There are multiple stressors derived from urbanizations that result in frequent disturbances on streams and rivers reducing water quality and threatens aquatic biota. P-glycoprotein (P-gp)-mediated multixenobiotic resistance (MXR) is a defence mechanism analogous to multidrug resistance (MDR), which has been demonstrated in several aquatic organisms. This system protects cells against the entry and the accumulation of xenobiotics and has been proposed as a biomarker for pollution assessment. We conducted a study in a post-urban reach of Esquel stream (Chubut Province) downstream a wastewater treatment plant, in order to assess the presence and activity of MXR in five freshwater macroinvertebrate species (Helobdella michaelseni, Helobdella simplex, Patagoniobdella variabilis, Hyalella curvispina and Chironomus riparius). We measured the accumulation of the model P-gp substrate rhodamine B (RB) in organisms previously exposed to pollution. Our results described the activity of the MXR system in the three species of leeches suggesting their suitability as the in vivo biomonitoring. We also identified a dependence of the transporter activity with the development stage in H. simplex, highlighting the importance of using organisms of similar size classes since it may affect observed results. Finally, we concluded that benthic freshwater macroinvertebrates possess different species-specific levels of MXR activity possibly influencing their natural distribution as well as their survival.

With industrialization, great amounts of trace elements and heavy metals have been excavated and released onto the surface of the earth and dissipated into the environments. Rapid screening technology for detecting major and trace elements as well as heavy metals in variety of environmental samples has been most desired. The objectives of this study were to determine the detection limits, accuracy, repeatability, and efficiency of an X-ray fluorescence spectrometer (Niton XRF analyzer) in comparison to the traditional analytical methods, inductively coupled plasma optical emission spectrometer (ICP-OES) in screening of major and trace elements of environmental samples including estuary soils and sediments, contaminated soils, and biological samples. XRF is a fast and non-destructive method for measuring the total concentration of multi-elements simultaneously. Contrary to ICP-OES, XRF analyzer is characterized by the limited preparation required for solid samples, non-destructive analysis, increased total speed and high throughout, decreased production of hazardous waste, and low running costs as well as multi-elemental determination and portability in the fields. The current comparative study demonstrates that XRF is a good rapid, non-destructive screening method for contaminated soils, sediments, and biological samples containing high concentrations of major and trace elements. Unfortunately, XRF does not have sensitive detection limits for most trace elements as ICP-OES, but it may serve as a rapid screening tool for locating hot spots in uncontaminated field soils and sediments, such as in the US Department of Energy’s Oak Ridge site.

In order to develop an effective and economical method for removing U(VI) from the low concentration radioactive wastewater with the U(VI) concentration of less than 1 mg L⁻¹, the biomass of Aspergillus niger was prepared and modified with ethylenediamine, and the biosorption of uranium from the low concentration radioactive wastewater by the unmodified and the modified biomasses was investigated in a batch system. The modified biomass exhibited the adsorption efficiency of 99.25 % for uranium under the optimum conditions that pH was 5.0, the contact time was 150 min, and the biosorbent dose was 0.2 g L⁻¹. The adsorption fitted well to Langmuir isotherm, and the maximum sorption capacity of the modified biomass for U(VI) was determined to be 6.789 mg g⁻¹which increased by 36.45 % compared with the unmodified biomass. The adsorption kinetics was better depicted by pseudo-second-order kinetic model. The Gibbs free energy change (ΔG⁰), enthalpy change (ΔH⁰), and entropy change (ΔS⁰) showed that the process of U(VI) adsorption was spontaneous, endothermic, and feasible. The changes in the groups, morphology, and the presence of U(VI) on the surface of the adsorbents which were characterized by FT-IR, SEM, and EDS, demonstrated that the U(VI) was successfully adsorbed onto the modified biomass. Moreover, the UO₂²⁺absorbed on the modified biomass can be released by 0.1 mol L⁻¹HNO₃with high desorption efficiency of 99.21 %. The results show that the modified biomass can remove U(VI) from low concentration radioactive wastewater more effectively than the unmodified biomass.

