Displaying publications 61 - 80 of 999 in total

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  1. Brändle J, Kunert N
    Tree Physiol, 2019 12 01;39(12):1975-1983.
    PMID: 31631217 DOI: 10.1093/treephys/tpz104
    Tree autotrophic respiratory processes, especially stem respiration or stem CO2 efflux (Estem), are important components of the forest carbon budget. Despite efforts to investigate the controlling processes of Estem in recent years, a considerable lack in our knowledge remains on the abiotic and biotic drivers affecting Estem dynamics. It has been strongly advocated that long-term measurements would shed light onto those processes. The expensive scientific instruments needed to measure gas exchange have prevented Estem measurements from being applied on a larger temporal and spatial scale. Here, we present an automated closed dynamic chamber system based on inexpensive and industrially broadly applied CO2 sensors, reducing the costs for the sensing system to a minimum. The CO2 sensor was cross-calibrated with a commonly used gas exchange system in the laboratory and in the field, and we found very good accordance of these sensors. We tested the system under harsh tropical climatic conditions, characterized by heavy tropical rainfall events, extreme humidity and temperatures, in a moist lowland forest in Malaysia. We recorded Estem of three Dyera costulata (Miq.) trees with our prototype over various days. The variation of Estem was large among the three tree individuals and varied by 7.5-fold. However, clear diurnal changes in Estem were present in all three tree individuals. One tree showed high diurnal variation in Estem, and the relationship between Estem and temperature was characterized by a strong hysteresis. The large variations found within one single tree species highlight the importance of continuous measurement to quantify ecosystem carbon fluxes.
    Matched MeSH terms: Ecosystem*
  2. Rácz IA, Szanyi S, Nagy A
    Biol Futur, 2023 Dec;74(4):393-400.
    PMID: 38349457 DOI: 10.1007/s42977-024-00203-9
    The importance of pollination and pollinators is easy to underestimate and impossible to overstate, since its importance goes far beyond the crop production and even the maintenance of plant populations. Most terrestrial ecosystems ultimately depend on the plant-pollinator interactions formed by million years coevolution. This is essential for both the daily functioning of the ecosystems and the long-term development of biodiversity. At the same time, the loss of biodiversity caused by climate change and human activities will soon lead to an ecological crisis, a catastrophe, which could endanger our life: For example, through the decline and loss of various ecosystem services. Such may be the pollination crisis, resulted from a significant loss of pollinating insects' diversity and abundance. The discovery of a pollinator Orthoptera species has encouraged researchers in the densely populated region of Indo-Malaysia to explore the potential role of orthopterans as pollinators. Although the flower visitation of some species has been already known, the role of orthopterans in pollination is scarcely revealed. Here, we collected and reviewed the available data in order to point out some factors of their importance and set priorities that may serve as a basis for further investigations regarding ecological, evolutionary and practical points of view.
    Matched MeSH terms: Ecosystem*
  3. 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: Ecosystem*
  4. Thapa S, Zaki SA
    J Therm Biol, 2024 Feb;120:103809.
    PMID: 38364574 DOI: 10.1016/j.jtherbio.2024.103809
    The sub-Himalayan region extends over 2500 km, extending over several countries. Though the effects of climate change is widely anticipated in the diverse but fragile ecosystem of the Himalayas, very less research has been conducted on the indoor environment of the buildings in these regions. In this study, a pre-validated model of 3-storey concrete residential building was used to study the indoor performance and thermal comfort in the face of climate change in the 8 (eight) different hill towns (hill stations) located from west to the east. Rise in ambient and indoor conditions were evident as a part of climate change with colder locations being affected the most. The thermal comfort assessment using both the climate chamber based PMV model and adaptive models revealed the decrease in cold related discomfort and increase in hot related discomfort. On an overall, the indoor conditions improved in these cold locations. The indoor and outdoor thermal condition and thermal comfort plummeted significantly with latitude and elevation. The heating demand in the future climate reduced by about 50-70 % in warmer locations, while the cooling demand increased by as much as 1000-2000 % in cold locations, respectively. Additionally, it was seen that the thermal environment and comfort both declined more rapidly with elevation in the locations lying in the western Himalayas as compared to those in the eastern Himalayas.
