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.

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.

Phytoremediation can be assisted by microorganisms, which promote plant growth and increase heavy metal availability in soil. In this study, we aimed at evaluating the effect of two plant growth-promoting bacteria (PGPB) on phytoextraction of copper (Cu) by maize. We chose the strains based on their ability to synthesize indole compounds, produce siderophores, solubilize phosphorus, and increase soil conductivity and extractable Cu in soil. Then, in glasshouse experiments, we assessed their ability to increase biomass, chlorophyll content, and Cu extraction by maize. Results showed that Acinetobacter sp. RG30 and Pseudomonas putida GN04 were overall the most active strains to synthesize indole, produce siderophores, and solubilize phosphorus, and hence selected for further studies. Also, both were able to significantly increase soil conductivity and release Cu from soil compared to control. Glasshouse experiments showed that Cu had a negative effect on plant growth, but inoculation with bacteria promoted plant growth and chlorophyll content in its presence (p < 0.05). Notably, the effect of inoculation on plant growth was larger on contaminated than on uncontaminated soil, which suggests an overall bacterial effect for alleviation of stress caused by Cu. Inoculation with RG30 or GN04 improved Cu extraction by maize (p < 0.05); interestingly, co-inoculation led to the highest accumulation (200 μg Cu/g plant dry weight). We conclude, therefore, that inoculation with RG30 and GN04 improves metal extraction by increasing plant growth, fitness, and availability of minerals in soil, which represents an important tool for the improvement of phytoextraction processes in polluted environments.

A pilot-scale constructed wetland treatment system (CWTS) was designed and built to produce biogeochemical conditions promoting processes targeted for removal of arsenic from simulated Bangladesh groundwater. Two CWTS series were designed to promote coprecipitation and sorption of arsenic with iron oxyhydroxides under oxidizing conditions, and two series were designed to promote precipitation of arsenic sulfide and coprecipitation of arsenic with iron sulfide under reducing conditions. Arsenic removal performance was greater in series with oxidizing conditions than in series with reducing conditions (mean outflow concentrations of 64 and 108 μg L⁻¹, respectively). Additions of zero-valent iron (ZVI) to oxidizing series and to reducing series enhanced arsenic removal (mean removal efficiencies of 72 and 42 %, respectively) compared to unamended series (27 and 20 %, respectively). Arsenic removal performance was significantly greater (α = 0.05) in the oxidizing series amended with ZVI than in the other series, with removal extents, efficiencies, and rate coefficients ranging from 6 to 79 μg L⁻¹, 40 to 95 %, and 0.13 to 0.77 day⁻¹, respectively. Results from this pilot-scale study demonstrate that a CWTS can decrease concentrations of arsenic in arsenic-contaminated water to below the World Health Organization (WHO) drinking water quality guideline of 10 μg L⁻¹.

The degradation of methyl orange (MO) in aqueous solution by microwave irradiation in the presence of granular-active carbon (GAC) was investigated. It was found that a synergistic rather than an additive effect of microwave irradiation and GAC contributes to the high-degradation efficiency. The ultraviolet and visible spectrum (UV–vis), infrared spectroscopy (IR), and scanning electron microscopy (SEM) measurements were conducted to trace the MO degradation process. It was demonstrated that the decrease in performance of GAC after repetitive use is largely attributed to the adsorption of some intermediate products on the surface of GAC. The regeneration of the spent GAC under microwave radiation was also investigated. The results show that the activity of spent GAC can be effectively recovered by microwave radiation and 74.1 % of its initial activity remains after six reaction cycles.

The degradation ability of newly isolated bacterial strain Ochrobactrum anthropi toward polychlorinated biphenyls (PCBs) was examined under aerobic conditions. The strain was isolated from historically PCB-contaminated sediments from Strážsky canal in eastern Slovakia, surrounding of the former PCB producer. The degradation ability of the strain was enhanced by addition of other substrates and degradation inducers—biphenyl, glucose, both biphenyl and glucose, ivy leaves, and pine needles. The adaptation of cells membrane toward PCBs in the presence of abovementioned substrates was evaluated with the changes in fatty acid composition (membrane saturation, cis–trans isomerization, and changes in branched fatty acids synthesis). The highest induction of PCB degradation and lowest cell adaptation in liquid medium was achieved using ivy leaves. On the other hand, lowest degradation was achieved when PCBs were added alone. Similar low degradation was observed in the presence of glucose addition together with biphenyl. Contrary, highest growth stimulation under the applied condition was observed. Obtained results indicated that addition of glucose together with biphenyl induced PCB degradation via bacterial growth stimulation, not via the induction of activity of degradation enzymes. Cut ivy leaves (containing terpenoic compounds serving as degradation inducer and structural analog of biphenyl) increased PCB removal from contaminated sediment by O. anthropi. Results indicate the degradation ability of O. anthropi toward penta-, hexa-, and hepta-chlorinated PCB congeners. The degradation of congeners with more than five chlorine atoms per molecule was detected in higher extent compared to dichlorinated congeners.

