In a rapid urbanization context, socio-economic development has caused large increases in carbon emissions. In this study, various techniques such as cointegration analysis, vector autoregression, and decoupling elastic function methods are applied to analyze the sequential collaborative relationship between economic development and carbon emissions in the process of urbanization in terms of the time-series lag relationship and the decoupling relationship. The main findings are as follows: (1) urbanization and carbon emissions displayed a temporal correlation relation with a lag of order 4, according to stability tests, and (2) the development of urbanization, economic growth, and changes in land use may be responsible for the time lag in carbon emissions. Furthermore, the mechanisms behind the effect of urbanization on carbon emissions are investigated to assist future carbon emissions reduction efforts. (3) From 1990 to 2014, carbon emissions and economic development showed a temporal evolution trend of “weak decoupling–expansionary coupling–weak decoupling” in the Pearl River Delta region, and there was an overall weak decoupling state: carbon emissions increased with growth in economic development, but the emissions growth rate was lower than the speed of economic development. (4) From 1990 to 2014, economic development showed a trend of sustained growth in the Pearl River Delta region, and differences were detected in the decoupling status between carbon emissions and economic development at different times. The overall decoupling status of the nine cities in the region was one of weak decoupling; however, the decoupling index, carbon emissions, and economic development levels displayed differences, whereby cities with high carbon emissions and high economic development levels were not necessarily the cities in which environmental pressures from economic development were the most severe. Our results have important theoretical and practical significance as they clarify the impact of economic development on carbon emissions in the process of urbanization, as well as the carbon emissions reduction work that must be undertaken in urban systems.

The present study reports the use of Citrus limetta (CL) residue for cultivating Chlorella sp. mixotrophically to augment production of biodiesel. The cultivation of Chlorella sp. using CL as media was carried out by employing a fed-batch technique in open tray (open tray+CL) and in software (BioXpert V2)–attached automated photobioreactor (PBR+CL) systems. Data showed the limit of nitrogen substituent and satisfactory organic source of carbon (OSC) in CL, causing > 2-fold higher lipid content in cells, cultivated in both the systems than in control. For the cells grown in both the systems, ≥ 3-fold enhancement in lipid productivity was observed than in control. The total fatty acid methyl ester (FAME) concentrations from lipids extracted from cells grew in PBR+CL and in open tray+CL techniques were calculated as 50.59% and 38.31%, respectively. The PBR+CL system showed improved outcomes for lipid content, lipid and biomass productivity, FAME characteristics and physical property parameters of biodiesel than those obtained from the open tray+CL system. The physical property parameters of biodiesel produced from algal cells grown in PBR+CL were comparable to existing fuel standards. The results have shown lower cold filter plugging point (− 6.57 °C), higher cetane number (58.04) and average oxidative stability (3.60 h). Collectively, this investigation unveils the novel deployment of CL as a cost-effective feedstock for commercialisation of biodiesel production.

Cadmium (Cd) is absorbed readily by rice plants and is transferred to humans when contaminated rice is consumed. Adding selenium (Se) to the plant nutrient solutions reduces the accumulation of Cd in the rice (Oryza sativa L.) seedlings. However, as the relevant underlying mechanism remains unclear, the aim of our study was to improve our understanding of the Se-mediated resistance to Cd stress in rice. We conducted hydroponic experiments to study the effects of selenite or selenate on Cd subcellular distribution and xylem transport in rice seedlings under Cd stress, and we investigated the antioxidative defense responses in the rice plants. We found that the supplementation of both Se forms decreased the Cd accumulations in the roots and shoots of the rice plants. The selenite addition significantly decreased the Cd contents in different subcellular fractions of the rice roots, increased the proportion of Cd distributed to soluble cytosol by 23.41%, and decreased the Cd distribution in the organelle by 28.74% in contrast with the treatment with Cd only. As regards the selenate addition, only the Cd distribution ratio of cytosol was increased by 13.07%. After adding selenite, a decrease of 55.86% in the Cd concentration in xylem sap was observed, whereas little change was found after treatment co-applied with selenate. The hydrogen peroxide (H₂O₂) and malondialdehyde(MDA) contents in the rice roots were elevated under Cd stress, and the addition of selenite and selenate decreased the H₂O₂ levels by 77.78% and 59.26%, respectively. Co-exposure to Cd and Se elevated the glutathione (GSH) accumulations in the rice shoots and roots, with the degree of increase being the following: co-applied with selenite > co-applied with selenate > Cd alone treatment. Exposure to Cd increased the catalase (CAT) activity in the roots significantly, whereas it decreased in the shoots. After selenite or selenate supplementation, the CAT activity in the rice roots increased compared with applying only Cd. Compared with the control, the addition of Cd or Se had no significant effect on the activities of peroxidase (POD) or ascorbate peroxidase (APX). Our results showed that Se affected the Cd accumulation in rice seedlings by altering the Cd subcellular distribution and decreasing the ROS induced by Cd stress. Such effects were more significant in the selenite than in the selenate applied treatment.

