Comparative toxicity of six test chemicals to lettuce using two root elongation test methods

Lettuce (Lactuca sativa L., cv buttercrunch) was used to evaluate and compare the results from two different root elongation phytotoxicity test methods with the same six test substances. Seeds were either germinated in the dark on an inclined filter paper substrate with one end immersed in test solution or germinated in 0.1 strength nutrient solution with a 16 hr light period in a glass bulb mixed and aerated with compressed air. Sodium fluoride, monosodium methanearsonate and monuron reduced lettuce root length at similar concentrations for both methods, while cadmium chloride and 2,4-D root inhibition occurred at concentrations approximately one order of magnitude smaller in the solution culture method than in the substrate method. Two orders of magnitude difference were observed between the two methods for silver nitrate. The results indicate that the solution method is at least as sensitive for all the chemicals tested and much more sensitive for some.     

Combining passive sampling and toxicity testing for evaluation of mixtures of polar organic chemicals in sewage treatment plant effluent

Effluent from sewage treatment plants has been associated with a range of pollutant effects. Depending on the influent composition and treatment processes the effluent may contain a myriad of different chemicals which makes monitoring very complex. In this study we aimed to monitor relatively polar organic pollutant mixtures using a combination of passive sampling techniques and a set of biochemistry based assays covering acute bacterial toxicity (Microtox), phytotoxicity (Max-I-PAM assay) and genotoxicity (umuC assay). The study showed that all of the assays were able to detect effects in the samples and allowed a comparison of the two plants as well as a comparison between the two sampling periods. Distinct improvements in water quality were observed in one of the plants as result of an upgrade to a UV disinfection system, which improved from 24x sample enrichment required to induce a 50% response in the Microtox assay to 84x, from 30x sample enrichment to induce a 50% reduction in photosynthetic yield to 125x, and the genotoxicity observed in the first sampling period was eliminated. Thus we propose that biochemical assay techniques in combination with time integrated passive sampling can substantially contribute to the monitoring of polar organic toxicants in STP effluents.     

Assessment of heavy metals in two commercial fish species of four Turkish seas

There is an increasingly need to assess the contaminant levels in fish as indicators of the health and well-being of both the fish and their consumers, including humans. Fish samples were collected through the coastal waters of Turkey and the contents of cadmium, copper, chrome, copper, iron, manganese, nickel, zinc and lead in the liver and muscle tissues were determined by ICP-AES. The highest levels of each metal were found in the liver and this was followed by the muscle in both species. Among the metals analyzed, Cu, Zn and Fe were the most abundant in the different tissues while Cd and Pb were the least abundant both in Mullus barbatus (red mullet) and Merlangius merlangus (whiting). Regional changes in metal (Cd, Cu, Pb, Fe and Zn) concentration were observed in the tissues of both species, but these variations may not influence consumption advisories.     

Seasonal availability and sensitivity of two field-collected mayflies for the development of a standardized toxicity test

Ecologically relevant toxicity tests may provide the best protection of sensitive aquatic fauna, but without established culturing or test methodology for such organisms, results may be unreliable and difficult to repeat. Further, field-collected organisms may not be feasible for routine testing purposes, as often required for permitted discharges. This study examined the feasibility of testing two field-collected mayflies, Isonychia bicolor and Maccaffertium spp., over a 1-year period. Seasonal comparisons of availability indicated I. bicolor and Maccaffertium spp. were most abundant during the winter months, resulting in 31 and 49 % of total organisms collected in 2009, while summer was the most difficult time to collect either species. Initial testing in January 2009 resulted in the highest no observable effect concentration (NOEC) values for survivorship (8 g NaCl for I. bicolor and 4 and 8 g NaCl/L for Maccaffertium spp.) when tested at 9°C. Subsequent tests conducted at 20–23°C resulted in 7-day NOEC values substantially lower (mean?=?1.44 and 1.59 g NaCl/L). Geometric means of exuviae indicated a dose-dependent response for I. bicolor exposed to NaCl, while no dose-dependent response was observed for Maccaffertium spp. with average number of molts varying from 4.93 in the 0.5 g NaCl/L concentration to 3.80 for control organisms followed by 2.24 (1 g NaCl/L). Averages again increased to 3.09 in the 2 g NaCl/L concentration, but declined in the highest concentrations (4–10 g NaCl/L). Based on the results of this feasibility study, field-collected mayflies appear to be too unpredictable in test responses, and therefore, such tests would be unreliable as stand-alone indicators of effluent toxicity.     

