Geo-accumulation index and contamination factors of heavy metals (Zn and Pb) in urban river sediment

The aim of the present study was to appraise the levels of heavy metal contamination (Zn and Pb) in sediment of the Langat River (Selangor, Malaysia). Samples were collected randomly from 15 sampling stations located along the Langat River. The parameters measured were pH, redox potential, salinity, electrical conductivity, loss of ignition, cation exchanges capacity (Na, Mg, Ca, K), and metal ions (Zn and Pb). The geo-accumulation index (I _geo) and contamination factor (C _f) were applied to determine and classify the magnitude of heavy metal pollution in this urban river sediment. Results revealed that the I _geo of Pb indicated unpolluted to moderately polluted sediment at most of the sampling stations, whereas Zn was considered to be within background concentration. The I _geo results were refined by the C _f values, which showed Pb with very high C _f at 12 stations. Zinc, on the other hand, had low to moderate C _f values. These findings indicated that the sediment of the Langat River is severely polluted with Pb. The Zn concentration at most sampling points was well below most sediment quality guidelines. However, 40% of the sampling points were found to have a Pb concentration higher than the consensus-based probable effect concentration of 128 mg/kg (concentrations above this value are likely to cause harmful effects). This result not only highlights the severity of Pb pollution in the sediment of the Langat River, but also the potential risk it poses to the environment.     

Greenhouse gas emissions from production and use of used cooking oil methyl ester as transport fuel in Thailand

Biodiesel, produced from various vegetable and/or animal oils, is one of the most promising alternative fuels for transportation in Thailand. Currently, the waste oils after use in cooking are not disposed adequately. Such oils could serve as a feedstock for biodiesel which would also address the waste disposal issue. This study compares the life cycle greenhouse gas (GHG) emissions from used cooking oil methyl ester (UCOME) and conventional diesel used in transport. The functional unit (FU) is 100 km transportation by light duty diesel vehicle (LDDV) under identical driving conditions. Life cycle GHG emissions from conventional diesel are about 32.57 kg CO₂-eq/FU whereas those from UCOME are 2.35 kg CO₂-eq/FU. The GHG emissions from the life cycle of UCOME are 93% less than those of conventional diesel production and use. Hence, a fuel switch from conventional diesel to UCOME will contribute greatly to a reduction in global warming potential. This will also support the Thai Government's policy to promote the use of indigenous and renewable sources for transportation fuels.     

Evaluation and sensitivity of cyanobacteria,Nostoc muscorum and Synechococcus PCC 7942 for heavy metals stress – a step toward biosensor

This study attempted to determine the effects of heavy metals on the photosynthetic blue-green algae for their potential to use as a biosensor. The bioaccumulation of metals and its effects on pigments of Nostoc muscorum and Synechococcus PCC 7942 were assessed. The culture was grown in BG 11 liquid medium supplied with different metals like mercury (Hg), lead (Pb), and cadmium (Cd) and incubated (µM 20 concentrations) for 10 days under optimal conditions. The accumulated amounts of metals were determined by atomic absorption spectroscopy (AAS). The stress effects on photosynthetic pigment chlorophyll a (Chl a) were monitored by laser-induced fluorescence (LIF). Bio-concentration factor (BCF) reached a peak in cells on the 2nd day of incubation followed by a gradual reduction. The highest reduction in the pigment concentrations (Chl a and β carotene) was observed at 20?µM?L^?1 Hg treatment. The results indicate that, cyanobacteria may serve as both potential species to be used as a biosensor and used to clean up heavy metals from contaminated water. These changes were analyzed with the long-term goal of exploiting cyanobacterial cells as biosensors.     

Environmental perception during rapid population growth and urbanization: a case study of Dhaka city

Dhaka city in Bangladesh has been passing through a hasty process of urbanization and population growth since the last few decades. Rapid growth of population, unplanned urbanization and industrialization in the periphery has generated pressure to the changes in land use pattern, which has also caused huge urban expansion. This expansion process is engulfing cultivated land, vegetation, wetlands and water bodies without considering their environmental impacts. This study argues that these changes and their scale of environmental impacts or sufferings are not equally distributed among the dwellers in Dhaka city. It seeks to explore variations of environmental qualities on the basis of people’s perceptions. The study finds that the dwellers in the city perceive their neighborhood environment differently, which may affect environmental qualities of the area and their sustainable management as well. Therefore, it is imperative to consider spatial variations and inequalities of environmental opportunities or sufferings in urban planning of Dhaka city.     

Sequential flotation of 4 components in silicon-based waste solar cells

Journal of Material Cycles and Waste Management - Si, Al, Cu, and Ag particles’ mixture which mainly composes pulverized silicon-based waste solar cells were individually separated by the...     

Hydroxychloroquine in COVID-19: therapeutic promises,current status,and environmental implications

Environmental Science and Pollution Research - The outbreak of novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has affected the entire world with its infectious spread and...     

Correction to: Does globalization affect the green economy and environment? The relationship between energy consumption,carbon dioxide emissions,and economic growth

Environmental Science and Pollution Research - A Correction to this paper has been published: https://doi.org/10.1007/s11356-021-15192-8     

Direct and Indirect Effects of Socioeconomic Factors on Age at First Marriage in Slum Areas,Bangladesh

This article attempts to examine the influence of some selected predictor variables on female age at first marriage in slum areas of Bangladesh. A path and multiple classification analysis （MCA） approach have been adopted. Authors thought that respondent＇s educational level and the mass media such as watching television have a significant direct impact on age at marriage, while the types of family and occupational status have an indirect effect on age at marriage.     

Rapid estimation of compost enzymatic activity by spectral analysis method combined with machine learning

The aim of this study was to investigate the feasibility of using visible near-infrared (VisNIR) diffuse reflectance spectroscopy (DRS) as an easy, inexpensive, and rapid method to predict compost enzymatic activity, which traditionally measured by fluorescein diacetate hydrolysis (FDA-HR) assay. Compost samples representative of five different compost facilities were scanned by DRS, and the raw reflectance spectra were preprocessed using seven spectral transformations for predicting compost FDA-HR with six multivariate algorithms. Although principal component analysis for all spectral pretreatments satisfactorily identified the clusters by compost types, it could not separate different FDA contents. Furthermore, the artificial neural network multilayer perceptron (residual prediction deviation = 3.2, validation r² = 0.91 and RMSE = 13.38 μg g^?1 h^?1) outperformed other multivariate models to capture the highly non-linear relationships between compost enzymatic activity and VisNIR reflectance spectra after Savitzky–Golay first derivative pretreatment. This work demonstrates the efficiency of VisNIR DRS for predicting compost enzymatic as well as microbial activity.     

Identification of erosion-prone areas using morphometric parameters,land use land cover and multi-criteria decision-making method: geo-informatics approach

Environment, Development and Sustainability - Soil erosion is the main driving force of several devastating natural hazards in the complex mountainous terrain of the Himalayas where the Teesta...