A dramatic increase in winter (December–February) temperature by 7.2 K (1.1 K per decade) since 1950 has occurred in the Ulan Bator basin, Mongolia. This increase in temperature strongly exceeds the global average of late twentieth century warming and even exceeds warming in most of the polar regions with pronounced increases in temperature. The exceptional warming is restricted to Ulan Bator within the Mongolian forest-steppe region and to wintertime. This suggests that the observed warming could result from radiative forcing by black carbon aerosols. In winter, Ulan Bator’s air is heavily polluted by particulate matter, including black carbon, originating from the combustion of low-quality fuel at low temperature. Winter smog has strongly increased in recent decades, concomitant to the increase in winter temperature, as the result of a strong increase in the city’s population. Exponential growth of Ulan Bator’s population started in the mid-twentieth century, but since 1990, altered socioeconomic frame conditions and a warming climate have driven more than 700,000 pastoralists from rural Mongolia to Ulan Bator where people live in provisional dwellings and cause Ulan Bator’s heavy air pollution. Tree-ring analysis from larch trees growing at the edge of the Ulan Bator basin shows negative correlation of stem increment with December temperature. This result suggests that milder winters promote herbivores and, thus, reduce the tree’s productivity. The negative impact of winter warming on the larch forests adds to adverse effects of summer drought and the impact of high sulfur dioxide emissions. Winter warming putatively associated with high atmospheric concentrations of black carbon aerosols in the Ulan Bator basin is an interesting example of a case where greenhouse gas-mediated climate warming in an area where people themselves hardly contribute to global greenhouse gas emissions affects both humans and ecosystems and causes additional local climate warming.

Municipal landfill soils are not able to retain heavy metals indefinitely, and these metals can migrate into the groundwater. Environmental contamination induced by toxic metals creates a societal health risk. The objective of this work is to study the ability of landfill soil to retain metals (Pb, Cd, Cu, Fe and Zn). The soil came from the municipal solid waste dump of the City of Yamoussoukro (Côte d’Ivoire). Operating parameters such as thickness of soil, metal concentration and filtered volume were investigated. A factorial experimental design was used to determine which parameters influence the metal retention rate. Thickness of soil and metal concentration were the most important factors influencing metal retention. Using a 2³ factorial matrix, the best performances for metal retention (99.8–100 % removal) were obtained by selecting a thickness of soil of 2.0 cm, an initial metal concentration of 50 mg L⁻¹ and 200 mL of metallic solution. The optimal experimental conditions for metal retention were then investigated using the Excel Solver program. Between 98.9 and 99.9 % of the metals were retained in subsequent experiments using these optimal conditions (soil thickness ranging between 10 and 14 cm and metal concentration of up to 300 mg L⁻¹ in 400 mL of metallic solution).

Untreated arsenic polluted groundwater is threatening people health, especially the people in rural areas. Soil may become one kind of promising natural material applied conveniently in rural areas for the treatment of arsenic polluted groundwater, due to its abundance, low cost, and high adsorption efficiency. The present study investigated arsenic(V) (As(V)) adsorption on two red soil samples weathered from granite (RSG) and sandstone (RSS). The two soil samples contain similar mineral types but show relatively high differences of content of iron, aluminum, and organic matter (OM), as well as point of zero charge (pHPZC) and specific surface area (SSA). Batch experiments were performed to examine the effect of initial As(V) concentration, solution pH, and temperature on the kinetics of the adsorption of As(V) by the two soil samples. The experimental results showed that the As(V) adsorption onto the two soil samples was influenced by the physicochemical properties of the soils, especially the content of iron and aluminum, the OM, as well as the pHPZC, and chemisorption was the main adsorption mechanism. The RSG sample with higher content of iron and aluminum and pHPZC showed relatively high adsorption efficiency. The OM played a negative role in the adsorption process, especially as the As/Fe molar ratio is higher. Higher adsorption capacities for the two soil samples were both obtained at lower initial As(V) concentration (1.50 and 4.0 mg/l), lower pH value (5.0), and higher temperature (313 K). Comparing to the RSS, the RSG is more suitable for the treatment of As(V)-polluted groundwater. Considering the experimental results and the natural conditions, the suggested operational conditions are pH around 7.0, temperature 293–303 K, As(V) concentration less than 4.0 mg/l, and hydraulic retention time no less than 180 min.

