Displaying publications 21 - 40 of 76 in total

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  1. Life cycle inventory of institutional medium-scaled co-composting of food waste and yard waste in tropical country
    Chee Guan Ng, Sumiani Yusoff
    Sains Malaysiana, 2015;44:517-527.
    The main objective of the present study was to provide a comprehensive LCI of medium scale composting of food waste
    and yard waste at institutional level, based on substance flow analysis (SFA). A secondary objective was to present the
    composition and assess the quality of the final compost product from composting of typical Asian organic waste (food
    waste and yard waste). The experiments were designed to represent a batch situation in an institutional medium size
    composting scenario with input material of food waste mixed with grass clippings and dried leaves. Two composting
    runs were carried out with the intention to showcase the heterogeneity of organic waste and study the effect of windrow
    size on the performance of the process. The input and output material were sampled and characterized in order to
    quantify the substance balance of the process. SFA was performed by means of the mass balance model STAN 2.5 to
    compute unknown parameters (gaseous emissions). SFAs have been performed for C, N, K, P, Cd, Cr, Cu, Ni and Pb. The
    composting windrows were fed with 212.4 and 393 kg, respectively. VS content reduction is greater in composting pile
    with larger size (Run 2). The loss of C during composting was recorded in the range of 0.146-0.166 kg/kg ww. The C
    losses via leachate were insignificant (0.02% of the total input C). The total N loss during the process was 0.005-0.012
    kg/kg ww. The leachate generation was measured as 0.012-0.013 kg/kg ww. The flows of selected heavy metals were
    assessed. Heavy metals were of minor significance due to low concentrations in the inputs (food waste and yard waste).
    Heavy metals were found to be released to the atmosphere. However, majority of heavy metals remain in the finished
    compost. The C/N reduction during the process was in the range of 10-23%. In general, the compost composition was
    considered to be within the ranges previously reported in literature and thus ready for application in gardening. The LCI
    presented in the present study can be used as a starting point for making environmental assessments of medium-scale
    co-composting of food waste and yard waste in tropical environment. No major environmental problems were identified
    from the process, except for the emissions of GHGs.
    Matched MeSH terms: Atmosphere
  2. Fulltext Undergraduate Medical Students' Perceptions on Feedback-Seeking Behaviour
    Oktaria D, Soemantri D
    Malays J Med Sci, 2018 Feb;25(1):75-83.
    PMID: 29599637 DOI: 10.21315/mjms2018.25.1.9
    Background: The concept of feedback-seeking behaviour has been widely studied, but there is still a lack of understanding of this phenomenon, specifically in an Indonesian medical education setting. The aim of this research was to investigate medical students' feedback-seeking behaviour in depth in one Indonesian medical school.

    Methods: A qualitative method was employed to explore the feedback-seeking behaviour of undergraduate medical students in the Faculty of Medicine at Universitas Lampung. Focus group discussions (FGDs) were conducted with four student groups and each group consisted of 7-10 students from the years 2012, 2013 and 2014. Data triangulation was carried out through FGDs with teaching staff, and an interview with the Head of the Medical Education Unit.

    Results: Study findings indicated that the motivation of students to seek feedback was underlain by the desire to obtain useful information and to control the impressions of others. Students will tend to seek feedback from someone to whom they have either a close relationship or whose credibility they value. The most common obstacle for students to seek feedback is the reluctance and fearfulness of receiving negative comments.

    Conclusions: Through the identification of factors promoting and inhibiting feedback-seeking behaviour, medical education institutions are enabled to implement the appropriate and necessary measures to create a supportive feedback atmosphere in the learning process.

    Matched MeSH terms: Atmosphere
  3. Fulltext An overview of mercury emission sources and application of activated carbon for mercury removal from flue gas
    Hidayu Abdul Rani, Nor Fadilah Mohamad, Sherif Abdulbari Ali, Matali, Sharmeela, Sharifah Aishah Sheikh Abdul kadir
    Scientific Research Journal, 2013;10(1):0-0.
    MyJurnal
    Mercury emission into the atmosphere is a global concern due to its detrimental effects on human health in general. The two main sources of mercury emission are natural sources and anthropogenic sources. Mercury emission from natural sources include volcanic activity, weathering of rocks, water movement and biological processes which are obviously inevitable. The anthropogenic sources of mercury emission are from coal combustion, cement production and waste incineration. Thus, in order to reduce mercury emission it is appropriate to investigate how mercury is released from the anthropogenic sources and consequently the mercury removal technology that can be implemented in order to reduce mercury emission into the atmosphere. Many alternatives have been developed to reduce mercury emission and the recent application of activated carbon showed high potential in the adsorption of elemental mercury. This paper discusses the ability of activated carbon and variable parameters that influence mercury removal efficiency in flue gas.