In this study, the potential effects of three modified industrial by-products—modified low-grade phosphate rock with soda dregs (MP), modified flue gasses desulfurization residue (MF), and a mixture of MF and phosphoric acid (MFP)—were evaluated in the remediation of heavy metal-contaminated agricultural soil at four different treatment levels. The effects of the amendments on the extractability and phytoavailability of soil heavy metals were tested using a standardized sequential extraction test and a pakchoi pot experiment. The impacts of the three amendments on soil quality was investigated, including changes of soil pH, availability of K, Ca, Mg, Si and P, and the effects on pakchoi growth. The addition of these amendments resulted in a significant decrease of labile fraction of the heavy metals in soil (p < 0.05) and a marked decrease in heavy metal uptake by pakchoi (p < 0.05) in the pot experiment. All the amendments improved soil quality as measured by neutralization of soil acidity, increased content of mineral nutrients of soil (specifically, available K, Ca, Mg, Si, and/or P), and enhanced pakchoi growth when compared to the controls. Significant correlations (positive/negative) were observed among these factors, indicating multiple effects of the amendments on the remediation process. The increased soil pH and elevated mineral nutrients contributed to the stabilization of heavy metals, and the remediated soil conditions resulted in improved growth of pakchoi. These results suggest that all three of the modified industrial by-products could be used for the remediation and restoration of heavy metal-contaminated agricultural soil.

A mathematical model is developed to investigate the effect of pH and salinity fluctuation on biogeochemical reactions and metals' behavior in sediments. The model includes one-dimensional vertical advective and diffusive transport of species, serial reductions of electron acceptors, and precipitation/dissolution of species, acid–base chemistry, and metal sorption to sediments. The model was tested using data obtained from laboratory microcosm experiments which exposed metal (Cd, Zn) contaminated sediment to alternating fresh and salty overlying water. The model successfully reproduces the contrasting metal's release behavior and the vertical profiles of pH, Cl⁻, SO₄²⁻, Mn and Fe in porewater and the acid volatile sulfides (AVS) and simultaneously extracted metals (SEM) in sediments. The model showed that FeOOH₍ₛ₎was the dominant sorption phase controlling the solubility of the metals at the surficial sediments while AVS controlled the solubility of the metals in anoxic sediments. The model also showed that the release of the metals to overlying water was controlled by the oxidation of metal sulfides in a very thin layer of oxic sediments (2–3 mm). The proposed model can be useful in managing metal contaminated sediments where pH and salinity are fluctuating by assessing the underlying biogeochemical processes and metals' behavior.

A series of miscible-displacement experiments was conducted to examine the impact of experiment conditions (detection limit, input pulse size, input concentration, pore-water velocity, contact time) on the performance of a mathematical solute transport model incorporating nonlinear, rate-limited sorption/desorption described by a continuous distribution reaction function. Effluent solute concentrations were monitored over a range of approximately seven orders of magnitude, allowing characterization of asymptotic tailing phenomenon. The model successfully simulated the extensive elution tailing observed for the measured data. Values for the mean desorption rate coefficient (ln k₂) and the variance of ln k₂were obtained through calibration of the model to measured data. Similar parameter values were obtained for experiments with different input pulse size, input concentration, pore-water velocity, and contact time. This suggests that the model provided a robust representation of sorption–desorption for this system tested. The impact of analytical detection limit was examined by calibrating the model to subsets of the breakthrough curves wherein the extent of the elution tail was artificially reduced to mimic a poorer detection limit. The parameters varied as a function of the extent of elution tail used for the calibrations, indicating the importance of measuring as full an extent of the tail as possible.

