Agricultural Sewage Research Articles

Studies for the Sustainable Management of Oyster Farms in Pukman Bay, Korea: Estimate of Primary Production

To develop sustainable management strategies for oyster farms in Pukman Bay, Korea, we estimated primary production using a numerical model. Because oysters are filter feeders, estimations of primary production (PP) are essential in developing management strategies. The daily PP ranged from 0.07 to 1.5 gC//d and showed significant spatial variations. The spatial distribution of PP was strongly associated with hydrodynamic features, and distinct patterns were observed in three different regions. In the inner bay, high PP was directly influenced by urban and agricultural sewage. The middle part of the bay had low PP, whereas PP in the outer area was high. PP was relatively low during the main oyster growth season, from late autumn to early winter. These findings represent important information for developing a management model for oyster farms in Pukman Bay.

Investigation of the fate of sulfonamides downgradient of a decommissioned sewage farm near Berlin, Germany

The drinking water production of a drinking water treatment plant in Berlin is affected by ambient contaminated groundwater. The three organic compounds para-toluenesulfonamide (p-TSA), ortho-toluenesulfonamide (o-TSA) and benzenesulfonamide (BSA) were identified in the catchment area of this plant. The groundwater pollution is a result of former sewage farm irrigation in the area, operating for almost 70 years until the 1980s. The distribution of the sulfonamides in the anoxic groundwater was investigated, and a large number of observation and production wells were sampled for this purpose. The contaminant plume is 25 m ⁎ 3000 m ⁎ 2000 m (depth, length, width) in size. The high concentrations of p-TSA, o-TSA and BSA in the groundwater show that the sulfonamides persist over decades in an anoxic aquifer environment. Groundwater quality assessment revealed that elevated concentrations of the analytes can be expected in the abstraction well galleries in the future. Therefore, sulfonamides should periodically be monitored in the drinking water (maximum allowed concentration of 0.30 µg/L of p-TSA and for o-TSA and BSA, a limit of 0.10 µg/L for unknown substances applies). Because of the widespread application and the persistence of the sulfonamides under anoxic conditions, our local investigations suggest that the substances may generally be present in groundwater under the influence of sewage irrigation. Incubation experiments were conducted under in situ hydrostatic pressure to study the behaviour of these trace organic compounds under different redox conditions (oxic and anoxic). Groundwater sampling equipment was either sterilised or not sterilised in order to distinguish between microbiological processes occurring in the aquifer and those representing sampling and storage artefacts (incubation experiments). Results showed that the addition of oxygen to the anoxic groundwater facilitates p-TSA and o-TSA degradation. Hence, while the substances are persistent under anoxic conditions, they are more degradable in the presence of oxygen. Results also illustrate that maintaining anoxic conditions or applying appropriate preservation techniques is necessary to ensure accurate analysis.

Wastewater Quality and the Risk of Intestinal Nematode Infection in Sewage Farming Families in Hyderabad, India

Use of sewage or wastewater in agriculture is becoming increasingly common as a result of a global water scarcity. Intestinal nematode infections have been identified as the main health risk associated with this practice. To protect consumer and farmer health, the World Health Organization (WHO) has established an intestinal nematode water quality standard. However, because of a lack of well-designed studies, the validity of this guideline is questioned. This report presents the findings of a study on the risk of intestinal nematode infections in farming families occupationally exposed to untreated and partially treated wastewater in Hyderabad, India. The study found an increased risk of hookworm (odds ratio [OR] 3.5, 95% confidence interval [CI] = 2.2-5.5), Ascaris lumbricoides (OR = 5.3, 95% CI = 2.0-14), and Trichuris trichiura (OR = 5.6, 95% CI = 1.8-18) infection when untreated wastewater (150 intestinal nematode ova/liter) was used for crop production. Use of partially treated wastewater (28 intestinal nematode ova/liter) was only associated with an increased risk (OR = 3.2, 95% CI = 1.2-8.6) of A. lumbricoides infection. The findings of the study suggest that the current WHO intestinal nematode guideline of 1 ova/liter is sufficient to protect farmer health.

