This study estimates the short- and long-run effects of Internet usage and economic growth on carbon dioxide (CO₂) emissions using annual time series macro data for Australia for the period 1985–2012. Autoregressive distributive lag (ARDL) bounds and Gregory–Hansen structural break cointegration tests are applied. ARDL estimates indicate no significant long-run relationship between Internet usage and CO₂ emissions, which implies that the rapid growth in Internet usage is still not an environmental threat for Australia. The study further indicates that higher level of economic growth is associated with lower level of CO₂ emissions; however, Internet usage and economic growth have no significant short-run relationship with CO₂ emissions. Financial development has both short-run and long-run significant positive association with CO₂ emissions. The findings offer support in favor of energy efficiency gains and a reduction in energy intensity in Australia. However, impulse response and variance decomposition analysis suggest that Internet usage, economic growth and financial development will continue to impact CO₂ emissions in the future, and as such, this study recommends that in addition to the existing measures to combat CO₂ emissions, Australia needs to exploit the potential of the Internet not only to reduce its own carbon footprint but also to utilize information and communication technology (ICT)-enabled emissions abatement potential to reduce emissions in various other sectors across the economy, such as, power, renewable energy especially in solar and wind energy, agriculture, transport and service.

This study proposes a model-based evaluation of the effect of different operating conditions with and without pre-denitrification treatment and applying three different solids retention times on the fouling mechanisms involved in membrane bioreactors (MBRs). A total of 11 fouling models obtained from literature were used to fit the transmembrane pressure variations measured in a pilot-scale MBR treating real wastewater for more than 1 year. The results showed that all the models represent reasonable descriptions of the fouling processes in the MBR tested. The model-based analysis confirmed that membrane fouling started by pore blocking (complete blocking model) and by a reduction of the pore diameter (standard blocking) while cake filtration became the dominant fouling mechanism over long-term operation. However, the different fouling mechanisms occurred almost simultaneously making it rather difficult to identify each one. The membrane “history” (i.e. age, lifespan, etc.) seems the most important factor affecting the fouling mechanism more than the applied operating conditions. Nonlinear regression of the most complex models (combined models) evaluated in this study sometimes demonstrated unreliable parameter estimates suggesting that the four basic fouling models (complete, standard, intermediate blocking and cake filtration) contain enough details to represent a reasonable description of the main fouling processes occurring in MBRs.

Chlorpyrifos (CHL) is an organophosphate compound that is widely used as an insecticide. Due to its repeated use and high environmental residual property, CHL is frequently passed into aquatic environments by runoff. Consequently, there may be an adverse effect on aquatic vertebrate animals, including fish. Therefore, in this study, we assessed how CHL affected Japanese medaka (Oryzias latipes). The acute toxicity of CHL in adult fish after 96 h of exposure was determined to be 212.50, 266.79, and 412.28 μg L⁻¹ (LC₂₅, LC₅₀, and LC₉₅, respectively). Acetylcholinesterase (AChE), glutathione S-transferase (GST), and carboxylesterase (CE) activities were obtained from the livers of dead or surviving fish, and the results showed 4.8-fold lower, 4.5-fold higher, and 18.6-fold lower activities for the AChE, GST, and CE, respectively, for 64-h exposure at a concentration of 400 μg L⁻¹ of CHL. In the embryo toxicity test, curved spines were observed in embryos that were exposed to CHL for 48 h in a concentration-dependent manner. With identification of biomarkers for CHL in the fish, two protein peaks, 5550.86 and 5639.79 m/z, were found to be upregulated. These two proteins can be used as protein biomarkers for CHL contamination in aquatic systems. A phosphatidyl choline with an m/z ratio of 556.32 dramatically decreased after CHL exposure in the fish; thus, it may be considered as a lipid biomarker for CHL. It is assumed as the first report to identify a phospholipid biomarker using a lipidomics approach in fish toxicology. Taken together, these results demonstrated the adverse effects of CHL on Japanese medaka and reveal several candidate biomarkers that can be used as diagnostic tools for determining CHL.

