Although the stabilization/solidification method has been widely used for remediation of heavy metal-contaminated soils in recent decades, the engineering behavior and mobility of heavy metal ions under alkaline groundwater conditions are still unclear. Therefore, the unconfined compressive strength test (UCS) combined with toxicity characteristic leaching procedure (TCLP) and general acid neutralization capacity (GANC) was used to investigate the effects of alkalinity (using NaOH to simulate alkalinity in the environment) on the mechanical and leaching characteristics of cement-solidified/stabilized (S/S) Zn-contaminated soils. Moreover, the microstructure was analyzed using the scanning electron microscope (SEM) technology. The results indicated that alkaline environment could accelerate the UCS development compared with specimens without soaking in NaOH solution,, regardless of whether the specimens contained Zn²⁺ or not. And the UCS varied obviously attributed to the variations of both NaOH concentration and soaking time. Except for the specimens soaked for 90 days, the leached Zn²⁺ concentrations were higher than that of without soaking. However, the leachability of Zn²⁺ in all the stabilized specimens is in the regulatory level. ANC results indicated that the Zn²⁺ leaching behavior can be divided into three stages related to the initial leachate pH. Moreover, SEM results proved that the alkaline environment could actually facilitate the cement hydration process. The results proved in the present paper could be useful in treating the heavy metal-contaminated soils involved in the solidification/stabilization technology under alkaline environment.

Zero-valent iron (Fe⁰) has been widely used for Cr(VI) removal; however, the removal mechanisms of Cr(VI) from aqueous solution under complex hydrogeochemical conditions were poorly understood. In this research, the mixed materials containing cast iron and activated carbon were packed in columns for the treatment of aqueous Cr(VI)-Cr(III) in groundwater with high concentration of Ca²⁺, Mg²⁺, HCO₃ ⁻, NO₃ ⁻, and SO₄ ²⁻. We investigate the influences of those ions on Cr(VI) removal, especially emphasizing on the reaction mechanisms and associated precipitations which may lead to porosity loss by using X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) techniques. The results show that the precipitations accumulated on the material surface were (Fe/Cr) (oxy)hydroxide, mixed Fe(III)-Cr(III) (oxy)hydroxides, Fe₂O₃, CaCO₃, and MgCO₃. During these reactions, the Cr(VI) was reduced to Cr(III) coupled with the oxidated Fe⁰ to Fe(II) through the galvanic corrosion formed by the Fe⁰-C and/or the direct electron transfer between Fe⁰ and Cr(VI). In addition, Cr(VI) could be reduced by aqueous Fe(II), which dominated the whole removal efficiency. The primary aqueous Cr(III) was completely removed together with Cr(III) reduced from Cr(VI) even when Cr(VI) was detected in the effluent, which meant that the aqueous Cr(III) could occupy the adsorption sites. In general, the combined system was useful for the Cr(VI)-Cr(III) treatment based on galvanic corrosion, and the hardness ions had a negative effect on Cr(VI) removal by forming the carbonates which might promote the passivation of materials and decrease the removal capacity of the system.

Organic amendments have been widely proposed as a remediation technology for metal-contaminated soils, but there exist controversial results on their effectiveness. In this study, the effect of pig manure addition on cadmium (Cd) bioavailability in Cd-contaminated soils was systematically evaluated by one dynamic, in situ technique of diffusive gradients in thin films (DGT) and four traditional methods based on the equilibrium theory (soil solution concentration and the three commonly used extractants, i.e., acetic acid (HAc), ethylenediamine tetraacetic acid (EDTA), and calcium chloride (CaCl₂). Wheat and maize were selected for measurement of plant Cd uptake. The results showed that pig manure addition could promote the growth of two plants, accompanied by increasing biomasses of shoots and roots with increasing doses of pig manure addition. Correspondingly, increasing additions of pig manure reduced plant Cd uptake and accumulation, as indicated by the decreases of Cd concentrations in shoots and roots. The bioavailable concentrations of Cd in Cd-contaminated soils reflected by the DGT technique obviously decreased with increasing doses of pig manure addition, following the same changing trend as plant Cd uptake. Changes in soil solution Cd concentration and extractable Cd by HAc, EDTA, and CaCl₂ in soils were similar to DGT measurement. Meanwhile, the capability of Cd resupply from solid phase to soil solution decreased with increasing additions of pig manure, as reflected by the decreases in the ratio (R) value of C DGT to C ₛₒₗ. Positive correlations were observed between various bioavailable indicators of Cd in soils and Cd concentrations in the tissues of the two plants. These findings provide stronger evidence that pig manure amendment is effective in reducing Cd mobility and bioavailability in soils and it is an ideal organic material for remediation of Cd-contaminated soils.

