This research aims at identifying the main deleterious effects of Cr(VI) on the photosynthetic apparatus and at selecting the most sensitive endpoints related to photosynthesis. To achieve this goal, we used lettuce (Lactuca sativa), a sensible ecotoxicological crop model. Three-week-old plants were exposed to 0, 50, 150 and 200 mg L⁻¹ of Cr(VI). These concentrations ranged from levels admitted in irrigation waters to values found in several Cr industry effluents and heavily contaminated environments. After 30 days of exposure, plants accumulated Cr preferably in roots and showed nutritional impairment, with decreases of K, Mg, Fe and Zn in both roots and leaves. Cr(VI)-exposed plants showed decreased levels of chlorophyll (Chl) a and anthocyanins, as well as decreased effective quantum yield of photostystem II (ΦPSII) and photochemical Chl fluorescence quenching (qp), but increases in the non-photochemical Chl fluorescence quenching (NPQ) and in the de-epoxidation state (DEP) of the xanthophyll cycle. Net CO₂ assimilation rate (P N) and RuBisCO activity were mostly impaired in the highest Cr(VI) concentration tested. Concerning the final products of photosynthesis, starch content was not affected, while soluble sugar contents increased. These alterations were accompanied by a reduction in protein content and in plant growth. Our results support that endpoints related to the photosynthesis photochemical processes (ΦPSII and the qp) and the content of anthocyanins are sensitive predictors of Cr(VI) toxicity. The advantages of using these parameters as biomarkers for Cr toxicity in plants are discussed. Finally, we report that, despite showing physiological disorders, L. sativa plants survived and accumulated high doses of Cr, and their use in environmental/decontamination studies is open to debate.

The scarcity of freshwater resources is a serious problem in arid regions, such as Tunisia, and marginal quality water is gradually being used in agriculture. This study aims to study the impact of treated urban wastewater for reuse in agriculture on the health of soil and food crops. The key findings are that the effluents of Sfax wastewater treatment plant (WWTP) did not meet the relevant guidelines, therefore emitting a range of organic (e.g., up to 90 mg L⁻¹ COD and 30 mg L⁻¹ BOD₅) and inorganic pollutants (e.g., up to 0.5 mg L⁻¹ Cu and 0.1 mg L⁻¹ Cd) in the receiving aquatic environments. Greenhouse experiments examining the effects of wastewater reuse on food plants such as tomato, lettuce, and radish showed that the treated effluent adversely affected plant growth, photosynthesis, and antioxidant enzyme contents. However, the pollution burden and biological effects on plants were substantially reduced by using a 50 % dilution of treated sewage effluent, suggesting the potential of reusing treated effluent in agriculture so long as appropriate monitoring and control is in place.

Heavy metals can be removed from the sludge using bioleaching technologies at thermophilic condition, thereby providing an option for biotreatment of wasted sludge generated from wastewater treatment. The purposes of this study were to establish a molecular biology technique, real-time PCR, for the detection and enumeration of the sulfur-oxidizing bacteria during the thermophilic sludge bioleaching. The 16S rRNA gene for real-time PCR quantification targeted the bioleaching bacteria: Sulfobacillus thermosulfidooxidans, Sulfobacillus acidophilus, and Acidithiobacillus caldus. The specificity and stringency for thermophilic sulfur-oxidizing bacteria were tested before the experiments of monitoring the bacterial community, bacterial number during the thermophilic sludge bioleaching and the future application on testing various environmental samples. The results showed that S. acidophilus was identified as the dominant sulfur-oxidizing bacteria, while A. caldus and S. thermosulfidooxidans occurred in relatively low numbers. The total number of the sulfur-oxidizing bacteria increased during the thermophilic bioleaching process. Meanwhile, the decrease of pH, production of sulfate, degradation of SS/VSS, and solubilization of heavy metal were found to correlate well with the population of thermophilic sulfur-oxidizing bacteria during the bioleaching process. The real-time PCR used in this study is a suitable method to monitor numbers of thermophilic sulfur-oxidizing bacteria during the bioleaching process.

An attempt of response surface methodology (RSM) has been made for more effective utilization and optimization for considerable reduction of operational conditions such as reaction time, aeration time, energy consumption, etc. for municipal wastewater treatment process using moving bed biofilm reactor (MBBR). A mathematical-statistical model was developed for the second-order response surface through the fit of a polynomial function and a central composite design (CCD) in the form of a full factorial design. CCD was employed to assess the interactive effects of the three main independent operational parameters, including biocarrier filling rate (0–70 %), aeration rate (0.21–0.42 m³ h⁻¹), and reactor run time (1–15 days), on the removal efficiency of chemical oxygen demand (COD), biochemical oxygen demand (BOD), and total Kjeldahl nitrogen (TKN). Analysis of variance expressed a high coefficient of determination (R ² = 0.84–0.95), thereby indicating that the model is significant. Using a desirability function for the highest COD (93 %), BOD (96 %), and TKN (69 %) removal, the optimum carrier filling rate, aeration rate, and reactor run time were identified to be 40 %, 0.21 m³ h⁻¹, and 7 days, respectively. It shows that RSM can be a suitable method to optimize the operational parameters of MBBR with enhanced removal efficiency and less power consumption.

