An influence of structural changes in ammonium cations on ecotoxicity of 2,2'-thiodiacetate mono and bis-salts

2,2'-Thiodiacetates with their excellent complexing properties may be used as metal extraction agents, fluorescent and superparamagnetic materials, antibacterial and anticancer medical agents, however there are no data concerning the environmental impact of 2,2'-thiodiacetates derivatives and data definying the potential hazard connected with their use. This study describes the ecotoxicity assessment of seven 2,2'-thiodiacetates with non-metallic, alkyl and aryl ammonium cations, which were obtained in an environmentally friendly, solvent-free syntheses. The ecotoxicity of these water soluble compounds was tested in aquatic and benthic environments using luminescent marine bacteria Vibrio fischeri (Microtox^® test) and the crustaceans Heterocypris incongruens (Ostracodtoxkit F™), respectively. The antimicrobial and antifungal activity against Trichoderma viridis, Aspergillus niger, Rhizoctonia solani and Escherichia coli was also investigated. The results showed how structural changes within ammonium cations themselves influence ecotoxicity: the QASs with alkylammonium cations exhibited a similar, rather low toxicity both to Vibrio fischeri and Heterocypris incongruens, and they would not pose a risk to these organisms in case of leakage. Higher toxicity was observed in case of two isoquinolinium salts, however it was rather associated with the heteroaromatic cation, than with the 2,2'-thiodiacetate anion.

Ammonium haloacetates - An alternative to glyphosate?

This study shows the design, synthesis and evaluation of eco(phyto)toxic and herbicidal activities of quaternary ammonium salts (QASs), derived from haloacetic acids, in context of the search for safer alternatives to the commonly used herbicide, N-(phosphonomethyl)glycine (glyphosate). The structure of the investigated QASs refers to the heteroatom sequence in the anion of glyphosate in which the (P-C)-N nitrogen atom was replaced by one or more halogens (F, Cl). The ecotoxicity of the synthesized QASs was tested against luminescent marine bacteria Vibrio fischeri (Microtox® test) and the crustaceans Heterocypris incongruens (Ostracodtoxkit F™). The phytotoxic effect of QASs was also studied with respect to spring barley (Hordeum vulgare) and common radish (Raphanus sativus L. radicula Pers.), whereas herbicidal activity was investigated in relation to popular weeds species gallant soldier (Galinsoga parviflora Cav.) and common sorrel (Rumex acetosa L.). The results showed that toxicity of the synthesized QASs depends on a number of halo-substituents, especially for bioluminescent bacteria Vibrio fischeri for which EC50 values were those varying the most. Phytotoxicity tests proved that the investigated QASs had a similar high, toxic effect both on monocotyledonous and dicotyledonous plants with exception of DIPA - DCA. Moreover, their herbicidal activity against common sorrel was comparable to glyphosate.

Toxicity of naphthenic acids to invertebrates: Extracts from oil sands process-affected water versus commercial mixtures

The toxicity of oil sands process-affected water (OSPW) has been primarily attributed to polar organic constituents, including naphthenic acid fraction components (NAFCs). Our objective was to assess the toxicity of NAFCs derived from fresh and aged OSPW, as well as commercial naphthenic acid (NA) mixtures. Exposures were conducted with three aquatic species: Hyalella azteca (freshwater amphipod), Vibrio fischeri (marine bacterium, Microtox^® assay), and Lampsilis cardium (freshwater mussel larvae (glochidia)). Commercial NAs were more toxic than NAFCs, with differences of up to 30-, 4-, and 120-fold for H. azteca, V. fischeri, and L. cardium, respectively, demonstrating that commercial NAs are not reliable surrogates for assessing the toxicity of NAFCs. Differences in toxicity between species were striking for both commercial NAs and NAFCs. Overall, V. fischeri was the least sensitive and H. azteca was the most sensitive organism. Responses of V. fischeri and H. azteca to NAFC exposures were consistent (< 2-fold difference) regardless of source and age of OSPW; however, effects on L. cardium ranged 17-fold between NAFCs. NAFCs derived from fresh OSPW sources were similarly or less toxic to those from aged OSPW. Our results support the need to better characterize the complex mixtures associated with bitumen-influenced waters, both chemically and toxicologically.