Controlling the confounding factors on cardiovascular diseases, such as long-time trend, calendar effect, and meteorological factors, a generalized additive model (GAM) was used to investigate the short-term effects of air pollutants (PM₁₀, SO₂, and NO₂) on daily cardiovascular admissions from March 1st to May 31st during 2007 to 2011 in Lanzhou, a heavily polluted city in western China. The influences of air pollutants were examined with different lag structures, and the potential effect modification by dust storm in spring was also investigated. Significant associations were found between air pollutants and hospital admissions for cardiovascular diseases both on dust event days and non-dust event days in spring. Air pollutants had lag effects on different age and gender groups. Relative risks (RRs) and their 95% confidence intervals (CIs) associated with a 10 μg/m³ increase were 1.14 (1.04~1.26) on lag1 for PM₁₀, 1.31 (1.21~1.51) on lag01 for SO₂, and 1.96 (1.49~2.57) on lag02 for NO₂ on dust days. Stronger effects of air pollutants were observed for females and the elderly (≥60 years). Our analysis concluded that the effects of air pollutants on cardiovascular admissions on dust days were significantly stronger than non-dust days. The current study strengthens the evidence of effects of air pollution on health and dust-exacerbated cardiovascular admissions in Lanzhou.

The paper presents the adsorption of Remazol brilliant blue (RBB) and Disperse orange 25 (DO25) dyes from aqueous solution of the mixture of dyes onto concentrated sulphuric acid-treated red mud (ATRM). First-order derivative spectrophotometric method was developed for the analysis of RBB and DO25 in mixed dye aqueous solution to overcome the limitations arising due to interference in the zero-order spectral method. The optimum conditions to maximize RBB adsorption favoured the adsorption of RBB, and those for DO25 favoured DO25 adsorption from the mixed dye aqueous solutions. Presence of a second dye always inhibited the adsorption of a target dye. The uptake and percentage adsorption of each of the dyes onto ATRM from the aqueous solution of the mixture of dyes decreased considerably with increasing concentrations of the other dye showing the antagonistic effect. Monocomponent Langmuir isotherm fitted the mixed dye adsorption equilibrium data better than the monocomponent Freundlich isotherm. However, monocomponent models are suitable for the fixed concentration of the other dye. Modified Langmuir isotherm model adequately predicted the multi-component adsorption equilibrium data for RBB-DO25-ATRM adsorption system with a good accuracy and is more generic from the application point of view.

Asaluyeh is one of the most heavily industrialised areas in the world where gas, petrochemical, and many downstream industries are located. This study aims to survey the biomonitoring of four metals and one metalloid in children living in the vicinity of Asaluyeh area. To do this, we analysed the creatinine-adjusted urinary levels of arsenic (As), cadmium (Cd), vanadium (V), manganese (Mn), and nickel (Ni) in 184 elementary schoolchildren (99 boys and 85 girls) living in Asaluyeh and compared them with a reference population. The comparisons were done for two seasons (spring and fall). The results showed that in the case area (Asaluyeh), the levels of As, V, Mn, and Ni were significantly higher and that of Cd was not significantly higher than the reference city for both seasons. The mean concentration of metal(loid)s in Asaluyeh (case) and Sadabad (reference) area as μg g⁻¹ creatinine was As 2.90 and 2.24, V 0.06 and 0.03, Mn 0.28 and 0.25, Ni 0.54 and 0.29, and Cd 0.31 and 0.28 in spring and As 3.08 and 2.28, V 0.07 and 0.03, Mn 0.30 and 0.26, Ni 0.91 and 0.30, and Cd 0.36 and 0.31 in the fall. Seasonal variations played a key role in determining urinary metal(loid) concentration, as we saw the significant level of As, Cd, V, and Ni in fall than in spring. With regard to the impact of gender on the absorption and accumulation of urinary metal(loid)s, boys showed higher levels of the studied elements, especially for As, than girls as outdoor activities are more popular among boys. Due to the values being lower than those reported in literature, more research is needed on various population groups and other exposure sources in order to judge whether living in the vicinity of the gas and petrochemical industries in Asaluyeh is a threat to nearby residents.