    Matched MeSH terms: Ecosystem*
  5. Sirichantakul K, Hmone ZW, Kyaw ML, Thandar C
    Zootaxa, 2024 Feb 07;5406(3):481-486.
    PMID: 38480137 DOI: 10.11646/zootaxa.5406.3.7
    A curious micropteous gaudy grasshopper (family Pyrgomorphidae), Burmorthacris subaptera was described by Kevan, Singh and Akbar in 1964 as a sole member of its genus based on a female and a male collected in Yenangyaung (upper Myanmar) on 27th and 28th August 1937 and which were deposited at the Academy of Natural Sciences of Philadelphia. The species has never been reported since then. The genus Burmorthacris is the northernmost of the Orthacris genus group genera, which includes mostly genera from Sri Lanka and Malaysia. Recently we rediscovered this B. subaptera in its type locality (Yenangyaung township in the Magway Region) in Myanmar, 85 years after the holotype and the paratype were collected in the same place, and furthermore herewith we present one more locality in another region where the species has been found (Nyaung-U township in the Mandalay Region). Due to the lack of basically any information on this species distribution and habitat, including also photographs of its natural coloration in this habitat, the present study provides the first-time photographs of B. subaptera in its natural habitat from both localities, as well as some insights into its morphology, especially coloration, habitat, and behavior.
    Matched MeSH terms: Ecosystem*
  6. Condit R, Ashton PS, Manokaran N, LaFrankie JV, Hubbell SP, Foster RB
    Philos Trans R Soc Lond B Biol Sci, 1999 Nov 29;354(1391):1739-48.
    PMID: 11605618
    Dynamics of the Pasoh forest in Peninsular Malaysia were assessed by drawing a comparison with a forest in Panama, Central America, whose dynamics have been thoroughly described. Census plots of 50 ha were established at both sites using standard methods. Tree mortality at Pasoh over an eight-year interval was 1.46% yr(-1) for all stems > or = 10 mm diameter at breast height (dbh), and 1.48% yr(-1) for stems > or = 100 mm dbh. Comparable figures at the Barro Colorado Island site in Panama (BCI) were 2.55% and 2.03%. Growth and recruitment rates were likewise considerably higher at BCI than at Pasoh. For example, in all trees 500-700 mm in dbh, mean BCI growth over the period 1985-1995 was 6 mm yr(-1), whereas mean Pasoh growth was about 3.5 mm yr(-1). Examining growth and mortality rates for individual species showed that the difference between the forests can be attributed to a few light-demanding pioneer species at BCI, which have very high growth and mortality; Pasoh is essentially lacking this guild. The bulk of the species in the two forests are shade-tolerant and have very similar mortality, growth and recruitment. The Pasoh forest is more stable than BCI's in another way as well: few of its tree populations changed much over the eight-year census interval. In contrast, at BCI, over 10% of the species had populations increasing or decreasing at a rate of >0.05 yr(-1) compared to just 2% of the species at Pasoh). The faster species turnover at BCI can probably be attributed to severe droughts that have plagued the forest periodically over the past 30 years; Pasoh has not suffered such extreme events recently. The dearth of pioneer species at Pasoh is associated with low-nutrient soil and slow litter breakdown, but the exact mechanisms behind this association remain poorly understood.
    Matched MeSH terms: Ecosystem
  7. Ojonubah, James Omaiye, Mohd Hafiz Mohd
    MyJurnal
    Interactions between multispecies are usual incidence in their habitats. Such interactions among the species are thought to be asymmetric in nature, which combine with environmental factors can determine the distributions and abundances of the species. Most often, each species responds differentially to biotic interactions and environmental factors. Therefore, predicting the presence-absence of species is a major challenge in ecology. In this paper, we used mathematical modelling to study the combined effects of biotic interactions (i.e. asymmetric competition) and environmental factors on the presence-absence of the species across a geographical region. To gain better insight on this problem, we performed invasion and numerical simulation analyses of the model of multispecies competitive dynamics. Different threshold values of competition coefficients were observed, which result in different phenomena; such as coexistence of species and priority effects. Consequently, we propose that asymmetric biotic interactions, combined with environmental factors can allow coexistence of relatively weak and strong species at the same location x.
