Benzo[a]pyrene (B[a]P) is an environmental toxicant and endocrine disruptor. Therefore, the aim of the present study was to investigate the toxicity of B[a]P in testis of rats and also to study the role of silymarin and thymoquinone (TQ) as natural antioxidants in the alleviation of such toxicity. Data of the present study showed that levels of testosterone, estrogen and progesterone were significantly decreased after treatment of rats with B[a]P. In addition, B[a]P caused downregulation of the expressions of steroidogenic enzymes including CYP17A1 and CP19A1, and decreased the activity of 17-β hydroxysteroid dehydrogenase (17β-HSD). Moreover, B[a]P decreased the activities of antioxidant enzymes including catalase (CAT), glutathione peroxidase (GPX) and superoxide dismutase (SOD), and significantly increased free radicals levels in testis of male rats. However, pretreatment of rats with silymarin prior to administration of B[a]P was found to restore the level of free radicals, antioxidant status, and activities of steroidogenic enzymes to their normal levels in testicular tissues. Moreover, histopathological finding showed that silymarin recovered the abnormalities occurred in tubules caused by B[a] P in testis of rats. On the other hand, TQ showed pro-oxidant effects and did not ameliorate the toxic effects of B[a] P on the testicular tissue since it decreased antioxidant enzymes activities and inhibited the protein expression of CYP11A1 and CYP21A2 compared to control rats. Moreover, TQ decreased the levels of testosterone, estrogen, and progesterone either in the presence or absence of B[a]P. It is concluded that B[a]P decreased testosterone levels, inhibited antioxidant enzymes activities, caused downregulation of CYP isozymes involved in steroidogenesis, and increased free radical levels in testis. Moreover, silymarin was more effective than TQ in restoring organism health and alleviating the deleterious effects caused by B[a]P in the testis of rats. Due to its negative impact, it is highly recommended to limit the use of TQ as a dietary supplement since millions of people in the Middle East are using it to improve their health.

The concentration partitioning between the sediment particle and the interstitial water phase plays an important role in controlling the toxicity of heavy metals in aquatic systems. The aim of this study was to assess the sediment quality in a polluted area of the Ziya River, Northern China. The contamination potential and bioavailability of six metals were determined from the concentrations of total metals and the bioavailable fractions. The results showed that the concentrations of Cr, Cu, Ni, Zn, and Pb exceeded the probable effect concentration at several sites. The high geoaccumulation indices showed that the sediments were seriously contaminated by Cd. The ratio of acid-volatile sulfide (AVS) to simultaneously extracted metal (SEM) was higher than 1, which indicated that the availability of metals in sediments was low. The risk assessment of interstitial waters confirmed that there was little chance of release of metals associated with acid-volatile sulfide into the water column. Values of the interstitial water criteria toxicity unit indicated that none of the concentrations of the studied metals exceeded the corresponding water quality thresholds of the US Environmental Protection Agency. Positive matrix factorization showed that the major sources of metals were related to anthropogenic activities. Further, if assessments are based on total heavy metal concentrations, the toxicity of heavy metals in sediment may be overestimated.

Three macrophyte species, Typha augustifolia (T. augustifolia), Phragmites australis (P. australis), and Acorus calamus L. (A. calamus L.), have been grown in hydroponic cultivation systems fed with synthetic wastewater. The experiment was designed as 3 × 2 factorial, with three species and two ratios of NH₄ ⁺/NO₃ ⁻ so as to investigate the nitrogen transformation and nitrogen removal capacity of each species. The nitrogen removal mechanism was further disclosed by comparing biomass production, nitrogen mass balance, and root exudates of the three plant species under different NH₄ ⁺/NO₃ ⁻ ratios. The results indicated there exists a linear relationship, with positive significance (r = 0.946, p < 0.05), between plant biomass and total nitrogen (TN) removal efficiency; in other words, biomass could best reflect plant ability to remove nitrogen. It is also found that NH₄ ⁺/NO₃ ⁻ ratio could influence plant biomass and root exudates significantly. Additionally, the hydrogen donor and source of energy in denitrification happened in this research were mainly organic acids and soluble sugars, accounting for approximately 50 % of the composition in root exudates.

