Physicochemical factors and sources of particulate matter at residential urban environment in Kuala Lumpur

Long-term measurements (2004–2011) of PM₁₀ (particulate matter with an aerodynamic diameter <10 μm) and trace gases (carbon monoxide [CO], ozone [O₃], nitrogen oxide [NO], oxides of nitrogen [NO_x], nitrogen dioxide [NO₂], sulfur dioxide [SO₂], methane [CH₄], nonmethane hydrocarbon [NMHC]) have been conducted to study the effect of physicochemical factors on the PM₁₀ concentration. In addition, this study includes source apportionment of PM₁₀ in Kuala Lumpur urban environment. An advanced principal component analysis (PCA) technique coupled with absolute principal component scores (APCS) and multiple linear regression (MLR) has been applied. The average annual concentration of PM₁₀ for 8 yr is 51.3 ± 25.8 μg m^?3, which exceeds the Recommended Malaysian Air Quality Guideline (RMAQG) and international guideline values. Detail analysis shows the dependency of PM₁₀ on the linear changes of the motor vehicles in use and the amount of biomass burning, particularly from Sumatra, Indonesia, during southwesterly monsoon. The main sources of PM₁₀ identified by PCA-APCS-MLR are traffic combustion (28%), ozone coupled with meteorological factors (20%), and windblown particles (1%). However, the apportionment procedure left 28.0 μg m^?3, that is, 51% of PM₁₀ undetermined.

Implications: Air quality is always a top concern around the globe. Especially in the South Asian regions, measures are not yet sufficient; as revealed in our studies, the concentrations of particulate matters exceed the tolerable limits. Long-term data analysis and characterization of particular matters and their sources will aid the policy makers and the concerned authority to adapt measures and policies according to the circumstances. Additionally, similar intensive studies will give insight about future implications of air quality management.     

Inactivation of pathogenic micro-organisms in hospital waste using a microwave

The aim of this study was to investigate the efficiency of dry sterilization by microwave in the inactivation of pathogenic bacteria in blood wastes. Eight bacteria strains were selected for this purpose and these are S. aureus, Salmonella sp., E. faecalis, K. pneumonia, P. aeruginosa, E. coli, Streptococcus Group B and Bacillus sp. Sterilization by microwave was carried out at 385, 450 and 700 watts for 1, 5 and 10 min, respectively. Isolation and enumeration of pathogenic bacteria before and after treatments were carried out using direct plate technique and inactivation was determined in terms of log reduction. Increasing the running time and power to 10 min and 700 watts did not increase log reduction of most of pathogenic bacteria especially of gram negative bacteria. Revival of pathogenic bacteria during the storage period might be aided by the presence of a low moisture content which helps bacterial cells to revive but not to reproduce or over-grow. It can be concluded that dry sterilization of blood wastes by microwave reduces the number and limited re-growth of these pathogenic bacteria during storage time, due to the lower moisture content in the blood wastes.     

Characterization of Urea Encapsulated by Biodegradable Starch-PVA-Glycerol

The influence of the blending ratio of biodegradable starch/polyvinyl alcohol (PVA)/glycerol in encapsulating urea has been investigated. It is found that water absorption capacity increased approximately 135 % as the amounts of starch, PVA and glycerol in the composite film increase. Therefore, the swell ability of the composite film is increased and the urea is released from the composite film in the wet environment. The FTIR shows that the urea had been encapsulated successfully in the composite films. Moreover, the soil burial biodegradation results indicated that the biodegradability of the starch/PVA/glycerol/urea composite film strongly depended on the PVA proportion in the composite film matrix. The DSC results show that the higher the amount of PVA in the composite film, the less change of the melting enthalpy value. The crystalline region of PVA remains after biodegradation.     

Evaluation of the giant reed (<Emphasis Type="Italic">Arundo donax</Emphasis>) in horizontal subsurface flow wetlands for the treatment of recirculating aquaculture system effluent

Introduction

Two emergent macrophytes, Arundo donax and Phragmites australis, were established in experimental subsurface flow, gravel-based constructed wetlands (CWs) receiving untreated recirculating aquaculture system wastewater.

Materials and methods

The hydraulic loading rate was 3.75 cm day^?1. Many of the monitored water quality parameters (biological oxygen demand [BOD], total suspended solids [TSS], total phosphorus [TP], total nitrogen [TN], total ammoniacal nitrogen [TAN], nitrate nitrogen [NO₃], and Escherichia coli) were removed efficiently by the CWs, to the extent that the CW effluent was suitable for use on human food crops grown for raw produce consumption under Victorian state regulations and also suitable for reuse within aquaculture systems.