The influence of metallurgy on the formation of welding aerosols

Recent research has indicated that insoluble ultrafine aerosols (ie., particles whose physical diameters are less than 100 nm) may cause adverse health effects due to their small size, and that toxicological response may be more appropriately represented by particle number or particle surface area. Unfortunately, current exposure criteria and the associated air-sampling techniques are primarily mass-based. Welding processes are high-temperature operations that generate substantial number concentrations of ultrafine aerosols. Welding aerosols are formed primarily through the nucleation of metal vapors followed by competing growth mechanisms such as coagulation and condensation. Experimental results and mathematical tools are presented to illustrate how welding metallurgy influences the chemical aspects and dynamic processes that initiate and evolve the resultant aerosol. This research suggests that a fundamental understanding of metallurgy and aerosol physics can be exploited to suppress the formation of undesirable chemical species as well as the amount of aerosol generated during a welding process.     

The relative influence of nutrients and habitat on stream metabolism in agricultural streams

Stream metabolism was measured in 33 streams across a gradient of nutrient concentrations in four agricultural areas of the USA to determine the relative influence of nutrient concentrations and habitat on primary production (GPP) and respiration (CR-24). In conjunction with the stream metabolism estimates, water quality and algal biomass samples were collected, as was an assessment of habitat in the sampling reach. When data for all study areas were combined, there were no statistically significant relations between gross primary production or community respiration and any of the independent variables. However, significant regression models were developed for three study areas for GPP (r ² = 0.79–0.91) and CR-24 (r ² = 0.76–0.77). Various forms of nutrients (total phosphorus and area-weighted total nitrogen loading) were significant for predicting GPP in two study areas, with habitat variables important in seven significant models. Important physical variables included light availability, precipitation, basin area, and in-stream habitat cover. Both benthic and seston chlorophyll were not found to be important explanatory variables in any of the models; however, benthic ash-free dry weight was important in two models for GPP.     

The influence of race and gender on perceptions of community impact

Since 1968, research in public transportation planning has included an increasing number of analyses of the perceptions and attitudes of people who use and live in proximity to the systems (Nash and Hille 1968, McMillan et al. 1969, Wachs 1976). The results of the study reported here suggest that race and gender may explain more about attitudes toward the community impact of a transit system than do the levels of user satisfaction with the system. The implication for future research in this area is that surveys employing “satisfaction” and “importance” as indicators may not be using appropriate indices of evaluation. This study reports the results of a 1980 attitude survey of the perceptions of black and white men and women living within a two-block corridor along the Metropolitan Atlanta Rapid Transit Authority (MARTA) east line in Atlanta, Georgia. The research supports the Atlanta Regional Commission (ARC) Transit Impact Monitoring Program (TIMP). The survey used a stratified random sample technique to identify 100 households in which in-home interviews were subsequently conducted. A further stratified sampling procedure designated the gender and age of persons to be interviewed. The analysis included the isolation of responses by gender and race and used the chi-square statistic at the 0.05 significance level. The results identity differences in responses of males and females, blacks and whites.     

Survey of four marine antifoulant constituents (copper,zinc, diuron and Irgarol 1051) in two UK estuaries