    Matched MeSH terms: Ecosystem
  8. Shafie NJ, Sah SA, Latip NS, Azman NM, Khairuddin NL
    Trop Life Sci Res, 2011 Dec;22(2):13-22.
    PMID: 24575214 MyJurnal
    We present an assessment of the diversity of Malaysian bats at two contrasting habitat types (secondary forest and oil palm plantation) along the Kerian River surveyed between February 2009 and February 2010. Three hundred and twenty nine individual bats from 13 species representing 4 families were recorded using 10 mist nets. The most commonly caught bat in the secondary forest was Cynopterus brachyotis (n=75), followed by Macroglossus minimus (n=10). Meanwhile, in the oil palm plantation, the most commonly caught bat was Cynopterus brachyotis (n=109), followed by Cynopterus horsfieldi (n=76). The netting efforts were equal for both habitat types. The total sampling nights for each habitat type was 5460. The oil palm plantation had a greater bat abundance that was significantly different from that of the secondary forest, with 209 and 120 individuals, respectively (Mann-Whitney U-test = 31.5, p<0.05). Our results suggest that there is no significant difference in species richness between the two sites. However, the invasion by disturbance-associated species of the secondary forest is indicative of negative effects on the forest and animal diversity in this area. Forest managers should consider multiple measures of forest fragmentation sensitivity before making any forest management decisions.
    Matched MeSH terms: Ecosystem
  9. Pramanik BK, Pramanik SK, Monira S
    Chemosphere, 2021 Nov;282:131053.
    PMID: 34098311 DOI: 10.1016/j.chemosphere.2021.131053
    Nano/microplastics (NPs/MPs), a tiny particle of plastic pollution, are known as one of the most important environmental threats to marine ecosystems. Wastewater treatment plants can act as entrance routes for NPs/MPs to the aquatic environment as they breakdown of larger fragments of the plastic component during the treatment process; therefore, it is necessary to remove NPs/MPs during the wastewater treatment process. In this study, understanding the effect of water shear force on the fragmentation of larger size MPs into smaller MPs and NPs and their removal by air flotation and nano-ferrofluid (i.e., magnetite and cobalt ferrite particle as a coagulant) and membrane processes were investigated as a proof-of-concept study. It is found that a two-blade mechanical impeller could fragment MPs from 75, 150 and 300 μm into mean size NPs/MPs of 0.74, 1.14 and 1.88 μm, respectively. Results showed that the maximum removal efficiency of polyethylene, polyvinyl chloride and polyester was 85, 82 and 69%, respectively, in the air flotation process. Increasing the dose of behentrimonium chloride surfactant from 2 to 10 mg/L improved the efficiency of the air flotation process for NPs/MPs removal. It is also found that the removal efficiency of NPs/MPs by the air flotation system depends on solution pH, size, and types of NPs/MPs. This study also found a less significant removal efficiency of NPs/MPs by both types of ferrofluid used in this study with an average removal of 43% for magnetite and 55% for cobalt ferrite. All three plastics tested had similar removal efficiency by the nano-ferrofluid particles, meaning that this removal technique does not rely on the plastic component type. Among all the process tested, both ultrafiltration and microfiltration membrane processes were highly effective, removing more than 90% of NPs/MPs fragment particles. Overall, this study has confirmed the effectiveness of using air flotation and the membrane process to remove NPs/MPs from wastewater.
    Matched MeSH terms: Ecosystem
  10. Curren E, Kuwahara VS, Yoshida T, Leong SCY
    Environ Pollut, 2021 Nov 01;288:117776.
    PMID: 34280748 DOI: 10.1016/j.envpol.2021.117776
    Microplastic pollution is a prevalent and serious problem in marine environments. These particles have a detrimental impact on marine ecosystems. They are harmful to marine organisms and are known to be a habitat for toxic microorganisms. Marine microplastics have been identified in beach sand, the seafloor and also in marine biota. Although research investigating the presence of microplastics in various marine environments have increased across the years, studies in Southeast Asia are still relatively limited. In this paper, 36 studies on marine microplastic pollution in Southeast Asia were reviewed and discussed, focusing on microplastics in beach and benthic sediments, seawater and marine organisms. These studies have shown that the presence of fishing harbours, aquaculture farms, and tourism result in an increased abundance of microplastics. The illegal and improper disposal of waste from village settlements and factories also contribute to the high abundance of microplastics observed. Hence, it is crucial to identify the hotspots of microplastic pollution, for assessment and mitigation purposes. Future studies should aim to standardize protocols and quantification, to allow for better quantification and assessment of the levels of microplastic contamination for monitoring purposes.