Irrigation of crops with microcystins (MCs)-containing waters—due to cyanobacterial blooms—affects plant productivity and could be a way for these potent toxins entering the food chain. This study was performed to establish whether MC-tolerant rhizobia could benefit growth, nodulation, and nitrogen metabolism of faba bean plants irrigated with MC-containing waters. For that, three different rhizobial strains—with different sensitivity toward MCs—were used: RhOF96 (most MC-sensitive strain), RhOF125 (most MC-tolerant strain), or Vicz1.1 (reference strain). As a control, plants grown without rhizobia and fertilized by NH₄NO₃ were included in the study. MC exposure decreased roots (30–37 %) and shoots (up to 15 %) dry weights in un-inoculated plants, whereas inoculation with rhizobia protects plants toward the toxic effects of MCs. Nodulation and nitrogen content were significantly impaired by MCs, with the exception of plants inoculated with the most tolerant strain RhOF125. In order to deep into the effect of inoculation on nitrogen metabolism, the nitrogen assimilatory enzymes (glutamine synthetase (GS) and glutamate synthase (GOGAT)) were investigated: Fertilized plants showed decreased levels (15–30 %) of these enzymes, both in shoots and roots. By contrast, inoculated plants retained the levels of these enzymes in shoots and roots, as well as the levels of NADH-GOGAT activity in nodules. We conclude that the microcystin-tolerant Rhizobium protects faba bean plants and improves nitrogen assimilation when grown in the presence of MCs.

In the present study, the radioactivity levels to which terrestrial non-human biota were exposed are examined. Organisms (grass and herbivore mammals) and abiotic components (soil) were collected during the period of 2010 to 2014 from grasslands where sheep and goats were free-range grazing. Natural background radionuclides (²²⁶Ra, ²²⁸Ra, ²²⁸Th) and artificial radionuclides (¹³⁷Cs, ¹³⁴Cs, ¹³¹I) were detected in the collected samples using gamma spectrometry. The actual measured activity concentrations and site-specific data of the studied organisms were imported in ERICA Assessment Tool (version 1.2.0) in order to provide an insight of the radiological dose rates. The highest activity concentrations were detected in samples collected from Lesvos island and the lowest in samples collected from Attiki and Etoloakarnania prefectures. The highest contribution to the total dose rate was clearly derived from the internal exposure and is closely related to the exposure to alpha emitters of natural background (²²⁶Ra and ²²⁸Th). The Fukushima-derived traces of ¹³⁷Cs, ¹³⁴Cs, and ¹³¹I, along with the residual ¹³⁷Cs, resulted in quite low contribution to the total dose rate. The obtained results may strengthen the adaptation of software tools to a wider range of ecosystems and may be proved useful in further research regarding the possible impact of protracted low level ionizing radiation on non-human biota. This kind of studies may contribute to the effective incorporation of dosimetry tools in the development of integrated environmental and radiological impact assessment policies.

The efficiency of five different single leaching reagents (tartaric acid (TA), citric acid (CA), CaCl₂, FeCl₃, EDTA) and two different composite leaching reagents (CA + FeCl₃, CA + EDTA) on removing Cu, Pb, Zn, and Cd from contaminated paddy soil in Hunan Province (in China) was studied. The results indicated that the efficiencies of CA, FeCl₃, and EDTA on extracting Cu, Pb, Cd, and Zn from soil were greater than that of TA and CaCl₂, and their extraction efficiencies were EDTA ≥ FeCl₃ > CA. The efficiencies of CA + FeCl₃ on extracting Cu, Pb, Cd, and Zn were higher than that of single CA or FeCl₃. The 25 mmol L⁻¹ CA + 20 mmol L⁻¹ FeCl₃ was a promising composite leaching reagent for paddy soil, and it could remove Cu (57.6 %), Pb (59.3 %), Cd (84.8 %), and Zn (28.0 %), respectively. With the same amount of leaching reagent, the efficiency of continuous leaching by several times was higher than that by once. In addition, the easily reducible and oxidizable fractions of heavy metals showed significant decrease during the process of leaching.

