Arsenic (As) contamination and bioaccumulation are a serious threat to agricultural plants. To address this issue, we checked the efficacy of As tolerant plant growth promoting bacteria (PGPB), zinc oxide nanoparticles (ZnO NPs) and oxalic acid (OA) in Luffa acutangula grown on As rich soil. The selected most As tolerant PGPB i.e Providencia vermicola exhibited plant growth promoting features i.e solubilzation of phosphate, potassium and siderophores production. Innovatively, we observed the synergistic effects of P. vermicola, ZnO NPs (10 ppm) and OA (100 ppm) in L. acutangula grown on As enriched soil (150 ppm). Our treatments both as alone and in combination alleviated As toxicity exhibited by better plant growth and metabolism. Results revealed significantly enhanced photosynthetic pigments, proline, relative water content, total sugars, proteins and indole acetic acid along with As amelioration in L. acutangula. Furthermore, upregulated plant resistance was manifested with marked reduction in the lipid peroxidation and electrolyte leakage and pronounced antagonism of As and zinc content in leaves under toxic conditions. These treatments also improved level of nutrients, abscisic acid and antioxidants to mitigate As toxicity. This marked improvement in plants’ defense mechanism of treated plants under As stress is confirmed by less damaged leaves cell structures observed through the scanning electron micrographs. We also found substantial decrease in the As bioaccumulation in the L. acutangula shoots and roots by 40 and 58% respectively under the co-application of P. vermicola, ZnO NPs and OA in comparison with control. Moreover, the better activity of soil phosphatase and invertase was assessed under the effect of our application. These results cast a new light on the application of P. vermicola, ZnO NPs and OA in both separate and combined form as a feasible and ecofriendly tool to alleviate As stress in L. acutangula.

Prenatal disinfection by-products (DBPs) exposure is linked with adverse birth outcomes. Genetic susceptibility to DBP metabolism may modify the exposure-outcome associations.To investigate whether CYP2E1 and GSTZ1 genetic polymorphisms modified the associations of prenatal DBP exposures with adverse birth outcomes.Two biomarkers of DBP exposures including trihalomethanes (THMs) in blood and trichloroacetic acid (TCAA) in urine were determined among 426 pregnant women from a Chinese cohort study. CYP2E1 (rs2031920, rs3813867, and rs915906) and GSTZ1 (rs7975) polymorphisms in cord blood were genotyped. Statistical interactions between prenatal DBP exposures and newborns CYP2E1 and GSTZ1 polymorphisms on birth outcomes (birth weight, birth length, and gestational age) were examined by multivariable linear regression with adjustment for potential confounders.We found that newborns CYP2E1 genetic polymorphisms (rs2031920 and rs3813867) modified the associations of maternal blood THMs or urinary TCAA levels with birth outcomes. However, these interactions were nonsignificant after Bonferroni correction for multiple comparisons, except for the interaction between maternal blood BrTHMs [sum of dibromochloromethane (DBCM), bromodichloromethane (BDCM), and bromoform (TBM)] and newborns CYP2E1 gene rs2031920 polymorphisms on birth weight (P for interaction = 0.003).Newborns genetic variations of CYP2E1 rs2031920 may modify the impacts of prenatal BrTHM exposure on birth weight. This finding needs to be further confirmed.

Exposure to trihalomethanes (THMs) and haloacetic acids (HAAs) has been individually associated with adverse male reproductive effects; however, their joint male reproductive toxicity is largely unknown. This study aimed to explore the joint effects of THMs and trichloroacetic acid (TCAA) on semen quality in a Chinese population. A total of 337 men presenting to the Reproductive Center of Tongjing Hospital, in Wuhan, China to seek semen analysis were included this study. Baseline blood THMs [chloroform (TCM), bromodichloromethane (BDCM), dibromochloromethane (DBCM), and bromoform (TBM)] and urinary TCAA were analyzed and dichotomized at their median levels. The joint effects of THMs and TCAA on below-reference semen quality parameters were evaluated by calculating the relative excess risk due to interaction (RERI). After adjusting for potential confounders, we found a suggestive synergistic effect between Br-THMs (sum of BDCM, DBCM, and TBM) and TCAA for below-reference sperm count (RERI = 2.14, 95% CI: −0.37, 4.91) (P = 0.076); men with high Br-THMs and TCAA levels (above the median) had 3.31 times (95% CI: 1.21, 9.07) elevated risk of having below-reference sperm count than men with low Br-THMs and TCAA levels (below the median). No apparent joint effects were observed between THMs and TCAA for other semen quality parameters. Our results suggest that co-exposure to Br-THMs and TCAA is associated with additive effects on decreased semen quality. However, further studies in a larger sample size and mechanistic studies are needed to confirm the findings.

