conventional pollutants and certain pharmaceutical compounds from wastewater effluents.

Background Cigarette butts are the most common form of litter, as an estimated 4.5 trillion cigarette butts are thrown away every year worldwide. Many chemical products are used during the course of growing tobacco and manufacturing cigarettes, the residues of which may be found in cigarettes prepared for consumption. Additionally, over 4000 chemicals may also be introduced to the environment via cigarette particulate matter (tar) and mainstream smoke. Methods Using US Environmental Protection Agency standard acute fish bioassays, cigarette butt-derived leachate was analysed for aquatic toxicity. Survival was the single endpoint and data were analysed using Comprehensive Environmental Toxicity Information System to identify the LC50 of cigarette butt leachate to fish. Results The LC50 for leachate from smoked cigarette butts (smoked filter + tobacco) was approximately one cigarette butt/l for both the marine topsmelt (Atherinops affinis) and the freshwater fathead minnow (Pimephales promelas). Leachate from smoked cigarette filters (no tobacco), was less toxic, with LC50 values of 1.8 and 4.3 cigarette butts/l, respectively for both fish species. Unsmoked cigarette filters (no tobacco) were also found to be toxic, with LC50 values of 5.1 and 13.5 cigarette butts/l, respectively, for both fish species. Conclusion Toxicity of cigarette butt leachate was found to increase from unsmoked cigarette filters (no tobacco) to smoked cigarette filters (no tobacco) to smoked cigarette butts (smoked filter + tobacco). This study represents the first in the literature to investigate and affirm the toxicity of cigarette butts to fish, and will assist in assessing the potential ecological risks of cigarette butts to the aquatic environment.

A summary of all existing information gathered since 1980 on contaminants in bairdiella (Bairdiella icistia), orangemouth corvina (Cynoscion xanthulus), and sargo (Anisotremus davidsonii) living in the Salton Sea is presented. Comparisons are made with an earlier analysis of contaminants in tilapia (Oreochromis mossambicus x O. urolepis hornorum hybrid). Risks are assessed for humans and piscivorous birds consuming these fish and for the health of the fish populations themselves. Of the 17 trace elements, 42 organic pesticides and 48 polychlorinated biphenyls (PCBs) sampled in whole-body and fillet samples of fish collected from the Salton Sea, only arsenic (As), selenium (Se), total DDT (tDDT), and total PCBs (tPCBs) were determined to be of potential concern for the health of human consumers. Recent average concentrations of total As in fillet tissue are 1.3 μg g−1 wet weight (ww) for bairdiella and 1.2 μg g−1 ww for corvina and tilapia, respectively, with the inorganic As fraction representing...