Airborne fine particulate matter (PM₂.₅) from five megacities including Beijing, Tianjin, Shijiazhuang, Baoding, and Jinan were collected during November 2014 and compared with similar periods in 2012 and 2013. The November 2014 period coincided with the Asia Pacific Economic Cooperation (APEC) Leaders Meeting during which measures to control pollution of the air were introduced. Concentrations of 11 elements in PM₂.₅ were quantified by inductively coupled plasma–mass spectrometry (ICP-MS) after microwave-assisted digestion. Potential effects of five toxic trace metals including Mn, Ni, Cu, Zn, Pb, and the metalloid As on health were assessed. In 2014, concentrations of PM₂.₅ were significantly less than during the same period in 2012 and 2013. Mean concentrations of six elements ranked in decreasing order, Zn > Pb > Cu ≈ Mn > As > Ni, and spatial concentrations ranked in decreasing order, Shijiazhuang > Baoding > Tianjin > Jinan > Beijing. Risks of the five metals and the metalloid As to health of humans were small, except for Mn in Shijiazhuang. Risks to health posed by other elements were less during the period of study. Risks posed by the five metals and As in Beijing were greater to varying degrees after the APEC meeting. Risks to health of humans during the APEC were overall lesser than the same period in 2012 and 2013, mostly due to lesser emissions due to the short-term control measures.

Nutrition and pollution stress stimulate genetic adaptation in microorganisms and assist in evolution of diverse metabolic pathways for their survival on several complex organic compounds. Persistent organic pollutants (POPs) are highly lipophilic in nature and cause adverse effects to the environment and human health by biomagnification through the food chain. Diverse microorganisms, harboring numerous plasmids and catabolic genes, acclimatize to these environmentally unfavorable conditions by gene duplication, mutational drift, hypermutation, and recombination. Genetic aspects of some major POP catabolic genes such as biphenyl dioxygenase (bph), DDT 2,3-dioxygenase, and angular dioxygenase assist in degradation of biphenyl, organochlorine pesticides, and dioxins/furans, respectively. Microbial metagenome constitutes the largest genetic reservoir with miscellaneous enzymatic activities implicated in degradation. To tap the metabolic potential of microorganisms, recent techniques like sequence and function-based screening and substrate-induced gene expression are proficient in tracing out novel catabolic genes from the entire metagenome for utilization in enhanced biodegradation. The major endeavor of today’s scientific world is to characterize the exact genetic mechanisms of microbes for bioremediation of these toxic compounds by excavating into the uncultured plethora. This review entails the effect of POPs on the environment and involvement of microbial catabolic genes for their removal with the advanced techniques of bioremediation.

Adsorption of the herbicide glyphosate and its main metabolite AMPA (aminomethylphosphonic acid) was investigated on 17 different agricultural soils. Batch equilibration adsorption data are shown by Freundlich adsorption isotherms. Glyphosate adsorption is clearly affected by equilibration concentrations, but the nonlinear AMPA adsorption isotherms indicate saturation of the adsorption sites with increasing equilibrium concentrations. pHCₐCₗ₂ (i.e. experimental pH) is the major parameter governing glyphosate and AMPA adsorption in soils. However, considering pHCₐCₗ₂ values, available phosphate amount, and amorphous iron and aluminium oxide contents by using a nonlinear multiple regression equation, obtains the most accurate and powerful pedotransfer rule for predicting the adsorption constants for these two molecules. As amorphous iron and aluminium oxide contents in soil are not systematically determined, we also propose a pedotransfer rule with two variables—pHCₐCₗ₂ values and available phosphate amount—that remains acceptable for both molecules. Moreover, the use of the commonly measured pHwₐₜₑᵣ or pHKCₗ values gives less accurate results compared to pHCₐCₗ₂ measurements. To our knowledge, this study is the first AMPA adsorption characterization for a significant number of temperate climate soils.

Agricultural practices are the main source of water contamination in rural areas. Rainfall events, and subsequently, soil leaching and storm runoff are mainly controlling the transfer of pollutants from diffuse sources in watersheds during floods. These periods are also very important to better understand their dynamics, particularly their different soil-river transfer pathways (surface runoff SR, subsurface runoff SSR, and groundwater flow GF). This study focuses on riverine transfers of both pesticides and trace elements. High-resolution monitoring of water discharge and water sampling were performed during a flood event that occured in May 2010 in an agricultural catchment of SW France. Chemical composition of major and trace elements, silica, alkalinity, pH and conductivity, DOC and POC, TSM, and commonly used pesticides were analyzed with a high sampling frequency. The different stream flow components (SR, SSR, and GF) were assessed using two independent hydrograph separation methods: a hydrological approach based on Maillet’s formula (1905) for the recession period and a chemical approach based on physico-chemical tracers, TSM for SR and PO₄³⁻ for GF. Both methods exhibited important contributions of SR (33 %) and SSR (40 %) to the total riverine pollutant transfers. The contribution of different components was also visible using concentration-discharge relationships which exhibited hysteresis phenomenon between the rising and the falling limbs of the hydrograph. Higher concentrations during the rising period (clockwise hysteresis) were characteristic of pollutants mainly exported by SR (trifluralin, Cd). Anticlockwise hysteresis with higher concentration during the recession period showed pollutants mainly exported by SSR (metolachlor, Cu). Moreover, significant relationships were highlighted between the controlling factors (DOC, POC, and TSM) and SR, SSR, and GF contributions: DOC and the complexed pollutants were highly correlated to SSR while POC, TSM, and the adsorbed pollutants were linked to SR. During the flood, K d of most pollutants increased, particularly at the beginning, and therefore, future studies should investigate their availability to living organisms and thus their toxicity. An additional characteristic equation between K d and K ₒw of the different pesticides was proposed to help future management, modelling, and estimation of pollutant transfers during floods.