Application and features of cascade aquatic plants system for sewage treatment

The effectiveness of settled sewage treatment by aquatic plants, such as water hyacinth (Eichhornia crassipes) and water lettuce (Pistia stratiotes), was tested in different modes of operation on laboratory and pilot scales. Laboratory-scale cascade and semi-continuous pilot experiments verified that the plants are capable of decreasing all tested water quality indicators to levels that permit the use of the purified water for irrigation of tree crops. This applies to biochemical oxygen demand (BOD), chemical oxygen demand (COD), total suspended solids (TSS) and turbidity. The laboratory cascade experiments demonstrate the capacity of the plants to reach and maintain levels of BOD (1.5–5 mg L−1), COD (20–40 mg L−1), TSS (0.5–5 mg L−1) and turbidity (0.4–2 NTU, nephelometric turbidity units) which are close to the lower bounds of these indicators. The plants’ performance in the cascade mode was found to be superior to other batch and continuous modes of operation. The efficiency and kinetics of pollutant removal is shown to change from one cascade container to the other. The primary effect of the wastewater treatment occurs in the first and second containers of the cascade system. In the third and fourth containers of the cascades, where the concentration of pollutants is significantly lower, the final polish of the treated water is achieved. Pilot-scale experiments, with 11 cycles of sewage dosage, demonstrated that the plants were capable (under summer conditions, with air temperature up to 33 °C) of holding the BOD below 2 mg L−1 after 20 days of periodic surges in the level of sewage. The results show that the use of this free water surface flow system (FWS) in a pulsed cascade mode enhances the treatment process of urban and agricultural sewage. The different stages of the cascade prove that the plants are effective in concentrated as well as in diluted or progressively treated sewage. Finally, the cascade is shown to perform close to lower bounds of the purification capacity of plants.

Temporal and spatial distribution patterns of heavy metals in soil at a long-standing sewage farm

Australia's oldest sewage farm in Werribee, Victoria is a significant public asset with more than 110 years of history and it now treats half of Melbourne's municipal sewage. Currently three parallel methods, i.e. lagoon, land filtration and grass filtration were used to treat raw sewage from Melbourne. The land filtration area is soil-pasture-cattle complex system and it operates on 3,633 ha of permanent pastures for livestock grazing. The land filtration area by intermittent irrigation of sewage occurs during the months of high evaporation from October to April. The monitoring study was aimed to find out the temporal and spatial distribution patterns of heavy metals in the soil at land filtration area in the long standing sewage farm. The monitoring results show that the temporal distribution patterns of Cd, Cr, Cu, Ni, Pb and Zn follow the exponential regression equations in soil layer 0-20 cm and the linear equations in soil layer 20-40 cm respectively. The accumulated concentrations of heavy metals in the soils are high enough for the land to be considered contaminated. The exponential trend of heavy metal of soil in land filtration area should be controlled immediately by soil remediation or by change of treatment process of flow configuration.

Behaviour and biodegradation of sulfonamides ( p-TSA, o-TSA, BSA) during drinking water treatment

Three sulfonamides – para-toluenesulfonamide ( p-TSA), ortho-toluenesulfonamide ( o -TSA) and benzenesulfonamide (BSA) – have recently been detected in groundwater within a catchment area of one drinking water treatment plant (DWTP), which is located downstream of a former sewage farm. The degradation pathways of p-TSA, o -TSA and BSA were investigated during drinking water treatment with incubation experiments and an experimental filter. Incubation experiments showed that p-TSA is removed during the treatment by microbiological processes. Removal of p-TSA is performed by adapted microorganisms only present in polluted groundwater. The elimination in an experimental filter of 1.6 m length applying filtration velocities from 2 to 6 m h −1 was ∼93% of p-TSA. The microbial degradation rates in the incubation experiment were ∼0.029 μg l −1 h −1 (zero order reaction). In the experimental filter, the reaction rate constants were around 0.0063 s −1 for all filtration velocities (1st order reaction). Drinking water treatment does not reduce the concentration of o -TSA and BSA under conditions encountered in Berlin. p-TSA, o -TSA and BSA were only measured in the low μg l −1 concentrations range in the purified water.

