Toxicity identification evaluation of Lake Orta (Northern Italy) sediments using the Microtox system

Toxicity identification evaluation of sediments in Liaohe River

Liaohe River has received significant attention in the northeast region and even in the entire country. As part of a recently completed water quality assessment, a series of water column and sediment toxicity tests was performed throughout the watershed. In the current study, we subjected sediments from the Liaohe River to toxicity identification evaluation manipulations and tests for chronic toxicity with midge (Chironomus riparius), with survival as the end point. In Phase I, the sediments were treated with zeolite, cation-exchange resin, and powdered coconut charcoal. Results confirmed that ammonia compounds were the major contaminants in terms of toxicity, although toxic effects from metals were also a concern in at least three sites. In Phase II identification, chemical analysis provided a strong evidence that the metals As and Cd are the probable causes of toxicity in the sediments, without the influence of ammonia. Temporally, ammonia is responsible for the toxicity of the selected sediments.

A model compound study: the ecotoxicological evaluation of five organic contaminants employing a battery of marine bioassays

This paper describes the ecotoxicological evaluation of five organic contaminants frequently detected in marine sediments (tributyltin, triphenyltin, benzo[a]pyrene, fluoranthene, and PCB 153) using three marine species (Vibrio fischeri, Tetraselmis suecica, and Tisbe battagliai). The sensitivity of each species varied for all compounds. The triorganotins were consistently the most toxic to all species. The applicability of each test system to assess the acute toxicity of environmental contaminants and their use in Toxicity Identification Evaluation (TIE) is discussed. Suitability of the Microtox and T. battagliai tests for employment in TIE studies were further assessed through spiking experiments with tributyltin. Results demonstrated that the most effective treatment to remove organotin toxicity from the sample was the C18 resin. The results of this study have important implications for risk assessment in estuarine and coastal waters in Ireland, where, at present the monitoring of sediment and water quality is predominantly reliant on chemical analysis alone.

Sulfamethoxazole abatement by means of ozonation

Sulfamethoxazole (SMX) is a bacteriostatic antibiotic largely used for diverse types of illness. Its widely use in humans and even in animals releases unmetabolized and active metabolites that have a strong potential in terms of effect in organisms. In this work, 200 mg L(-1) solution of sulfamethoxazole was treated by ozonation at different pH. Results showed that ozonation was proved to be an efficient method to degrade sulfamethoxazole. After 15 min of ozonation (corresponding dose=0.4 g of ozone L(-1)), the complete antibiotic abatement was almost achieved with just 10% of mineralization. The biodegradability and toxicity of the ozonation intermediates were also studied. A biodegradability enhancement (increment of BOD(5)/COD ratio) from 0 to 0.28 was observed after 60 min of ozonation. The acute toxicity of the intermediates was followed by the Microtox test and the toxicity profile showed a slight acute toxicity increment in the first stage of ozonation. The pH variation had an important role in the TOC and COD removal, promoting their growth with the increment of alkalinity. The second order kinetic constants for the ozonation of the SMX in an order of magnitude of 10(5) L mol(-1)s(-1) were also determined for pH 5 and 7.

In vitro cytotoxicity and genotoxicity of chlorinated drinking waters sampled along the distribution system of two municipal networks

When chlorine is used as a disinfectant for drinking water it may react with organic materials present in or released by the water pipes and thus form by-products that may represent a genotoxic hazard. The aim of this study was to assess the potential genotoxicity and cytotoxicity of extracts of chlorinated drinking water supplied by local aquifers of two Italian towns, Plants 1 and 2, located in the sub-Alpine area and on the Po plain, respectively. The raw water fell within the legal limits with regards to its chemical and physical properties. Water from Plant 2 contained higher levels of total organics (TOC) and nitrate than water from Plant 1. Water was sampled at different points along the distribution networks to evaluate the influence of the system on the amount and quality of the by-products. Cytotoxic and genotoxic damage was assessed in freshly isolated human white blood cells (WBC) and Hep-G2 cells by use of the micronucleus (MN) test and the Comet assay to measure primary DNA damage. While they did not show significant cytotoxicity, all Plant 1 water concentrates induced short-time genotoxic effects on leukocytes at concentrations > or =1 Lequiv./mL. Plant 2 samples were able to induce cytotoxic effects in both Hep-G2 cells and leukocytes. Furthermore, although there was no significant increase in MN frequency, DNA migration was strongly increased both in human leukocytes (> or =0.5 Lequiv./mL, 1h treatment, water samples collected from all points) and in Hep-G2 cells (> or =0.75 Lequiv./mL, 24 h treatment, tap water sampled at the nearest distribution point). The current use of these in vitro cytotoxicity/genotoxicity tests together with the normal chemical analyses could provide information to help water-works managers and health authorities evaluate drinking water quality and adopt strategies to reduce genotoxic compounds in tap water and prevent human exposure to these compounds.

Unraveling the causes of the toxicity of extremely acid waters of volcanic origin

A river ecosystem in East Java, Indonesia, fed by a volcanic lake with high concentrations of dissolved metals and a low pH, was found to support only few macroinvertebrates. To unravel the causes of toxicity and to determine the level of dilution necessary to obtain non-toxic water, a bioassay was conducted with the fairy shrimp Thamnocephalus platyurus. A partial toxicity identification evaluation (TIE) approach was used with EDTA as a chelating agent to relate toxicity to pH and metal concentrations. Three water samples were tested, with pHs ranging from 0.72 to 4.5, and diluted with water from a neutral river to different degrees. The dilution factor necessary to achieve no more than 50% mortality in the Thamnotox test (Ldf(50)) varied from >300 at the most acidic site, to 7 for water of pH 2.6 and 1.5 for water of pH 4.5. Toxicity was best explained from both low pH and high concentrations of metals, especially Al and Fe. The key role of Al and Fe in the toxicity was confirmed by relating concentrations of the different compounds in the river water to toxicity data from the literature. EDTA addition did not significantly influence Ldf(50) or the lethal pH 50% (LpH(50)), suggesting a large effect, besides cationic components and pH, of anions (F, SO(4) and Cl).

