A simple and robust analytical method for the determination of perfluorinated carboxylic acids (PFCAs) with C₂ to C₈ chains, based on solid-phase extraction (SPE) and liquid chromatography-tandem mass spectrometry (LC-MS/MS), was developed, validated and applied to tap water, groundwater and surface water. Two stationary phases for LC (Obelisc N and Kinetex C₁₈) and two materials with weak anion-exchange properties for SPE (Strata X-AW and Oasis WAX) were evaluated. Robust separation and retention was achieved with the reversed phase column and an acidic eluent. Quantitative extraction recoveries were generally achieved for PFCAs with C > 3, but extraction efficiencies were different for the two shortest chained analytes: 36 to 114% of perfluoropropanoate (PFPrA) and 14 to 99% of trifluoroacetate (TFA) were recovered with Strata X-AW, while 93 to 103% of PFPrA and 40 to 103% of TFA were recovered with Oasis WAX. The sample pH was identified as a key parameter in the extraction process. One-step elution-filtration was introduced in the workflow, in order to remove sorbent particles and minimise sample preparation steps. Validation resulted in limits of quantification for all PFCAs between 0.6 and 26 ng/L. Precision was between 0.7 and 15% and mean recoveries ranged from 83 to 107%. In groundwater samples from sites impacted by per- and polyfluoroalkyl substances (PFASs), PFCA concentrations ranged from 0.056 to 2.2 μg/L. TFA and perfluorooctanoate were the predominant analytes. TFA, however, revealed a more ubiquitous occurrence and was found in concentrations between 0.045 and 17 μg/L in drinking water, groundwater and surface water, which were not impacted by PFASs.

Currently, the emergence of clinically relevant multi-resistant bacteria and the associated β-lactamases resistance genes which threaten the last frontier for antibiotics presents a major challenge for medical treatment. Xiangjiang River is typically contaminated with heavy metals due to the intensive metal mining activities within this watershed. The occurrence and distribution of several β-lactam antibiotics and ten β-lactam resistance genes (blaTEM, blaVIM, blaSHV, blaGES, blaDHA, blaOXA₋₁, blaOXA₋₂, blaOXA₋₁₀, blaCMY₋₂, and blaₐₘₚC) were investigated in the Xiangjiang River, China. The absolute abundance of bla genes was as high as (7.0 ± 0.6) × 10⁶ copies/mL for surface water and (2.3 ± 0.7) × 10⁸ copies/g for sediment. In contrast, all the detected β-lactam antibiotic compounds were below the detection limit. The distribution of individual bla gene subtypes was correlated with speciation of heavy metals which might affect the bacterial community structure. The principal coordinate analysis (PCoA) and Mantal test reconfirmed that the heavy metals had a correlation with the bla genes and the bla genes were correlated with bacterial community structure, suggesting that heavy metals impacted on the distribution of the bla genes by shifting bacterial community structure under the long-term selective pressure. The microcosm experiments indicated metal-induced persistence of bla genes in the resistant bacteria (Bacillus megaterium, Staphylococcus epidermidis). The persistence of β-lactam resistance under metal selective pressure is beneficial to the survival of resistant bacteria, thereby contributing to the shift of the bacterial community structure, consequently impacts on the distribution of bla genes.

The primary objective of mobile phone technology is to achieve communication with any person at any place and time. In the modern era, it is impossible to ignore the usefulness of mobile phone technology in cases of emergency as many lives have been saved. However, the biological effects they may have on humans and other animals have been largely ignored and not been evaluated comprehensively. One of the reasons for this is the speedy uncontrollable growth of this technology which has surpassed our researching ability. Initiated with the first generation, the mobile telephony currently reaches to its fifth generation without being screened extensively for any biological effects that they may have on humans or on other animals. Mounting evidences suggest possible non-thermal biological effects of radiofrequency electromagnetic radiation (RF-EMR) on brain and behavior. Behavioral studies have particularly concentrated on the effects of RF-EMR on learning, memory, anxiety, and locomotion. The literature analysis on behavioral effects of RF-EMR demonstrates complex picture with conflicting observations. Nonetheless, numerous reports suggest a possible behavioral effect of RF-EMR. The scientific findings about this issue are presented in the current review. The possible neural and molecular mechanisms for the behavioral effects have been proposed in the light of available evidences from the literature.

Activated carbon (AC) with high specific surface area was prepared by using bifunctional H₃PO₄ agent, which led to dehydrating and activation effects through hydrothermal pretreatment and subsequent pyrolysis process. N₂ adsorption and desorption isotherms of AC showed a high BET surface area of 2434 m² g⁻¹ and a total volume of pores (VT) of 2.0447 m³ g⁻¹ for AC. The morphology and the chemical components of hydrochar and AC were characterized by scanning electron microscopy and Fourier transform infrared spectroscopy, which indicated that H₃PO₄ was benefitting for the formation of porous structure of AC. Subsequently, the effect of H₃PO₄ in hydrothermal pretreatment and activation process was investigated by comparative experiments. The removal and adsorption of methylene blue (MB) dye with different concentrations onto the AC were studied. The monolayer equilibrium adsorption capacity was 644 mg g⁻¹, showing that AC has good adsorption qualities for methylene blue (MB). The adsorption balance data of MB on AC was best fitted to the Redlich-Peterson model. The adsorption kinetic data fit better to the pseudo-first-order model at low MB concentration, and the pseudo-second-order and Elovich models fit better when the MB concentration was rising.

