High concentrations of uranium(VI) in the Witwatersrand Basin, South Africa from mining leachate is a serious environmental concern. Treatment systems are often ineffective. Therefore, optimization of a bioremediation system that facilitates the bioreduction of U(VI) based on biostimulation of indigenous bacterial communities can be a viable alternative. Tolerance of the indigenous bacteria to high concentrations of U and the amount of citric acid required for U removal was optimized. Two bioreactor studies which showed effective U(VI) removal more than 99 % from low (0.0037 mg L⁻¹) and high (10 mg L⁻¹) concentrations of U to below the limit allowed by South African National Standards for drinking water (0.0015 mg L⁻¹). The second bioreactor was able to successfully adapt even with increasing levels of U(VI) feed water up to 10 mg L⁻¹, provided that enough electron donor was available. Molecular biology analyses identified Desulfovibrio sp. and Geobacter sp. among known species, which are known to reduce U(VI). The mineralogical analysis determined that part of the uranium precipitated intracellularly, which meant that the remaining U(VI) was precipitated as U(IV) oxides and TEM-EDS also confirmed this analysis. This was predicted with the geochemical model from the chemical data, which demonstrated that the treated drainage was supersaturated with respect to uraninite > U₄O₉ > U₃O₈ > UO₂₍ₐₘ₎. Therefore, the tolerance of the indigenous bacterial community could be optimized to remediate up to 10 mg L⁻¹, and the system can thus be upscaled and employed for remediation of U(VI) impacted sites.

A combined chemical and biological analysis of samples from a major obsolete pesticide and persistent organic pollutant (POP) dumpsite in Northern Tajikistan was carried out. The chemical analytical screening focused on a range of prioritized compounds and compounds known to be present locally. Since chemical analytics does not allow measurements of hazards in complex mixtures, we tested the use of a novel effect-based approach using a panel of quantitative high-throughput CALUX reporter assays measuring distinct biological effects relevant in hazard assessment. Assays were included for assessing effects related to estrogen, androgen, and progestin signaling, aryl hydrocarbon receptor-mediated signaling, AP1 signaling, genotoxicity, oxidative stress, chemical hypoxia, and ER stress. With this panel of assays, we first quantified the biological activities of the individual chemicals measured in chemical analytics. Next, we calculated the expected sum activity by these chemicals in the samples of the pesticide dump site and compared the results with the measured CALUX bioactivity of the total extracts of these samples. The results showed that particularly endocrine disruption-related effects were common among the samples. This was consistent with the toxicological profiles of the individual chemicals that dominated these samples. However, large discrepancies between chemical and biological analysis were found in a sample from a burn place present in this site, with biological activities that could not be explained by chemical analysis. This is likely to be caused by toxic combustion products or by spills of compounds that were not targeted in the chemical analysis.

The concentrations of metals/metalloids in blood plasma collected from 111 healthy residents (51 female, 60 male) in Hong Kong (obtained from the Hong Kong Red Cross Blood Transfusion Service, from March to April 2008) were quantified by means of a double-focusing sector field inductively coupled plasma optical emission spectrometer (ICP-OES). Results showed that concentrations of these toxic metals such as Hg, Cd, and Pb in Hong Kong residents were not serious when compared with other countries. Males accumulated significantly higher (p < 0.05 or 0.01) Fe (female 0.92 mg/L; male 1.28), Sn (0.44 μg/L; 0.60), Cr (0.77; 0.90), Hg (1.01; 1.73), and Pb (23.4; 31.6) than females. Smokers accumulated significantly higher (p < 0.05) Cd (smoker 0.27 μg/L; nonsmoker 0.17) and Pb (32.8; 17.6) than nonsmokers. Positive correlations were found between concentrations of As, Cd, Pb, and Hg, with respect to seafood diet habit, body mass index (BMI), and age. More intensive studies involving more samples are needed before a more definite conclusion can be drawn, especially on the causal relationships between concentrations of metals/metalloids with dietary preference and lifestyle of the general public.