Bosten Lake, a typical rump lake in an oasis in northwest China, was chosen to evaluate the distribution, sources, pollution status, and potential ecological risk of heavy metals. Sediment samples were collected from the lake, and results showed that the values of the eight heavy metals all fell within the Second Soil National Standard, while the average and maximum values of the metals were higher than the background values of the study. Multivariate statistical analysis showed that sediment concentrations of Cd, Pb, Hg, and Zn were mainly influenced by man sources. In comparison, Cu, Ni, Cr, and As were primarily natural in origin. Enrichment factor analysis (EF) and the geo-accumulation index evaluation method (I gₑₒ) showed that Cd, Hg, and Pb fell under low and partial serious pollution levels, while Zn, As, Cr, Ni, and Cu mainly were characterized under no pollution and low pollution levels. The potential ecological hazards index (RI) showed that among the eight heavy metals, Pb, Hg, and Cd posed the highest potential ecological risk, with potential ecological hazards indices (RI) of 29.06, 27.71, and 21.54 %, respectively. These findings demonstrated that recent economic development in the area of the basin has led to heavy metal accumulation in the surface sediments of the lake.

Ecological light pollution occurs when artificial lights disrupt the natural regimes of individual organisms or their ecosystems. Increasing development of shoreline habitats leads to increased light pollution (e.g., from cottages, docks, automobile traffic), which could impact the ecology of littoral zones of lakes and rivers. Smallmouth bass (Micropterus dolomieu) engage in sole paternal care, guarding their nest continually, day and night, to protect their developing offspring. Any alterations to their behaviour—either directly because of the response to light or indirectly due to changes in nest predator activity and associated response of the bass—could lead to increased energetic demands for fish that have a fixed energy budget and ultimately reduce reproductive success. To examine this issue, tri-axial accelerometer biologgers were externally attached to nesting smallmouth bass during the egg stage to determine whether light pollution (i.e., dock lights with low levels of continuous light and spotlights with high intensity irregular light simulating automobile traffic) altered behaviour of nesting males relative to control fish. Our study revealed that both types of light pollution increased overall bass activity level compared with the control group. The intermittent light treatment group had the highest activity and exhibited large fluctuations between night and day activity levels. Fish in the continual light treatment group displayed statistically higher activity than the control fish but showed limited fluctuations between day and night activity levels. Our results suggest that continuous or intermittent light sources, common in shoreline habitats that have been developed, have the potential to alter the behaviour and thus energy use of nest-guarding fish. This study contributes to the growing body of literature on the ecological consequences of light pollution in aquatic ecosystems.

Amaranthus hybridus L. has great potential for use in phytoremediation of soils contaminated with cadmium (Cd). In this study, we found higher absorption of Cd by the roots of A. hybridus than by its other organs. To understand the mechanism of Cd accumulation in A. hybridus roots, a comparative proteomic approach was used to differentiate the two-dimensional electrophoretic profiles of root proteins in Cd-free and Cd-treated plants. Twenty-eight differentially expressed proteins were successfully identified using matrix-assisted laser desorption/ionization tandem time-of-flight mass spectrometry. Of these, 10 were specifically expressed under Cd stress, and another 11 were upregulated and 7 downregulated by >2.5-fold under Cd stress. We observed increased expression of proteins involved in energy metabolism, protein metabolism, stress and defense, and signal transduction. These changes likely enhanced Cd tolerance and enrichment in A. hybridus. The downregulated proteins were mainly involved in the synthesis of microRNAs, cell walls, and other structural components. These observations were further confirmed by quantitative fluorescence PCR. The resulting differences in protein expression patterns suggest that redirection of root cell metabolism might be an important survival mechanism for A. hybridus under Cd stress.

As major endocrine disruptors, natural estrogens such as 17β-estradiol (E2) have been found with adverse effects on animals and humans. How to control E2 pollution as well as that of other estrogens in the environment is a worldwide concern. A novel E2-degrading bacterium (strain JX-2) was isolated from the activated sludge of a sewage treatment plant and was identified as Rhodococcus sp. Strain JX-2 grew well and metabolized up to 94 % of the substrate E2 added (30 mg L⁻¹) within 7 days at 30 °C. The optimal environmental conditions for E2 degradation by JX-2 were pH 7.0 and 30 °C. Strain JX-2 was immobilized in sodium alginate. The optimal conditions for strain JX-2 immobilization were 4 % sodium alginate, 1:1 bacteria/sodium alginate ratio, 5 % CaCl₂⋅2H₂O, and 6 h crosslinking time. The degradation performance of immobilized strain JX-2 was apparently superior to that of the free strain, particularly under pH <6.0 or >8.0 either below 20 or above 35 °C. Immobilized strain JX-2 removed E2 in natural sewage and cow dung with removal efficiency of more than 64 and 81 %, respectively. This is the first report of utilizing immobilized bacteria to remove estrogens in sewage and livestock manure. The results suggest that strain JX-2 could be used to remove E2 from the environment efficiently.