A summary of all existing information collected since 1980 on contaminants in tilapia from the Salton Sea is presented and risks to humans and fish-eating birds assessed. Of the 17 trace elements, 42 organic pesticides and 48 polychlorinated biphenyls (PCBs) analyzed in tilapia whole body and fillet samples, only selenium (Se), arsenic (As) and possibly dichlorodiphenyltrichloroethane (DDE) were found at levels high enough to be of concern for fish, birds or humans. Average current concentration of arsenic (As) was 0.7 µg g−1 wet weight (ww) in whole body samples and 1.2 µg g−1 ww in fillet samples, or 2.8 and 5.7 µg g−1 dry weight (dw), respectively. Inorganic As averaged 0.006 µg g−1 ww (0.03 µg g−1 dw) in fillet samples, which represented 0.3% of total As. By U.S. Environmental Protection Agency (U.S.EPA) guidelines, As levels in tilapia pose no threat of non-cancerous adverse health effects in children and adults. As is a known human carcinogen, however, and U.S.EPA cancer risk assessment procedures indicate that a weekly consumption of 540 g (19 oz) or more for 70 years would increase the upper bound cancer risk by 1 in 100,000 consumers exposed. Average current Se concentration was 2.2 µg g−1 ww in tilapia whole body samples and 1.9 µg g−1 ww in fillet (8.3 and 9 µg g−1 dw, respectively). Consumption of Se-contaminated tilapia was found to present no unacceptable risk for adverse health effects for adults consuming up to 1000 g (35 oz) of fillet per week even when additional intakes of Se from other food items were taken into account. Similarly, children weighing 30 kg or more could safely eat up to 430 g (15 oz) of tilapia fillet on a weekly basis. A health advisory issued by the State of California in 1986 recommended, on the basis of Se levels, that consumption of any fish from the Salton Sea be limited to 114 g (4 oz) every 2 weeks, but the rationale and calculations on which that advisory was based are unavailable. We suggest that the existing health advisory for Salton Sea tilapia be revised by the state in light of this new information and updated risk parameters for As and Se. Dichlorodiphenyltrichloroethane (DDE) was detected in all samples of tilapia, with current levels averaging 0.085 µg g−1 in whole tilapia and 0.032 µg g−1 in fillet ww. Compared to screening values proposed by the U.S. EPA, these concentrations are unlikely to cause non-cancerous health effects in anglers, but one might exceed a 1 × 10−5 increase in cancer risk by consuming more than 4 meals of tilapia per week. Similarly, polychlorinated biphenyls (PCBs) were detected in tilapia fillets at levels that may increase the cancer risk for those anglers also eating more than 4 meals of tilapia per week. These determinations are based, however, on DDE concentrations reported from a small sample size (n = 4), and on screening values recommended by U.S.EPA. The paucity of DDE and total DDT analyses carried out in recent times on the edible portion of Salton Sea tilapia warrants additional analyses in order to evaluate the need for issuance of a fish consumption advisory with regards to long term exposure to total DDT via consumption of Salton Sea fish. With regards to the potential impact on fish and piscivorous birds, we cannot conclude whether concentrations of As in tilapia could pose a threat to the fish and the birds feeding on them. Se concentrations, however, may be elevated enough to negatively affect fish health, and reproduction and immune systems of piscivorous birds, but definitive studies are lacking. Total DDT and PCB concentrations in whole tilapia are not elevated enough to have adverse effects on fish and piscivorous birds. Fish harvesting for fish meal production has been proposed for the Salton Sea. Based on whole fish dry weight values of 61% protein and 21% ash, and the determined contaminant levels, tilapia could yield a meal of reasonable quality for use in formulating poultry, livestock and aquaculture feeds.

In order to assess the microbial water quality of the lagoon canals of Venice, Italy and nearby beach on Lido island, a study was conducted using real-time RT-PCR to enumerate levels of hepatitis A virus (HAV) and enteroviruses in these marine waters over a 3-year period from 2003 to 2005. A total of 17 sites (9 lagoon canal and 8 beach sites) were assayed. For the canals of the Venice Lagoon, 78% were positive for both HAV and enteroviruses, with levels ranging from 75 to 730 and 3 to 1,614 genome copies/L, respectively. At Lido beach, HAV was never detected, but enteroviruses were detected in all Lido beach samples at levels ranging from 2 to 71 genome copies/L. There was a statistically significant correlation between thermotolerant coliform densities and HAV levels (p=0.0002), but the relationship between thermotolerant coliform densities and enterovirus levels was not significant (p>0.05). Despite the fact that enteroviruses were detected at low levels in the surfzone at Lido beach, the risk for enteroviral infection (calculated using the beta-Poisson model) for recreational exposure from swimming, was in the range of 1.9 x 10(-3) - 6.1 x 10(-2), yielding a disease risk at or below the level (5% for gastroenteritis) deemed acceptable by European Guide standards.

Six years after re-connection of an oxbow lake from periodically to permanently connected to the main channel, the restoration success was assessed. This permanently connected oxbow lake was compared with the main channel of the Elbe River and with a periodically connected oxbow lake by means of comparisons of the aquatic macroinvertebrates, fish and aquatic macrophyte communities. The permanently connected oxbow was suited as important replacement habitat for riverine invertebrates, especially for clubtails (Odonata) and unionid mussels (Bivalvia). The periodically connected oxbow lake was colonized by typical species for shallow lakes. As expected, riverine species did not occur. Meanwhile, the invertebrate community in the main channel was poor and dominated by invasive species (Dikerogammarus villosus, Dreissena polymorpha). The results concerning fish showed a clear dominance of the rheophilic species spined loach (Cobitis taenia) in the permanently connected oxbow lake and of the indifferent species roach (Rutilus rutilus) and European perch (Perca fluviatilis) in the periodically connected oxbow lake. However, species number was highest in the main channel. For macrophytes, quantity, number of taxa and growth forms and diversity were lower in the permanently compared to the periodically connected oxbow lake. In conclusion, the re-connection of oxbow lakes to main channels can be an important measure for native species conservation, especially macroinvertebrates, and hence for the implementation of the Water Framework Directive.