    Matched MeSH terms: Atmosphere
  4. Rainwater chemistry of acid precipitation occurrences due to long-range transboundary haze pollution and prolonged drought events during southwest monsoon season: climate change driven
    Payus CM, Jikilim C, Sentian J
    Heliyon, 2020 Sep;6(9):e04997.
    PMID: 33005801 DOI: 10.1016/j.heliyon.2020.e04997
    The purposes of this research were to study the characteristics chemistry of pH, anions and cations in rainwater, and to identify the possible sources that contributing to the acid precipitation during southwest monsoon season with occurrence of extreme drought event. During the southwest monsoon season, it normally occurs along with haze phenomenon that every year will hit Southeast Asia. This condition will aggravate with high acidic particles in the atmosphere due to the prolonged drought. The analysed parameters which involved pH, anions (NO3-, SO42- and Cl-) and cations (Ca2+, Mg2+, Na+ and K+) were analysed using pH meter, Hach DR 2800, argentometric method and ICP-OES. From the findings, it showed that acid rain occurred during the southwest monsoon season with the range of pH values from 4.95 ± 0.13 to 6.40 ± 0.03 and the total average of pH 5.71 ± 0.32. Anions NO3-, SO42- and Cl- were found to be the dominant compositions of the acid rain occurrences with higher concentrations detected. In overall, rural area recorded with higher acidity of precipitation at total average of pH 5.54 ± 0.39 compared to urban area at pH 5.77 ± 0.26. Rural area surprisingly recorded higher frequency occurrences of acid rain with pH lesser than 5.6 and below compared to urban area. As for public health and safety, all rainwater samples during the acid rain event were found exceeded the allowable limits of NWQS and WHO standards, that shown not suitable for skin contact, recreational purposes even for drinking purposes.
    Matched MeSH terms: Atmosphere
  5. Fulltext Malaysia collaborates with the new york academy of sciences to develop an innovation-based economy
    Wahome M, Rubinstein E
    Malays J Med Sci, 2011 Jul;18(3):1-3.
    PMID: 22135594 MyJurnal
    If Malaysia is to become a high-income country by 2020, it will have to transform into a knowledge-based, innovation economy. This goal will be achieved by developing an atmosphere conducive to experimentation and entrepreneurship at home; while reaching out to partners across the globe. One of Malaysia's newest partnerships is with the New York Academy of Sciences. The Academy has expertise in innovation and higher education and a long history of promoting science, education, and science-based solutions through a global network of scientists, industry-leaders, and policy-makers. Malaysia's Prime Minister, Dato' Sri Mohd Najib Tun Abdul Razak, leveraged the Academy's network to convene a science, technology, and innovation advisory council. This council would provide practical guidance to establish Malaysia as an innovation-based economy. Three initial focus areas, namely palm-oil biomass utilisation, establishment of smart communities, and capacity building in science and engineering, were established to meet short-term and long-term targets.
    Matched MeSH terms: Atmosphere
  6. Fulltext Tropical forests post-logging are a persistent net carbon source to the atmosphere
    Mills MB, Malhi Y, Ewers RM, Kho LK, Teh YA, Both S, et al.
    Proc Natl Acad Sci U S A, 2023 Jan 17;120(3):e2214462120.
    PMID: 36623189 DOI: 10.1073/pnas.2214462120
    Logged and structurally degraded tropical forests are fast becoming one of the most prevalent land-use types throughout the tropics and are routinely assumed to be a net carbon sink because they experience rapid rates of tree regrowth. Yet this assumption is based on forest biomass inventories that record carbon stock recovery but fail to account for the simultaneous losses of carbon from soil and necromass. Here, we used forest plots and an eddy covariance tower to quantify and partition net ecosystem CO2 exchange in Malaysian Borneo, a region that is a hot spot for deforestation and forest degradation. Our data represent the complete carbon budget for tropical forests measured throughout a logging event and subsequent recovery and found that they constitute a substantial and persistent net carbon source. Consistent with existing literature, our study showed a significantly greater woody biomass gain across moderately and heavily logged forests compared with unlogged forests, but this was counteracted by much larger carbon losses from soil organic matter and deadwood in logged forests. We estimate an average carbon source of 1.75 ± 0.94 Mg C ha-1 yr-1 within moderately logged plots and 5.23 ± 1.23 Mg C ha-1 yr-1 in unsustainably logged and severely degraded plots, with emissions continuing at these rates for at least one-decade post-logging. Our data directly contradict the default assumption that recovering logged and degraded tropical forests are net carbon sinks, implying the amount of carbon being sequestered across the world's tropical forests may be considerably lower than currently estimated.