    Matched MeSH terms: Ecosystem
  11. Tan SF, Samsudin A
    Sensors (Basel), 2021 Oct 06;21(19).
    PMID: 34640967 DOI: 10.3390/s21196647
    The inherent complexities of Industrial Internet of Things (IIoT) architecture make its security and privacy issues becoming critically challenging. Numerous surveys have been published to review IoT security issues and challenges. The studies gave a general overview of IIoT security threats or a detailed analysis that explicitly focuses on specific technologies. However, recent studies fail to analyze the gap between security requirements of these technologies and their deployed countermeasure in the industry recently. Whether recent industry countermeasure is still adequate to address the security challenges of IIoT environment are questionable. This article presents a comprehensive survey of IIoT security and provides insight into today's industry countermeasure, current research proposals and ongoing challenges. We classify IIoT technologies into the four-layer security architecture, examine the deployed countermeasure based on CIA+ security requirements, report the deficiencies of today's countermeasure, and highlight the remaining open issues and challenges. As no single solution can fix the entire IIoT ecosystem, IIoT security architecture with a higher abstraction level using the bottom-up approach is needed. Moving towards a data-centric approach that assures data protection whenever and wherever it goes could potentially solve the challenges of industry deployment.
    Matched MeSH terms: Ecosystem
  12. Dharmaraj S, Ashokkumar V, Hariharan S, Manibharathi A, Show PL, Chong CT, et al.
    Chemosphere, 2021 Jun;272:129601.
    PMID: 33497928 DOI: 10.1016/j.chemosphere.2021.129601
    Recently, the COVID-19 disease spread has emerged as a worldwide pandemic and cause severe threats to humanity. The World Health Organisation (WHO) releases guidelines to help the countries to reduce the spread of this virus to the public, like wearing masks, hand hygiene, social distancing, shutting down all types of public transports, etc. These conditions led to a worldwide economic fall drastically, and on the other hand, indirect environmental benefits like global air quality improvement and decreased water pollution are also pictured. Currently, use of face masks is part of a comprehensive package of the prevention and control measures that can limit the spread of COVID-19 since there is no clinically proven drugs or vaccine available for COVID-19. Mostly, face masks are made of petroleum-based non-renewable polymers that are non-biodegradable, hazardous to the environment and create health issues. This study demonstrates the extensive use of the face mask and how it affects human health and the marine ecosystem. It has become a great challenge for the government sectors to impose strict regulations for the proper disposal of the masks as medical waste by the public. Neglecting the seriousness of this issue may lead to the release of large tonnes of micro-plastics to the landfill as well as to the marine environment where mostly end-up and thereby affecting their fauna and flora population vastly. Besides, this study highlights the COVID-19 spread, its evolutionary importance, taxonomy, genomic structure, transmission to humans, prevention, and treatment.
    Matched MeSH terms: Ecosystem
  13. Kumar V, Sharma N, Duhan L, Pasrija R, Thomas J, Umesh M, et al.
    Environ Toxicol Pharmacol, 2023 Mar;98:104045.
    PMID: 36572198 DOI: 10.1016/j.etap.2022.104045
    Microplastics are the small fragments of the plastic molecules which find their applications in various routine products such as beauty products. Later, it was realized that it has several toxic effects on marine and terrestrial organisms. This review is an approach in understanding the microplastics, their origin, dispersal in the aquatic system, their biodegradation and factors affecting biodegradation. In addition, the paper discusses the major engineering approaches applied in microbial biotechnology. Specifically, it reviews microbial genetic engineering, such as PET-ase engineering, MHET-ase engineering, and immobilization approaches. Moreover, the major challenges associated with the plastic removal are presented by evaluating the recent reports available.
    Matched MeSH terms: Ecosystem
  14. Kabyl A, Yang M, Shah D, Ahmad A
    Int J Environ Res Public Health, 2022 Nov 17;19(22).
