Phthalates are widely used as plasticizer in various consumer domestic products and are known to disturb the male reproductive function in rodents. This study investigated the involvement of oxidative stress and the atrophy of the testes in pubertal rats exposed to mono-n-butyl phthalate (MBP). Four-week-old pubertal male rats were separated into three groups. In group I, 21 rats were fed rat chow containing 2 % MBP for 3 days. In group II, 21 rats were fed rat chow containing 2 % MBP for 3 days and antioxidant vitamins C (250 mg/kg/day) and E (50 mg/kg/day) were injected daily. In group III, 21 rats were fed standard rat chow and used as controls. After 3 days, each testis was weighed and the germ cell development was evaluated using the Johnsen score. The urinary 8-hydroxy-2′-deoxyguanosine (8-OHdG) levels were measured as a biological marker of oxidative DNA damage. The mean testis weight was significantly lower for group I than groups II or III (p < 0.05). The mean Johnsen score was significantly lower for group I than for groups II or III (p < 0.05). Urinary 8-OHdG concentrations were higher in group I than in groups II or III. Short-time exposure to MBP may therefore induce oxidative DNA damage in rat testes, while antioxidant vitamins administered during exposure may protect against this stress.

The photodegradation processes of fenpropathrin and λ-cyhalothrin were studied in hexane, methanol/water (1:1, v/v), and acetone in both ultraviolet light and simulated sunlight. Intermediates in the photodegradation process were identified using gas chromatography/mass spectrometry (GC/MS), and the analysis of intermediates was used to speculate on possible photodegradation pathways. The photodegradation processes of fenpropathrin and λ-cyhalothrin followed pseudo first-order kinetics. The photodegradation rates varied according to the solvent in decreasing order: hexane > methanol/water (1:1, v/v) > acetone. The effects of substances coexisting in the environment on the photodegradation of pyrethroids were also investigated in the research. Acetone, humic acid, and riboflavin increased photodegradation rates while L-ascorbic acid slowed the process. This study provides a theoretical basis for the removal of pyrethroid pollution from the natural environment.

To understand the transport and fate of antibiotic resistance genes in wastewater treatment plants, 12 resistance genes (ten tetracycline resistance genes, two sulfonamides genes) and class 1 integron gene (intI1) were studied in five wastewater treatment plants with different treatment processes and different sewage sources. Among these resistance genes, sulfonamides genes (sul1 and sul2) were of the most prevalent genes with detection frequency of 100 %. The effluent water contained fewer types of resistance genes than the influent in most selected plants. The abundance of five quantified resistance genes (tetG, tetW, tetX, sul1, and intI1) decreased in effluent of plants treating domestic or industrial wastewater with anaerobic/aerobic or membrane bioreactor (MBR) technologies, but tetG, tetX, sul1, and intI1 increased along the treatment units of plants treating vitamin C production wastewater by anaerobic/aerobic technology. In plant treating cephalosporins production wastewater by UASB/aerobic process, the quantities of tetG, tetX, and sul1 first decreased in anaerobic effluent water but then increased in aerobic effluent water.

Bioaccumulation, subcellular distribution, and acute toxicity of yttrium (Y) were evaluated in Nymphoides peltata. The effects of Y concentrations of 1–5 mg L⁻¹applied for 4 days were assessed by measuring changes in photosynthetic pigments, nutrient contents, enzymatic and non-enzymatic antioxidants, and ultrastructure. The accumulation of Y in subcellular fractions decreased in the order of cell wall > organelle > soluble fraction. Much more Y was located in cellulose and pectin than in other biomacromolecules. The content of some mineral elements (Mg, Ca, Fe, Mn, and Mo) increased in N. peltata, but there was an opposite effect for P and K. Meanwhile, ascorbate, and catalase activity decreased significantly for all Y concentrations. In contrast, peroxidase activity was induced, while initial rises in superoxide dismutase activity and glutathione content were followed by subsequent declines. Morphological symptoms of senescence, such as chlorosis and damage to chloroplasts and mitochondria, were observed even at the lowest Y concentration. Pigment content decreased as the Y concentration rose and the calculated EC₅₀and MPC of Y for N. peltata were 2 and 0.2 mg L⁻¹after 4 days of exposure, respectively. The results showed that exogenous Y was highly available in water and that its high concentration in water bodies might produce harmful effects on aquatic organisms. N. peltata is proposed as a biomonitor for the assessment of metal pollution in aquatic ecosystems.