Biomonitoring of toxicity, using the Ceriodaphnia dubia acute toxicity test, was performed on a gasoline-contaminated aquifer in San Diego, Calif. undergoing in situ bioremediation. The bioremediation approach here featured nitrate enrichment of extracted groundwater (with subsequent reinfiltration back into the aquifer) to stimulate bacterial denitrification. Dentrification has been shown to support biodegradation of the monoaromatic hydrocarbons—benzene, toluene, ethylbenzene, and the isomers of xylene (BTEX). During the period between the start of bioremediation (October, 1989) and the end of nutrient enrichment (March, 1992), BTEX levels at the two most contaminated wells on site (MW1 and MW5) were reducted by about 81 and 99%, respectively. In acute bioassays of groundwater from MW1 during the first 6 months of bioremediation, concentrations of groundwater from about 3 to 10% produced 50% mortality of Ceriodaphnia after 24 h exposure, whereas groundwater concentrations of greater than 20% were required after remediation. When the 24-h LC50's for mortality were plotted as a function of BTEX concentration, the slope of the regression line was similar for both laboratory and field nitrate-enrichment studies. At MW5, where the BTEX level was dramatically reduced by 99% during bioremediation, the 24-h LC50 after bioremediation increased to 56% (from initial values of 12–15%), while uncontaminated groundwater from a well up-gradient of the gasoline leak, showed an LC50 value of 74%. These results demonstrate that even after bioremediation of an aquifer (with an associated BTEX reduction of 81–99%), the toxicity (as measured by Ceriodaphnia ) of the groundwaters may not be reduced to precontamination levels.

Scirpus validus was grown hydroponically and exposed to the pharmaceuticals, carbamazepine and naproxen at concentrations of 0.5–2.0 mg L −1 for an exposure duration of up to 21 d. By the end of experiment, carbamazepine elimination from the nutrient solution reached to 74%, while nearly complete removal (>98%) was observed for naproxen. Photodegradation and biodegradation played only minor roles for carbamazepine elimination, while naproxen showed a high potential for both photodegradation and biodegradation. Levels of carbamazepine ranged from 3.3 to19.0 μg g −1 (fresh weight) in the roots and 0.3–0.7 μg g −1 (fresh weight) in the shoots, while naproxen concentrations were 0.2–2.4 μg g −1 (fresh weight) in the roots and 0.2–2.8 μg g −1 (fresh weight) in the shoots. Bioaccumulation factors (BAFs) for carbamazepine ranged from 5.5 to 13.0 for roots and 0.3–1.0 for shoots, and uptake by S. validus accounted for up to 22% of the total mass loss of carbamazepine in the nutrient solutions. All BAFs for naproxen were less than 4.2 and plant uptake accounted for less than 5% of the total mass loss of naproxen, implying that plant uptake was not significant in naproxen elimination. The rather limited plant uptake of naproxen was not surprising despite the fact that its log K ow is close to the optimal range (1.8–3.1) for maximal potential for plant uptake. Apparently, for ionizable compounds such as naproxen, the effects of p K a and pH partitioning might be more important than lipophilicity.

The treatment efficiencies of floating treatment wetlands (FTWs) containing two types of macrophytes, Typha angustifolia and Canna iridiflora, were investigated in a pilot scale study in the tropical climate of Sri Lanka. In batch experiments, over 80 % of biological oxygen demand (BOD5) and ammonium (NH 4 + -N) removal was observed, while nitrate (NO 3 − -N) removal was over 40 %. Typha angustifolia showed slightly higher BOD5, NH 4 + -N and NO 3 − -N removal than Canna iridiflora. Because of higher and steady root growth, Typha angustifolia resulted in a better performance and has a greater potential to extract nutrients from wastewater and allow water-plant interactions than Canna iridiflora whose root mat is thick and compact. Similar to the batch system, the continuous flow systems performed better at most times with Typha angustifolia. FTWs with Typha angustifolia may be considered a possible solution for lake restoration where there are space and cost constraints.