To better understand the precursor of disinfection by-products (DBPs) and provide useful information for water utilities to manage the drinking water, a study of DBP formation was conducted through chlorination of leaf organic matter (OM) from phoenix tree and algal OM from Chlorella vulgaris. DBPs investigated include trichloromethane (TCM), trichloroacetic acid (TCAA), dichloroacetic acid (DCAA), chloroacetic acid (CAA), dichloroacetonitrile (DCAN) and trichloroacetonitrile (TCNM). Results show that the specific yields (μg/mg C) of C-DBPs (TCM, CAA, DCAA and TCAA) from leaf OM were higher but the specific yields of N-DBPs (DCAN and TCNM) were lower than those from algal OM. Correlation analysis revealed that C-DBPs yields (μg/L) were significantly (p < 0.01) interrelated with each other (r = 0.937–0.996), and for each C-DBP, the hydrophobic OM contributed more to their formation (61–90% of total yields) as compared with hydrophilic OM. In spite of these characteristics, an in-depth examination was conducted revealing that the hydrophobicity and aromaticity of C-DBPs precursors were in the order of TCAA > DCAA & TCM > CAA. DCAN precursors were highly variable: they were dominated by hydrophobic OM (leaf OM: 86%) or hydrophilic OM (algal OM: 61%). Hydrophilic OM was the most important precursor for TCNM (76–79% of total yields), followed by hydrophobic neutral and base substances (29–45% of total yields), but the hydrophobic acids exhibited an inhibition role in TCNM formation.

Phosphorus (P) is limiting nutrient in many soils, and P availability may often depend on iron (Fe) speciation. Colloidal iron phosphate (FePO₄cₒₗₗ) is potentially present in soils, and we tested the hypothesis that phytate exudation by Pteris vittata might dissolve FePO₄cₒₗₗ by growing the plant in nutrient solution to which FePO₄cₒₗₗ was added. The omission of P and Fe increased phytate exudation by P. vittata from 434 to 2136 mg kg⁻¹ as the FePO₄cₒₗₗ concentration increased from 0 to 300 mM. The total P in P. vittata tissue increased from 2880 to 8280 mg kg⁻¹, and the corresponding increases in the trichloroacetic acid (TCA) extractable P fractions were inorganic P (860–5100 mg kg⁻¹), soluble organic P (250–870 mg kg⁻¹), and insoluble organic P (160–2030 mg kg⁻¹). That is, FePO₄-solubilizing activity was positive correlated with TP, TCA P fractions in P. vittata, TP in growth media, and root exudates. This study shows that phytate exudation dissolved FePO₄cₒₗₗ due to the chelation effect of phytic acid on Fe; however, the wider question of whether phytic acid excretion was prompted by deprivation of P, Fe, or both remains to be answered.

This work focuses on the development of electro-absorption and photoelectro-absorption technologies to treat gases produced by a synthetic waste containing the highly volatile perchloroethylene (PCE). To do this, a packed absorption column coupled with a UV lamp and an undivided electrooxidation cell was used. Firstly, it was confirmed that the absorption in a packed column is a viable method to achieve retention of PCE into an absorbent-electrolyte liquid. It was observed that PCE does not only absorb but it was also transformed into phosgene and other by-products. Later, it was confirmed that the electro-absorption process influenced the PCE degradation, favoring the transformation of phosgene into final products. Opposite to what is expected, carbon dioxide is not the main product obtained, but carbon tetrachloride and trichloroacetic acid. Both species are also hazardous but their higher solubility in water opens possibilities for a successful and more environmental-friendly removal. The coupling with UV-irradiation has a negative impact on the degradation of phosgene. Finally, a reaction mechanism was proposed for the degradation of PCE based on the experimental observations. Results were not as expected during the planning of the experimental work but it is important to take in mind that PCE decomposition occurs in wet conditions, regardless of the applied technology, and this work is a first approach to try to solve the treatment problems associated to PCE gaseous waste flows in a realistic way.

The Henry's law constant of trichloroacetic acid [K′H (mol kg⁻¹ atm⁻¹) for the equilibrium CCl₃COOH₍g₎ ⇌ CCl₃COOH₍ₐq₎] has been determined from measured partial pressures over aqueous solutions at 298.15 K and 308.15 K. Its value is given by: ln(K′H) = (11.21 ± 0.5) – 8.66 × 10³ (l/Tᵣ – l/T) where T (K) is temperature and Tᵣ is equal to 298.15 K, for an aqueous phase dissociation constant (Kₐ) of 0.55 mol kg⁻¹ determined from literature osmotic coefficient and electromotive force data. Accuracy is estimated to be 4–30% in the product K′HKₐ. Trichloroacetic acid is highly soluble and will partition strongly into aqueous atmospheric aerosols, and completely into fog and cloud water. Its occurrence and transport in the environment are therefore to be associated primarily with liquid phases.