    Matched MeSH terms: Atmosphere
  7. Soil carbon stocks in Sarawak, Malaysia
    Padmanabhan E, Eswaran H, Reich PF
    Sci Total Environ, 2013 Nov 1;465:196-204.
    PMID: 23541401 DOI: 10.1016/j.scitotenv.2013.03.024
    The relationship between greenhouse gas emission and climate change has led to research to identify and manage the natural sources and sinks of the gases. CO2, CH4, and N2O have an anthropic source and of these CO2 is the least effective in trapping long wave radiation. Soil carbon sequestration can best be described as a process of removing carbon dioxide from the atmosphere and relocating into soils in a form that is not readily released back into the atmosphere. The purpose of this study is to estimate carbon stocks available under current conditions in Sarawak, Malaysia. SOC estimates are made for a standard depth of 100 cm unless the soil by definition is less than this depth, as in the case of lithic subgroups. Among the mineral soils, Inceptisols tend to generally have the highest carbon contents (about 25 kg m(-2) m(-1)), while Oxisols and Ultisols rate second (about 10-15 kg m(-2) m(-1)). The Oxisols store a good amount of carbon because of an appreciable time-frame to sequester carbon and possibly lower decomposition rates for the organic carbon that is found at 1m depths. Wet soils such as peatlands tend to store significant amounts of carbon. The highest values estimated for such soils are about 114 kg m(-2) m(-1). Such appreciable amounts can also be found in the Aquepts. In conclusion, it is pertinent to recognize that degradation of the carbon pool, just like desertification, is a real process and that this irreversible process must be addressed immediately. Therefore, appropriate soil management practices should be instituted to sequester large masses of soil carbon on an annual basis. This knowledge can be used effectively to formulate strategies to prevent forest fires and clearing: two processes that can quickly release sequestered carbon to the atmosphere in an almost irreversible manner.
    Matched MeSH terms: Atmosphere
  8. Fulltext Investigation of East Asian Emissions of CFC-11 Using Atmospheric Observations in Taiwan
    Adcock KE, Ashfold MJ, Chou CC, Gooch LJ, Mohd Hanif N, Laube JC, et al.
    Environ Sci Technol, 2020 Apr 07;54(7):3814-3822.
    PMID: 32126759 DOI: 10.1021/acs.est.9b06433
    Recent findings of an unexpected slowdown in the decline of CFC-11 mixing ratios in the atmosphere have led to the conclusion that global CFC-11 emissions have increased over the past decade and have been attributed in part to eastern China. This study independently assesses these findings by evaluating enhancements of CFC-11 mixing ratios in air samples collected in Taiwan between 2014 and 2018. Using the NAME (Numerical Atmospheric Modeling Environment) particle dispersion model, we find the likely source of the enhanced CFC-11 observed in Taiwan to be East China. Other halogenated trace gases were also measured, and there were positive interspecies correlations between CFC-11 and CHCl3, CCl4, HCFC-141b, HCFC-142b, CH2Cl2, and HCFC-22, indicating co-location of the emissions of these compounds. These correlations in combination with published emission estimates of CH2Cl2 and HCFC-22 from China, and of CHCl3 and CCl4 from eastern China, are used to estimate CFC-11 emissions. Within the uncertainties, these estimates do not differ for eastern China and the whole of China, so we combine them to derive a mean estimate that we term as being from "(eastern) China". For 2014-2018, we estimate an emission of 19 ± 5 Gg year-1 (gigagrams per year) of CFC-11 from (eastern) China, approximately one-quarter of global emissions. Comparing this to previously reported CFC-11 emissions estimated for earlier years, we estimate CFC-11 emissions from (eastern) China to have increased by 7 ± 5 Gg year-1 from the 2008-2011 average to the 2014-2018 average, which is 50 ± 40% of the estimated increase in global CFC-11 emissions and is consistent with the emission increases attributed to this region in an earlier study.
