Environmental & Analytical Toxicology

We report here the acute and chronic toxicity of two commercial formulations of herbicides whose active ingredient is glyphosate (Glacoxan® and Estrella®). The acute toxicity was tested toward two fish species Danio rerio and Poecilia reticulata by evaluating the mortality. The chronic toxicity was assessed in D. rerio by measuring the biochemical parameters glutamic pyruvic transaminase (AST) and glutamic oxaloacetic transaminase (ASL). In addition the analysis of haematological parameters (morphological study) was carried out. The results indicate that both herbicides produce acute toxicity toward the two tested species. In addition the biochemical parameters displayed high values as a sign of chronic toxicity. Thereby, indicating that both herbicides may produce environmental damage.

Zooplankton plays an important role to study the faunal bio-diversity of aquatic ecosystems. It is occurrence and distribution influences the fishery potentials. The fishes mostly breed in areas where the planktonic organisms are plenty so that their young ones could get sufficient food for survival and growth. The zooplankton composition during the study period includes the members of Foraminifera, Rotatoria, Calanoida, Cyclopoida, Harpacticoidea, Doliolida, Appendicularia, Decapoda, Sagittoida, Amphipoda, Coelentrata, Pteropoda, Cladocera and larval forms. In station I, about 88 species of zooplankton were recorded. In station II, about 92 species of zooplankton were recorded. The zooplankton population densities were ranged from 23,150 to 80,890 org/l in station I and 23,197 to 80,691org/l in station II. The Shannon - Wiener's diversity index (H') values were ranged from 4,505 bits/ind. to 5,915 in station I and 4,590 bits/ind. to 5,928bits/ind. in station II. The Simpson richness was ranged from 0.662 to 0.995 in station I and 0.665 to 0.998 in station II. The Pielou’s evenness (J') was ranged from 0.590 to 0.952 in station I and 0.513to 0.952 in station II respectively.

The present study focuses on cadmium toxicity on morphology and selected biochemical parameters of Pistia. The laboratory experiments were conducted for the assessment of morphological index parameters (MIP), biochemical parameters and accumulation of cadmium in plants at its various concentrations (0.1, 0.5, 1.0, 1.5 and 2.0 ppm) at the regular interval for 12 days exposure. Pistia showed visible symptoms like withering of roots, chlorosis and necrosis at higher concentration (2.0 ppm), however, the plant showed normal growth at lower concentration (0.1 ppm). The estimation of biochemical parameters (Total chlorophyll, Protein and Carbohydrate) of test plants showed a significant increase at lower concentration (0.1 ppm) of cadmium. The biochemical parameters decrease with increase in exposure concentration and duration. The toxic effect of cadmium is directly proportional to its concentration and duration. The accumulation of cadmium by Pistia stratiotes was maximum at 4 days exposure duration and marginal at subsequent concentrations and exposure duration. With respect to biochemical parameters the concentrations are significant. However, metal accumulation is significant at concentrations and exposure duration.

Reliable and cost-effective early-life stage (ELS) bioassays incorporating practical experimentation without compromising scientific relevance are crucial in chemical risk assessment. This study investigated the use of 20 days-post-fertilization life stage (20dpfZF) of zebrafishDanio rerio to screen environmental chemicals known to be estrogenicin adult fish. Firstly, studies with key genes in steroidogenesis were conducted; the brain isoform of aromatase gene (cyp19a1b) being the most prominently expressed biomarker. Regulation of mRNA levels of molecular biomarkers, vitellogenin 1 gene (vtg1) and cyp19a1b were selected to assess the endocrine modulation by xenoestrogens, 17α-ethinylestradiol (EE2), 4-n-nonylphenol (NP), 4-t-octylphenol (OP) and bisphenol A (BPA). Groups of 20dpfZF (n=15) as three replicates were exposed to chemicals over a five-day period in aerated static setups. Exposure of 20dpfZF to sediment spiked with EE2 (nominal 3μg g-1dw) was also conducted to assess the sensitivity of this life-stage to sediment with estrogenic potency. Whole body homogenates of exposed juveniles showed the estrogenic potential of chemicals in the order: EE2 > OP > BPA > NP. Higher relative expression of cyp19a1b was noticed at lower ambient concentrations of EE2, although vtg1 showed more pronounced expression to it. The 20dpfZF responded in a dose-related way to sediment spiked with EE2, expanding its use as a general aquatic animal model. The suitability of 20dpfZF as an in vivo model, along with stable expression of reference genes was established. In addition to consistent expression pattern of key target genes on xenoestrogenicity, it serves as a practical screening model for the risk assessment of environmental chemicals and samples with estrogenic potential.

Determination of natural and synthetic estrogens in Waste Water Treatment Plants (WWTP) is fundamental for risk assessment regarding the endocrine disrupting effects in the aquatic environment. A methodology of analysis based on HPLC procedure with UV detection and a C18 analytical column has been developed for the simultaneous determination of estrogens in water samples in less than 9 minutes. The estrogens analysed were estrone, 17 β-estradiol, 17 α-ethinylestradiol and estriol. A pre-concentration of the analytes in water samples, was achieved using a SPE procedure with polymeric Strata-X cartridges. Average recoveries of the hormones ranged between 85-120% of concentrations tested. The use of SPE-HPLC method allows limits of detection of 0.089 μg L-1 for estrone, 0.25 μg L-1 for estradiol, 0.45 μg L-1 for estriol and 0.11 μg L-1 for ethinylestradiol. Samples collected from nine WWTP´s raw wastewaters and treated wastewaters located at the Portugal Central Region, were analyzed and the concentrations obtained were in the range of 0.15-0.72 μg L-1 for estrone, 0.10-0.51 μg L-1 for estradiol, and 0.11-0.23 μg L-1 for ethinylestradiol.

One sequencing batch reactor (SBR) seeded with anaerobic granular sludge was started-up to enrich simultaneous partial nitrification and anaerobic ammonia oxidation (Anammox) bacteria. The SBR could be operated successfully through first enriching Anammox bacteria under strictly anaerobic condition during the first stage and then controlling the dissolved oxygen (DO) in the reactor between 0.3 and 0.6 mg/L during the second and third stage, and eventually the maximum total nitrogen removal rate could reach 63.7%. Besides, a dynamic mathematical model including nitrification, Anammox, COD oxidation and denitrification was developed for the simulation of the performance of biological processes. The dynamic mathematical model was extended with two parts: model correction factors of DO, and Haldane kinetics for Anammox. Subsequently, a set of experiments and simulations were carried out to analyze the effects of substrate nitrite and DO on SBR system, and to validate the model. Research results indicated that biological processes could be inhibited by a certain nitrite concentration 20~30mg/L, and high or low DO concentration was not in favor of operation of SBR system. In addition, the simulation results were consistent with the experimental results, which illuminated that the mathematical model was appropriate for the modeling of simultaneous partial nitrification, Anammox and denitrification process in a single reactor, thus it could estimate the impact of specific parameters and predict the efficiency of system.