Surge in petroleum prices, its drying sources and degradation in air quality focused interest on renewable energy sources as substitute for existing fuels for internal combustion engines. This study highlights the combustion, performance, and emission characteristics of diesel engines fueled with compressed natural gas (CNG) as primary fuel and castor (Ricinus communis) oil methyl ester (COME) as pilot fuel. COME was produced from non-edible grade Ricinus communis oil. The biodiesel fuel properties and characterization was done as per ASTM D6751 specifications. The CNG was inducted through inlet manifold fumigation at a consistent flow rate of 15 l/min under dual-fuel mode. It is evident from the test results that B20-CNG yields brake thermal efficiency of 23.6% when compared to 25 and 27% for D-CNG and diesel fuel, respectively. The peak cylinder gas pressure was lower in dual-fuel mode when compared to conventional diesel. The emission results show increase in NOₓ emission by 24.5 and 28.4% for D-CNG and B20-CNG, respectively when compared to baseline diesel fuel at full engine load. There was increase in HC emission by 6.7 and 11% whereas CO emissions decreased by 31.6 and 37.4% for B20-CNG and D-CNG, respectively at similar operating conditions. Reduction in smoke opacity by 49.4 and 59.6% was achieved respectively for D-CNG and B20-CNG under dual-fuel mode. On the whole, COME exhibits a better pilot fuel choice for dual-fuel combustion mode in comparison to conventional fossil petroleum diesel in terms of combustion, performance, and emissions characteristics.

The original publication of this paper contains a mistake. The correct image of figure 4 is shown in this paper. The original article has been corrected.

In this study, the effects of medium carbon chain alcohol (1-heptanol)-enhanced air sparging (AS) on the remediation of benzene-contaminated aquifers in different media (medium sand, channelized flow; gravel, bubbly flow) were investigated by comparison with a commonly used surfactant (sodium dodecylbenzene sulfonate (SDBS)). The results showed that the addition of 1-heptanol and SDBS significantly increased the air saturation in AS process under different airflow modes. Combined with water retention curves, 1-heptanol had the same effect on reducing the surface tension of groundwater and stabilizing bubbles as SDBS. In the study of benzene pollution removal, when the removal efficiency of the benzene pollutant exceeded 95%, the time required for surfactant-enhanced AS (SEAS) and alcohol-enhanced AS (AEAS) in medium sand was shortened by 28.6% and 52.4%, respectively, and the time required for SEAS and AEAS in gravel media was shortened by 16.7% and 58.3%, respectively, compared with the time required for AS. This finding indicated that the addition of SDBS or 1-heptanol could significantly increase the removal rate of benzene pollutants. Under the same surface tension conditions, the removal effect of 1-heptanol on the benzene pollutant was better than that of SDBS. This difference was due to the disturbance of the flow field during AEAS process causing the 1-heptanol on the gas-liquid interface to volatilize in the carrying gas, thereby inducing Marangoni convection on the interface, enhancing the gas-liquid mass transfer rate, and increasing the removal rate of benzene on the interface. Therefore, 1-heptanol is promising as a new reagent to enhance AS to remediate groundwater pollution.

The present study evaluated the effects of low doses of atrazine administered during gestation and breastfeeding on sperm characteristics of the wild rodent Calomys laucha. Adult females were divided into groups of 10 and administered different doses of atrazine through gavage, during gestational or breastfeeding period. At 3 months of age, the F1 adult male progeny of these females was evaluated. We observed a drastic reduction in the total and progressive motility of male sperm cells at all doses and during both the exposure periods. Moreover, the plasma membrane integrity of adult male sperm cells decreased at all doses of atrazine administered during the breastfeeding, whereas the membrane fluidity of these cells increased at all tested doses. Atrazine led to a decrease in the sperm mitochondrial functionality at all doses and during both exposure periods. The damage to the sperm DNA was higher in males exposed to the highest dose (1.0 mg/kg) during the gestation period, and in animals exposed to the lowest dose of atrazine (0.1 mg/kg) during breastfeeding period. Furthermore, the highest dose (1.0 mg/kg) of atrazine reduced the sperm concentration. Furthermore, the reduced levels of reactive oxygen species (ROS) were observed at all evaluated doses in males exposed during the gestation period. These results suggest that the administration of low doses of atrazine at critical periods of development may permanently reduce the sperm quality in C. laucha.