In this work, trace determination of nitrite in river water samples was studied using solvent stir bar microextraction system with three-hollow fiber configuration (3HF-SSBME) as a preconcentration step prior to UV–Vis spectrophotometry. The obtained results showed that the increase in the number of solvent bars can improve the extraction performance by increasing the contact area between acceptor and sample solutions. The extraction process relies on the well-known oxidation–reduction reaction of nitrite with iodide excess in acidic donor phase to form triiodide, and then its extraction into organic acceptor phase using a cationic surfactant. Various extraction parameters affecting the method were optimized and examined in detail. Detection limit of 1.6 μg L⁻¹ and preconcentration factor of 282 can be attained after an extraction time of 8 min under the optimum conditions of this technique. The proposed method showed a linear response up to 1000 μg L⁻¹ (r² = 0.996) with relative standard deviation values less than 4.0%. The accuracy of the developed method was assessed using the Griess technique. Finally, the proposed method was successfully employed for quantification of nitrite in river water samples (Ghezelozan, Zanjan, Iran).

The goals of this study were to analyze if there is a difference in the stable isotopic ratio (δ¹³C and δ¹⁵N) of macrobenthic species sampled at two sandy beaches (one close to a river mouth and the other far from any freshwater input) and to identify differences in the stable isotopic ratio (δ¹³C and δ¹⁵N) in different body parts of three representative species of two Brazilian sandy beach macrofaunas: the polychaete Hemipodia californiensis, the mollusk bivalve Donax hanleyanus, and the crustacean decapod Emerita brasiliensis. No significant differences were detected in the δ¹³C stable isotopic ratio between the two sites analyzed; however, in the δ¹⁵N stable isotopic ratio, a significant difference was observed. Regarding the intraspecific response of stable isotopic ratio, D. hanleyanus showed a significant difference in carbon among different body part structures, while a trend for significance was observed for nitrogen isotopes. The differences were significant for both isotopes in E. brasiliensis, and no differences were observed among the body part structures in H. californiensis. There were significant differences in E. brasiliensis carapaces with regard to the δ¹⁵N stable isotopic ratio between the muscle and the whole body. Although the δ¹³C and δ¹⁵N stable isotopic ratio differs significantly in the digestive tract, muscles, and whole body of D. hanleyanus, such differences were not enough to determine changes in their trophic levels and food sources. Similar stable isotopic ratios were observed in the whole body, proboscis, and teeth of H. californiensis, highlighting this species as the top predator. In conclusion, stable isotopic analysis of benthic trophic structure can be employed as a tool in coastal management plans or environmental impact studies.

Design and synthesis of arsenic adsorbents with high performance and excellent stability has been still a significant challenge. In this study, we anchored nano-zero-valent iron (NZVI) on the surface of graphene-silica composites (GS) with high specific surface area, forming the NZVI/GS nano-composite. The prepared nano-materials were used to remove As(III) and As(V) through adsorption from aqueous solutions. The results indicated that NZVI particles were dispersed well on the surface of GS, and the NZVI/GS showed great potential to remove As(III) and As(V). Adsorption performance of NZVI/GS for As(III) and As(V) highly depended on the pH of solutions. The experimental data fitted well with the pseudo-second-order kinetic model and the Langmuir isotherm model. The calculated maximum adsorption capacities of NZVI/GS for As(III) and As(V) were up to 45.57 mg/g and 45.12 mg/g at 298 K, respectively, and the adsorption equilibrium could be reached within 60 min. The residual concentrations of As(III) and As(V) after treatment with 0.4 g/L NZVI/GS can meet with the drinking water standard of WHO when the initial concentrations were below 4 mg/L and 3 mg/L, respectively. Moreover, the as-prepared NZVI/GS had excellent anti-interference ability during the process of As removal in the presence of foreign ions. During the As removal process, As(III) was oxidized to As(V), which could be removed through adsorption by electrostatic attraction and complexation. These results indicated that the as-synthesized NZVI/GS composite is a promising adsorbent for the removal of arsenic from aqueous solutions.