    Matched MeSH terms: Atmosphere
  9. Fulltext Long-term carbon sink in Borneo's forests halted by drought and vulnerable to edge effects
    Qie L, Lewis SL, Sullivan MJP, Lopez-Gonzalez G, Pickavance GC, Sunderland T, et al.
    Nat Commun, 2017 12 19;8(1):1966.
    PMID: 29259276 DOI: 10.1038/s41467-017-01997-0
    Less than half of anthropogenic carbon dioxide emissions remain in the atmosphere. While carbon balance models imply large carbon uptake in tropical forests, direct on-the-ground observations are still lacking in Southeast Asia. Here, using long-term plot monitoring records of up to half a century, we find that intact forests in Borneo gained 0.43 Mg C ha-1 per year (95% CI 0.14-0.72, mean period 1988-2010) above-ground live biomass. These results closely match those from African and Amazonian plot networks, suggesting that the world's remaining intact tropical forests are now en masse out-of-equilibrium. Although both pan-tropical and long-term, the sink in remaining intact forests appears vulnerable to climate and land use changes. Across Borneo the 1997-1998 El Niño drought temporarily halted the carbon sink by increasing tree mortality, while fragmentation persistently offset the sink and turned many edge-affected forests into a carbon source to the atmosphere.
    Matched MeSH terms: Atmosphere
  10. Fulltext The FLUXNET2015 dataset and the ONEFlux processing pipeline for eddy covariance data
    Pastorello G, Trotta C, Canfora E, Chu H, Christianson D, Cheah YW, et al.
    Sci Data, 2020 07 09;7(1):225.
    PMID: 32647314 DOI: 10.1038/s41597-020-0534-3
    The FLUXNET2015 dataset provides ecosystem-scale data on CO2, water, and energy exchange between the biosphere and the atmosphere, and other meteorological and biological measurements, from 212 sites around the globe (over 1500 site-years, up to and including year 2014). These sites, independently managed and operated, voluntarily contributed their data to create global datasets. Data were quality controlled and processed using uniform methods, to improve consistency and intercomparability across sites. The dataset is already being used in a number of applications, including ecophysiology studies, remote sensing studies, and development of ecosystem and Earth system models. FLUXNET2015 includes derived-data products, such as gap-filled time series, ecosystem respiration and photosynthetic uptake estimates, estimation of uncertainties, and metadata about the measurements, presented for the first time in this paper. In addition, 206 of these sites are for the first time distributed under a Creative Commons (CC-BY 4.0) license. This paper details this enhanced dataset and the processing methods, now made available as open-source codes, making the dataset more accessible, transparent, and reproducible.
    Matched MeSH terms: Atmosphere
  11. Uncovering the dynamics in global carbon dioxide utilization research: a bibliometric analysis (1995-2019)
    Wong SL, Nyakuma BB, Nordin AH, Lee CT, Ngadi N, Wong KY, et al.
    Environ Sci Pollut Res Int, 2021 Mar;28(11):13842-13860.
    PMID: 33196996 DOI: 10.1007/s11356-020-11643-w
    The anthropogenic emission of carbon dioxide (CO2) into the atmosphere is recognized as the main contributor to global climate change. To date, scientists have developed various strategies, including CO2 utilization technologies, to reduce global carbon emissions. This paper presents the global scientific landscape of the CO2 utilization research from 1995 to 2019 based on a bibliometric analysis of 1875 publications extracted from Web of Science. The findings indicate a major increase in the number of publications and citations received from 2015 to 2019, denoting a fast-emerging research trend. The dynamics of global CO2 utilization research is partly driven by China's policies and research funding to promote low-carbon economic development. Applied Energy is recognized as a core journal in this research topic. The utilization of CO2 is a multidisciplinary topic that has progressed by multidimensional collaborations at the country and organizations levels, while the formation of co-authorship networks at the individual level is mostly influenced by the authors' affiliations. Keyword co-occurrence analysis reveals a rapid evolution in the CO2 utilization strategies from chemical fixation in carbonates and epoxides to pilot-scale testing of power-to-gas technologies in Europe and the USA. The development of efficient power-to-fuel technologies and biological utilization routes (using microalgae and bacteria) will probably be the next research priorities in CO2 utilization research.