Effect of low-level alpha-radiation on bioluminescent assay systems of various complexity

This study addresses the effects of low-level alpha-radiation on bioluminescent assay systems of different levels of organization: in vivo and in vitro. Three bioluminescent assay systems are used: intact bacteria, lyophilized bacteria, and bioluminescent system of coupled enzyme reactions. Solutions of 241Am(NO3)3 are used as a source of alpha-radiation. It has been shown that activation processes predominate in all the three bioluminescent assay systems subjected to short-term exposure (20-55 h) and inhibition processes in the systems subjected to longer-term exposure to radiation. It has been found that these effects are caused by the radiation component of 241Am3+ impact. The intensity of the 241Am3+ effect on the bioluminescent assay systems has been shown to depend on the 241Am3+ concentration, level of organization and integrity of the bioluminescent assay system. The bioluminescent assay systems in vivo have been found to be highly sensitive to 241Am3+ (up to 10(-17) M).

Bioluminescence and exogenous compounds: physico-chemical basis for bioluminescent assay

Bioluminescent systems are convenient objects to study mechanisms of influence of exogenous molecules on living organisms. Classification of physical and physico-chemical mechanisms of the effects of luminous bacteria Photobacterium leiognathi on bioluminescent reactions is suggested. Five mechanisms are discussed: (1) change of electron-excited states' population and energy transfer, (2) change of efficiency of S-T conversion in the presence of external heavy atom, (3) change of rates of coupled reactions, (4) interactions with enzymes and variation of enzymatic activity, (5) nonspecific effects of electron acceptors. Effects of various groups of chemical compounds are discussed according to the classification suggested. The compounds are: a series of fluorescent dyes, organic oxidizers, organic and inorganic heavy-atom containing compounds, and metallic salts. Applications of fluorescence time-resolved and steady-state techniques, as well as bioluminescence kinetics study, are discussed. The patterns of exogenous compounds' influence form a physico-chemical basis for bioluminescent ecological assay.

The use of Microtox to assess toxicity removal of industrial effluents from the industrial district of Camaçari (BA, Brazil)

The treatment efficiency, as toxicity removal, of complex effluents from the Industrial District of Camaçari (BA, Brazil), after biological treatment with activated sludge was evaluated using Microtox. Samples of the equalised effluent (EE) were collected prior to treatment together with samples of the treated effluent (TE), which remained 24 h in the treatment plant. Rehydrated colonies of Vibrio fischeri were exposed to sequential dilutions of EE and TE to assess luminosity interference. Values for EC50 were calculated, together with the respective toxicity units. In all, twenty assays of each effluent type were carried out and the mean toxicity removal was 92.71%, while the chemical oxygen demand (COD) presented mean reduction of 83.04%. There was a variability of an order of magnitude between the Microtox results for the two types of effluents. The mean EC50 values were 2.12 for EE and 47.78% for TE. In spite of its weakness in some conditions, the Microtox system demonstrated to work adequately in assessing effluent toxicity removal in this treatment plant and therefore can be used for further toxicity removal programs.

A review on the application of microbial toxicity tests for deriving sediment quality guidelines

The results of microbial toxicity tests are needed for the risk assessment of polluted sediments. In comparison with animals the anaerobic microorganisms are more tolerant to natural sediment conditions whereas they are more sensitive for a number of specific pollutants. Microbial toxicity tests from a literature search were classified in seven categories. Category A, B and C use polluted sediments and are applied for sediment monitoring. In category D, a pure chemical is added and the organisms and the test conditions were derived from sediment. Therefore this category can be used for setting sediment quality guidelines which protect sediment functions for the toxic effects of chemicals. In category E, organisms from a polluted site are separated from the sediment and are tested with pure chemicals. Organisms from a more polluted site can be more tolerant to a local pollutant. This is called pollution-induced community tolerance and can be used as evidence for the occurrence of toxic effects in a specific sediment. In category F pure chemicals are tested with a pure culture of microorganisms under sediment conditions. The results of category F tests can be combined with single species tests with animals and plants to obtain sediment quality guidelines sufficient for species protection. This can be compared with the sediment quality guidelines which protect sediment functions. When one of these quality guidelines is exceeded for a compound at a specific location a category E test can be used to determine whether the compound shows toxic effects in that sediment.

Bioluminescence assays: effects of quinones and phenols

The influence of a series of quinones and phenols on bacteria bioluminescence systems was investigated. Three bioluminescence systems used in ecological monitoring were compared: (1) water-soluble; (2) immobilized in starch gel coupled enzyme systems: NADH:FMN-oxidoreductase-luciferase; (3) luminescent bacteria. Bioluminescence inhibition constants of quinones and phenols and bioluminescence induction periods were compared. These kinetic parameters are proportional to quinone concentrations and depend on the quinone redox potential. Different effects of the substances are related to structure and properties of the bioluminescence systems. The set of bioluminescence assays for quinones and phenols monitoring should include two bioluminescence systems: 1 (or 2) and 3.