A field survey of antifoulant concentrations was undertaken in two UK estuaries (Hamble and Orwell) in 1998 and 1999. The two locations offered variations in physical aspects (Orwell estuary being significantly larger than the Hamble) as well as differences in boat densities (Hamble having almost twice as many vessels moored in the estuary and marinas). Samples were analysed for copper, zinc, diuron and Irgarol 1051, and were collected in summer and winter in order to identify potential seasonal variations in concentrations. The effect that different marina types (e.g. locked marina, one located in a natural inlet and pontooned ones in the open estuary) had on antifoulant concentrations were also investigated. Concentrations of the organic booster biocides, diuron and Irgarol 1051 in the marinas and estuaries were mainly influenced by leaching from antifoulant paints applied to the hulls of leisure craft, and so levels reflected the number of vessels present in the water. As a consequence significantly higher concentrations were found in marinas (up to ca. 900 ng l(-1) for diuron and 240 ng l(-1) for Irgarol 1051) compared with estuaries (up to ca. 400 ng l(-1) for diuron and 100 ng l(-1) for Irgarol 1051) and in summer compared with winter. Sediment concentrations of Irgarol 1051 and diuron were rarely detectable other than in the marinas where high concentrations were detected near slipways assumed to be derived from washed off paint chips. Dissolved concentration profiles for copper and zinc in the estuaries and marinas were different from those for the organic booster biocides partly because other sources of these metals contributed to estuarine and marina loads. In particular, riverine loads and inputs from sacrificial anodes attached to leisure craft, exhibited a major influence of estuarine levels of zinc. Consequently, only in the Hamble estuary for copper was there a clear distinction between summer (typically 3-4 microg l(-1)) and winter dissolved values (typically 1-2 microg l(-1)) that could be largely attributable to the leaching of antifoulant paints. Sediment concentrations for both metals were similar for both estuaries, with little variation between winter and summer values (Zn ranging from 28 to 614 mg kg(-1) and Cu from 6 to 1016 mg kg(-1)) as with the organic booster biocides highest levels were measured at the base of slipways in marinas.     

Phytoplankton distribution during two contrasted summers in a Mediterranean harbour: combining automated submersible flow cytometry with conventional techniques

Present study was conducted in rapidly growing city Islamabad, and surface soils were collected from three major land cover types viz., built-up, drain side, and green areas. A total of seven physicochemical parameters and 11 metals were determined in surface soils. Factor analysis based on principal component analysis explained total variance of 68.0%, 64.5%, and 60.2% of three land cover types and showed high loadings for major elements (Mg and K) in built-up and green area and Fe in drain side. Top soil pollution index was carried out by using geo-accumulation index and metal pollution index (MPI₆). Concentration of major elements (Ca, Mg, Na, K) in surface soils is derived by parent material, whereas concentration of Fe, Ni, Pb, and Zn were mainly related with anthropogenic sources. Geostatistical methods such as kirging identified hotspot areas of metal contamination by Pb, Ni, and Zn in built-up areas influenced mainly by vehicular emissions and waste disposal. The results stresses that land clearing should be avoided to reduce contamination and management of urban soils.     

The influence of pH and temperature on the aqueous geochemistry of neodymium in near surface conditions

Geochemical calculations were employed for the solubility and speciation of neodymium in a model soil solution as a function of pH. The calculations were based on the recently determined stability constants for Nd and solubility product for the Nd end-member of mineral monazite (NdPO(4)). Simulations were carried out at near neutral pH (pH 6.0 to pH 7.5) and 25 degrees C at the atmospheric CO(2) partial pressure. Additional calculations were also performed to assess Nd mobility at the extreme temperature conditions (300 degrees C) at neutral pH. Our results suggest that relatively dilute (Ionic Strength, I = 0.1), low-temperature waters may transport very small quantities of rare earth elements and actinides to the surficial environment at near neutral pH conditions. Evidently, higher temperature or extreme fluid composition may have a greater potential for mobilization of these elements. The results are pertinent to researchers interested in engineering applications for the precipitation of Nd and surrogate actinides from aqueous nuclear wastes.     

The influence of geometry and draught shields on the performance of passive samplers

Passive samplers provide an excellent opportunity to perform indicative measurements or establish a dense network of measuring sites. A drawback compared with conventional active measuring methods is the larger spread of results. This variation can, to a large extent, be attributed to the influence of temperature, sampler geometry and wind on sampling results. A proper design of sampler geometry and optimum choice of draught shield can reduce the influence of wind velocity on a badge type sampler to less than 10%. Wire mesh screens prove to be inadequate in damping turbulence. Filters give good results. Attention should be paid to the size and isolation value of the walls of the sampler to prevent thermal updrafts occurring within the sampler. Tube type samplers are less influenced by wind, provided that turbulence is prevented from influencing diffusion within the sampler.     