In this study, the leaching of 14 substituted phenylurea herbicides (PUHs) through disturbed soil columns packed with three different soils was investigated in order to determine their potential for groundwater pollution. Simultaneously, a series of experiments were conducted to demonstrate the effect of four different organic wastes (composted sheep manure (CSM), composted pine bark (CPB), spent coffee grounds (SCG) and coir (CR)) on their mobility. All herbicides, except difenoxuron, showed medium/high leachability through the unamended soils. In general, addition of agro-industrial and composted organic wastes at a rate of 10 % (w/w) increased the adsorption of PUHs and decreased their mobility in the soil, reducing their leaching. In all cases, the groundwater ubiquity score (GUS) index was calculated for each herbicide on the basis of its persistence (as t½) and mobility (as KOC). The results obtained point to the interest in the use of agro-industrial and composted organic wastes in reducing the risk of groundwater pollution by pesticide drainage.

Enzyme activity and microbial population in soils have important roles in keeping soil fertility. ZJ0273 is a novel pyrimidynyloxybenzoic-based herbicide, which was recently developed in China. The effect of ZJ0273 on soil enzyme activity and microbial population in two different soils was investigated in this study for the first time. The protease activity was significantly inhibited by ZJ0273 and this inhibiting effect gradually weakened after 60-day incubation. The results also showed that ZJ0273 had different stimulating effects on the activities of dehydrogenase, urease, and catalase. Dehydrogenase was consistently stimulated by all the applied concentrations of ZJ0273. The stimulating effect on urease weakened after 60-day incubation. Catalase activity was subject to variations during the period of the experiments. The results of microbial population showed that the number of bacteria and actinomycetes increased in ZJ0273-treated soil compared with the control after 20 days of incubation, while fungal number decreased after only 10 days of incubation in soils. DT50 (half-life value) and k (degradation rate constant) of ZJ0273 in S1 (marine-fluvigenic yellow loamy soil) and S2 (Huangshi soil) were found 69.31 and 49.50 days and 0.010 and 0.014 day⁻¹, respectively.

A high-throughput test of cell growth inhibition was performed using mouse embryonic stem (ES) cells to assess chemical toxicities. We herein demonstrated using a 96-well culture plate approach and the MTT assay that this method was suitable for prioritization of chemicals for their cytotoxic properties. In order to categorize chemicals, we used p53 gene-modified mouse ES cells as well as wild-type ES cells. The p53 gene is a well-known tumor suppressor and controls programmed cell death (apoptosis) and cellular senescence that is triggered by DNA-damaging agents such as alkylating agents and radiation. In the present study, p53-deficient ES cells were found to be more resistant to a tumor initiator, diethylnitrosamine (DEN), than wild-type ES cells, suggesting the inhibition of apoptosis or senescence by a dysfunction in p53. Chromosome aberrations were more frequently detected in p53-deficient ES cells than in wild-type cells, indicating genomic instability due to the deletion of p53. Other tumor initiators, methyl methanesulfonate (MMS) and N-methyl-N-nitrosourea (NMU), did not reveal apparent differences in cytotoxicity between wild-type and p53-deficient ES cells. Thus, ES test system using gene-modified ES cells may be used to categorize chemicals by detecting their characteristic effects on apoptosis, genotoxic potentials as well as general cytotoxicity.

In the present study, ameliorating role of hydrogen sulfide (H₂S) in oilseed rape (Brassica napus L.) was studied with or without application of H₂S donor sodium hydrosulfide (NaHS) (0.3 mM) in hydroponic conditions under three levels (0, 0.1 and 0.3 mM) of aluminum (Al). Results showed that addition of H₂S significantly improved the plant growth, photosynthetic gas exchange, and nutrients concentration in the leaves and roots of B. napus plants under Al stress. Exogenously applied H₂S significantly lowered the Al concentration in different plant parts, and reduced the production of malondialdehyde and reactive oxygen species by improving antioxidant enzyme activities in the leaves and roots under Al stress. Moreover, the present study indicated that exogenously applied H₂S improved the cell structure and displayed clean mesophyll and root tip cells. The chloroplast with well-developed thylakoid membranes could be observed in the micrographs. Under the combined application of H₂S and Al, a number of modifications could be observed in root tip cell, such as mitochondria, endoplasmic reticulum, and golgi bodies. Thus, it can be concluded that exogenous application of H₂S under Al stress improved the plant growth, photosynthetic parameters, elements concentration, and biochemical and ultrastructural changes in leaves and roots of B. napus.

