As China and other developing countries continue to urbanize over the next decades, construction and demolition waste (CDW) management has been becoming a significant challenge for urban sustainability in terms of the environment, economy, and safety. However, accurate estimations or statistics of CDW generation are absent from the official national report in spite of their importance to devise sensible interventions to tackle CDW-related problems. This paper examines and compares the applications of three prevailing methods for estimating CDW, including the weight-per-construction-area method (WAM), buildings’ life span-based method, and weight-per-capita method. Specifically, China has been chosen as the case study. This study implies that the weight-per-construction-area method is more appropriate because of the data availability and accuracy at a city or national level. The results of WAM indicate that a total of 4.1 billion metric tons (Bt) of CDW were generated in China in 2016, mainly from demolition waste (85%). Taking the changes of buildings’ life span into account, a projection analysis reveals that the cumulative CDW generation will be 50 Bt between 2017 and 2040 in China (equal to approximately 38 years cumulative generation of global municipal solid waste). Overall, the findings provide some methodological options for scholars, practitioners, and decision-makers to more accurately estimate the amount of the CDW and to develop a more environmentally sound management strategy.

Rice fallow, a rainfed lowland agro-ecology, is presently gaining particular attention for sustainable cropping intensification in the South Asia. Nevertheless, cropping intensification of rice-fallow areas is largely challenged by non-availability of irrigation, the poor financial status of farmers and soil constraints. Indeed, fast depletion of the soil residual moisture remains the primary obstacle for growing a crop in succession in rice fallows. A field investigation was carried out to identify the most adaptable rice-winter crop rotation and to customize appropriate crop establishment practice for a winter crop that could conserve the soil moisture. Treatments comprised of three crop establishment practices for winter crops [utera (relay cropping, i.e. broadcasting of seeds in standing rice crop 15 days before harvesting), zero tillage (ZT) and ZT with mulching (ZTM)], and five post-rainy-season crops (lentil, chickpea, lathyrus, mustard and linseed). Results showed that lathyrus and lentil could be the potential winter crop in the rice-fallow condition of Eastern India. Except for mustard crop, the productivity of all the winter crops was higher in utera cropping, which was primarily attributed to early crop growth and higher soil moisture content over ZT and ZTM treatments. The higher water use efficiency was recorded under utera cropping over ZT and ZTM treatments. Higher system productivity (system rice equivalent yield) in rice–utera lathyrus (9.3 t ha⁻¹) and rice–utera lentil (8.1 t ha⁻¹) led to higher net returns and production efficiency over other treatments (winter crop × crop establishment practice). Benefits of rice residue mulching were prominent in lentil, mustard and linseed crop productivity. Energy use efficiency of different crop establishment practices follows the trend of utera > ZT > ZTM (p < 0.05), being highest in rice–utera lathyrus (5.3) followed by rice–utera lentil (4.8) crop rotations. The simulated data shows that winter crops grown under utera led to less emission of greenhouse gas (GHG) and low global warming potential (GWP) as compared to ZT and ZTM treatments. Rice–lathyrus, rice–lentil and rice–chickpea systems had lower N₂O emission than rice–mustard and rice–linseed rotations. Hence, lathyrus and lentil could be included in rice fallows ideally with utera for sustainable cropping intensification and improving the farmers’ income in Eastern India.

The combined treatment systems have become a potential alternative to treat highly polluted industrial wastewater to achieve high-quality treated effluents. The current review focuses on the treatment systems compromising electrocoagulation (EC) as a pretreatment step followed by a biological treatment step. The reasons for applying EC as a pretreatment process were mainly to (1) detoxify the wastewater by removing inhibitors of the biotreatment step or (2) to remove the major part of the COD or (3) the dissolved materials that could cause fouling to membrane bioreactors or (4) to increase the activity of the microorganisms. This combination represents a new and promising application characterized by higher performance and removal efficiency. The main published findings related to this application are presented and analyzed. Besides, the statistical models used to optimize the process variables and the kinetics of microorganism growth rate are discussed herein. Most of the previous investigations were conducted in a laboratory-scale level with biologically treated water as a feed to the EC process. Only a few works applied a hybrid system consisting of the biological step and the EC step. In all studies, improved performance and higher removal efficiencies of the combined process were achieved particularly when applying aluminum electrodes, providing more than 95% removal efficiency. Many researchers have reported that they had faced a significant problem in the operation of the electrocoagulation process associated with the reduction of electrodes’ efficiency caused by deposits of the coagulation complex. This problem needs to be effectively resolved.