    Matched MeSH terms: Atmosphere*
  12. Fluxes of ions in precipitation, throughfall and stemflow in an urban forest in Kuala Lumpur, Malaysia
    Radzi Abas M, Ahmad-Shah A, Nor Awang M
    Environ Pollut, 1992;75(2):209-13.
    PMID: 15092035
    A study was carried out to determine the chemical composition of bulk precipitation, throughfall and stemflow in an urban forest in Kuala Lumpur, Malaysia. The mean weekly rainfall recorded during the period of study was 63.2 mm. Throughfall, stemflow and canopy interception of incident precipitation were 77.1%, 1.2% and 21.7% respectively. Bulk precipitation, througfall and stemflow were acidic, the pH recorded being 4.37, 4.71 and 4.15 respectively. In all cases the dominant ions were NO3, SO4, Cl, NH4, K, Ca and Na. Of the ions studied Ca, K, Cl, SO4, Mg and Mn showed net increases in passing through the forest canopy, while NH4, Na, NO3, Zn, H and Fe showed net retention. This study shows that the urban environment of Kuala Lumpur contributes considerable amounts of materials to the atmosphere, as reflected by the high ionic contents in bulk precipitation, throughfall and stemflow.
    Matched MeSH terms: Atmosphere
  13. Fulltext Monitoring of radionuclide contamination in food samples in Malaysia due to daiichi reactor accident in Fukushima, Japan
    Nurrul Assyikeen Md. Jaffary, Wo, Yii Mei, Abdul Kadir Ishak, Noor Fadzilah Yusof, Kamarozaman Ishak, Maziah Mahmud, et al.
    Jurnal Sains Nuklear Malaysia, 2015;27(1):14-20.
    MyJurnal
    On March 11, 2011, a serious accident occurred in Daiichi nuclear reactor plant, Fukushima,
    Japan which caused radioactive materials been released into the atmosphere in the form of
    aerosols and dust particles. Sea water around the plant was also found contaminated with high
    radioactivity readings. These radioactive materials could be transported by the winds and ocean
    current across international borders and cannot be controlled by human. Thus, a continuous
    monitoring activity of radionuclide content in the air and sea water needs to be conducted by the
    authorities. In addition to radioactivity monitoring, Malaysia should also control the entry of
    contaminated food in order to prevent radionuclide ingestion by human. The radionuclide 131I,
    134Cs and 137Cs were used as a measure of pollution levels and counted with gamma spectrometry
    using standard analysis method suggested by AOAC International. In this paper, details description
    of the role of Radiochemical and Environment Group, Nuclear Malaysia who’s responsible in
    analyzing the radioactivity in the food samples due to Fukushima Daiichi, Japan accident was
    included. The radioactivity limit adopted and analysis results from this monitoring were discussed
    Matched MeSH terms: Atmosphere
  14. Fulltext Design, synthesis and biological profile of heterocyclic benzimidazole analogues as prospective antimicrobial and antiproliferative agents
    Tahlan S, Kumar S, Ramasamy K, Lim SM, Shah SAA, Mani V, et al.
    BMC Chem, 2019 Dec;13(1):50.
    PMID: 31384798 DOI: 10.1186/s13065-019-0567-x
    Background: Nitrogen containing heterocycles are widely used and investigated by pharmaceutical industry, as they are important in discovery and designing of new drug molecules. Drugs with a benzimidazole nucleus possess exclusive structural features and electron-rich atmosphere, which enable them to bind to a number of biologically important targets and result in a wide range of activities. This has served as the basis of the present study whereby new scaffolds with benzimidazole moiety were designed and synthesized.

    Methods: The structures of synthesized compounds were confirmed by physicochemical and spectral means. The synthesized compounds were screened for their antimicrobial and antiproliferative activities by tube dilution and Sulforhodamine B (SRB) assays, respectively.

    Results and conclusion: The in vitro biological screening results revealed that compound Z24 exhibited promising antimicrobial and anticancer activities which are comparable to standards.

    Matched MeSH terms: Atmosphere
  15. Composition and distribution of surfactants around Lake Chini, Malaysia
    Latif MT, Wanfi L, Hanif NM, Roslan RN, Ali MM, Mushrifah I
    Environ Monit Assess, 2012 Mar;184(3):1325-34.