The formation of volatile DBPs and haloacetic acids (HAAs) from algal organic matter (AOM) in different chloramination conditions (i.e., different monochloramine (NH₂Cl) dosages, pH values, and bromide concentrations) was studied. In chloramination of AOM, HAAs were the major DBP species, followed by trihalomethanes (THMs), haloacetonitriles (HANs), and haloketones (HKs). The levels of THMs, HAAs, HKs, and HANs generated in chloramination were 75%, 69%, 68%, and 122% of those in chlorination, respectively. The concentrations of THMs and HAAs both doubled as the NH₂Cl dosage doubled. The proportions of bromodichloromethane and dibromochloromethane in THMs and the proportions of dichloroacetic acid and trichloroacetic acid in HAAs increased with the NH₂Cl dosage. Accelerating the pH value enhanced the formation of THMs, HAAs, and HANs, respectively, and favored the formation of brominated THMs. The HAN species distribution was unaffected by the NH₂Cl dosage and pH. Increasing bromide levels slightly increased the yield of THMs and slightly decreased the yields of HAAs and HKs. The species shift from the chlorinated to the brominated was more significant for THMs and HANs than for HAAs. The THM-BSF and dichloroacetonitrile-BSF values were lower in chloramination than in chlorination. The high pH value and bromide level significantly accelerated the THM-BSFs. The maximum values of THM-BSFs and dichloroacetonitrile-BSF were 0.6 and 0.5.

This study evaluated the effect of low-pressure ultraviolet (UV) irradiation on the formation of disinfection by-products (DBPs) from algal organic matter of Microcystis aeruginosa during subsequent chlorination and chloramination. The algal organic matter includes extracellular organic matter (EOM) and intracellular organic matter (IOM). The fluorescence excitation-emission matrix spectra indicated that the humic/fulvic acid-like organics of EOM and the protein-like organics of IOM may be preferentially degraded by UV treatment. UV irradiation with low specific UV absorbance values was effective in reducing the formation of trihalomethanes and dichloroacetic acid from EOM and IOM during the subsequent chlorination. During the UV-chloramine process, higher UV dose (1000 mJ/cm²) led to the decrease of the formation of dichloroacetic acid, trichloroacetic acid, and haloketones from IOM by an average of 24%. Furthermore, UV irradiation can slightly increase the bromine substitution factors (BSFs) of haloacetic acids from EOM during chlorination, including dihaloacetic acids and trihaloacetic acids in the presence of bromide (50 μg/L). However, UV irradiation did not shift the formation of DBPs from IOM to more brominated species, since the BSFs of trihalomethanes, dihaloacetic acids, trihaloacetic acids, and dihaloacetonitriles almost kept unchanged during UV-chlorine process. As for UV-chloramine process, UV irradiation decreased the BSFs of trihalomethanes, while increased the BSFs of dihaloacetic acid for both EOM and IOM. Overall, the UV pretreatment process is a potential technology in treating algae-rich water.

Pharmaceuticals in water are commonly found and are not efficiently removed by current treatment processes. Degradation of antiepileptic drug carbamazepine (CBZ) by UV/chlorine advanced oxidation process was systematically investigated in this study. The results showed that the UV/chlorine process was more effective at degrading CBZ than either UV or chlorination alone. The CBZ degradation followed pseudo-first order reaction kinetics, and the degradation rate constants (kₒbₛ) were affected by the chlorine dose, solution pH, and natural organic matter concentration to different degrees. Degradation of CBZ greatly increased with increasing chlorine dose and decreasing solution pH during the UV/chlorine process. Additionally, the presence of natural organic matter in the solution inhibited the degradation of CBZ. UV photolysis, chlorination, and reactive species (hydroxyl radical •OH and chlorine atoms •Cl) were identified as responsible for CBZ degradation in the UV/chlorine process. Finally, a degradation pathway for CBZ in the UV/chlorine process was proposed and the formation potentials of carbonaceous and nitrogenous disinfection by-products were evaluated. Enhanced formation of trichloroacetic acid, dichloroacetonitrile, and trichloronitromethane precursors should be considered when applying UV/chlorine advanced oxidation process to drinking water.