South Asia is susceptible to drought due to high variation in monthly precipitation. The drought indices deriving from remote sensing data have been used to monitor drought events. To secure agricultural land in South Asia, timely and effective drought monitoring is very important. In this study, TRMM data was utilized along with remote sensing techniques for reliable drought monitoring. The Drought Severity Index (DSI), Temperature Vegetation Drought Index (TVDI), NDVI, and Normalized Vegetation Supply Water Index (NVSWI) are more helpful in describing the drought events in South Asia due to the dryness and low vegetation. To categorize drought-affected areas, the spatial maps of TRMM were used to confirm MODIS-derived TVDI, DSI, and NVSWI. The DSI, TVDI, NVSWI, and Normalized Monthly Precipitation Anomaly Percentage (NAP) indices with an integrated use of MODIS-derived ET/PET and NDVI were selected as a tool for monitoring drought in South Asia. The seasonal DSI, TVDI, NVSWI, NAP, and NDVI values confirmed that South Asia suffered an extreme drought in 2001, which continued up to 2003. The correlation was generated among DSI, NAP, NVWSI, NDVI, TVDI, and TCI on a seasonal basis. The significantly positive correlation values of DSI, TVDI, and NVSWI were in DJF, MAM, and SON seasons, which were described as good drought monitoring indices during these seasons. During summer, the distribution values of drought indicated that more droughts occurred in the southwest regions as compared to the northeast region of South Asia. From 2001 to 2017, the change trend of drought was characterized; the difference of drought trend was obviously indicated among different regions. In South Asia, generally, the frequency of drought showed declining trends from 2001 to 2017. It was verified that these drought indices are a comprehensive drought monitoring indicator and would reduce drought risk in South Asia.

Advanced oxidation processes (AOPs) have been highly efficient in degrading contaminants of emerging concern (CEC). This study investigated the efficiency of photolysis, peroxidation, photoperoxidation, and ozonation at different pH values to degrade doxycycline (DC) in three aqueous matrices: fountain, tap, and ultrapure water. More than 99.6% of DC degradation resulted from the UV/H₂O₂ and ozonation processes. Also, to evaluate the toxicity of the original solution and throughout the degradation time, antimicrobial activity tests were conducted using Gram-positive (Bacillus subtilis) and Gram-negative (Escherichia coli) bacteria, and acute toxicity test using the bioluminescent marine bacterium (Vibrio fischeri). Antimicrobial activity reduced as the drug degradation increased in UV/H₂O₂ and ozonation processes, wherein the first process only 6 min was required to reduce 100% of both bacteria activity. In ozonation, 27.7 mg L⁻¹ of ozone was responsible for reducing 100% of the antimicrobial activity. When applied the photoperoxidation process, an increase in the toxicity occurred as the high levels of degradation were achieved; it means that toxic intermediates were formed. The ozonated solutions did not present toxicity.

The Eastern Mediterranean and its Cilician Basin offshore waters have oligotrophic features with low nutrient concentrations, low primary production, and high water transparency. However, the wide shelf area of the Cilician Basin is subject to contaminated river inflows with enhanced nutrient loads and direct discharges of urban wastewaters of southern Turkey, leading to develop local eutrophic/mesotrophic conditions in the inner sites of Mersin and Iskenderun Bays on the Cilician Basin. For the assessment of changing trophic status of the coastal and the bay water bodies under anthropogenic pressures since the 1980s, five extensive field studies were performed in summer and winter periods of 2014, 2015, and 2016. Physical and eutrophication-related biochemical parameters (salinity, temperature, Secchi Disk Depth, nutrients, dissolved oxygen, chlorophyll-a) were measured at 65 stations in different water bodies occupying the Northeastern (NE) Mediterranean coastal, offshore areas and bays. The collected data sets were used in scaling the trophic status of the visited water bodies of NE Mediterranean coastal, offshore areas and semi-enclosed bays, using novel classification tools of Trophic Index (TRIX), Eutrophication Index (E.I.), chl-a, and HELCOM Eutrophication Assessment Tool (HEAT), developed by different experts for highly productive seas. These tools, which can successfully classify highly productive coastal water masses under human pressures, and their sensitivities have been tested for scaling of the current trophic status of the NE Mediterranean coastal water bodies being subject to human pressures. The scaling results of classical TRIX, E.I., and chl-a indices in the NE Mediterranean water masses are not sensitive enough to differentiate mesotrophic and eutrophic water bodies because these indices principally assume to have higher concentrations of eutrophication-related parameters in the least effected (reference) water bodies. The HEAT tool, which uses a site-specific “reference value” for each eutrophication-indicator, has allowed us to produce more reliable and sensitive scaling of the current trophic status of the NE Mediterranean shelf areas, even though we used only the “reference values” derived from the composite data sets. The results of the indices were compared with the HEAT tool and the actual status was assessed from observations, indicating revision requirements of the multi-metric classification tools. For this goal, scales of natural (oligotrophic) and anthropogenic (eutrophic) levels of eutrophication indicators should be determined at a sub-basin scale using long-term site-specific observations in the NE Mediterranean. The revised scale ranges of TRIX for oligotrophic, mesotrophic, and eutrophic water bodies of Mersin Bay are in line with ranges of TRIX classification tool proposed for Aegean Sea waters, which can be used to assess trophic status of the entire Eastern Mediterranean and Aegean coastal seas (surface salinity > 37.5) having oligotrophic properties in the offshore waters.