In order to study potential antioxidant defense mechanisms, the effects of increasing concentrations of lead (Pb) on polyamines (PAs), various thiols, vitamins C and E, and proline contents in sterilized seedlings of Nymphoides peltata (S.G. mel.) Kuntze were investigated after 5 days of exposure. The levels of total putrescine (Put), spermidine (Spd), and spermine (Spm) decreased significantly, while the ratio of (Spd + Spm)/Put first increased but then declined as the concentration of Pb increased. The trends for free, perchloric acid soluble-conjugated (PS-conjugated), and perchloric acid insoluble-bound (PIS-bound) PAs were similar to the trend seen for total PAs. Moreover, reduced glutathione (GSH), nonprotein thiols (NP-SH), phytochelatins (PCs), and vitamin C were induced at high Pb concentrations. No significant change was observed in vitamin E. An initial decline in proline content was followed by an increase as the Pb concentration rose. The reduced level of Put and elevated contents of GSH, NP-SH, PCs, vitamin C, and proline were found to be associated with antioxidant efficiency, which supports the hypothesis that they could play a significant role in the adaptation mechanisms of N. peltatum under Pb stress.

The present study aimed to establish the seasonal variations in the redox potential ranges of young Tibouchina pulchra plants growing in the Cubatão region (SE Brazil) under varying levels of oxidative stress caused by air pollutants. The plants were exposed to filtered air (FA) and non-filtered air (NFA) in open-top chambers installed next to an oil refinery in Cubatão during six exposure periods of 90 days each, which included the winter and summer seasons. After exposure, several analyses were performed, including the foliar concentrations of ascorbic acid and glutathione in its reduced (AsA and GSH), total (totAA and totG) and oxidized forms (DHA and GSSG); their ratios (AsA/totAA and GSH/totG); the enzymatic activities of superoxide dismutase (SOD), ascorbate peroxidase (APX), catalase (CAT) and glutathione reductase (GR); and the content of malondialdehyde (MDA). The range of antioxidant responses in T. pulchra plants varied seasonally and was stimulated by high or low air pollutant concentrations and/or air temperatures. Glutathione and APX were primarily responsible for increasing plant tolerance to oxidative stress originating from air pollution in the region. The high or low air temperatures mainly affected enzymatic activity. The content of MDA increased in response to increasing ozone concentration, thus indicating that the pro-oxidant/antioxidant balance may not have been reached.

Nano-silver is increasingly used in consumer products from washing machines and refrigerators to devices marketed for the disinfection of drinking water or recreational water. The nano-silver in these products may be released, ending up in surface water bodies which may be used as drinking water sources. Little information is available about the stability of the nano-silver in sources of drinking water, its fate during drinking water disinfection processes, and its interaction with disinfection agents and disinfection by-products (DBPs). This study aims to investigate the stability of nano-silver in drinking water sources and in the finished drinking water when chlorine and chloramines are used for disinfection and to observe changes in the composition of DBPs formed when nano-silver is present in the source water. A dispersion of nano-silver particles (10 nm; PVP-coated) was used to spike untreated Ottawa River water, treated Ottawa River water, organic-free water, and a groundwater at concentrations of 5 mg/L. The diluted dispersions were kept under stirred and non-stirred conditions for up to 9 months and analyzed weekly using UV absorption to assess the stability of the nano-silver particles. In a separate experiment, Ottawa River water containing nano-silver particles (at 0.1 and 1 mg/L concentration, respectively) was disinfected by adding sodium hypochlorite (a chlorinating agent) in sufficient amounts to maintain a free chlorine residual of approximately 0.4 mg/L after 24 h. The disinfected drinking water was then quenched with ascorbic acid and analyzed for 34 neutral DBPs (trihalomethanes, haloacetonitriles, haloacetaldehydes, 1,1 dichloro-2-propanone, 1,1,1 trichloro-2-propanone, chloropicrin, and cyanogen chloride). The results were compared to the profile of DBPs obtained under the same conditions in the absence of nano-silver and in the presence of an equivalent concentration of Ag⁺ ions (as AgNO₃). The stability of the nano-silver dispersions in untreated Ottawa River water, with a dissolved organic carbon concentration of 6 mg/L, was significantly higher than the stability of the nano-silver dispersions in distilled, organic-free water. Nano-silver particles suspended in the groundwater agglomerated and were quickly and quantitatively removed from the solution. Our data confirm previous observations that natural dissolved organic matter stabilizes nano-silver particles, while the high-ionic strength of groundwater appears to favor their agglomeration and precipitation. As expected, nano-silver was not stable in Ottawa River water through the chlorination process, but survived for many days when added to the Ottawa River water after treatment with chlorine or chloramines. Stirring appeared to have minimal effect on nano-silver stability in untreated and treated Ottawa River water. The profile of DBPs formed in the presence of nAg differed significantly from the profile of DBPs formed in the absence of nAg only at the 1 mg/L nAg concentration. The differences observed consisted mainly in reduced formation of some brominated DBPs and a small increase in the formation of cyanogen chloride. The reduced formation of brominated congeners may be explained by the decrease in available bromide due to the presence of Ag⁺ ions. It should be noted that a concentration of 1 mg/L is significantly higher than nAg concentrations that would be expected to be present in surface waters, but these results could be significant for the disinfection of some wastewaters with comparably high nano-silver concentrations.