The selection of shade trees with appropriate spacing is important for minimising their impact on nutrient accumulation by understorey cash crops in agroforestry systems. Cocoa trees may be intercropped with overstorey legume or non-legume shade trees. A legume tree and/or a non-legume timber tree with edible kernels (Gliricidia sepium and Canarium indicum, respectively) are used as shade trees in cocoa plantations particularly in Papua New Guinea. This study explored the nutrient concentrations of cocoa beans in response to both tree-shade species and shade-tree spacing regime. The study also investigated the extent to which C. indicum tree spacing altered the nutrient concentrations of canarium kernels. G. sepium trees in the study had a final spacing of 12 m × 12 m while the spacing regimes of either 8 m × 8 m or 8 m × 16 m used for C. indicum. The calcium (Ca) concentrations of cocoa beans did not differ significantly between plants located next to G. sepium and plants located next to C. indicum. Cocoa beans next to C. indicum trees with spacing of 8 m × 16 m had higher potassium (K) concentrations than those next to G. sepium trees. However, phosphorus (P) concentrations of cocoa beans next to C. indicum trees with spacing of 8 m × 8 m or next to G. sepium trees were significantly higher than those next to C. indicum trees with spacing of 8 m × 16 m. The K concentrations in cocoa beans and soil were not correlated nor were the P concentrations in cocoa beans and soil. Correlations between nutrients in leaves and cocoa beans, or between leaves and canarium kernels, were not strong. Our results suggest that cocoa and canarium trees can be intercropped successfully, and that they do not compete for soil nutrients.

The magnetic properties of particulate matter (PM) deposited on the needles of Juniperus formosana along an urban street in Lanzhou city were measured to evaluate the variations of PM concentration in different seasons by varying distance from the road. The magnetism of PM deposited in this context was significantly higher in winter than in summer, which may reflect changes of atmospheric particle concentrations. Needle samples which were collected from the road-facing side exhibiting significantly stronger magnetism compared with those which were collected from the opposite side of the road, indicating the distance from pollution source to the needles as a factor controls the amount of PM. The results of this study show that the needles of Juniperus formosana are effective traps for PM and can therefore be used to monitor pollution fluxes in different seasons in an important urban context in NW China.

Diffuse nitrate pollution in groundwater is currently considered one of the major causes of water quality degradation. Determining the sources of nitrate contamination is an important first step for a better management of water quality. Thus, the isotopic composition of nitrate (δ¹⁵NNO₃ and δ¹⁸ONO₃) and boron (δ¹¹B) were used to evaluate nitrate contamination sources and to identify geochemical processes occurring in the shallow and deep aquifers of the Turin-Cuneo plain (NW Italy). The study area is essentially an agricultural zone, where use of synthetic nitrogenous fertilizers and organic manure is a common practice and the connection to sewer services is locally lacking. Also livestock farming are highly developed. A groundwater sampling campaign was performed on 34 wells in the shallow aquifer and 8 wells in the deep aquifers, to analyze nitrate, chloride, boron, δ¹⁵NNO₃, δ¹⁸ONO₃ and δ¹¹B. Isotope data of nitrate indicate that nitrate contamination in the Turin-Cuneo plain originates from mixtures of synthetic and organic sources, slightly affected by denitrification, and manure or septic tank effluents. Moreover, boron isotopes were used to discriminate further among the main anthropogenic sources of pollution. The analyses results confirm that both animal manure and domestic sewage, especially under the city of Turin, can contribute to the nitrate contamination. The isotope analysis was also used for the evaluation of denitrification and nitrification processes: contrary to expectations, a significant denitrification phenomenon was assessed only in the shallow unconfined aquifer, especially in the Poirino Plateau, the most contaminated sector of the study area.