Occurrence of estrogenic chemicals in South Korean surface waters and municipal wastewaters

Broad scale monitoring of estrogenic compounds was performed at 19 sampling points throughout the Yeongsan and Seomjin river basins and 5 wastewater treatment plants (WWTPs) adjacent to the Gwangju area, Korea, from December 2005 to August 2007. The concentrations of estrogenic compounds, including estrone (E1), 17β-estradiol (E2), 17α-ethynylestradiol (EE2), bisphenol-A, nonylphenol (NP) and 4-octylphenol (OP), in the samples was measured with gas chromatography/mass spectrometry (GC-MS). In addition, the estrogenic activities throughout the river were investigated using the E-screen assay. Of the six estrogenic chemicals, NP (114.6-336.1 ng L(-1)) and EE2 (0.23-1.90 ng L(-1)) were detected at the highest and lowest levels, respectively in both the river waters and the WWTP effluents. Bisphenol-A showed the largest concentration range, from 7.5 to 335 ng L(-1). The concentrations of E1, E2 and octylphenol ranges were 3.6-69.1, 1.2-10.7, and 2.2-16.9 ng L(-1), respectively. According to the calculated estradiol equivalent concentration (EEQ); however, no estrogenic contribution was observed due to the phenolic compounds in the river waters and effluents. E1 and E2 dominated in both the river water and effluent samples, with contributions to the calculated EEQ of over 79 and 77%, respectively. Conversely, EE2 was rarely detected in the river waters (21%) and effluents (0%). The largest contribution of EE2 to the calculated EEQ was 21% in the river water at S-7. The levels of E1, E2, and EE2 were remarkably decreased in the effluents, indicating that the 5 WWTPs did not contribute to the estrogenic effect of the receiving streams. Overall, the WWTPs did not contributed to the estrogenic activity of the receiving waters, but the livestock industry or wildlife may play an important role in the estrogenic contribution to river water.     

The effect of temperature and NaCl concentration on the kinetic method of toxicity determination using Vibrio fischeri

In this paper the effect of temperature and NaCl concentration on the kinetic method of toxicity determination using Vibrio fischeri was studied for 50 ppm Zn(2+). This work shows that both NaCl concentration and temperature affect the kinetics of toxicity as well as the luminescence of the bacteria, and hence these are important factors that need to be considered in the development of a miniaturised portable instrument. Furthermore, this work shows that the conditions for which the kinetic test was most sensitive, i.e. exhibited the greatest response, were 23 degrees C and 2% NaCl. However, at these conditions small variations in temperature and NaCl concentration could lead to great errors in the results. Thus 12.5 degrees C and 2% NaCl are preferred as at these conditions the obtained results are more robust. Although at the latter conditions the toxicity rate constant was found to be 5.5 times less than that for 23 degrees C, the value is comparable to that obtained for 15 degrees C. From the data available it was also found that the temperature dependence of the toxicity rate fits the Arrhenius equation, in a behaviour similar to that of simpler chemical reactions.     

The influence of estuarine water quality on cover of barnacles and Enteromorpha spp.

The influence of ambient water quality on the settlement of barnacles and the green alga Enteromorpha spp. to an artificial substratum in the estuaries of Sydney, Australia, was investigated to test the efficacy of both groups of organisms as indicators of changes in water quality due to urban stormwater runoff and/or sewage overflows. Wooden settlement panels were immersed for 4 months on 17 occasions between 1996 and 2005 at 11 locations known to vary in water-quality parameters (conductivity, total uncombined ammonia, oxidised nitrogen, total nitrogen, filterable phosphorus, total phosphorus, faecal coliforms and chlorophyll-a) and ambient meteorological conditions (total rainfall, maximum rainfall). Water-quality data were collected during the time that the settlement panels were deployed. Cover of barnacles was highly variable among locations (range 1.2?C55.2%). Hierarchical partitioning found that chlorophyll-a, total phosphorus and total nitrogen had significant independent positive effects on barnacle cover. Together, these variables explained 26% of the variation in barnacle cover. Mean cover of Enteromorpha spp., however, did not vary significantly among locations suggesting that other potentially more important factors are influencing its settlement and growth. The results of this study suggest that barnacle cover is likely to be a useful indicator of some components of water quality.     