Humic acid has a controversial effect on the biological treatment processes. Here, we have investigated humic acid effects on the Anammox activity by studying the nitrogen removal efficiencies in batch and continuous conditions and analyzing the microbial community using Fluorescence in situ hybridization (FISH) technique. The results showed that the Anammox activity was affected by the presence of humic acid at a concentration higher than 70 mg/L. In fact, in the presence of humic acid concentration of 200 mg/L, the Anammox activity decreased to 57% in batch and under continuous condition, the ammonium removal efficiencies of the reactor decreased from 78 to 41%. This reduction of Anammox activity after humic acid addition was highlighted by FISH analysis which revealed a considerable reduction of the abundance of Anammox bacteria and the bacteria living in symbiosis with them. Furthermore, a total inhibition of Candidatus Brocadia fulgida was observed. However, humic acid has promoted heterotrophic denitrifying bacteria which became dominant in the reactor. In fact, the evolution of the organic matter in the reactor showed that the added humic acid was used as carbon source by heterotrophic bacteria which explained the shift of metabolism to the favor of heterotrophic denitrifying bacteria. Accordingly, humic acid should be controlled in the influent to avoid Anammox activity inhibition.

The adsorption of Ciprofloxacin (CPX) from aqueous solution by Pomegranate peels (POP) was investigated in a batch process. The influence of time (5–60 min) and CPX concentration (100–10,000 mg/L) on the adsorption ability of POP was studied. The POP was characterized by FTIR, scanning electron microscopy (SEM), and Zeta sizer. The kinetic of adsorption was analyzed by the pseudo-first-order and the pseudo-second-order kinetic equations using non-linear regression analysis. As well as non-linear regression analysis of Langmuir and Freundlich models were applied to specify the best non-linear curves, fitted to experimental data and estimate isotherm parameters. In order to assess the best-fit kinetic model or adsorption isotherm, three error analysis methods were used to evaluate the result of adsorption process, namely the sum of the squares of the errors (SSE), residual root mean square error (RMSE), and chi-square (χ2). On the basis of low three error analysis and high correlation (R²) of determination, it can be concluded that both the non-linear form of pseudo-second-order kinetic model and non-linear form of Langmuir are best suited to explain the adsorption of CPX onto POP. The maximum adsorption capacity for pomegranate peel as calculated by non-linear Langmuir curve was much higher than in previous work (999 mg/g) at natural pH (4–5) and 25 °C. The high adsorption capacity of POP makes them very low-cost and effective adsorbent materials for CPX from aqueous solution.

Climate change will affect the dynamics of the hydrogeological systems and their water resources quality; in particular nitrate, which is herein taken as a paradigmatic pollutant to illustrate the effects of climate change on groundwater quality. Based on climatic predictions of temperature and precipitation for the horizon of 2021 and 2050, as well as on land use distribution, water balances are recalculated for the hydrological basins of distinct aquifer systems in a western Mediterranean region as Catalonia (NE Spain) in order to determine the reduction of available water resources. Besides the fact that climate change will represent a decrease of water availability, we qualitatively discuss the modifications that will result from the future climatic scenarios and their impact on nitrate pollution according to the geological setting of the selected aquifers. Climate effects in groundwater quality are described according to hydrological, environmental, socio-economic, and political concerns. Water reduction stands as a major issue that will control stream-aquifer interactions and subsurface recharge, leading to a general modification of nitrate in groundwater as dilution varies. A nitrate mass balance model provides a gross estimation of potential nitrate evolution in these aquifers, and it points out that the control of the fertilizer load will be crucial to achieve adequate nitrate content in groundwater. Reclaimed wastewater stands as local reliable resource, yet its amount will only satisfy a fraction of the loss of available resources due to climate change. Finally, an integrated management perspective is necessary to avoid unplanned actions from private initiatives that will jeopardize the achievement of sustainable water resources exploitation under distinct hydrological scenarios.