Effect of Evapotranspiration on the Salinity of Wastewater Treated By Aquatic Plants

The shortage of good quality water resources is becoming an important issue in arid and semi-arid zones. Irrigation systems must be developed that are capable of delivering low quality wastewater while taking into account environmental and health requirements. For this reason, the availability of water resources of marginal quality, such as desalinated wastewater, can be a significant contribution to the water supply. We investigated changes in salinity, in conjunction with evaporation kinetics of treated wastewater by aquatic plants. These plants enhance the removal of pollutants by consuming them in the form of plant nutrients and through the microbial activity on their roots. In particular, this treatment applies to urban and agricultural sewage, where treatment units of different sizes can be applied at the pollution source while acting as green environments. In these treatment units, increased salinity due to effect of evapotranspiration (ET) must be managed. The rates of evaporation (E) from the free water surface and transpiration (T) from the plants were determined under field and laboratory conditions. To this end, batch experiments were performed with floating and emergent aquatic plants. After 4 days in the presence of floating plants, the biochemical oxygen demand (BOD) decreased from its 100-110 mg L(-1) initial value down to 30-40 mg L(-1) (65% to 70% removal), concurrent with a 2% to 5% increase in the chlorides level, and 5% to 8% in the electroconductivity. The ET rates were found to be a significant factor in the water balance governing the treatment process. The results of this work provide guidelines for recommended wastewater treatment times that safeguard against undesirable rises in salinity, yet with marginal change in parameters such as BOD. The change of salinity is shown to be relatively minor in the first days of treatment where the change in BOD is faster, whereas in the following days the picture is reversed. This result indicates the advantage of applying shorter treatment periods when the rise in salinity is avoided.

Urban metabolism and river systems: an historical perspective – Paris and the Seine, 1790–1970

Abstract. The aim of this paper is to analyse metabolic interaction between Paris and the Seine during the industrial era, 1790–1970, a period marked by strong population growth, technological changes, and the absence of specific legislation on environmental issues. The viewpoint focuses on exchanges of waters and wastes between city and river, quantifying them and tracing their evolution in the light of the strategies implemented by the stakeholders in charge. The study combines industrial ecology, local history and the history of technology. From 1790 to 1850, waste matters, and especially excreta, were considered as raw materials, not refuse: they generated real profits. The removal of human excreta aimed not only at improving urban hygiene, but at producing the fertilizers needed in rural areas. Discharging them into the river was out of the question. But after the 1860s, several factors upset this exploitation, notably domestic water supply: night soil became more and more liquid, difficult to handle and to turn into fertilizer; once utilised, the water had to be removed from the house; at the same time, the sewerage system developed and had negative impacts on the river. Even so, Parisian engineers continued to process sewage using techniques that would not only ensure hygiene but also conciliate economic and agricultural interests: combined sewerage system and sewage farms. Both of these early periods are thus noteworthy for a relative limitation of the river's deterioration by urban wastes. Not until the 1920s, when domestic water supply had become the standard and excreta came to be considered as worthless waste, was the principle of valorisation abandoned. This led to important and long-lasting pollution of the Seine (despite the construction of a treatment plant), aggravating the industrial pollution that had been in evidence since the 1840s. Analysing the priorities that led to the adoption of one principle or another in matters of urban hygiene and techniques, with the causes and consequences of such changes, enables us to understand the complex relations between Paris and the Seine. From raw material to waste matter, from river to drain, the concept of quality in environment remains the underlying theme.

Identification and significance of sulphonamides ( p-TSA, o-TSA, BSA) in an urban water cycle (Berlin, Germany)