The Sub-Saharan Africa (SSA) is far lag behind the sustainable targets that set out in the United Nation’s Sustainable Development Goals (SDGs), which is highly needed to embark the priorities by their member countries to devise sustainable policies for accessing clean technologies, energy demand, finance, and food production to mitigate high-mass carbon emissions and conserve environmental agenda in the national policy agenda. The study evaluated United Nation’s SDGs for environmental conservation and emission reduction in the panel of 35 selected SSA countries, during a period of 1995–2016. The study further analyzed the variable’s relationship in inter-temporal forecasting framework for the next 10 years’ time period, i.e., 2017–2026. The parameter estimates for the two models, i.e., CO₂ model and PM₂.₅ models are analyzed by Generalized Method of Moment (GMM) estimator that handle possible endogeneity issue from the given models. The results rejected the inverted U-shaped Environmental Kuznets Curve (EKC) for CO₂ emissions, while it supported for PM₂.₅ emissions with a turning point of US$5540 GDP per capita in constant 2010 US$. The results supported the “pollution haven hypothesis” for CO₂ emissions, while this hypothesis is not verified for PM₂.₅ emissions. The major detrimental factors are technologies, FDI inflows, and food deficit that largely increase carbon emissions in a panel of SSA countries. The IPAT hypothesis is not verified in both the emissions; however, population density will largely influenced CO₂ emissions in the next 10 years’ time period. The PM₂.₅ emissions will largely be influenced by high per capita income, followed by trade openness, and technologies, over a time horizon. Thus, the United Nation’s sustainable development agenda is highly influenced by socio-economic and environmental factors that need sound action plans by their member countries to coordinate and collaborate with each other and work for Africa’s green growth agenda.

Transport sector contributed numerous carbon emissions in China. It is important to promote low-carbon bicycle-sharing using in China. This paper aims to analyze the influencing factors of the satisfaction and engagement of bicycle-sharing in China. An extended model of customer satisfaction is established, which considers both customer satisfaction theory and customer engagement theory. We explore the different effect of convenience, health, safety, and facility on satisfaction of bicycle-sharing using. We also explore the role of satisfaction on three different dimensions of engagement: enthusiasm, participation, and social interaction. Multi-group structure equation model is employed to explore the different roles of gender on the determinants of satisfaction and engagement of bicycle-sharing using. The findings reveal that facilities had the larger effect on satisfaction of bicycle-sharing using than safety and health for male. Safety had the largest influence on satisfaction of bicycle-sharing using for female, followed by facility, convenience, and health.

Excess nitrogen in the ecosystem could result in eutrophication and harmful algal bloom in an ecosystem. Low impact development (LID) facilities, regarded as an integral part of green infrastructures for flow control and water quality management may include, but are not limited to, dry/wet ponds, green roof, bioswale or linear ditch, vegetated natural strip, exfiltration trench, piping networks with underdrain or reuse options, and bioswale. This study presents a new approach using a linear ditch along a roadside for LID with the aid of two green sorption media that are designed for co-treatment of stormwater and groundwater for nutrient removal. The stormwater is primarily from agricultural discharge and transportation stormwater runoff. Two recipes of green sorption media, including the green sorption media and woodchip, were examined and compared through a laboratory-scale column study and a field-scale test bed media under various influent concentrations and flow conditions. The green sorption media were found more appropriate than the woodchip media for field-scale applications because the green sorption media may exhibit long-standing microenvironments and hydraulic patterns to provide a homogeneous hydraulic retention time and infiltration rate for nutrient removal. Therefore, such a new LID practice may not only mitigate the impact from various surface stormwater runoffs but also co-treat groundwater and stormwater for nutrient removal.