This study provides a full description of the responses of the crop energy plant Zea mays to stress induced by Cd and Pb, in view of a possible extensive use in phytoattenuation of metal-polluted soils. In this perspective, (i) the uptake capability in root and shoot, (ii) the changes in growth pattern and cytological traits, and (iii) the photosynthetic efficiency based on photochemistry and the level of key proteins were investigated in hydroponic cultures. Both metals were uptaken by maize, with a translocation factor higher for Cd than Pb, but only Cd-treated plants showed a reduced growth compared to control (i.e., a lower leaf number and a reduced plant height), with a biomass loss up to 40%, at the highest concentration of metal (10⁻³ M). The observation of cytological traits highlighted ultrastructural damages in the chloroplasts of Cd-treated plants. A decline of Rubisco and D1 was observed in plants under Cd stress, while a relevant increase of the same proteins was found in Pb-treated plants, along with an increase of chlorophyll content. Fluorescent emission measurements indicated that both metals induced an increase of NPQ, but only Cd at the highest concentration determined a significant decline of Fᵥ/Fₘ. These results indicate a different response of Z. mays to individual metals, with Pb triggering a compensative response and Cd inducing severe morpho-physiological alterations at all investigated levels. Therefore, Z. mays could be successfully exploited in phytoattenuation of Pb-polluted soil, but only at very low concentrations of Cd to avoid severe plant damages and biomass loss.

It is evident from the past studies that dust fallout is a severe concern due to its impact to urban air quality and public health. This study mainly examines the spatial and seasonal variation of dustfall at ambient levels and chemical characterization of its insoluble fraction for Kharagpur Town, India. Dustfall samples were collected monthly for 1 year (July 2014 to June 2015) from four sampling sites. The results showed that the maximum dustfall deposition is found during summer (March to June) and in the range of 2.01 ± 0.36 to 15.74 ± 3.83 ton km⁻² month⁻¹, and minimum deposition is during monsoon season (July to October) in the range of 0.42 ± 0.72 to 7.38 ± 5.8 ton km⁻² month⁻¹. Selected metals like Sc, V, Cr, Co, Ni, Zn, Y, Zr, Ce, Hf, and Pb were analyzed using the high-resolution inductively coupled mass spectrometer (HR-ICP-MS) technique, and the contamination level of heavy metals was assessed using the geoaccumulation index (Igₑₒ) and enrichment factor (EF). To estimate the sources for the metallic contaminants, principal component analysis (PCA) was conducted. The US EPA health risk assessment model was applied to determine the hazard index and hazard quotient values. The results show the significant level of enrichment for Pb (EF = 41.79) and Cr (EF = 4.39). The Igₑₒ values point out moderate contamination by Pb (Igₑₒ = 2.01) and Cr (Igₑₒ = 1.6) in Kharagpur Town. This study suggests that in the context of noncancer risk of heavy metals as determined by the hazard index (HI) and hazard quotient (HQ) values, ingestion is the main source of exposure to dust in adults and children followed by dermal contact. Considering the inhalation route, carcinogenic risk level of Cr, Co, and Ni for adults and children is lower than the EPA’s safe limit (10⁻⁶ to 10⁻⁴), indicating that cancer risk of these metals due to exposure to dustfall in Kharagpur is negligible.

Based on the Tapio decoupling model, this paper calculates the decoupling indexes of the transportation output and the transportation carbon emissions of China’s 30 provinces and municipalities from 2006 to 2015. The research period (2006–2015) is divided into the 11th Five-Year Plan period (FYP) (2006–2010) and the 12th FYP period (2011–2015). On this basis, we conduct a comparative analysis to describe the spatial-temporal evolution of the decoupling states of transportation output and transportation carbon emissions. Furthermore, in order to deeply analyze the reasons for the evolution of the decoupling states during the 12th FYP period compared with the 11th FYP period, the LMDI decomposition method is used to decompose and compare the factors affecting the transportation carbon emissions in the two periods. The results show the following: (1) from the national point of view, the decoupling relationship between transportation output and transportation carbon emissions improved gradually, with small fluctuations from 2006 to 2015; (2) from the provincial point of view, their decoupling states mainly were expansive negative decoupling and weak decoupling, and the spatial evolution of the two decoupling states is significantly different; (3) the reductions in the transportation energy intensity and transportation intensity were the main factors inhibiting the increase of transportation carbon emissions in the 11th and 12th FYP periods, respectively. The growth of per-capita wealth was the decisive factor driving the increase in transportation carbon emissions in the two periods; (4) in contrast to the causes of decreases in the carbon emission variations in the 11th FYP period, in the 12th FYP period, the significant reduction in transportation intensity is the main reason causing the significant decrease of carbon emission variations. However, the transportation energy intensity and the transportation intensity fail to reduce simultaneously in the two periods.