Because of the nature of the water cycle in Berlin, a number of persistent wastewater residues are present in the surface water and may potentially reach the groundwater via bank filtration and artificial recharge. The occurrence and behaviour of the wastewater residues para-toluenesulphonamide ( p-TSA), ortho-toluenesulphonamide ( o-TSA) and benzenesulphonamide (BSA) through wastewater treatment, surface water, bank filtration and drinking water treatment was studied. In addition, groundwater below a former sewage farm was investigated. All three compounds are ubiquitous in the aquatic environment of Berlin. p-TSA concentrations are much higher than those of o-TSA and BSA. p-TSA was found in high concentrations in the wastewater influent (2 to 15 μg/L), in the wastewater effluent (<0.15 to 2.34 μg/L) and in sewage farm groundwater (<0.05 to 20 μg/L) and in lower concentrations in the surface water (<0.05 to 1.15 μg/L), bank filtrate (<0.05 to 0.30 μg/L) and drinking water (<0.05 to 0.54 μg/L). p-TSA is considerably depleted during waste- and drinking water treatment (∼90% reduction each). The concentration ranges for o-TSA and BSA in wastewater influents were 0.11 to 8 μg/L and <0.05 to 0.64 μg/L, respectively, while the values for wastewater effluents were 0.14 to 4 μg/L for o-TSA and 0.25 to 0.49 μg/L for BSA. Wastewater treatment and drinking water treatment do not reduce the concentrations of o-TSA and BSA. The behaviour of o-TSA during wastewater treatment varies largely between different wastewater treatment plants where concentrations increase, remain constant or decrease. BSA forms during treatment. The concentrations measured in surface water, sewage farm groundwater, bank filtrate and drinking water were <0.05 to 1.74 μg/L for o-TSA and <0.05 to 0.53 μg/L for BSA.

Hydrophobicity of Soil Colloids and Heavy Metal Mobilization

Drying of soil may increase the hydrophobicity of soil and affect the mobilization of colloids after re-wetting. Results of previous research suggest that colloid hydrophobicity is an important parameter in controlling the retention of colloids and colloid-associated substances in soils. We tested the hypothesis that air-drying of soil samples increases the hydrophobicity of water-dispersible colloids and whether air-drying affects the mobilization of colloid-associated heavy metals. We performed batch experiments with field-moist and air-dried (25 degrees C) soils from a former sewage farm (sandy loam), a municipal park (loamy sand), and a shooting range site (loamy sand with 25% C(org)). The filtered suspensions (<1.2 microm) were analyzed for concentrations of dissolved and colloidal organic C and heavy metals (Cu, Cd, Pb, Zn), average colloid size, zeta potential, and turbidity. The hydrophobicity of colloids was determined by their partitioning between a hydrophobic solid and a hydrophilic aqueous phase. Drying increased hydrophobicity of the solid phase but did not affect the hydrophobicity of the dispersed colloids. Drying decreased the amount of mobilized mineral and (organo-)mineral colloids in the sewage farm soils but increased the mobilization of organic colloids in the C-rich shooting range soil. Dried samples released less colloid-bound Cd and Zn than field-moist samples. Drying-induced mobilization of dissolved organic C caused a redistribution of Cu from the colloidal to the dissolved phase. We conclude that drying-induced colloid mobilization is not caused by a change in the physicochemical properties of the colloids. Therefore, it is likely that the mobilization of colloids in the field is caused by increasing shear forces or the disintegration of aggregates.

Identification of Iron−Cyanide Complexes in Contaminated Soils and Wastes by Fourier Transform Infrared Spectroscopy

Persistent cyanide species in soil are mainly iron-cyanide (Fe-CN) complexes. They originate from anthropogenic inputs of compounds such as Fe4[Fe(II)(CN)6]3 in deposited gas-purifier wastes (GPW) or K2Zn3[Fe(II)(CN)6]2 in deposited blast-furnace sludge (BFSI). Fe-CN species in de-inking sludge (DIS) and sewage farm soils (SF) are still unknown. We investigated 35 soil and waste samples from 15 European sites and five synthesized Fe-CN-containing compounds by Fourier transform infrared spectroscopy. Furthermore, we determined the contents of total and adsorbed CN and pH. In all samples (pH 2.2-9.5), adsorbed Fe-CN complexes were negligible. In GPW and DIS samples, Fe4[Fe(II)(CN)6]3 and KFe[FeII(CN)6] were the only Fe-CN compounds (total CN contents 0.4-449 g kg(-1)). Several BFSI samples were free of CN. The spectra of other BFSI samples partially indicated dissolution of the characteristic compound K2Zn3[Fe(II)(CN)6]2, resulting in a loss of CN (contents < 12.3 g kg(-1)). Distinctive changes in BFSI with respect to CN speciation occurred within relatively short periods, <20 years. Dissolution of K2Zn3[Fe(II)(CN)6]2 was followed by dissociation of free CN from [Fe(CN)6](3-/4-) and adsorption of [Fe(II)(CN)6](4-) on organic surfaces. In DIS and SF samples, Fe4[Fe(11)(CN)6]3 and K2Zn3[Fe(II)(CN)6]2 (SF only) were identified.