In the study, an activated carbon was prepared by co-pyrolyzing rice straw and sewage sludge with ZnCl₂ activation (SS-RS AC) and used to remove Cr(VI) from wastewater. Firstly, for the preparation of SS-RS AC, the yield and iodine number were used to determine the appropriate addition percentage of rice straw. Then, a series of batch experiments including initial pH, adsorption kinetics and isotherms, and ionic strength as well as Fourier transform infrared (FT-IR) analysis of SS-RS AC before and after adsorption were performed to explore the Cr(VI) adsorption removal behavior and mechanism of SS-RS AC prepared from sewage sludge with the appropriate rice straw addition percentage. The results showed that the appropriate addition percentage of rice straw was 20%. For the Cr(VI) adsorption removal with SS-RS AC, the initial pH of solution significantly influenced the removal efficient. The highest efficiency of Cr(VI) adsorption removal (97.7%) could be attained at pH 2.0. The adsorption kinetics and isotherm data were best fitted by the pseudo-second-order model and the Langmuir-Freundlich model, respectively. The prepared SS-RS AC had the maximum Cr(VI) adsorption removal capacity of 138.69 mg/g at 40 °C. The main mechanisms for the Cr(VI) removal with SS-RS AC involve the electrostatic attraction and the reduction of Cr(VI). Carboxy, amine, and hydroxyl groups were found to act as electron donor groups, contributing to the reduction of Cr(VI). The ionic strength had an adverse effect on the Cr(VI) removal. Overall, the prepared SS-RS AC can be used as an alternative and low-cost adsorbent for the removal of Cr(VI).

The effects of solid content (10–80 g/L) on the bioleaching of heavy metals (HMs) from pig manure (PM) were investigated using indigenous sulfur-oxidizing bacteria. The results showed that an increase in solid content increased the PM buffering capacity, which slowed the rates of pH reduction, ORP increase, and sulfur oxidation and decreased the solubilization efficiency of HMs from PM. Approximately 75–99% of Cu, 76–99% of Zn, and 55–88% of Mn were leached from PM with solid contents of 10–80 g/L after 28 days of bioleaching. However, the content of HMs in bioleached manure did not meet the requirement for agricultural application when the solid content was ≥ 60 g/L after 28 days of bioleaching. The solubilization of HMs from PM was well-described by a kinetic equation. Regression analysis showed that Cu solubilization was primarily controlled by ORP, and pH seemed to be the sole factor responsible for the solubilization of Zn and Mn. Additionally, nutrient (N, P, K, and organic matter) loss significantly increased when PM solid content decreased from 40 to 20 g/L. Therefore, the recommended solid content for the bioleaching of HMs from PM is 40 g/L.

Environmental reservoirs of fecal indicator bacteria (FIB) are attracting increasing attention because of the ambiguity they present when assessing the microbial quality of water. FIB can survive and even grow in various environmental reservoirs which means FIB measured in the water column may not have originated directly from a fecal source. Sediment and periphyton, i.e., aquatic biofilms growing on submerged rocks, have been shown to harbor large populations of FIB in the environment. However, little is known about the spatial and temporal dynamics of FIB in periphyton. The objective of this work was to determine levels of the common FIB, Escherichia coli and enterococci, in creek water, sediment, and periphyton during the summer and winter. FIB were measured during two summer and winter sampling dates at five locations along a 2.8-km stretch of creek in Beltsville, Maryland. Significant differences in FIB by location were only observed for E. coli in water at one time point. Levels of FIB significantly declined from summer to winter in all media. FIB concentrations in periphyton ranged from 10² to 10⁴ gdw⁻¹ in the summer and from 10⁰ to 10⁴ CFU gdw⁻¹ in the winter. When compared on a dry weight basis, periphyton contained higher concentrations of FIB than the sediment. Variability of FIB was in the order of water < sediment < periphyton. Levels of E. coli and enterococci measured in the same sample showed significant positive correlation in all media (rₛ = 0.87, 0.48, 0.70, for water, sediment, and periphyton, respectively). Results from this work show that fecal bacteria can persist in creek periphyton which may act as both a reservoir for fecal pathogens as well as a probable source of fecal bacteria to the water column.

Recent efforts to aggregate, process, and use biodiversity information have appended novel opportunities and challenges for the field, and a rapid increase in studies that integrate and analyze data in the biological-ecological realm. We developed a web-based GIS system for the wildlife of Khouzestan Province that provides potential distribution maps and other spatial and nonspatial data on the wildlife of Khouzestan Province and its protected areas. We used MaxEnt and a fuzzy inference system to model distributions of species. Our application was structured using a client/server architecture, and the database design and construction was carried out using PostgreSQL/PostGIS, and GeoServer to serve maps. The mapping interface was developed using OpenLayers; ASP.NET was selected for designing the user interface. We used qualitative-quantitative methods to develop, design, refine, and finalize our system particularly as regards usability. The design approach resulted in a user-friendly interface that allows both specialists and non-specialists to quickly and efficiently run models to estimate potential distributions of species. Our application highlights what can be accomplished with a biodiversity-oriented web application.