Evaluation of a field scale agricultural nonpoint source simulation model against field experiment data is an important step that must be considered before a model can be used as a management tool. Field soil water content and metribuzin residue adsorbed in soil profile were intensively monitored and measured by the gravimetric method and the LC-MS/MS method, respectively, for a soybean field plot located at the Asian Institute of Technology, Thailand. The Root Zone Water Quality Model (RZWQM) was evaluated based on laboratory-measured soil hydraulic properties and pesticide residue in Bangkok clay soil. Reasonable agreement exists between the soil water content measured and predicted by RZWQM for 10–20 and 30–40 cm soil depths. The model slightly overestimated the pesticide residue at 0–10 cm soil depth 1 day after application at surface, whereas pesticide residue at 10–20 and 30–40 cm soil depths was in agreement with model acceptance. These results indicate that RZWQM can be used when properly calibrated to predict the movement of water and metribuzin through the soil profile in the tropical zone.

Passive air samplers were deployed at six locations across the province of Manitoba, Canada, to represent areas with, or at various distances from, agricultural herbicide applications. During the growing seasons in 2008 and 2009, the four southern sites always demonstrated mixtures of current-use herbicides (CUHs) in air, but CUHs were not detected at the two northern sites that were 400 and 800 km away from Manitoba’s most northern boundary of agricultural herbicide applications. The masses of the CUHs detected in the air were most strongly positively associated with their estimated masses typically applied in a ~100-km²township area surrounding the sampling sites (r = 0.70 to 0.74) and to a lesser extent with their estimated mass applied in incrementally larger areas (r = 0.53 to 0.59). The masses of CUHs detected in air were also significantly positively associated with their estimated masses applied at a provincial level (r = 0.45 to 0.52) but not with their reported half-lives in air, suggesting that a system of maintaining records of herbicide use data, even at a coarse scale, can strongly improve agri-environmental risk assessments. Of the nine CUHs detected, MCPA [(4-chloro-2-methylphenoxy)acetic acid] and bromoxynil, which are widely applied in Manitoba agriculture, were the only herbicides detected at all four southern sites. Triallate and metolachlor which have low use in Manitoba were the only CUHs detected in the winter months, confirming that these herbicides are relatively persistent in the air and may undergo long-range transport. Four passive air samplers, each installed 0.5 to 1.5 km apart at the same location, showed variations in the herbicide masses detected with the coefficient of variation ranging from 10 % for bromoxynil in 2008 to 137 % for MCPA in 2009. These variations were particularly observed not only for the two herbicides applied on-site (MCPA and clopyralid) but also for four herbicides transported into the area from longer distances (2,4-D (2,4-dichlorophenoxyacetic acid), bromoxynil, ethalfluralin, and triallate). Future regional-scale research should therefore consider deploying multiple sets of passive air samplers at a site to obtain a more representative measure of herbicide air concentrations.

The samples of natural and iron-modified clinoptilolite (GC, Na-GC, Fe1-GC, and Fe2-GC) were assessed as adsorbent for arsenate removal by batch and column studies. The influences of retention time, pH, adsorbent dosage, and initial arsenate concentration on the arsenate adsorption efficiency were investigated. The experiments demonstrated that Fe1-GC has the highest arsenate removal efficiency with the adsorption capacity of 8.4 μg g⁻¹at equilibrium time of 60 min. Both the Fe1-GC and Fe2-GC removed arsenate effectively over the initial pH range 4–10. Adsorption capacity of Fe1-GC was adequately described by Freundlich isotherm. According to the results of the desorption performance experiments, the Fe1-GC was used six times until arsenic removal efficiency was reduced to 19 %. The adsorption percentage of arsenic increased with the diminish of initial concentration of arsenic and increase of adsorbent dose for all types of clinoptilolite. The column study demonstrated that Fe1-GC was achieved to reduce final arsenate of about 10 μg L⁻¹or below for up to 300 bed volumes in a continuous flow mode. The results of this study show that Fe1-GC can be used as an alternative adsorbent for arsenate removal.

Development and utilization of low-cost and effective adsorbents for the adsorption processes is a research focus in recent years. In this work, the porous and flexible film was prepared without any pretreatment from the feather keratin deposits produced during the extraction of soluble keratin from chicken feathers. Characteristics of the prepared biosorbent were investigated using thermogravimetric apparatus, X-ray diffraction, Fourier transform infrared, and scanning electron microscopy. Batch adsorption assays were carried out to remove methylene blue (MB) from aqueous solution. The results showed that the extent of MB adsorption on the biosorbent increased with an increase in initial dye concentration, contact time, solution pH, and biosorbent dosage. The equilibrium data were best described by Langmuir isotherm than other isotherm models. The maximum monolayer adsorption uptake was 156.5 mg/g at pH 7 for an initial dye concentration of 200 mg/l. Kinetic studies indicated that the adsorption process of MB followed pseudo-second-order kinetics. Nevertheless, the intra-particle diffusion model confirmed that the adsorption of MB was a two-step process: a rapid surface adsorption followed by intra-particle diffusion. Thermodynamic parameters such as ΔG°, ΔH°, and ΔS° were calculated, indicating that the adsorption process was spontaneous and endothermic.