Quantitative determination of three sulfonamides in environmental water samples using liquid chromatography coupled to electrospray tandem mass spectrometry

An analytical method was developed to detect the three sulfonamides para-toluenesulfonamide ( p-TSA), ortho-toluenesulfonamide ( o-TSA) and benzenesulfonamide (BSA) in environmental water samples at concentrations down to 0.02 μg/L using liquid chromatography coupled to tandem mass spectrometry (HPLC–MS/MS). Wastewater, surface water, groundwater and drinking water samples from Berlin (Germany) were analysed for all three compounds which appear to be ubiquitously present in the aquatic environment. p-TSA was found in high concentrations in the wastewater (<0.02–50.8 μg/L) and in groundwater below a former sewage farm (<0.02–41 μg/L), and in lower concentrations in the surface water (<0.02 to 1.15 μg/L) and drinking water (<0.02–0.27 μg/L). o-TSA and BSA were detected in considerably lower concentrations. The study makes clear that p-TSA should be monitored because of its comparatively high concentration in Berlin's drinking water.

Direct Determination of Estrogenic and Antiestrogenic Activities Using an Enhanced Plant Two-Hybrid System

This paper reports a simple, low-cost, and extremely sensitive reporter-gene assay system for comprehensive analysis of estrogenic activity using transgenic Arabidopsis thaliana: the EPTH system. It had the capability to detect 17beta-estradiol at a concentration of 10 pM. The system was rendered 5 times more sensitive than a previous system [Tojo, T.; Tsuda, K.; Wada, T.; Yamazaki, K. Ecotoxicol. Environ. Saf. 2006, 64, 106-114) (1)] by increasing the copy number of the transactivation domain fused to a nuclear receptor co-activator. The system can efficiently detect other estrogenic and antiestrogenic substances. Estrogenic activities were determined in treated sewage samples from four distinct sewage farms using the system. Results showed that the system can detect estrogenic activity directly and more efficiently than a yeast two-hybrid system without any manipulation for extraction and condensation of hydrophobic compounds and aseptic treatment. Furthermore, the system also is useful as a powerful tool for discovery of a new category of natural estrogenic substances that are undetectable by previous plant and yeast systems.

Trace compounds of biogas from different biogas production plants

Biogas composition and variation in three different biogas production plants were studied to provide information pertaining to its potential use as biofuel. Methane, carbon dioxide, oxygen, nitrogen, volatile organic compounds (VOCs) and sulphur compounds were measured in samples of biogases from a landfill, sewage treatment plant sludge digester and farm biogas plant. Methane content ranged from 48% to 65%, carbon dioxide from 36% to 41% and nitrogen from <1% to 17%. Oxygen content in all three gases was <1%. The highest methane content occurred in the gas from the sewage digester while the lowest methane and highest nitrogen contents were found in the landfill gas during winter. The amount of total volatile organic compounds (TVOCs) varied from 5 to 268 mg m −3 , and was lowest in the biogas from the farm biogas plant. Hydrogen sulphide and other sulphur compounds occurred in landfill gas and farm biogas and in smaller amounts in the sewage digester gas. Organic silicon compounds were also found in the landfill and sewage digester gases. To conclude, the biogases in the different production plants varied, especially in trace compound content. This should be taken into account when planning uses for biogas.