Trimethylamine (TMA) is a volatile organic compound which causes not only unpleasant odor but also health concerns to humans. The average emission of TMA from food and fishery industries is 20.60 parts per billion (ppb) and emission from the gas exhausters is even higher which reaches 370 parts per million (ppm). In order to select the best plant TMA removal agent, in this study, 13 plants were exposed to 100 ppm of TMA and the remaining TMA concentration in their system was analyzed by gas chromatography (GC). Furthermore, plant metabolites from the selected plant were identified by gas chromatography-mass spectrometry (GC-MS). The result showed that Euphorbia milii was the most superior plant for TMA removal and could absorb up to 90 % of TMA within 12 h. E. milii absorbed TMA via leaf and stem with 55 and 45 % uptake efficiency, respectively. Based on its stomatal movement during the exposure to TMA, it was implied that the plant switched the photosynthetic mode from crassulacean acid metabolism (CAM)-cycling to CAM and CAM-idling. The switching of photosynthetic mode might reduce the stomata role in TMA absorption. Fatty acids, alkanes, and fatty alcohols in the plant leaf wax were also found to contribute to TMA adsorption. Leaf wax, stomata, and other leaf constituents contributed 58, 6, and 36 %, respectively, of the total TMA absorption by the leaf. The analysis and identification of plant metabolites confirmed that TMA was degraded and mineralized by E. milii.

The sorption behavior of 17α-ethinylestradiol by a surface-modified zeolitic tuff with hexadecyltrimethylammonium (HDTMA) was investigated. The zeolitic material (clinoptilolite) was treated with 0.1 M of sodium chloride solution and then with 25 and 50 mM of HDTMA solutions. The sorption kinetics shows that the maximum removal percentage of 96.87 % was reached at 36 h for the zeolite with 25 mM HDTMA, while with 50 mM of HDTMA, the maximum removal of 98.34 % was achieved at 44 h. Furthermore, pseudo-first-order, pseudo-second-order, and Elovich models were analyzed and the kinetic data exhibited a good fit with the pseudo-second-order model, indicating that the sorption mechanism is chemisorption. The isotherms for the sorption of 17α-ethinylestradiol showed that sorption capacity was 0.7073 and 0.6943 mg/g for 25 and 50 mM, respectively, at 25 °C and showed a partition mechanism. Moreover, the pH influence on the sorption process was studied and the sorption capacity was increased as the pH decreases.

The rheology of digested sludge affects the flow hydrodynamics, dewaterability, and the polymer consumption in wastewater treatment plants. The rheological characteristics of digested sludge are highly dependent on changes in total solid concentration, temperature, and polymer dose. Hence, this study aims at investigating the impacts of total solid concentration, temperature, and polymer dose on the rheological characteristics and the dewaterability of digested sludge. Investigating the relationship between rheological and physicochemical characteristics of sludge can also serve as a tool to optimize essential process parameters. Different homogenized digested sludge samples were subjected to rheological measurement on rotational stress-controlled rheometer equipped with Peltier concentric cylinder system. The shear stress–shear rate and viscosity–shear rate curves were then developed before and after polymer conditioning at various temperatures and solid concentrations. Different rheological model were fitted to the shear stress–shear rate and viscosity–shear rate rheograms, and the model with the best fitting and more practical significance was selected to determine key rheological parameters. The relationship between dewaterability and digested sludge rheology was also developed. The rheological characteristics of digested sludge during polymer conditioning and flocculation process was significantly affected by temperature and solid concentration; hence, polymer dose can be reduced by operating the dewatering process at optimum temperature condition and varying the polydose as a function of the total solid concentration and viscosity of the digested sludge. The dewaterability as measured in capillary suction time (CST) improved with increasing polymer dose up to 12 kg/t DS but further increase in polymer dose resulted in the deterioration of the dewaterability due to overdosing.