Spatial distribution and quantification of endocrine-disrupting chemicals in Sado River estuary, Portugal

The important Portuguese Sado River estuary has never been investigated for the presence of potentially endocrine-disrupting chemicals (EDCs), such as natural estrogens (estradiol, estrone), pharmaceutical estrogens (17α-ethynylestradiol), phytoestrogens (daidzein, genistein and biochanin A), or industrial chemicals (4-octylphenol, 4-nonylphenol, and bisphenol A). Thus, the main objective of this study was to evaluate their presence at 13 sampling points distributed between both the industrial and the natural reserve areas of the estuary, zones 1 and 2, respectively. For that, water samples collected in summer and winter were processed by solid phase extraction and analyzed by high-performance liquid chromatography with photodiode array detection and gas chromatography–mass spectroscopy. Results showed that estrone, ethynylestradiol, all the aforementioned phytoestrogens as well as bisphenol A and 4-octylphenol were found in zone 1. In zone 2, neither estrogens nor 4-OP were found. However, in the same zone, daidzein (500 ng/L) and genistein (320 ng/L) attained their highest levels in summer, whereas biochanin A peaked in winter (170 ng/L). Furthermore, bisphenol A was also found in some areas of zone 2, but showed similar concentrations in both surveys (about 220 ng/L). This study demonstrated that the Sado River estuary had low EDCs levels, suggesting that the Sado’s high hydrodynamic activity may be involved in the dilution of local pollution. It was suggested that at the current levels of concentrations, all assayed EDCs are unlikely to individually cause endocrine disruption in local animals. However, under a continuous exposure scenario, an additive and/or synergistic action of the estrogenic chemicals load can not be excluded, and so, continuous monitoring is advisable.     

Behaviour of selected endocrine-disrupting chemicals in three sewage treatment plants of Beijing, China

Occurrence and fate of eight kinds of selected endocrine-disrupting compounds (EDCs) in three sewage treatment plants (STPs) of Beijing, China was investigated. These EDCs, composed of 4-octylphenol (4-OP), 4-n-nonylphenol (4-n-NP), bisphenol A (BPA), estrone (E1), 17α-estradiol (17α-E2), 17β-estradiol (E2), estriol (E3) and 17α-ethinylestradiol (EE2), in every step of STPs, were simultaneously analysed by gas chromatography/mass spectrometry after derivatisation. All the EDCs were detected in the influents of three STPs, and BPA was the most abundant compound. The concentrations of EDCs ranged from 36.6 ng/l of 17α-E2 (STP C) to 1342.3 ng/l of BPA (STP B) in the influent sewages and from below limits of detection of E2 and E3 (STP C) to 142.5 ng/l of E1 (STP B) in the effluent sewages. The STPs could not remove alkylphenols effectively from the aqueous phase with less than 40% reduction. BPA decreased over 90%, and steroid estrogens achieved considerable reductions from 64.8% of E2 to 94.9% of E3. Generally, biological treatment was more effective in removing alkylphenols, BPA and natural estrogens from the aqueous phase than primary treatment. However, the synthetic estrogen, EE2, was mostly removed by the primary treatment with about 63.5% reduction. It is the first time that the concentration of 17α-E2 in the sewage of China was reported in this paper. The compound might have a bearing with the waste effluents of dairy farms around urban area of Beijing.     

The influence of denture cleansers on the release of organic compounds from soft lining materials

Biocompatibility constitutes the most fundamental requirement with respect to all dental materials to be applied within the oral cavity. In its environment, various toxic compounds may be released by dental materials which pose potential threats to the patient's health. Due to the fact that dentures remain in the oral cavity for a very long time, a detailed examination and verification of prosthetic materials with a view to their toxicity seems to be essential. By using very sensitive measurement techniques such as gas chromatography, one may determine which compounds are released by these materials. The aim of this paper was to determine the influence of various denture cleansers on the release of organic compounds from four soft dental materials used in prosthetics for lining dentures. These materials when placed in commonly used disinfectants (Corega Tabs, sodium hypochlorite, chlorhexidine, hydrogen peroxide), as well as in artificial saliva, produced 13 chemical compounds such as monomers (methyl methacrylate, ethyl methacrylate, dodecyl methacrylate), plasticizers (dibutyl phthalate, diethyl phthalate, tributyl acetylcitrate) and others (e.g. benzophenone). A comparison of chemical compounds released from acrylic-based materials and those released from silica-based materials demonstrated that acrylic-based materials are less resistant to disinfectants.