Fly ash and slag are important by-products obtained from combustion of municipal sewage sludge (MSS) after pelletization. The quantitative environmental impact assessment of heavy metals in fly ash and slag, compared to MSS, were performed in accordance with bioavailability and eco-toxicity, geo-accumulation index (GAI), risk assessment code (RAC), and potential ecological risk index (PERI). The results demonstrated that not only direct but also long-term bioavailability and eco-toxicity of heavy metals in fly ash and slag decreased except direct bioavailability and eco-toxicity of Pb in fly ash. The GAI demonstrated that combustion significantly weakened (P < 0.05) the pollution levels of heavy metals. PERI indicated that all risks attributed to heavy metals were significantly lowered (P < 0.05) from 777.07 (very high risk) in MSS to 288.72 (moderate risk) and 64.55 (low risk) in fly ash and slag, respectively. In terms of the RAC, seven heavy metals had low even no risk to the environments after combustion besides As in slag. The environmental risk of heavy metals in fly ash and slag was decreased compared with MSS. However, the results of PERI showed that fly ash had a moderate risk.

The response specificity of three metallothionein (MT) genes (CdMT, CuMT and Cd/CuMT) was assessed after long-term exposure (20 days) of Cantareus aspersus eggs to cadmium (Cd) (2 to 6 mg/L) or to the fungicide Bordeaux mixture (BM) (2.5 and 7.5 g/L). MT gene expression measured by quantitative real-time PCR (qRT-PCR) revealed that in the unexposed embryos, the transcript levels of the three MT genes decreased significantly through embryonic development. However, the CdMT gene was strongly upregulated with increasing Cd exposure concentration, whereas the transcript levels of the other two genes increased less pronouncedly, but significantly above an exposure concentration of 4 mg Cd/L. Upon exposure to BM, all three MT genes were significantly upregulated above a BM concentration of 2.5 g/L. It is concluded that long-term Cd exposure in hatched snails induced patterns of MT gene expression that differed from those obtained after short-term exposure (24 h).

Polybrominated diphenyl ethers (PBDEs) are known as ubiquitous pollutants in ecological systems and thus pose a great threat to the health of humans and other organisms due to their bioamplification and bioaccumulation along the food chain. The present study was designed to investigate the biosorption capacity of biochar for the removal of 4-monobromodiphengl ether and its synergistic effect when used as a carrier to immobilize the 4-monobromodiphengl ether-degrading strain Sphingomonas sp. DZ3. The raw biochar material was prepared by pyrolyzing maize straw at 350 °C under oxygen-limited conditions. The maximum biosorption capacity of biochar for 4-bromodiphengl ether was determined to be 50.23 mg/L under an initial concentration of 800 mg/L at pH 7.0 and 40 °C. The data obtained from the biosorption studies were fitted successfully with the pseudo-first-order kinetic and Freundlich isotherm models. The Weber–Morris model analysis indicated that intraparticle diffusion was the limiting step in the biosorption of 4-bromodiphengl ether onto the biosorbent. The values of thermodynamic parameters △G0 were calculated as −24.61 kJ/mol (20 °C), −24.35 kJ/mol (30 °C), and −23.98 kJ/mol (40 °C), △S ⁰ was −8.45 kJ/mol/K, and △H ⁰ was 21.36 kJ/mol. The artificial neural network analysis indicated that the initial concentration appeared to be the most influential parameter on the biosorption processes. The removal rate of 4-bromodiphengl ether achieved using the biochar-microorganism system was increased by 63 and 83 % compared with the rates obtained with biochar and the strain individually, respectively. The morphology of the biochar and immobilized strain was determined using a scanning electron microscope, and information of the surface functional groups of biochar was obtained through an infrared spectra study.