While point source pollutions have gradually been controlled in recent years, the non-point source pollution problem has become increasingly prominent. The receiving waters are frequently polluted by the initial stormwater from the separate stormwater system and the wastewater from sewage pipes through stormwater pipes. Consequently, calculating the intercepted runoff depth has become a problem that must be resolved immediately for initial stormwater pollution management. The accurate calculation of intercepted runoff depth provides a solid foundation for selecting the appropriate size of intercepting facilities in drainage and interception projects. This study establishes a separate stormwater system for the Yishan Building watershed of Fuzhou City using the InfoWorks Integrated Catchment Management (InfoWorks ICM), which can predict the stormwater flow velocity and the flow of discharge outlet after each rainfall. The intercepted runoff depth is calculated from the stormwater quality and environmental capacity of the receiving waters. The average intercepted runoff depth from six rainfall events is calculated as 4.1 mm based on stormwater quality. The average intercepted runoff depth from six rainfall events is calculated as 4.4 mm based on the environmental capacity of the receiving waters. The intercepted runoff depth differs when calculated from various aspects. The selection of the intercepted runoff depth depends on the goal of water quality control, the self-purification capacity of the water bodies, and other factors of the region.

Intimate coupling of photocatalysis and biodegradation (ICPB) provides superior treatment for the degradation of bio-recalcitrant compounds, such as chlorophenol. Photocatalytically generated intermediates can be promptly used by the enclosed biofilms. Chlorophenol degradation can theoretically be accelerated by a co-substrate or be compromised by the competition for photocatalytic reactive oxygen species (ROS); however, studies to examine the comparison are limited in number. Non-chlorinated phenols commonly co-exist in real wastewater; thus, we evaluated the influence of phenol (hard to photo-oxidize) and pyrocatechol (easy to photo-oxidize) on the degradation of 4-chlorophenol (4CP). The removal efficiency of 4CP was 51%, which increased to 62% after phenol addition. Meanwhile, the dechlorination efficiency of 4CP increased from 47 to 63%; similarly, the living/dead cell ratio increased from 49/51 to 79/21. However, pyrocatechol addition led to a decrease in 4CP removal efficiency to 32% and a reduction in living/dead cell ratio to 35/65. The differences in the results were attributed to the extra electron donors provided by the photodegraded products of phenol to bacteria, which enhanced 4CP degradation; meanwhile, pyrocatechol competed with 4CP for ROS, thus inhibiting its degradation. Competition for ROS and co-substrate properties should be considered in the treatment of phenolic wastewater by ICPB.

Pesticide residues are an important aspect of environmental pollution. Environmental avermectin residues have produced adverse effects in organisms. Many pesticides exert their toxic effects via the mechanism of autophagy. The purpose of this study was to examine the changes in autophagy levels and in autophagy-related genes, including LC3, Beclin 1, Dynein, ATG5, TORC1, and TORC2, resulting from exposure to subchronic levels of AVM in liver tissue in the king pigeon model. We observed abundant autophagic vacuoles with extensively degraded organelles, autophagosomal vacuoles, secondary lysosomes, and double-membrane structures in the liver. The expression levels of the autophagy-related genes LC3-I, LC3-II, Beclin 1, ATG5, and Dynein were up-regulated; however, TORC1 and TORC2 expression levels were down-regulated. These changes occurred in a concentration-dependent manner after AVM exposure for 30, 60, and 90 days in pigeons. Taken together, these results suggested that AVM increased the autophagic flux and that upregulation of autophagy might be closely related to the hepatotoxicity of AVM in birds.

Nowadays, there is an amplified interest in maintaining suitable indoor air quality (IAQ). Besides a wide range of available interventions, air cleaners are considered a valuable tool, since based on inexpensive and easily implementing technologies to improve IAQ. The purpose of this work is to combine the TiO₂-photocatalysis with the electrostatic and adsorption processes, in order to improve efficiency and reliability. A TiO₂-photocatalytic oxidation combined with an electrostatic filter has been studied. Nitrogen oxides reduction and degradation of many VOC over different catalyst support were monitored jointly with CO and CO₂ production. The coupling of photocatalysis with an external electric field enhances efficiency of the process. The choice of materials with diversified adsorptive characteristics plays an important role in the durability of the process over time.