    PMID: 21472384 DOI: 10.1007/s10661-011-2043-5
    This study aims to determine the composition of surfactants in the lake surface microlayer, rainwater, and atmospheric aerosols in the area surrounding Lake Chini, Pahang. Surfactants in the lake surface microlayer were taken from seven different stations around the lake, while samples of rainwater were taken from five different sampling stations. The samples of atmospheric aerosols were collected from the Lake Chini Research Centre which is in close proximity to the lake. The colorimetric analysis method was used to determine the composition and concentration of anionic surfactants as methylene blue active substances (MBAS) and cationic surfactants as disulphine blue active substances (DBAS). The concentration of anionic surfactants, as MBAS, in the surface microlayer ranged between 0.08 to 0.23 μmol L(-1), while the range of concentration of cationic surfactants as DBAS ranged from 0.09 to 0.11 μmol L(-1). The concentration of MBAS was higher in rainwater when compared to surfactants in the lake surface microlayer. The high concentration of surfactants in the fine mode of atmospheric aerosols suggests that natural and anthropogenic sources of surfactants contribute to the atmospheric surfactants.
    Matched MeSH terms: Atmosphere/chemistry
  16. Oxygenation of frog gastric mucosa in vitro
    Kidder GW, Montgomery CW
    Am J Physiol, 1975 Dec;229(6):1510-3.
    PMID: 2018
    We have recently shown that 5% CO2/95% O2 in the serosal bathing solution, with 100% O2 in the mucosal solution, results in CO2-diffusion limitation of acid secretion in bullfrog gastric mucosa. Changing to 10% CO2/90% 02 on both surfaces doubles the acid secretory rate. We calculate that, were the rate of oxygen consumption to increase significantly as a result of secretory stimulation, the tissue would now be oxygen limited. This prediction is tested by raising the P02 by increasing the total pressure in a hyperbaric chamber. Since no change in acid secretory rate or potential difference was observed upon changing from PO2 = 0.9 to PO2 = 1.9 atm, we conclude that the tissue is not O2 limited at normal pressure. Decreasing PO2 below 0.9 atm, by contrast, decreases the acid secretory rate and raises both PD and resistance. We infer that the rate of oxygen consumption did not rise significantly when acid secretion was increased by supplying sufficient CO2.
    Matched MeSH terms: Atmosphere Exposure Chambers
  17. Colourimetric determination of features of an air sampling technique optimal for detection of surfactants
    Nur Hazimah Abdul Halim, Norfazrin Mohd Hanif, Mohamed Rozali Othman, Mohd Talib Latif
    Sains Malaysiana, 2010;39:175-179.
    Surfactants in the atmosphere may act as cloud condensation nuclei, with a potentially negative impact on the global climate. Therefore, accurate determination of surfactants is crucial in order to investigate the possible effects of surfactants on the atmosphere. The aim of this study was to identify the optimum sampling method for measuring the maximum quantity of surfactants present in ambient air. Air samples were collected using a range of air sampling pumps that were made to vary in terms of flow rate, storage period, type of absorbing solution and the characteristics of the impinger tube. Samples obtained were analysed by colourimetry for anionic and cationic surfactants as methylene blue-active substances (MBAS) and disulphine blue-active substances (DBAS), respectively. Absorbance was measured at 650 nm for MBAS and 628 nm for DBAS using UV-visible spectrophotometer. We found that the optimum sampling method consisted of an absorbent solution (deionised water, buffer solution and methylene blue/disulphine blue solution) with the flow rate of 1.0 L/min. The concentration of surfactants in all sampling methods remained constant regardless of the storage period (1 day and 4 days), indicating that surfactants in the absorbing solution are quite stable. Covering the impinger tube was shown to influence the amount of both anionic and cationic surfactants detected.
    Matched MeSH terms: Atmosphere
  18. The exchange of water and energy between a tropical peat forest and the atmosphere: Seasonal trends and comparison against other tropical rainforests
    Tang ACI, Stoy PC, Hirata R, Musin KK, Aeries EB, Wenceslaus J, et al.
    Sci Total Environ, 2019 Sep 15;683:166-174.