Adsorption is one of the best methods for arsenic removal from water which is established in the last few decades. Biosorption by natural biosorbents and agricultural by-product is an environmental friendly approach and has proved to be a cost-effective and non-hazardous technology for the removal of heavy metals from water. This paper describes batch test findings conducted to evaluate the feasibility of using sugarcane bagasse (SCB) as an industrial by-product of sugar industry to remove arsenic (As) from water and compare the results with the efficiency of activated carbon (AC) for arsenic (As) removal. The effects of three parameters, such as pH, adsorbent dosage (Cₐ), and initial metal concentration (C₀) on the adsorption of arsenic were evaluated by using response surface methodology (RSM). It is discovered that AC and SCB removed up to ~89 and ~98 % of arsenic, respectively. The uptake capacities yielded from the batch experiment were about 31.25 mg/g for AC at pH ~7.4 and 11.9 mg/g for SCB at pH ~9. The equilibrium times achieved were 120 and 150 min for SCB and AC, respectively. This study shows that SCB is an efficient low-cost biosorption for arsenic removal from water.

Air pollution contributes substantially to global health burdens; however, less is known about pollution patterns in China and whether they differ from those elsewhere. We evaluated temporal and spatial heterogeneity of air pollution in Lanzhou, an urban Chinese city (April 2009–December 2012), and conducted a systematic review of literature on air pollution and health in Lanzhou. Average levels were 141.5, 42.3, and 47.2 μg/m³for particulate matter with an aerodynamic diameter ≤10 μm (PM₁₀), NO₂, and SO₂, respectively. Findings suggest some seasonality, particularly for SO₂, with higher concentrations during colder months relative to warmer months, although a longer time frame of data is needed to evaluate seasonality fully. Correlation coefficients generally declined with distance between monitors, while coefficients of divergence increased with distance. However, these trends were not statistically significant. PM₁₀levels exceeded Chinese and other health-based standards and guidelines. The review identified 13 studies on outdoor air pollution and health. Although limited, the studies indicate that air pollution is associated with increased risk of health outcomes in Lanzhou. These studies and the high air pollution levels suggest potentially serious health consequences. Findings can provide guidance to future epidemiological studies, monitor placement programs, and air quality policies.

The bacterial communities in the intestinal tracts of earthworm were isolated by culture-dependent approaches. In total, 72 cultures were isolated and purified from the gut of an earthworm under aerobic culture condition, out of which 25 isolates were laccase positive. Isolate 33, a good laccase producer was identified as Bacillus safensis DSKK5, using both biochemical and molecular approaches. It was found to produce maximum laccase activity at 0.75 % of wheat bran, 37 °C, and pH 6.2. Further, copper sulfate and copper chloride showed a maximum laccase production. In order to understand the affinity of binding and interaction between toxic dyes and bacterial laccase, homology models were generated. The resulted models were further validated and used for docking studies with commonly used industrial dyes. Molecular docking using CCDC GOLD software gave a good score with all the textile dyes. Further, validation using molsoft ICM software showed a good binding energy of −104.25, −106.00, −113.98, and −100.36, with commercial dyes, i.e., procion blue, procion green, procion red, and reactive yellow 86, respectively. Experimental data showed a maximum decolorization with procion green (85.66 %) and procion red (85.58 %), which validate the molsoft ICM results, i.e., −106.00 and −113.98, respectively.

We have developed a decision support system that prompts the user for site and contaminant characteristics from petroleum extraction and transportation processes and filters out those technologies that are most adequate for site remediation from the categories of remedial methods in its database. The computerized rule-based structure facilitates the evaluation and selection of the most applicable and feasible treatment technology for petroleum-contaminated soil on a site polluted from pipeline deterioration, which this paper presents as a case study. The technology-screening feature is a useful tool in the early evaluation phase of the soil remediation process and can assist specialists in the simulation of various scenarios. The system has accurately estimated pollutant migration and extent for preliminary soil investigations and provided recommendations in accordance with the current remedial actions taken at these petroleum-contaminated sites. The decision elaboration is close to the situations often encountered in real life.