The correlation of total and extractable heavy metals from soil and domestic sewage sludge and their transfer to maize ( Zea mays L.) plants

A study to understand the mobility and transport of heavy metals (HMs) from soil and soil amended with sewage sludge to maize plants was carried out. The total and ethylenediaminetetraaceticacid (EDTA)-extractable HMs in agricultural soil and untreated domestic sewage sludge samples, and the correlation between the total and extractable metals in soil and sewage sludge were carried out. Pot experiments were performed to study the transfer of HMs to maize grains, grown in soil (control) and in soil amended with sewage sludge (test samples). The total and extractable HMs in soil, sewage sludge, and maize grains were analysed by FAAS/ETAAS (flame atomic absorption spectrometer/electrothermal atomic absorption spectrometer) after digestion in microwave oven. Statistically significant correlations were obtained between the total contents of Cu, Cd, As and their respective extractable fractions in soil, while in domestic wastewater sludge (DWS) the better correlation was observed only for Ni and Cd. The edible part of maize plants (grains) from test samples presented high concentration of Zn, Pb, Ni, Cd, Cu, As, and Cr concentrations (80.7–85.6, 3.8–3.95, 2.35–2.5, 0.75–0.82, 3.21–3.29, 0.23–0.27, and 0.22–0.29 mg kg−1, respectively). Good correlations were found between metals in exchangeable fractions of both soil and DWS and total metals in control and test samples of maize grains. The transfer factor of all HMs from DWS to maize grains was also determined.

Habitat Selection and Winter Food Resources of the Water PipitAnthus spinolettain South-Western Poland

In winter 2004/2005, 1532 Water Pipits were recorded during 37 censuses carried out along an established route on a sewage farm flooded with wastewater (Wrocław, SW Poland). Single birds were seen in nearly 39% of all 299 encounters, while the largest concentrations, between 16–28 individuals, accounted for 9%. 78% of all birds were observed on meadows flooded with communal wastewater. The remaining ones stayed around irrigation ditches (n = 172, 11.5%), sedimentation basins (n = 88, 5.9%) and reedbeds (n = 72, 4.8%). The mean size of the Water Pipit concentration was largest on the meadows (mean ± SE = 6.54 ± 0.50 individuals) and smallest at the sedimentation basins (mean = 1.44 ± 0.14). In this winter season (December-first half of March), rainfall enlarged numbers of birds to forage on the meadows, and the thickness of the snow cover was positively correlated with bird abundance at the sedimentation basins. The dominant available prey items inhabiting the warm wastewater were Diptera larvae (96%), 88% of which belonged to the genus Eristalis. The mean (± SD) invertebrate biomass was highest in the basin sediments (1.03 ± 1.14 g/dm3 of deposits), and lowest on the flooded meadows (0.20 ± 0.37 g/dm3 of deposits). The results point to the significance of the artificial environmental conditions created by warm sewage water, which enable the birds to remain largely independent of the weather and thus to overwinter in a cold region of central Europe.

Sorption and Fractionation of Copper in Soil at a Sewage Irrigation Farm in Australia

Copper (Cu) is an important heavy metal to be considered in soil contamination, because high concentrations of copper in soil produce toxic effects and may accumulate in plant tissues. In Australia's oldest sewage irrigation farm, located in Werribee, Victoria, soil in the land filtration area is contaminated by Cu. However, Cu content in herbage tissues is in the normal range and has been trending downward since 1979. Therefore, studies on the sorption capacity and sequential extraction of Cu in soil at the Werribee Farm is of significance, not only for better understanding the mechanism of transport, chemical processes, and plant uptake of Cu, but also in providing information for the practical management of sewage farm soils. Methods of combining sorption isotherms with sequential extraction procedures were adopted, and the results showed that the soil in the land filtration area at Werribee Farm has a high sorption capacity for Cu, and distribution coefficients, Kf of Cu, were 629 L kg−1 in surface soils (0–20 cm) and 335 L kg−1 in subsurface soils (20–40 cm). The sequential extraction fractions demonstrate that exchangeable and carbonate fractions are very low, only comprising 3.49 to 5.49% of total copper. The other fractions are also discussed. This characteristic of Cu in soil is related to the low concentration of Cu in plant tissues.