    PMID: 31132697 DOI: 10.1016/j.scitotenv.2019.05.217
    Tropical rainforests control the exchange of water and energy between the land surface and the atmosphere near the equator and thus play an important role in the global climate system. Measurements of latent (LE) and sensible heat exchange (H) have not been synthesized across global tropical rainforests to date, which can help place observations from individual tropical forests in a global context. We measured LE and H for four years in a tropical peat forest ecosystem in Sarawak, Malaysian Borneo using eddy covariance, and hypothesize that the study ecosystem will exhibit less seasonal variability in turbulent fluxes than other tropical ecosystems as soil water is not expected to be limiting in a tropical forested wetland. LE and H show little variability across seasons in the study ecosystem, with LE values on the order of 11 MJ m-2 day and H on the order of 3 MJ m-2 day-1. Annual evapotranspiration (ET) did not differ among years and averaged 1579 ± 47 mm year-1. LE exceeded characteristic values from other tropical rainforest ecosystems in the FLUXNET2015 database with the exception of GF-Guy near coastal French Guyana, which averaged 8-11 MJ m-2 day-1. The Bowen ratio (Bo) in tropical rainforests in the FLUXNET2015 database either exhibited little seasonal trend, one seasonal peak, or two peaks. Volumetric water content (VWC) and VPD explained a trivial amount of the variability of LE and Bo in some of the tropical rainforests including the study ecosystem, but were strong controls in others, suggesting differences in stomatal regulation and/or the partitioning between evaporation and transpiration. Results demonstrate important differences in the seasonal patterns in water and energy exchange across different tropical rainforest ecosystems that need to be understood to quantify how ongoing changes in tropical rainforest extent will impact the global climate system.
    Matched MeSH terms: Atmosphere*
  19. Multiple regression analysis in modeling of columnar ozone in Peninsular Malaysia
    Tan KC, Lim HS, Mat Jafri MZ
    Environ Sci Pollut Res Int, 2014 Jun;21(12):7567-77.
    PMID: 24599658 DOI: 10.1007/s11356-014-2697-y
    This study aimed to predict monthly columnar ozone (O3) in Peninsular Malaysia by using data on the concentration of environmental pollutants. Data (2003-2008) on five atmospheric pollutant gases (CO2, O3, CH4, NO2, and H2O vapor) retrieved from the satellite Scanning Imaging Absorption Spectrometer for Atmospheric Chartography (SCIAMACHY) were employed to develop a model that predicts columnar ozone through multiple linear regression. In the entire period, the pollutants were highly correlated (R = 0.811 for the southwest monsoon, R = 0.803 for the northeast monsoon) with predicted columnar ozone. The results of the validation of columnar ozone with column ozone from SCIAMACHY showed a high correlation coefficient (R = 0.752-0.802), indicating the model's accuracy and efficiency. Statistical analysis was utilized to determine the effects of each atmospheric pollutant on columnar ozone. A model that can retrieve columnar ozone in Peninsular Malaysia was developed to provide air quality information. These results are encouraging and accurate and can be used in early warning of the population to comply with air quality standards.
    Matched MeSH terms: Atmosphere/chemistry*
  20. Termite assemblages, forest disturbance and greenhouse gas fluxes in Sabah, East Malaysia
    Eggleton P, Homathevi R, Jones DT, MacDonald JA, Jeeva D, Bignell DE, et al.
    Philos Trans R Soc Lond B Biol Sci, 1999 Nov 29;354(1391):1791-802.
    PMID: 11605622
    A synthesis is presented of sampling work conducted under a UK government-funded Darwin Initiative grant undertaken predominantly within the Danum Valley Conservation Area (DVCA), Sabah, East Malaysia. The project concerned the assemblage structure, gas physiology and landscape gas fluxes of termites in pristine and two ages of secondary, dipterocarp forest. The DVCA termite fauna is typical of the Sunda region, dominated by Termes-group soil-feeders and Nasutitermitinae. Selective logging appears to have relatively little effect on termite assemblages, although soil-feeding termites may be moderately affected by this level of disturbance. Species composition changes, but to a small extent when considered against the background level of compositional differences within the Sunda region. Physiologically the assemblage is very like others that have been studied, although there are some species that do not fit on the expected body size-metabolic rate curve. As elsewhere, soil-feeders and soil-wood interface-feeders tend to produce more methane. As with the termite assemblage characteristics, gross gas and energy fluxes do not differ significantly between logged and unlogged sites. Although gross methane fluxes are high, all the soils at DVCA were methane sinks, suggesting that methane oxidation by methanotrophic bacteria was a more important process than methane production by gut archaea. This implies that methane production by termites in South-East Asia is not contributing significantly to the observed increase in levels of methane production worldwide. Biomass density, species richness, clade complement and energy flow were much lower at DVCA than at a directly comparable site in southern Cameroon. This is probably due to the different biogeographical histories of the areas.
    Matched MeSH terms: Atmosphere
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