Results and discussion

The BOD, TSS, TP, TN, TAN, and E. coli removal in the A. donax and P. australis beds was 94%, 67%, 96%, 97%, 99.6%, and effectively 100% and 95%, 87%, 95%, 98%, 99.7%, and effectively 100%, respectively, with no significant difference (p?>?0.007) in performance between the A. donax and P. australis CWs. In this study, as expected, the aboveground yield of A. donax top growth (stems + leaves) (15.0?±?3.4 kg wet weight) was considerably more than the P. australis beds (7.4?±?2.8 kg wet weight). The standing crop produced in this short (14-week) trial equates to an estimated 125 and 77 t ?ha^?1 year^?1 biomass (dry weight) for A. donax and P. australis, respectively (assuming that plant growth is similar across a 250-day (September–April) growing season and a single-cut, annual harvest).

Conclusion

The similarity of the performance of the A. donax- and P. australis-planted beds indicates that either may be used in horizontal subsurface flow wetlands treating aquaculture wastewater, although the planting of A. donax provides additional opportunities for secondary income streams through utilization of the energy-rich biomass produced.

     

Promising role of plant hormones in translocation of lead in Sesbania drummondii shoots

Lead (Pb) accumulation in Sesbania drummondii shoots was enhanced by 654 and 415% in the presence of 100 microM IAA and 100 microM NAA, respectively, compared to control plants (Pb alone). However, when IAA or NAA was added along with EDTA, Pb accumulation further increased in shoots by 1349% and 1252%, respectively. Scanning electron microscopic observations revealed that Pb particles in both leaf and stem of Pb+EDTA+IAA and Pb+EDTA+NAA treated plants were concentrated in the region of vascular bundles. In root tissue, Pb particles were present between epidermis to stele region. Plant growth in both treatments (Pb+100 microM IAA and Pb+100 microM NAA) was comparable to control plants; however, it was significantly inhibited in the treatments containing Pb+EDTA and EDTA at concentrations of 10 microM of IAA or NAA. Moreover, the photosynthetic efficiency and strength of the treated plants were not affected in the presence of IAA or NAA and EDTA.     

Contamination levels of selected organochlorine and organophosphate pesticides in the Selangor River, Malaysia between 2002 and 2003

In Malaysia, rivers are the main source of public water supplies. This study was conducted from 2002 to 2003 to determine the levels of selected organochlorine and organophosphate pesticides in the Selangor River in Malaysia. Surface water samples have been collected seasonally from nine sites along the river. A liquid-liquid extraction followed by gas chromatography-mass spectrometry technique was used to determine the trace levels of these pesticide residues. The organochlorine pesticides detected were lindane, heptachlor, endosulfan, dieldrin, endosulfan sulfate, o,p'-DDT, p,p'-DDT, o,p'-DDE and p,p'-DDE whereas for organophosphate pesticides, they were chlorpyrifos and diazinon. At the river upstream where a dam is located for public water supply, incidents of pesticide levels exceeding the European Economic Community Directive of water quality standards have occurred. Furthermore, the wetland ecosystems located at the downstream of the river which houses the fireflies community is being threatened by occasional pesticide levels above EPA limits for freshwater aquatic organisms. The occurrence of these residual pesticides in the Selangor River can be attributed to the intense agriculture and urban activity.     

Physico-chemical removal of iron from semi-aerobic landfill leachate by limestone filter

Limestone has been proven effective in removing metals from water and wastewater. A literature review indicated that limestone is capable of removing heavy metals such as Cu, Zn, Cd, Pb, Ni, Cr, Fe and Mn are through a batch process or by filtration technique. The removal capability is reported at up to 90%. However, to date most of the studies have been focused on synthetic wastewater. The present study attempts to investigate the suitability of limestone to attenuate total iron (Fe) from semi aerobic leachate at Pulau Burung Landfill Site in Penang, Malaysia. Iron was found in significant quantities at the landfill site. The study also aims to establish the Fe isotherm and breakthrough time of the proposed limestone filter for post-treatment to the migrating landfill leachate before its release to the environment. The Fe isotherms were established using a batch equilibrium test, while the breakthrough characteristics were determined using continuous flow permeating through a limestone column. The latter was used in order to simulate the continuous flow of leachate that would occur in the proposed limestone filter. The limestone media used in the experiment contain more than 90% CaCO3 with particle sizes ranging from 2 to 4 mm. Four filter columns (each 150 mm in diameter and 1000 mm depth) were installed at the landfill site. Metal loadings were kept below 0.5 kg /m3 day and the experiment was run continuously for 30 days. Initial results indicated that 90% of Fe can be removed from the leachate based on retention time of 57.8 min and surface loading of 12.2 m3/m2 day. For the batch study on the Fe isotherm, the results indicated that limestone is potentially useful as an alternative leachate treatment system at a relatively low cost.     

Carbon emissions from the peat fire problem—a review

Environmental Science and Pollution Research - Peat fires in tropical peatland release a substantial amount of carbon into the environment and cause significant harm to peatlands and the ecology,...