    PMID: 36429909 DOI: 10.3390/ijerph192215190
    Oil spills are environmental pollution events that occur due to natural disasters or human activities, resulting in a liquid petroleum hydrocarbon release in the environment, especially into the marine ecosystem. Once oil spills happen, they cause detrimental consequences to the environment, living organisms, and humans. Although there are increasing oil and gas activities in the Arctic region, which is abundant with undiscovered oil and gas resources, the harsh environmental conditions of the region, such as the ice coverage, cold temperatures, long periods of darkness, and its remoteness, pose significant challenges to managing the risk of accidental oil spills in ice-infested waters. In this paper, a bibliometric analysis has been applied to study the global work on oil spill research in ice-infested waters. The paper aims to present an overview of the available oil spill response methods in ice-infested waters, identify the current trends of the research on oil spills in ice-infested waters, and determine the challenges with the future research directions based on the bibliometric analysis. The analysis includes a total number of 77 articles that have been published in this research field which were available in the Scopus database, involving 193 authors from 17 countries dating from 1960 to September 2022. During the bibliometric analysis, the top five most productive authors and countries as well as the most cited publications on oil spills in ice-infested waters have been identified; the authors' cooperation network and the cooperation network between the countries in oil spills research in ice-infested waters have been created; a co-citation analysis and a terms analysis have been performed to identify the popular terms and topics. For future directions, it is recommended for researchers (1) to study real oil spills as much as possible to obtain a good overview through replication under different situations; (2) to develop a new technique for the careful examination and management of the potential risks; (3) to study oil separation from the recovered oil-ice mixture.
    Matched MeSH terms: Ecosystem
  15. Sarijan S, Azman S, Said MIM, Jamal MH
    Environ Sci Pollut Res Int, 2021 Jan;28(2):1341-1356.
    PMID: 33079353 DOI: 10.1007/s11356-020-11171-7
    The utilization of plastics has now become a threat to the environment as it generates microplastic particles (<5 mm in size). The increasing studies on the occurrence of microplastics in different environmental compartments have raised concern about the potential effects on ecosystems and living organisms. Of these, numerous studies are focused on marine environments. The occurrence of microplastics is recently extended to the freshwater environments, including river systems, streams, lakes, pond, creek, and estuarine rivers. This paper overviews the current knowledge and research findings on the occurrence of microplastics in water, sediment, and fish in freshwater environments. The review also covers the adopted methodology and impacts of microplastics to the ecosystem. Future perspectives are discussed as well in this review.
    Matched MeSH terms: Ecosystem
  16. Kurniawan TA, Haider A, Ahmad HM, Mohyuddin A, Umer Aslam HM, Nadeem S, et al.
    Chemosphere, 2023 Jun;325:138367.
    PMID: 36907482 DOI: 10.1016/j.chemosphere.2023.138367
    The generation of microplastics (MPs) has increased recently and become an emerging issue globally. Due to their long-term durability and capability of traveling between different habitats in air, water, and soil, MPs presence in freshwater ecosystem threatens the environment with respect to its quality, biotic life, and sustainability. Although many previous works have been undertaken on the MPs pollution in the marine system recently, none of the study has covered the scope of MPs pollution in the freshwater. To consolidate scattered knowledge in the literature body into one place, this work identifies the sources, fate, occurrence, transport pathways, and distribution of MPs pollution in the aquatic system with respect to their impacts on biotic life, degradation, and detection techniques. This article also discusses the environmental implications of MPs pollution in the freshwater ecosystems. Certain techniques for identifying MPs and their limitations in applications are presented. Through a literature survey of over 276 published articles (2000-2023), this study presents an overview of solutions to the MP pollution, while identifying research gaps in the body of knowledge for further work. It is conclusive from this review that the MPs exist in the freshwater due to an improper littering of plastic waste and its degradation into smaller particles. Approximately 15-51 trillion MP particles have accumulated in the oceans with their weight ranging between 93,000 and 236,000 metric ton (Mt), while about 19-23 Mt of plastic waste was released into rivers in 2016, which was projected to increase up to 53 Mt by 2030. A subsequent degradation of MPs in the aquatic environment results in the generation of NPs with size ranging from 1 to 1000 nm. It is expected that this work facilitates stakeholders to understand the multi-aspects of MPs pollution in the freshwater and recommends policy actions to implement sustainable solutions to this environmental problem.