A comprehensive analysis of heavy metal speciation, risk, and bioavailability in the sediments of three rivers in northern China (Shaocun River (SR), Wangyang River (WR), and Xiao River (XR)) was conducted. The results showed that higher pollution input resulting from urbanization and industrialization caused higher heavy metal contents and bioavailable proportion in the studied sediments. Total contents of all studied metals (Cr, Cu, Ni, Pb, and Zn) in the sediments of SR, WR, and XR were 270.31, 902.62, and 2367.46 mg/kg, respectively. The average percentages of bioavailable fractions were 31.16, 61.73, and 81.69 %, respectively. Cr, Ni, and Pb were all mainly observed in the B4 (residual) fraction in the studied sediments, with an average percentage of 42.03, 48.19, and 55.08 %, respectively. Cu was mainly observed in the B2 (reducible) fraction (40.53 %). Zn was mainly observed in the B1 (exchangeable/acid soluble/carbonate) fraction (36.01 %), resulting in medium or high risk associated with Zn in the sediments of SR, WR, and XR. Sedimentary heavy metal risk and bioavailability associated with regional urbanization and industrialization should be taken into consideration with respect to the health of aquatic ecosystems.

Steel slag has been widely used as amendment and silicon fertilizer to alleviate the mobility and bioavailability of heavy metals in soil. The objective of this study was to evaluate the influence of particle size, composition, and application rate of slag on metal immobilization in acidic soil, metals uptake by rice and rice growth. The results indicated that application of slag increased soil pH, plant-available silicon concentrations in soil, and decreased the bioavailability of metals compared with control treatment, whereas pulverous slag (S1) was more effective than granular slag (S2 and S3). The acid-extractable fraction of Cd in the spiked soil was significantly decreased with application of S1 at rates of 1 and 3 %, acid-extractable fractions of Cu and Zn were decreased when treated at 3 %. Use of S1 at both rates resulted in significantly lower Cd, Cu, and Zn concentrations in rice tissues than in controls by 82.6–92.9, 88.4–95.6, and 67.4–81.4 %, respectively. However, use of pulverous slag at 1 % significantly promotes rice growth, restricted rice growth when treated at 3 %. Thus, the results explained that reduced particle size and suitable application rate of slag could be beneficial to rice growth and metals stabilization.

A field experiment was conducted to examine the degradation and impact of two post-emergence herbicides (imazethapyr and quizalofop-p-ethyl) on soil ecosystems at a half recommended rate (HRE), recommended rate (RE), and double recommended rate (DRE) during kharif peanut cultivation. Herbicides were innocuous to soil microbial activity at HRE, however, showed some significant influences at RE and DRE, and exerted temporary toxic effects on microbial biomass carbon and fluorescein diacetate hydrolyzing activity. Dehydrogenase activity also declined for a shorter period except imazethapyr application at DRE. Acid phosphatase activity was inhibited whereas alkaline phosphatase activity fluctuated between promotion and inhibition, but promotion was predominant suggesting a direct role of alkaline soil environment. Soil NH₄ ⁺ and NO₃ ⁻ nitrogen were increased by the herbicides at initial (after 7 days) and last phases (after 30 days), respectively. After an early period of inhibition, urease activity returned to the control level after 30 days. Dissipation of imazethapyr residues fitted best to bi-exponential order rate kinetics at DRE and RE, whereas it followed first-order rate kinetics at HRE. The residues of quizalofop-p-ethyl were found only up to 1 day after application suggesting its rapid conversion to active acid metabolites. Both the herbicides had transient harmful effects on most of the soil microbiological parameters.

The characterization of suitable microsites for tree seedling establishment and growth is one of the most important tasks to achieve the restoration of native forest using natural processes in disturbed sites. For that, we assessed the natural Quercus petraea forest expansion in a 20-year-old reclaimed open-cast mine under sub-Mediterranean climate in northern Spain, monitoring seedling survival, growth, and recruitment during 5 years in three contrasting environments (undisturbed forest, mine edge, and mine center). Seedling density and proportion of dead branches decreased greatly from undisturbed forest towards the center of the mine. There was a positive effect of shrubs on Q. petraea seedling establishment in both mine environments, which increase as the environment undergoes more stress (from the mine edge to the center of the mine), and it was produced by different shrub structural features in each mine environment. Seedling survival reduction through time in three environments did not lead to a density reduction because there was a yearly recruitment of new seedlings. Seedling survival, annual growth, and height through time were greater in mine sites than in the undisturbed forest. The successful colonization patterns and positive neighbor effect of shrubs on natural seedlings establishment found in this study during the first years support the use of shrubs as ecosystem engineers to increase heterogeneity in micro-environmental conditions on reclaimed mine sites, which improves late-successional Quercus species establishment.