To protect forest cultures against browsing, chemical repellents can be used. With their applications, however, a problem arises with disruption of biological and chemical equilibria in the environment (e.g., soil-plant system). The aim of this study were to assess possible interactions of repellents, denatonium benzoate (DB), and capsaicin (Cps), with the soil matrix, especially the impact of their addition on the mobility of individual micronutrients and macronutrients, such as calcium, copper, iron, magnesium, manganese, phosphorus, sulfur, and zinc, and to verify the hypothesis that the presence of repellent compounds does not affect the plant-available nutrient concentrations in soil. Batch laboratory soil sorption experiment and the “diffusive gradient in thin films” (DGT) technique were applied to evaluate the elements’ mobility in the soils. Sorption experiment using Chernozem and Fluvisol showed decreased mobile forms of Cu and S with the additions of both repellents and conversely increased mobile forms of Ca and Mn for DB, in both soil types. With increasing Cps rates, the mobile forms of Fe in Chernozem decreased and Mn in Fluvisol increased. The DGT experiment confirmed increased mobile/available Mn in both soils for both repellents and Fe in Fluvisol in the case of capsaicin. Soil application of both, DB and Cps, suggested to be able to influence the elements’ mobility, particularly, Mn mobility in soil significantly increased after repellent application. Their possible behavior in rhizosphere soil/soil solution should be investigated in further research.

This study investigates removal of total nitrogen (TN) in moving bed biofilm reactor (MBBR) supported with high-density polyethylene for biofilm formation and ibuprofen (IBU) as a carbon source. At first, the microorganisms have been acclimated for 45 days. In the optimum condition, TN removal of more than 80 % was reached. Optimization results of simultaneous removal of IBU and TN showed that the obtained removal efficiencies for IBU and TN are close together and the correlation coefficients have high values. The obtained results show that MBBR bioreactor could remove 72.03 % IBU and 81.1 % TN at 145.15 h and TN concentration of 156.37 mg/L. Biodegradation constant (k bᵢₒₗ) values were varying from 0.4 to 0.009 L/g biomass.d, which represents that IBU is a hard biodegradable or persistent substance. This study demonstrated that the proposed MBBR is highly effective for the simultaneous removal of IBU and TN in wastewater.

The impact of nanoparticles (NPs) in phytoplankton is understudied, particularly with respect to the organism’s physiology and environmentally relevant concentrations. In the present research, we investigated the effects of titanium dioxide nanoparticles (nano-TiO₂) in the physiology of Scenedesmus bijugus, a freshwater cosmopolitan phytoplankter, exposed to concentrations ranging from 3.30 × 10⁻⁹ mol L⁻¹ (log −8.48) to 3.70 × 10⁻⁷ mol L⁻¹ (log −6.43), which includes environmentally relevant values. The nano-TiO₂ concentrations in the medium and in the cells were determined in experiments that lasted 96 h. Controlled environmental conditions were used throughout and a variety of endpoints were monitored. These included cell density, cell viability, chlorophyll a concentration, growth rates, maximum quantum yield of photosystem II (ΦM), intracelular proteins and carbohydrates, and proteins:carbohydrates ratios. The results showed that cell viability was the most sensitive parameter for the detection of the nano-TiO₂ effects, being followed by ΦM. At the concentration of 3.90 × 10⁻⁸ mol L⁻¹ (log −7.40), there was an increase of nano-TiO₂ injured cells, and at 3.70 × 10⁻⁷ mol L⁻¹ (log −6.43) 24%, ΦM decrease in comparison with the controls was obtained. Different from several literature results, we showed that nano-TiO₂ particles at environmentally relevant concentrations affected microalgae physiology, and this was dependent on the endpoint used to evaluate the effect.