This study examined the survival of indigenous coliphages (serving as indicators of viral pollution) during operation of a field-scale (1140 m 3 day −1 ) water hyacinth ( Eichhornia crassipes ) treatment system in San Diego, CA. At a hydraulic residence time of 4.4 days, about 20% of the indigenous coliphages could be recovered after flow through the water hyacinth pond. The decay rates of coliphages in stagnant mesocosms with the water hyacinth plant ( k = −0.015 h −1 ) and in wastewater incubated in dialysis bags suspended in the pond ( k = −0.019 h − ) were both greater than the value for coliphage decay in the operational water hyacinth system ( k = −0.014 h −1 ), indicating that filtration/adsorption of coliphage by the root matrix is not a major contributor to coliphage reduction. Coliphage decay in mesocosms without plants was more rapid ( k = −0.024 h −1 ) than in planted mesocosms ( k = −0.015 h −1 ) and covered mesocosms ( k = −0.011 h −1 ). These results suggest the important role of sunlight in coliphage inactivation, and reflect the fact that coliphage decay in the presence of the plant is slower than the natural decay rate in wastewater without plants.

The effect of hydroperiod on nutrient removal efficiency from simulated wastewater was investigated in replicate wetland mesocosms (area, 2 m 2 , planted with Scirpus californicus ). Alternate draining and flooding of sediments (pulsed discharge) increased nutrient removal efficiency compared to the continuous-flow “control”. Average PO 4 3− removal efficiency was 20–30% higher in wetland mesocosms that drained twice daily compared to the control. Inorganic N removal efficiency was less affected than phosphate removal by hydroperiod variation. At the higher NH 4 + loading rate (1.83 g N m −2 day −1 ), inorganic N removal efficiency was consistently 5–20% higher in pulsed-discharge wetland mesocosms than in the control. At the lower NH 4 + loading rate (0.9 g N m −2 day −1 ), pulsed-discharge hydrology had no effect on inorganic N removal efficiency. Twice-daily drainage exhibited average inorganic N removal efficiencies of 96% (lower N loading rate) and 87% (higher N loading) and average phosphate removal efficiencies of 81% (lower P loading) and 90% (higher P loading). Mass balance data from the continuous-flow treatment revealed that the aquatic macrophyte Scirpus californicus was the most important nutrient sink, assimilating 50% of the NH 4 + and PO 4 3− supply. The high plant productivity in the mesocosms (15.6 kg m −2 year −1 ) occurred under conditions of high light (high edge per mesocosm area) and high root contact with nutrient-rich influent (shallow, sandy substrate) and may overestimate plant uptake in larger wetlands. The addition of a nitrification-inhibitor (N-Serve) indicated that 34% of the NH 4 + supply was transformed to NO 3 − by nitrifying bacteria.

Scirpus californicus (giant bulrush) wetland mesocosms were subjected to four hydroperiods (pulsed-discharge regimes). The most frequently pulsed treatment (twice per day) was the most efficient at removing metals from synthetic wastewater. This was attributed to the formation of iron oxyhydroxides, which complex with the metals. The continuously flooded treatment had slightly lower removal rates. After a year of metal additions, mean removal efficiencies were 75–78% for cadmium, chromium, and zinc, 84% for lead, and 55% for mickel. Most of the metals were retained in the soil. The fine roots accumulated roughly 35% of the added cadmium, 6% of the copper, and 13% of the zinc. The shoots, rhizomes, and coarse roots each accumulated about 1% or less of the added metals. Indications are that wetland treatment, especially with hydroperiod manipulation, can reduce metal concentrations in wastewater and, therefore, in downstream ecosystems.

