Are deep eutectic solvents benign or toxic?

In continuation of investigation for environmentally benign protocol for new solvents termed deep eutectic solvents (DESs), it is herein reported results concerning the toxicity and cytotoxicity of choline chloride (ChCl) based DESs with four hydrogen bond donors including glycerine, ethylene glycol, triethylene glycol and urea. The toxicity was investigated using two Gram positive bacteria Bacillus subtilis and Staphylococcus aureus, and two Gram negative bacteria Escherichia coli and Pseudomonas aeruginosa. The cytotoxicity effect was tested using the Artemia salina leach. It was found that there was no toxic effect for the tested DESs on all of the studied bacteria confirming their benign effects on these bacteria. Nevertheless, it was found that the cytotoxicity of DESs was much higher than their individual components (e.g. glycerine, ChCl) indicating that their toxicological behavior is different. For our best knowledge this is the first time that toxicity and cytotoxicity of DESs were studied. The toxicity and cytotoxicity of DESs varied depending on the structure of components. Careful usage of the terms non-toxicity and biodegradability must be considered. More investigation on this matter is required.     

Spatio-temporal characteristics of PM10 concentration across Malaysia

The recurrence of forest fires in Southeast Asia and associated biomass burning, has contributed markedly to the problem of trans-boundary haze and the long-range movement of pollutants in the region. Air pollutants, specifically particulate matter in the atmosphere, have received extensive attention, mainly because of their adverse effect on people's health. In this study, the spatial and temporal variability of the PM10 concentration across Malaysia was analyzed by means of the rotated principal component analysis. The results suggest that the variability of the PM10 concentration can be decomposed into four dominant modes, each characterizing different spatial and temporal variations. The first mode characterizes the southwest coastal region of the Malaysian Peninsular with the PM10 showing a peak concentration during the summer monsoon i.e. when the winds are predominantly southerlies or southwesterlies, and a minimal concentration during the winter monsoon. The second mode features the region of western Borneo with the PM10 exhibiting a concentration surge in August–September, which is likely to be the result of the northward shift of the Inter Tropical Convergence Zone (ITCZ) and the subsequent rapid arrival of the rainy season. The third mode delineates the northern region of the Malaysian Peninsular with strong bimodality in the PM10 concentration. Seasonally, this component exhibits two concentration maxima during the late winter and summer monsoons, as well as two minima during the inter-monsoon periods. The fourth dominant mode characterizes the northern Borneo region which exhibits weaker seasonality of the PM10 concentration. Generally, the seasonal fluctuation of the PM10 concentration is largely associated with the seasonal variation of rainfall in the country. However, in addition to this, the PM10 concentration also fluctuates markedly in two timescale bands i.e. 10–20 days quasi-biweekly (QBW) and 30–60 days lower frequency (LF) band of the intra-seasonal timescales. These intra-seasonal fluctuations show strong seasonality with the largest fraction of variance occurring during the boreal summer and the weakest variance during the winter. Generally, the LF intra-seasonal oscillation is stronger compared to the QBW intra-seasonal band.     

The impacts of the waterfront development in Iskandar Malaysia

The increasing number of waterfront projects shows that the concept of waterfront development has contributed to the advancement of the Malaysian construction industry. This study seeks to assess the impacts of the implementation of waterfront development in Iskandar Malaysia eliciting the perceived relative importance of these impacts. A comprehensive literature review has been conducted to collate the potential impacts of the waterfront development. A total of 363 sets of questionnaires were distributed to the contractors and developers registered under G7 category of the Construction Industry Development Board in Malaysia. Results show that the most significant influence of the waterfront development is related to economic benefits, while environmental impacts are not considered as a priority for this category of stakeholders. In addition, this study also indicates that the implementation of the waterfront projects has generated numerous job opportunities within the developed region. Moreover, exchanging knowledge in the planning and managing of the waterfront development is imperative to the development of the waterfront projects. Nevertheless, the shortcomings of these developments, such as the negative environmental impact on natural beaches and the coastline (i.e. pollution) as well as human-related issues (i.e. excessive human settlement), should not be taken lightly. This research confirms that the reclamation of land for waterfront development is closely correlated with the destruction of these natural structures.     

Performance of the hybrid growth sequencing batch reactor (HG-SBR) for biodegradation of phenol under various toxicity conditions

Hybrid growth microorganisms in sequencing batch reactors have proven effective for treating the toxic compound phenol, but the toxicity effect under different toxicity conditions has rarely been discussed. Therefore, the performance of the HG-SBR under toxic, acute and chronic organic loading can provide the overall operating conditions of the system. Toxic organic loading(TOL) was monitored during the first 7 hr while introducing50 mg/L phenol to the system. The system was adversely affected with the sudden introduction of phenol to the virgin activated sludge, which caused a low degradation rate and high dissolved oxygen consumption during TOL. Acute organic loading(AOL) had significant effects at high phenol concentrations(600, 800 1000 mg/L). The specific oxygen uptake rate(SOUR) gradually decreased to 4.9 mg O_2/(g MLVSS·hr) at 1000 mg/L of phenol compared to 12.74 mg O_2/(g MLVSS·hr) for 200 mg/L of phenol. The HG-SBR was further monitored during chronic organic loading(COL) over 67 days. The effects of organic loading were more apparent at 800 mg/L and 1000 mg/L phenol concentrations, as the removal range was between 22%–30% and 18%–46% respectively, which indicated the severe effects of COL.     