Application of Eichhornia crassipes and Pistia stratiotes for treatment of urban sewage in Israel

The effectiveness of sewage purification by aquatic plants, such as water hyacinth ( Eichhornia crassipes) and water lettuce ( Pistia stratiotes), was tested on laboratory and pilot scales. Cascade and semi-continuous pilot experiments verified that the plants are capable of decreasing all tested indicators of water quality to levels that permit the use of the purified water for irrigation of tree crops. This applies to biochemical oxygen demand (BOD), chemical oxygen demand (COD), total suspended solids (TSS), and turbidity. The laboratory-scale tests confirm the capacity of the plants to reach and hold reasonably low levels of BOD (5–7 mg L −1) and COD (40–50 mg L −1) and very low levels of TSS (3–5 mg L −1) and turbidity (1–2 NTU). In the experimental pilot setup, with circulation, COD decreased from 460 to 100 mg L −1 after 2.5–4 days of treatment, while 6–7 days were required to this end without circulation. This doubled the active pond area and provided a two-level hydraulic loading (8 and 12 L min −1) with circulation that proved to be effective during the summer as well as the winter season. The outflow concentrations were 50–85 mg L −1 of COD and 4–6 mg L −1 of BOD. The results show that the use of this free water surface flow system (FWS) and its low maintenance system for treatment of urban and agricultural sewage is a viable option.

해양생태독성평가를 위한 표준시험생물로서의 식물플랑크톤에 관한 연구

A series of experiments was conducted to identify the potential of five phytoplankton species as standard test species for marine ecotoxicological tests. The candidate phytoplankton species are Skeletonema costatum, Heterosigma akashiwo, Prorocentrum micans, Isochrysis galbana, and Tetraselmis suecica. Salinity tolerance and sensitivity on potassium dichromate as a reference material were identified. Toxicity of eleven ocean dumped sewage sludges and four red tide expellent extracts were estimated by the inhibition of population growth rates (PGR) of marine diatom S. costatum, While most species revealed relatively weak tolerance on salinity, T. suecica demonstrated the highest salinity tolerance ranged from <TEX>$5\~35$</TEX> psu and the others <TEX>$15\~35$</TEX> psu. H. akashiwo revealed the highest sensitivity as 72h <TEX>$IC_{50}$</TEX>=0.76mg/L and T. suecica the lowest as 72h <TEX>$IC_{50}$</TEX>=8.89mg/L on potassium dichromate. Sludge extracts from industrial waste, domestic sewage and livestock farm waste sludge showed high toxicity as 72h <TEX>$IC_{50}$</TEX><<TEX>$2\%$</TEX> and lowest toxicity from filtration bed sludge as 72h <TEX>$IC_{50}$</TEX>=<TEX>$30.50\%$</TEX> NOEC (No Observed Effective Concentration) of sludge extract ranged from <<TEX>$0.4\%$</TEX> to <TEX>$1.6\%$</TEX> and this indicated high phytotoxicity of ocean dumped sewage sludge. The test sensitivity of phytoplankton PGR inhibition was much higher than those of marine rotifer Brachionus plicatilis mortality test and bioluminescent inhibition test by marine bacteria Vibrio fischeri, and comparable with the sea urchin (Strongylocentrotus intermedius) fertilization test. As a result the phytotoxicity test using phytoplankton PGR inhibition (<TEX>$IC_{50}$</TEX>) must be a useful tool for marine phyto-toxicological evaluation of ocean dumped materials.

Genetic toxicity in surface water from Guaíba Hydrographic Region under the influence of industrial, urban and agricultural sewage in the Drosophila Wing-Spot Test

Mutagenic and recombinagenic activity of surface waters in the Guaíba Hydrographic Region (RS, Brazil) was investigated using the SMART in Drosophila melanogaster. Two positive results in Caí River (September 2000 and August 2001) and in Taquari River (August 2001 and February 2002) – linked to direct recombinagenic toxicants were observed. In Jacuí samples, an indirect mutagenic and recombinagenic action was detected in a September 2000 collection and a direct recombinational activity was observed in February 2002. Also in February 2002 – samples from Dilúvio Brook and Guaíba Lake (GPC) were able to induce wing spots by mitotic recombinagenesis. The former sampling site showed toxicants to have a direct action, and the latter an increment in mitotic recombination that depended on metabolic action. The SMART wing test shows that all positive responses were mainly related to homologous mitotic recombination.