Ammonia is a key alkaline species, playing an important role by neutralizing atmospheric acidity and inorganic secondary aerosol production. On the other hand, the NH₃/NH₄ ⁺ increases the acidity and eutrophication in natural ecosystems, being NH₃ classified as toxic atmospheric pollutant. The present study aims to give a better comprehension of the nitrogen content species distribution in fine and coarse particulate matter (PM₂.₅ and PM₂.₅–₁₀) and to quantify ammonia vehicular emissions from an urban vehicular tunnel experiment in the metropolitan area of São Paulo (MASP). MASP is the largest megacity in South America, with over 20 million inhabitants spread over 2000 km² of urbanized area, which faces serious environmental problems. The PM₂.₅ and PM₂.₅–₁₀ median mass concentrations were 44.5 and 66.6 μg m⁻³, respectively, during weekdays. In the PM₂.₅, sulfate showed the highest concentration, 3.27 ± 1.76 μg m⁻³, followed by ammonium, 1.14 ± 0.71 μg m⁻³, and nitrate, 0.80 ± 0.52 μg m⁻³. Likewise, the dominance (30 % of total PM₂.₅) of solid species, mainly the ammonium salts, NH₄HSO₄, (NH₄)₂SO₄, and NH₄NO₃, resulted from simulation of inorganic species. The ISORROPIA simulation was relevant to show the importance of environment conditions for the ammonium phase distribution (solid/aqueous), which was solely aqueous at outside and almost entirely solid at inside tunnel. Regarding gaseous ammonia concentrations, the value measured inside the tunnel (46.5 ± 17.5 μg m⁻³) was 3-fold higher than that outside (15.2 ± 11.3 μg m⁻³). The NH₃ vehicular emission factor (EF) estimated by carbon balance for urban tunnel was 44 ± 22 mg km⁻¹. From this EF value and considering the MASP traffic characteristics, it was possible to estimate more than 7 Gg NH₃ year⁻¹ emissions that along with NOx are likely to cause rather serious problems to natural ecosystems in the region.

The success of the emission reduction measures undertaken by authorities in the Asia-Pacific Economic Cooperation summit 2014 demonstrated that the Beijing-Tianjin-Hebei air quality can be improved by introducing integrated emission reduction measures. This paper combines observation data, emission reduction measures, and air quality simulations that were applied before, during, and after the emission control measure implement to analyze the chemical composition change and relationship between emissions and concentrations of pollutants in region. The 24-h PM₂.₅ samples were collected in the city Beijing, Shijiazhuang, and Tangshan during the period of 20 October to 25 November, 2014. The total PM₂.₅ mass was measured. PM₂.₅ samples were used for the analysis of inorganic elements, selected ions, and organic carbon (OC) and element carbon (EC). PM₂.₅ concentrations during the emission control period were decreased. Total PM₂.₅ concentrations were reduced by 54, 26, and 39 % when compared to non-emission control period in Beijing, Shijiazhuang, and Tangshan. The average element concentrations were reduced significantly by 75 % in Beijing, 37 % in Shijiazhuang, and 36 % in Tangshan. After the Asia-Pacific Economic Cooperation (APEC) conference, the average element concentration increased. At both cities, the concentration secondary water-soluble ions, primary carbon, and element carbon were reduced. However, the concentration of secondary carbon species increased in Beijing due to photochemical oxidants change. More stringent control of regional emissions will be needed for significant reductions of fine particulate pollution in the region to continue to improve air quality.

Reports on the occurrence and diversity of antibiotic-resistant bacteria and genes, which are considered to be emerging pollutants worldwide, have, to date, not been published on South Korean agricultural soils. This is the first study to investigate the persistence of tetracycline (oxytetracycline, tetracycline, and chlortetracycline)-resistant bacterial community and genes in natural and long-term fertilized (NPK, pig, and cattle manure composts) agricultural soils in South Korea. The results showed that oxytetracycline and chlortetracycline could be the dominant residues in animal manures; regular fertilization of manures, particularly pig manures, may be the prime cause for the spread and abundance of tetracycline resistance in South Korean agricultural soils. Both the country’s natural and agricultural soils are reservoirs of antibiotic-resistant species. Of the 113 tetracycline-resistant isolates identified (19 typical bacterial genera and 36 distinct species), approximately 40 to 99 % belonged to Gram-positive bacteria and Bacillus constituted the predominant genera. Of the 24 tet genes targeted, tetG, tetH, tetK, tetY, tetO, tetS, tetW, and tetQ were detected in all soil samples, highlighting their predominance and robust adaptability in soils. Meanwhile, it is suggested that tetC, tetE, tetZ, tetM, tetT, and tetP(B) are the common residues in pig manures, and furthermore, the treatment of soils with pig manures may wield a different impact on the tet gene resistome in agricultural soils. This study thus highlights the necessity for regulating the usage of tetracyclines in South Korean animal farming. This must be followed by proper monitoring of the subsequent usage of animal manures especially that derived from pig farms located in agricultural soils.