A scheme of selective removal of metal ions from chromium-containing synthetic solutions with the following chemical composition, Cr (VI)-Fe (III), Cr (VI)-Fe (III)-Ni (II), Cr (VI)-Fe (III)-Ni (II)-Zn (II), and Cr (VI)-Fe (III)-Ni (II)-Zn (II)-Cu (II)) by Shewanella xiamenensis biofilm immobilized on a zeolite support, was proposed. Three biological processes, biosorption, bioaccumulation, and longtime bioreduction, were applied for metal removal. The process of Zn (II), Ni (II), and Cu (II) showed to be pH dependent. The maximum removal of Ni (II) was achieved during a 1-hour biosorption process at pH 5.0–6.0, of Zn (II) at pH 5.0, and of Cu (II) at pH 3.0. Chromium (VI) and Fe (III) ions were more efficiently removed by bioaccumulation. Chromium (VI) removal in the studied systems varied from 16.4% to 34.8 and of iron from 55.8 to 94.6%. In a long-term bioreduction experiment, it was possible to achieve complete reduction of Cr (VI) to Cr (III) ions by Shewanella xiamenensis in 42 days and by Shewanella xiamenensis biofilm on zeolite in 35 days. Shewanella oneidensis can be effectively used to remove metal ions from chemically complex effluents.

Unrefined sea salt originates from seawater, typically by natural evaporation. Being minimally processed, it contains the natural minerals and impurities of seawater. Despite the wide applications of salt for culinary and food preservation purposes, the available composition data is particularly limited. Since seawater often contains various harmful substances at a trace or ultra-trace level, their determination in unrefined salt is significant in terms of quality control and food safety. Twenty-four (24) samples of unrefined sea and rock salts retailed in Greece were studied in terms of their trace metals and polycyclic aromatic hydrocarbon (PAH) content, which constitute the usual pollutants examined in seawater. In addition, samples’ color and mineralogy were recorded and their attenuated total reflectance Fourier transform infrared (ATR FT-IR) spectra were obtained. No statistically significant differences were found between sea and rock salts regarding their trace metal (Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, Zn) content (excluding V) and the 15 PAHs examined. ATR FT-IR succeeded to discriminate among sea, rock, flower, and underground salty water salts. Compared with the typical trace metal concentrations in seawater, quite high Pb values were determined in both sea and rock salts, whereas outliers in the rest of the trace elements examined were scarce. Median values of the sum of PAH (ΣPAHs) concentrations were calculated equal to 2.1 and 2.6 ng g⁻¹ for sea and rock salts, respectively. Environmental interactions of salt production with trace elements and PAHs are also discussed.

Lake Hamana is a semi-enclosed brackish lake amid agricultural and residential land. Monthly vertical profiles of nutrients, total phosphorus (TP), and total nitrogen (TN) at twelve sampling stations in the lake were obtained from 1995 to 2016. Freshwater samples were also obtained from five stations in the river flowing into the lake. Significant decreases were seen in phosphate, TP, and TN concentrations at most lake and all river stations. Decrease in phosphate concentration reflects reduced organic matter and nutrient load into the lake due to increased sewage coverage. Nitrate concentration significantly increased at four stations, whereas ammonium and TN concentrations significantly decreased. This could be due to inefficient nitrification/denitrification of wastewater. At all stations, the nitrogen to phosphate ratio in surface water was higher than 16 and increased significantly. Therefore, phosphate limitation could be strengthened by the decrease in phosphate and increase in nitrate concentrations in the lake.

Balamtetik is the receiving body of the Rio Grande de Comitán and is located just at the outskirts of the Montebello National Park, Chiapas, México. Multi-elemental, infrared spectra, ¹³⁷Cs, ²¹⁰Pb, and diatom analyses in a 75-cm sediment core were used to reconstruct the recent disturbance history of the lake. The sequence chronology, based mostly on ¹³⁷Cs profiles, allowed to infer high sedimentation rates in Balamtetik (~ 7 mm/year) and a nearly cyclic series of disturbance events that can be related to anthropogenic causes such as deforestation and increased development of agriculture and urban areas at local and regional scale. These disturbance events show high local and regional erosion (high Ca, TIC, and Ti), soil organic matter (IR spectra), eutrophication (high P and diatoms), and anoxic bottom water conditions (low Mn) and can be dated to the early 1950s, the late 1950s, and from the 1980s until the 2000s. The entrance of wastewaters is related with an increase in salinity inferred by the diatom record and the organic matter type. The first two disturbance events are related to changes in land use during the agrarian reform that started during the 1940s; the last event is related with the increase in local population and the introduction of intensive agriculture. This last phase of disturbance corresponds with the reports of fish mortality events around 2003; however, high lake turbidity and anoxic bottom waters seem to have been established since the 1980s. The record from Lake Balamtetik also shows that during the intermediate periods, there was a recovery of the lake and its catchment; however, the future trends might be different, as the increase in the speed of organic matter and nutrients arrival to the lake reduces its resilience.