    Matched MeSH terms: Ecosystem
  17. Elbeltagi A, Pande CB, Kumar M, Tolche AD, Singh SK, Kumar A, et al.
    Environ Sci Pollut Res Int, 2023 Mar;30(15):43183-43202.
    PMID: 36648725 DOI: 10.1007/s11356-023-25221-3
    Agriculture, meteorological, and hydrological drought is a natural hazard which affects ecosystems in the central India of Maharashtra state. Due to limited historical data for drought monitoring and forecasting available in the central India of Maharashtra state, implementing machine learning (ML) algorithms could allow for the prediction of future drought events. In this paper, we have focused on the prediction accuracy of meteorological drought in the semi-arid region based on the standardized precipitation index (SPI) using the random forest (RF), random tree (RT), and Gaussian process regression (GPR-PUK kernel) models. A different combination of machine learning models and variables has been performed for the forecasting of metrological drought based on the SPI-6 and 12 months. Models were developed using monthly rainfall data for the period of 2000-2019 at two meteorological stations, namely, Karanjali and Gangawdi, each representing a geographical region of Upper Godavari river basin area in the central India of Maharashtra state which frequently experiences droughts. Historical data from the SPI from 2000 to 2013 was processed to train the model into machine learning model, and the rest of the 2014 to 2019-year data were used for testing to forecast the SPI and metrological drought. The mean square error (MSE), root mean square error (RMSE), adjusted R2, Mallows' (Cp), Akaike's (AIC), Schwarz's (SBC), and Amemiya's PC were used to identify the best combination input model and best subregression analysis for both stations of SPI-6 and 12. The correlation coefficient ([Formula: see text]), mean absolute error (MAE), root mean square error (RMSE), relative absolute error (RAE), and root relative squared error (RRSE) were used to perform evaluation for SPI-6 and 12 months of both stations with RF, RT, and GPR-PUK kernel models during the training and testing scenarios. The results during testing phase revealed that the RF was found as the best model in forecasting droughts with values of [Formula: see text], MAE, RMSE, RAE (%), and RRSE (%) being 0.856, 0.551, 0.718, 74.778, and 54.019, respectively, for SPI-6 while 0.961, 0.361, 0.538, 34.926, and 28.262, respectively, for SPI-12 scales at Gangawdi station. Further, the respective values of evaluators at Karanjali station were 0.913 and 0.966, 0.541 and 0.386, 0.604 and 0.589, 52.592 and 36.959, and 42.315 and 31.394 for PUK kernel and RT models, respectively, during SPI-6 and SPI-12. Machine learning models are potential drought warning techniques because they take less time, have fewer inputs, and are less sophisticated than dynamic or scientific models.
    Matched MeSH terms: Ecosystem
  18. Rakib MRJ, Al Nahian S, Madadi R, Haider SMB, De-la-Torre GE, Walker TR, et al.
    Environ Sci Process Impacts, 2023 May 25;25(5):929-940.
    PMID: 36939043 DOI: 10.1039/d3em00014a
    Microplastic (MP) pollution is a major global issue that poses serious threats to aquatic organisms. Although research on MP pollution has been extensive, the relationship between MPs and water quality parameters in estuarine water systems is unclear. This work studied the spatiotemporal distribution and characteristics of MPs in the Karnaphuli River estuary, Bangladesh. MP abundance was calculated by towing with a plankton net (300 μm mesh size) at three river gradients (up-, mid- and downstream) and the association between physicochemical parameters of water (temperature, pH, salinity, electrical conductivity, total dissolved solids, and dissolved oxygen) and MP distribution patterns was also investigated. Mean MP abundance in water was higher during the wet season (April) (4.33 ± 2.45 items per m3) compared to the dry season (September) (3.65 ± 2.54 items per m3). In descending order, the highest MP abundance was observed downstream (6.60 items per m3) > midstream (3.15 items per m3) > upstream (2.22 items per m3). pH during the wet season (April) and temperature during the dry season (September) were key physicochemical parameters that correlated with river MP abundance (r = -0.74 and 0.74 respectively). Indicating that if the Karnaphuli River water has low pH or high temperature, there is likely to be high MPs present in the water. Most MP particles were film-shaped, white in color, and 1-5 mm in size. Of the six polymers detected, polypropylene (PP), polystyrene (PS), polyethylene terephthalate (PET), and cellulose were predominant, comprising roughly 17-19% each. These results can be used to model MP transport in the freshwater ecosystem of the Karnaphuli River estuary in Bangladesh to help develop future mitigation strategies.