Influence of ozonation and biodegradation on toxicity of industrial textile wastewater

The textile industry demands huge volumes of high quality water which converts into wastewater contaminated by wide spectrum of chemicals. Estimation of textile wastewater influence on the aquatic systems is a very important issue. Therefore, closing of the water cycle within the factories is a promising method of decreasing its environmental impact as well as operational costs. Taking both reasons into account, the aim of this work was to establish the acute toxicity of the textile wastewater before and after separate chemical, biological as well as combined chemical-biological treatment. For the first time the effects of three different combinations of chemical and biological methods were investigated. The acute toxicity analysis were evaluated using the Microtox^® toxicity test. Ozonation in two reactors of working volume 1 dm³ (stirred cell) and 20 dm³ (bubble column) were tested as chemical process, while biodegradation was conducted in two, different systems - Sequence Batch Reactors (SBR; working volume 1.5 dm³) and Horizontal Continuous Flow Bioreactor (HCFB; working volume 12 dm³). The untreated wastewater had the highest toxicity (EC50 value in range: 3-6%). Ozonation caused lower reduction of the toxicity than biodegradation. In the system with SBR the best results were obtained for the biodegradation followed by the ozonation and additional biodegradation - 96% of the toxicity removal. In the second system (with HCFB) two-stage treatment (biodegradation followed by the ozonation) led to the highest toxicity reduction (98%).

Identification of sulfonylurea biodegradation pathways enabled by a novel nicosulfuron-transforming strain Pseudomonas fluorescens SG-1: Toxicity assessment and effect of formulation

Nicosulfuron is a selective herbicide belonging to the sulfonylurea family, commonly used on maize culture. A bacterial strain SG-1 was isolated from an agricultural soil previously treated with nicosulfuron. This strain was identified as Pseudomonas fluorescens and is able to quantitatively dissipate 77.5% of nicosulfuron (1mM) at 28°C in the presence of glucose within the first day of incubation. Four metabolites were identified among which ASDM (2-(aminosulfonyl)-N,N-dimethyl-3-pyridinecarboxamide) and ADMP (2-amino-4,6-dimethoxypyrimidine) in substantial proportions, corresponding to the hydrolytic sulfonylurea cleavage. Two-phase dissipation kinetics of nicosulfuron by SG-1 were observed at the highest concentrations tested (0.5 and 1mM) due to biosorption. The extend and rate of formulated nicosulfuron transformation were considerably reduced compared to those with the pure active ingredient (appearance of a lag phase, 30% dissipation after 10days of incubation instead of 100% with the pure herbicide) but the same metabolites were observed. The toxicity of metabolites (standardized Microtox^® test) showed a 20-fold higher toxicity of ADMP than nicosulfuron. P. fluorescens strain SG-1 was also able to biotransform two other sulfonylureas (metsulfuron-methyl and tribenuron-methyl) with various novel pathways. These results provide new tools for a comprehensive picture of the sulfonylurea environmental fate and toxicity of nicosulfuron in the environment.

Microbial toxicity of ionic species leached from the II-VI semiconductor materials, cadmium telluride (CdTe) and cadmium selenide (CdSe)

This work investigated the microbial toxicity of soluble species that can potentially be leached from the II-VI semiconductor materials, cadmium telluride and cadmium selenide. The soluble ions tested included: cadmium, selenite, selenate, tellurite, and tellurate. Their toxicity towards the acetoclastic and hydrogen-consuming trophic groups in a methanogenic consortium as well as towards a bioluminescent marine bacterium, Aliivibrio fischeri (Microtox(®) test), was assessed. The acetoclastic methanogenic activity was the most affected as evidenced by the low 50% inhibiting concentrations (IC50) values obtained of 8.6 mg L(-1) for both cadmium and tellurite, 10.2 mg L(-1) for tellurate, and 24.1 mg L(-1) for selenite. Both tellurium oxyanions caused a strong inhibition of acetoclastic methanogenesis at low concentrations, each additional increment in concentration provided progressively less inhibition increase. In the case of the hydrogenotrophic methanogenesis, cadmium followed by selenite caused the greatest inhibition with IC50 values of 2.9 and 18.0 mg L(-1), respectively. Tellurite caused a moderate effect as evidenced by a 36.8% inhibition of the methanogenic activity at the highest concentration tested, and a very mild effect of tellurate was observed. Microtox(®) analyses showed a noteworthy inhibition of cadmium, selenite, and tellurite with 50% loss in bioluminescence after 30 min of exposure of 5.5, 171.1, and 458.6 mg L(-1), respectively. These results suggest that the leaching of cadmium, tellurium and selenium ions from semiconductor materials can potentially cause microbial toxicity.