For decades, untreated sewage flowing northward from Tijuana, Mexico, via the Tijuana River has adversely affected the water quality of the recreational beaches of San Diego, California. We used quantitative reverse transcription-PCR to measure the levels of hepatitis A virus (HAV) and enteroviruses in coastal waters near the United States-Mexico border and compared these levels to those of the conventional fecal indicators, Escherichia coli and enterococci. Over a 2-year period from 2003 to 2005, a total of 20 samples were assayed at two sites during both wet and dry weather: the surfzone at the mouth of the Tijuana River and the surfzone near the pier at Imperial Beach (IB), California (about 2 km north of the mouth of the Tijuana River). HAV and enterovirus were detected in 79 and 93% of the wet-weather samples, respectively. HAV concentrations in these samples ranged from 105 to 30,771 viral particles/liter, and enterovirus levels ranged from 7 to 4,417 viral particles/liter. The concentrations of HAV and enterovirus were below the limit of detection for all dry weather samples collected at IB. Regression analyses showed a significant correlation between the densities of both fecal bacterial indicators and the levels of HAV ( R 2 > 0.61, P < 0.0001) and enterovirus ( R 2 > 0.70, P < 0.0001), a finding that supports the use of conventional bacterial indicators to predict the levels of these viruses in recreational marine waters.

A real-time RT-PCR method utilizing SYBR Green chemistry was developed to detect and enumerate hepatitis A virus (HAV) in ocean water. Ocean water samples were taken at the Tijuana River mouth (Tijuana, Mexico) and Imperial Beach pier (1.4 km north of the Tijuana River mouth in San Diego, California) following four separate rain events. A total of eight samples were collected, one from each location, each consisting of 4 l of ocean water. Using conventional RT-PCR and primers based on the conserved sequence at the VP3-VP1 genes of HAV, a 247 bp cDNA was amplified from six out of eight rain event water samples. HAV cDNA (confirmed by sequence analysis) was cloned into a TOPO vector (Invitrogen, Carlsbad, CA), and four primer sets were designed for application in SYBR Green real-time RT-PCR. The water samples were shown to contain inhibitors that affected real-time RT-PCR amplifications, however diluting the cDNA solution enabled successful amplification. Using real-time RT-PCR, HAV could be detected in all eight samples. Depending on the rain event, the viral load in these samples varied from 90 to 3523 copies of HAV/L of ocean water near the mouth of the Tijuana River, and 347 to 2656 copies/l near the Imperial Beach pier. The sensitivity, quantitative ability and the high throughput nature of SYBR Green real-time RT-PCR will be useful in monitoring HAV contamination in seawater.

We compared the cytotoxic effect of coumarin and its derivatives, 7-hydroxycoumarin (7-OHC), 4-hydroxycoumarin (4-OHC), o-hydroxyphenyl acetic acid (OHPAA) and o-coumaric acid (CA), on cultured hepatocytes from human, rat, mouse and rabbit liver. At 10(-5) and 5 x 10(-5) M, coumarin and its derivatives did not give rise to any signs of toxicity on cultured hepatocytes of the four species. At 10(-4) M, coumarin, but not its derivatives, induced release of lactate dehydrogenase (LDH) into the medium, especially in rat hepatocyte cultures. Intracellular LDH activities were correspondingly reduced. The cytotoxic effect of coumarin in cultured rat hepatocytes was evidenced on morphological examination and from the results of the 3-(4,5-dimethylthiazol-2-yl)-2,5- diphenyltetrazolium (MTT) reduction test. At higher concentrations (5 x 10(-4) M), 7-OHC and CA were also found to be cytotoxic in cultured rat hepatocytes. The cytotoxic effect of coumarin (5 x 10(-4) M) was decreased in the presence of SKF 525-A, a cytochrome P450 inhibitor. Interspecies comparisons showed that rat hepatocytes were the most sensitive to the toxicity of coumarin and its derivatives, whereas human hepatocytes were the most resistant. Our results suggest that the cytotoxicity of coumarin is metabolism and species-dependent. Thus, the rat may not be a suitable model for evaluating the pharmacological hazards of coumarin in humans.