Bioaccumulation and physiological effects of mercury in Sesbania drummondii

The accumulation of mercury and its effect on growth, photosynthesis and antioxidative responses were studied in Sesbania drummondii seedlings. Mercury concentration in shoots as well as in the roots increased with increasing Hg concentrations in the growth solution. The accumulation of Hg was more in roots than shoots. At 100 mg l-1 Hg concentration, shoots accumulated 998 mg Hg kg -1 dry weight (dw) while roots accumulated 41,403 mg Hg kg-1 dw. Seedlings growth was not significantly affected at lower concentrations of Hg. A concentration of 100 mg l-1 Hg inhibited growth by 36.8%, with respect to control. Photosynthetic activity was assessed by measuring chlorophyll a fluorescence by determination of Fv/Fm and Fv/Fo values. Photosynthetic integrity was not affected up to 50 mg l-1 Hg concentration, however, concentrations higher than 50 mg l-1 affected photosynthetic integrity. Sesbania responded to Hg induced oxidative stress by modulating non-enzymatic antioxidants [glutathione (GSH) and non-protein thiols (NPSH)] and enzymatic antioxidants: superoxide dismutase (SOD), ascorbate peroxidase (APX) and glutathione reductase (GR). Glutathione content and GSH/GSSG ratio increased up to a concentration of 50 mg l-1 while slight down at 100 mg l-1 Hg. The content of NPSH significantly increased with increasing Hg concentrations in the growth medium. The activities of antioxidative enzymes, SOD, APX and GR followed the same trends as antioxidants first increased up to a concentration of 50 mg l-1 Hg and then slight decreased. The results of present study suggest that Sesbania plants were able to accumulate and tolerate Hg induced stress using an effective antioxidative defense mechanisms.     

Impact of economic capabilities and population agglomeration on PM2.5 emission: empirical evidence from sub-Saharan African countries

Environmental Science and Pollution Research - The utilization of economic capabilities to raise production in the economy enhances the industrial activities and use of transportation. These...     

Assessing the impacts of globalization and gender parity on economic growth: empirical evidence from OIC countries

The contemporary debate on globalization and gender equality has a strong impact on economic growth. The present study analyzes the impacts of globalization and gender parity on economic growth in the Organization of Islamic Cooperation (OIC) 47 member countries for the period (1991–2017), using System GMM panel data technique. The results of system GMM have also been empirically estimated by making two groups (viz., low-income and high-income OIC member countries from the World Bank data classification, 2019) to examine the robustness of globalization and gender parity on economic growth. The results reveal that there is a negative impact of globalization on economic growth in the overall sample of OIC countries. When estimated by decomposing low-income countries and high-income countries, globalization has a significantly positive impact on economic growth in the case of high-income OIC countries, whereas globalization slashes GDP in the case of low-income OIC countries. The study finds that there is a positive impact of gender parity (ratio of female to male labor force work participation) on economic growth. Moreover, foreign remittances, government expenditures, capital formation, and human capital are also becoming the causes of a significant increase in economic growth in OIC member countries.     

Impacts of and adaptation to climate change on the oil palm in Malaysia: a systematic review

Environmental Science and Pollution Research - The interaction and the interplay of climate change with oil palm production in the Southeast Asia region are of serious concern. This particularly...     

Baseline study of methane emission from open digesting tanks of palm oil mill effluent treatment

Anthropogenic release of greenhouse gases, especially CO₂ and CH₄ has been recognized as one of the main causes of global warming. Several measures under the Kyoto Protocol 1997 have been drawn up to reduce the greenhouse gases emission. One of the measures is Clean Development Mechanisms (CDM) that was created to enable developed countries to cooperate with developing countries in emission reduction activities. In Malaysia, palm oil industry particularly from palm oil mill effluent (POME) anaerobic treatment has been identified as an important source of CH₄. However, there is no study to quantify the actual CH₄ emission from the commercial scale wastewater treatment facility. Hence, this paper shall address the CH₄ emission from the open digesting tanks in Felda Serting Hilir Palm Oil Mill. CH₄ emission pattern was recorded for 52 weeks from 3600 m³ open digesting tanks. The findings indicated that the CH₄ content was between 13.5% and 49.0% which was lower than the value of 65% reported earlier. The biogas flow rate ranged between 0.8 l min⁻¹ m⁻² and 9.8 l min⁻¹ m⁻². Total CH₄ emission per open digesting tank was 518.9 kg day⁻¹. Relationships between CH₄ emission and total carbon removal and POME discharged were also discussed. Fluctuation of biogas production was observed throughout the studies as a result of seasonal oil palm cropping, mill activities, variation of POME quality and quantity discharged from the mill. Thus only through long-term field measurement CH₄ emission can be accurately estimated.     

Spatial assessment of groundwater quality in Guna Tana landscape

This study focuses on investigating the quality of groundwater for irrigation and drinking water purposes. Spatial distribution of physicochemical and microbiological parameters was assessed from samples collected from springs, hand‐dug wells, and boreholes found the Guna Tana landscape. A total of 70 samples were considered for physical, chemical, and bacteriological water quality determination. The results revealed that most of the groundwater quality index (WQI) values lie between good and excellent. The maximum, minimum, mean, and standard deviation of each water quality parameter were prepared for evaluating groundwater quality. According to the WQI values, more than 83% of the water samples were classified as excellent water for drinking. More than 92% of the water samples showed low sodium hazards for irrigation and about 48% and 46% of the water samples were classified as within the excellent and good water classes for irrigation based on their electrical conductance levels. Therefore, the groundwater that is found in the Guna Tana landscape could be used for drinking and irrigation purposes without any advanced treatment.