(Eco)toxicity and biodegradability of protic ionic liquids

Ionic liquids (ILs) are often claimed to be "environmentally friendly" compounds however, the knowledge of their potential toxicity towards different organisms and trophic levels is still limited, in particular when protic ionic liquids (PILs) are addressed. This study aims to evaluate the toxicity against various microorganisms and the biodegradability of four PILs namely, N-methyl-2-hydroxyethylammonium acetate, m-2-HEAA; N-methyl-2-hydroxyethylammonium propionate, m-2-HEAPr; N-methyl-2-hydroxyethylammonium butyrate, m-2-HEAB; and N-methyl-2-hydroxyethylammonium pentanoate, m-2-HEAP. The antimicrobial activity was determined against the two bacteria, Sthaplylococcus aureus ATCC-6533 and Escherichia coli CCT-0355; the yeast Candida albicans ATCC-76645; and the fungi Fusarium sp. LM03. The toxicity of all PILs was tested against the aquatic luminescent marine bacterium Vibrio fischeri using the Microtox(®) test. The impact of the PILs was also studied regarding their effect on lettuce seeds (Lactuta sativa). The biodegradability of these PILs was evaluated using the ratio between the biochemical oxygen demand (BOD) and the chemical oxygen demand (COD). The results show that, in general, the elongation of the alkyl chain tends to increase the negative impact of the PILs towards the organisms and biological systems under study. According to these results, m-2-HEAA and m-2-HEAP are the less and most toxic PILs studied in this work, respectively. Additionally, all the PILs have demonstrated low biodegradability.

Time-dependence in mixture toxicity prediction

The value of time-dependent toxicity (TDT) data in predicting mixture toxicity was examined. Single chemical (A and B) and mixture (A+B) toxicity tests using Microtox(®) were conducted with inhibition of bioluminescence (Vibrio fischeri) being quantified after 15, 30 and 45-min of exposure. Single chemical and mixture tests for 25 sham (A1:A2) and 125 true (A:B) combinations had a minimum of seven duplicated concentrations with a duplicated control treatment for each test. Concentration/response (x/y) data were fitted to sigmoid curves using the five-parameter logistic minus one parameter (5PL-1P) function, from which slope, EC25, EC50, EC75, asymmetry, maximum effect, and r(2) values were obtained for each chemical and mixture at each exposure duration. Toxicity data were used to calculate percentage-based TDT values for each individual chemical and mixture of each combination. Predicted TDT values for each mixture were calculated by averaging the TDT values of the individual components and regressed against the observed TDT values obtained in testing, resulting in strong correlations for both sham (r(2)=0.989, n=25) and true mixtures (r(2)=0.944, n=125). Additionally, regression analyses confirmed that observed mixture TDT values calculated for the 50% effect level were somewhat better correlated with predicted mixture TDT values than at the 25 and 75% effect levels. Single chemical and mixture TDT values were classified into five levels in order to discern trends. The results suggested that the ability to predict mixture TDT by averaging the TDT of the single agents was modestly reduced when one agent of the combination had a positive TDT value and the other had a minimal or negative TDT value.

Ecotoxicity analysis of cholinium-based ionic liquids to Vibrio fischeri marine bacteria

Cholinium-based ionic liquids are quaternary ammonium salts with a wide range of potential industrial applications. Based on the fact that the cholinium is a complex B vitamin and widely used as food additive, the cholinium-based ionic liquids are generically regarded as environmentally "harmless" and thus, accepted as "non-toxic", although their ecotoxicological profile is poorly known. This work provides new ecotoxicological data for ten cholinium-based salts and ionic liquids, aiming to extend the surprisingly restricted body of knowledge about the ecotoxicity of this particular family and to gain insight on the toxicity mechanism of these compounds. The results reported here show that not all the cholinium tested can be considered harmless towards the test organism adopted. Moreover, the results suggest that the cholinium family exhibits a different mechanism of toxicity as compared to the imidazolium ionic liquids previously described in the literature.