Environmental pollution from livestock production, particularly swine production, is often managed by the use of constructed wetlands, which incorporate plants such as Myriophyllum elatinoides as a means of treating wastewater. The M. elatinoides purification system has been shown to effectively remove, via nitrification and denitrification, more than 90 % of the total nitrogen (TN) and 84 % of the NH₄ ⁺-N produced in swine wastewater. However, the mechanisms of variation in aquatic environmental factors and how the interaction of these factors affects denitrification by microorganisms in sediments remain poorly understood. In this study, the impacts of dissolved oxygen (DO), TN, NH₄ ⁺-N, and NO₃ ⁻-N on the abundance, diversity, and community distribution of denitrifiers in the sediments from different concentrations and types of wastewater including tap water (CK), two strengths of synthetic wastewater: 200 mg NH₄ ⁺-N L⁻¹ (T1) and 400 mg NH₄ ⁺-N L⁻¹ (T2), swine wastewater diluted 50 % (T3), and swine wastewater (T4) were investigated in a microcosm experiment. A significant improvement was observed in the abundance of denitrification genes (nirK and nirS) in response to increased NO₃ ⁻-N and DO in the swine wastewater sediments. The abundance of these denitrification genes was highest in the T4 sediments compared with other treatments. Terminal restriction fragment length polymorphism (T-RFLP) analysis revealed that the DO, TN, and NH₄ ⁺-N positively impacted the richness index (S) of the nirK denitrifiers in T1, whereas the NO₃ ⁻-N negatively affected the Simpson diversity index (D) of nirK and nirS denitrifiers in T3 and T4. However, the NO₃ ⁻-N positively affected the nirK and nirS denitrifier community distribution, whereas the DO negatively affected the nirK and nirS denitrifier distribution in T3 and T4. These findings will be helpful in that they allow us to recognize the effects of environmental factors on the formation of the denitrifiers in the sediments in a M. elatinoides purification system.

Brominated flame retardants (BFRs) are a group of widely used compounds that, due to their limited biodegradability, exhibit excessive persistence in the environment. The persistence and high toxicity of these compounds to the natural biota causes great environmental concern. We investigated the biodegradation of the BFR dibromoneopentyl glycol (DBNPG) under continuous culture conditions using a miniature membrane bioreactor (mMBR) to assess its feasibility as a bioremediation approach. This system demonstrated long-term, stable biodegradation of DBNPG (>90 days), with an average removal rate of about 50 %. Pyrosequencing of the 16S rRNA gene of the microorganisms involved in this process revealed the dominance of reads affiliated with the genus Brevundimonas of the Alphaproteobacteria class during the different mMBR operational stages. The bacterial community was also dominated by reads affiliated with the Sinorhizobium and Sphingopyxis genera within the Alphaproteobacteria class and the Sediminibacterium genus of the Sphingobacteria class. Real-time PCR used to analyze possible changes in the population dynamics of these four dominant groups revealed their consistent presence throughout the long-term mMBR biodegradation activity. Two genera, Brevundimonas and Sphingopyxis, were found to increase in abundance during the acclimation period and then remained relatively stable, forming the main parts of the consortium over the prolonged active stage.

This study was conducted to investigate the biodegradation ability of the mixed culture of Trichoderma viride and Aspergillus niger through the study of the organic matter extracted from rice straw and the lignocellulose structure by using gas chromatography–mass spectrometer (GC-MS) and Fourier transform infrared spectroscopy (FTIR). The results of the GC-MS showed that the mixed culture possessed shorter alkane (heptane) at the end of the incubation and more kinds of organic matter (except the alkanes, 29 kinds of organic matter were detected) than the pure cultures. It could be deduced that the organic matter could indicate the degradation degree of the lignocellulose to some extent. Moreover, pinene was detected in the mixed culture on days 5 and 10, which might represent the antagonistic relationship between T. viride and A. niger. The analysis of FTIR spectrums which indirectly verified the GC-MS results showed that the mixed culture possessed a better degradation of rice straw compared with the pure culture. Therefore, the methods used in this research could be considered as effective ones to investigate the lignocellulose degradation mechanism in mixed culture.