The objective of our study was to show that pure cultures of Klebsiella pneumoniae and Acinetobacter calcoaceticus could be Induced to accumulate large amounts of phosphorus (P), when P-starved cultures were enriched with phosphorus either in suspended growth or immobilized cell reactors. Suspended growth cultures of K. pneumoniae were more efficient than those of A. calcoaceticus, with specific uptake rates of 14.1 - 17.1 mg P1−1 hr−1 per O.D. unit, and 5.4 - 10.0 mg P1−1 hr −1 per O.D. unit, respectively. The absolute rate of P accumulation of 24.6 mg P1−1 hr−1 measured for a K. pneumoniae culture was among the highest ever reported in the literature. In an immobilized cell system, which facilitates the separation of the cells (for recycling) from the liquid phase, K. pneumoniae cells entrapped in agar gel beads, remained viable and showed rates of P uptake of 6.1 and 7.9 mg P1−1 hr−1. K. pneumoniae cultures also showed a high capacity for removing dissolved phosphate from municipal wastewater, with greater than 95% P removal in two hours. These studies suggest the important role such high-phosphate accumulating bacteria may play in wastewater treatment systems designed for enhanced biological phosphorus removal.

This report describes investigations using artificial wetlands which quantitatively assess the role of each of three higher aquatic plant types, Scirpus validus (bulrush), Phragmites communis (common reed) and Typha latifola (cattail), in the removal of nitrogen (via sequential nitrification-denitrification), BOD and TSS from primary municipal wastewaters. During the period August 1983–December 1984, the mean ammonia concentration of 24.7 mg l−1 in the primary wastewater inflow (hydraulic application rate = 4.7 cm day−1) was reduced to mean effluent levels of 1.4 mg l−1 for the bulrush bed, 5.3 mg l−1 for the reed bed and 17.7 mg l−1 for the cattail bed, as compared to a mean value of 22.1 mg l−1 for the unvegetated (control) bed. For all three vegetated beds, the mean effluent ammonia values were significantly below that for the unvegetated bed and for the inflow. The bulrushes and reeds (in that order) proved to be superior at removing ammonia, both with mean effluent levels significantly below that for the cattail bed. The high ammonia-N (and total N) removal efficiencies shown by the bulrush and reed beds are attributed to the ability of these plants to translocate O2 from the shoots to the roots. The oxidized rhizosphere so formed stimulates sequential nitrification-denitrification. Similarly BOD removal efficiencies were highest in the bulrush and reed beds, both with mean effluent BOD levels (5.3 and 22.2 mg l−1, respectively) significantly below that for the unvegetated bed (36.4 mg l−1) and equal to or better than secondary treatment quality (30 mg l−1). Our results demonstrate that higher aquatic plants can indeed play a significant role in secondary and advanced (N removal) wastewater treatment by wetland systems, a role that is completely distinct from that associated with their pollutant uptake capacity.

Little is known about the ability of wetlands to remove disease-causing viruses from municipal wastewater. In this study we examined the survival of several indicators of viral pollution (indigenous F-specific bacteriophages, seeded MS2 bacteriophage, and seeded human poliovirus type 1) applied in primary municipal wastewater to artificial wetland ecosystems. Only about 1% of the indigenous F-specific RNA bacteriophages survived flow through the vegetated wetland beds at a 5-cm-day-1 hydraulic application rate during the period from June through December 1985. The total number of indigenous F-specific bacteriophages (F-specific RNA and F-specific DNA phages) was also reduced by about 99% by wetland treatment, with the mean inflow concentration over the period of an entire year reduced from 3,129 to 33 PFU ml-1 in the outflow of a vegetated bed and to 174 PFU ml-1 in the outflow of an unvegetated bed. Such superior treatment by the vegetated bed demonstrates the significant role of higher aquatic plants in the removal process. Seeded MS2 bacteriophage and seeded poliovirus were removed more efficiently than were the indigenous bacteriophages, with less than 0.2% of MS2 and 0.1% of the poliovirus surviving flow at the same hydraulic application rate. The decay rate (k) of MS2 in a stagnant wetlands (k = 0.012 to 0.028 h-1) was lower than that for flowing systems (k = 0.44 to 0.052 h-1), reflecting the enhanced capacity for filtration or adsorption of viruses by the root-substrate complex (and associated biofilm).(ABSTRACT TRUNCATED AT 250 WORDS)