    Matched MeSH terms: Ecosystem
  19. Lee YL, Jaafar NR, Ling JG, Huyop F, Abu Bakar FD, Rahman RA, et al.
    Int J Biol Macromol, 2024 Apr;263(Pt 1):130284.
    PMID: 38382786 DOI: 10.1016/j.ijbiomac.2024.130284
    Polyethylene terephthalate (PET) is one of the most produced plastics globally and its accumulation in the environment causes harm to the ecosystem. Polyethylene terephthalate hydrolyse (PETase) is an enzyme that can degrade PET into its monomers. However, free PETase lacks operational stabilities and is not reusable. In this study, development of cross-linked enzyme aggregate (CLEA) of PETase using amylopectin (Amy) as cross-linker was introduced to solve the limitations of free PETase. PETase-Amy-CLEA exhibited activity recovery of 81.9 % at its best immobilization condition. Furthermore, PETase-Amy-CLEA exhibited 1.37-, 2.75-, 2.28- and 1.36-fold higher half-lives than free PETase at 50 °C, 45 °C, 40 °C and 35 °C respectively. Moreover, PETase-Amy-CLEA showed broader pH stability from pH 5 to 10 and could be reused up to 5 cycles. PETase-Amy-CLEA retained >70 % of initial activity after 40 days of storage at 4 °C. In addition, lower Km of PETase-Amy-CLEA indicated better substrate affinity than free enzyme. PETase-Amy-CLEA corroded PET better and products yielded was 66.7 % higher than free PETase after 32 h of treatment. Hence, the enhanced operational stabilities, storage stability, reusability and plastic degradation ability are believed to make PETase-Amy-CLEA a promising biocatalyst in plastic degradation.
    Matched MeSH terms: Ecosystem
  20. Mokhtari M, Ghaffar MA, Usup G, Cob ZC
    PLoS One, 2015;10(1):e0117467.
    PMID: 25629519 DOI: 10.1371/journal.pone.0117467
    In tropical regions, different species of fiddler crabs coexist on the mangrove floor, which sometimes makes it difficult to define species-specific habitat by visual inspection. The aim of this study is to find key environmental parameters which affect the distribution of fiddler crabs and to determine the habitats in which each species was most abundant. Crabs were collected from 19 sites within the mudflats of Sepang-Lukut mangrove forest. Temperature, porewater salinity, organic matter, water content, carbon and nitrogen content, porosity, chlorophyll content, pH, redox potential, sediment texture and heavy metals were determined in each 1 m2 quadrate. Pearson correlation indicated that all sediment properties except pH and redox potential were correlated with sediment grain size. Canonical correspondence analysis (CCA) indicated that Uca paradussumieri was negatively correlated with salinity and redox potential. Sand dwelling species, Uca perplexa and Uca annulipes, were highly dependent on the abundance of 250 μm and 150 μm grain size particles in the sediment. Canonical Discriminative Analysis (CDA) indicated that variation in sediment grain size best explained where each crab species was most abundant. Moreover, U. paradussumieri commonly occupies muddy substrates of low shore, while U. forcipata lives under the shade of mangrove trees. U. annulipes and U. perplexa with the high number of spoon tipped setae on their second maxiliped are specialized to feed on the sandy sediments. U. rosea and U. triangularis are more common on muddy sediment with high sediment density. In conclusion, sediment grain size that influences most sediment properties acts as a main factor responsible for sediment heterogeneity. In this paper, the correlation between fiddler crab species and environmental parameters, as well as the interaction between sediment characteristics, was explained in order to define the important environmental factors in fiddler crab distributions.
    Matched MeSH terms: Ecosystem*
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