The effect of dairy manure amendments to agricultural soil on the yield-scaled nitrous oxide (N₂O) emissions remains unclear. We hypothesize that an optimum ratio of dairy manure to synthetic fertilizers leads to large nitrogen use efficiency (NUE) and small yield-scaled N₂O emissions. The aims of this study were to (1) quantify the variations in the crop yields and N₂O emissions from winter wheat-summer maize cropping systems in Northwest China, (2) determine the responses of the NUE and yield-scaled N₂O emission to the ratio of organic materials to synthetic fertilizers, and (3) evaluate the relationship between the NUE and yield-scaled N₂O emissions. Field measurements were conducted within long- and short-term fertilization experiments between the years of 2014 and 2016. Treatments included synthetic fertilizers, synthetic fertilizers plus crop residues, and synthetic fertilizers plus dairy manure at both sites. The annual grain yields and N₂O emissions varied from 13.3 to 18.0 Mg ha⁻¹ and from 1.3 to 3.6 kg N ha⁻¹, respectively, across the treatments. The yield-scaled N₂O emissions related negatively to the NUE, suggesting that agronomic aims of improving NUE are an effective approach to mitigate N₂O emissions. The ratio of organic materials to synthetic fertilizers was not a significant limit on the NUE and yield-scaled N₂O emissions. We conclude that organic amendments appeared to play a minor influence on the promotion of the NUE and N₂O mitigation.

Ni-Al-CO₃-layered double hydroxide (LDH) with Ni:Al ratio (3:1) and their nanocomposites with alginate and chitosan beads were prepared and examined for their efficiency in removal of Cd²⁺ and Cu²⁺ ions from wastewater. Different parameters such as contact time, pH value, adsorbent weight, and heavy metal ion concentration on the removal efficiency were examined and reported. The prepared beads were examined using X-ray diffraction (XRD), TEM, SEM, and FTIR. Our results revealed a successful preparation of the LDH in rhombohedral hexognal crystal form and the alginate-LDH-chitosan beads. The optimized batch experiment conditions in ambient room temperature were found to be 2 g/L adsorbent dose, 50 mg/L initial concentration of meal, contact time of 2 h, and pH ~ 5 and 6 for removal of Cu²⁺ and Cd²⁺, respectively. The adsorption process was well fitted with Langmuir and Freundlich isotherm models (higher R²), with trivial advantage for Freundlich approach. Kinetic studies showed that the adsorption of both Cd²⁺ and Cu²⁺ followed the pseudo-second-order. The current study demonstrated that the Ni-Al-CO₃ LDH and their novel alginate-chitosan-based nanocomposite could be further tailored and used as efficient adsorbents for the uptake of heavy metals from wastewater.

To evaluate the association between the presence of asthma and allergy, and airborne endotoxin in homes of school-age children in Kaohsiung City, Taiwan, with a case–control study design by matching the age and class exposure. Data collection of home visits included an interviewer-administered questionnaire and air sampling of participants’ homes for endotoxin, bacteria, and fungi, as well as temperature and relative humidity measurements. Endotoxin was detected in all air samples with a median value of 0.67 EU m⁻³. In the adjusted logistic regression model, household airborne endotoxin was associated with higher prevalence of asthma and allergy; OR = 4.88 (95% CI 1.16–20.55) for Q3 (between 0.67 and 1.97 EU m ⁻³) vs. Q1 (< 0.31 EU m ⁻³), with statistical significance. Airborne fungi were associated with higher prevalence of asthma and allergy; OR = 4.47 (95% CI 1.13–17.69) for Q3 (between 314 and 699 CFU m ⁻³) vs. Q1 (< 159 CFU m ⁻³) in adjusted logistic regression models. Airborne endotoxin and fungi were significantly associated with children’s asthma and allergy.