In the current study, the toxicity bioassay of three pollutants abamectin (ABM), thiamethoxam (TMX), and acrylamide (ACR) against land snails Theba pisana was measured. Also, the ecotoxicological effects of dietary exposure to sublethal concentration (1/20 LC₅₀) of these pollutants for 2-week exposure and 1-week recovery on some physiological endpoints evaluated as feeding activity, growth response, and carbonic anhydrase activity as a marker in charge of shell formation and seromucoid level as a marker in charge of mucus synthesis of the snails were studied. The results exhibited that the 48-h LC₅₀ values were 0.91, 313.8, and 45.7 μg/g dry food for ABM, TMX, and ACR, respectively. The sublethal concentrations of these pollutants in the diet after 2-week exposure were found to reduce the food consumption and inhibit growth rate of the snails. Also, the data illustrated that carbonic anhydrase activity was significantly decreased. On the other hand, there was a significant increase in the seromucoid level as a marker responsible for mucus synthesis in ABM- and TMX-exposed snails, while ACR showed significantly decreased level when compared to control. After 1-week recovery, the tested endpoints of treated snails were slightly repaired but still less than that of the untreated animals. The overall outcome of this investigation suggests the utility of this animal as a good bioindicator organism for ABM, TMX, and ACR exposure in pollution monitoring studies.

Silver nanoparticles (AgNPs) were prepared by reacting Kyllinga brevifolia extract (KBE) with AgNO₃ aqueous solution at room temperature (22 ± 3 °C). The phytochemical constituents in KBE responsible for the reduction process were identified as carbohydrate, protein, and plant sterols (stigmasterol and campesterol). KBE was also found to function as a capping agent for stabilization of AgNPs. The AgNPs were stable at room temperature and had a quasi-spherical shape with an average particle size 22.3 nm. The use of KBE offers not only eco-friendly and non-pathogenic path for AgNPs formation, it also induced rapid formation of the AgNPs. Methylene blue (MB) removal was then done on the AgNPs in the presence of either KBE or NaBH₄. Ninety-three percent removal of MB was achieved with a rate of reaction 0.2663 min⁻¹ in the solution with KBE+AgNPs (pH 2). However, in NaBH₄+AgNPs system, 100% MB removal was achieved at pH 8–10. The reaction rate was 2.5715 min⁻¹ indicating a fast removal rate of MB dye. The process of reduction occurs via electron relay effect whereas in KBE+AgNPs system, sedimentation occurred along with the reduction process. Nevertheless, the use of KBE+AgNPs system is preferred as the reducing agent is more benign to the environment.

The goals of this paper are to examine whether the environmental Kuznets curve (EKC) holds and to investigate whether renewable energy consumption can decrease CO₂ emissions in the USA using monthly data spanning the period 2000:M01–2018:M07. For these purposes, the paper employs a cointegration test with a regime shift and observes the long-run coefficients before and after the regime shift. The findings support the presence of the EKC. The findings also indicate that renewable energy consumption has negative effects on CO₂ emissions, while these effects are greater when the share of renewable energy consumption in total energy consumption is higher in the USA. Theoretical and practical implications for these findings are discussed.

Simultaneous removal of coexisting metals and dyes from industrial wastewaters is challenging, and the mutual effects behind the co-adsorption of these pollutants remain unclear. Herein, interlayer-expanded MoS₂ (IE-MoS₂) nanosheets prepared by a one-pot simple and scalable method were tested to simultaneously remove toxic metals and cationic dyes. The adsorption capacities of IE-MoS₂ nanosheets were 499, 423, 500, 355, and 276 mg/g for Pb(II), Cu(II), methylene blue, malachite green, and rhodamine B, respectively, in a mono-contaminant system. Interestingly, the sequestration amount of Pb(II) was dependent on the concentrations of dyes in the binary Pb(II)−dye systems, while uptake of cationic dyes was almost not influenced by coexisting Pb(II). The simultaneous adsorption mechanism was further confirmed by spectroscopic methods. The IE-MoS₂ nanosheets were easily regenerated and reused for six adsorption−desorption cycles without structure destruction, thus avoiding the potential hazards of nanomaterial to the ecosphere. More interestingly, high-efficiency uptake of Pb(II) from intentionally contaminated natural water and model textile effluent was obtained by using a column filled with IE-MoS₂ nanosheets. In summary, IE-MoS₂ nanosheets with facile and scalable synthesis method, efficient adsorption performance, and excellent reusability showed potential promise for the integrative treatment of complex wastewater bearing both metals and organic pollutants.