Cadmium (Cd) is a non-essential environmental endocrine-disrupting compound found in water and a potential threat to aquatic habitats. Cd has been shown to have various short-term effects on aquatic animals; however, evidence for long-term effects of Cd on vocal communications in amphibians is lacking. To better understand the long-term effects of low-dose Cd on acoustic communication in amphibians, male Xenopus laevis individuals were treated with low Cd concentrations (0.1, 1, and 10 μg/L) via aqueous exposure for 24 months. At the end of the exposure, the acoustic spectrum characteristics of male advertisement calls and male movement behaviors in response to female calls were recorded. The gene and protein expressions of the androgen receptor (AR) were determined using Western blot and RT-PCR. The results showed that long-term Cd treatment affected the spectrogram and formant of the advertisement call. Compared with the control group, 10 μg/L Cd significantly decreased the first and second formant frequency, and the fundamental and main frequency, and increased the third formant frequency. One and 10-μg/L Cd treatments significantly reduced the proportion of individuals responding to female calls and prolonged the time of first movement of the male. Long-term Cd treatment induced a downregulation in the AR protein. Treatments of 0.1, 1, and 10 μg/L Cd significantly decreased the expression of AR mRNA in the brain. These findings indicate that long-term exposure of Cd has negative effects on advertisement calls in male X. laevis.

The removal of cyanide compounds in soil by leaching was investigated in flask and column tests. All the experiments were conducted under alkaline conditions to prevent loss of hydrogen cyanide. Results showed that leaching progressed rapidly when the leaching temperature or the initial cyanide concentration was high. The obtained cyanide data in the flask test fitted an inner diffusion process, as described by a shrinking core model. In the batch column test, the cyanide concentration decreased from 44.06 to 9.86 mg/kg when the leaching intensity was 79 L/(m² h) after 23.8 h leaching. The leaching process for the cyanide compounds was divided into two stages according to the batch column test despite the decrease in the leaching velocity as the cyanide concentration in soil declined. Cyanide removal in the batch column test was better than that in the flask test due to the higher gradient of cyanide concentration. The aqueous solution containing cyanide compounds was decomposed effectively by the hybrid process of ozone and UV rays. Furthermore, the leaching and decomposition of the soil and leaching wastewater were performed with a continuous column test with circulating leaching liquid. The cyanide compounds in the soil and wastewater were removed effectively.

The present work describes synthesis, detailed characterization, and application of bare and surfactant-modified titania nanomaterials (NMs) for various wastewater treatment applications as individual cases like cadmium (Cd) removal, methylene blue (MB) dye degradation, and treatment of real textile and dyeing industry effluent. These NMs are used as adsorbents and photocatalysts in an indegenously developed end-to-end treatment process and a photocatalytic reactor for treatment of textile wastewater. The used NMs are suitably filtered and recovered for reuse; however, still this work focusses on the extent of potential risk and environmental safety of these engineered NMs towards seed germination and plant growth, in the event they escape wastewater treatment plants and reach out to natural water bodies and soil systems, accumulate over a period of time, and comes in contact with plant species. For synthesis, sol-gel method was utilized; cetyltrimethylammonium bromide (CTAB) and sodium dodecyl sulfate (SDS) were used as cationic and anionic surfactants, respectively, to act as particle growth templates and improve surface morphology. Detailed characterization involved XRD (X-ray diffraction), FTIR (Fourier-transform Infrared Spectroscopy), SEM (Scanning Electron Microscopy), TEM (Transmission Electron Microscopy), EDX (Energy Dispersive X-ray analysis), and BET (Brunauer-Emmett-Teller) surface area analysis. Improved morphology and surface properties, from irregular shape in Bare TiO₂ to spherical shape in surfactant-modified titania, led to enhanced Cd removal and MB dye degradation efficiency. Bare TiO₂ was used for complete treatment of textile wastewater, which took 5 h in achieving water quality, which is safe for discharge and reuse as per norms of Central Pollution Control Board (CPCB), Govt. of India. Phytotoxicity studies of these NMs at a wide concentration range (0–1000 mg L⁻¹⁾ were undertaken towards Vigna radiata, and 500 mg L⁻¹ concentration was found to be optimally safe for seed germination and plant growth.