The invasive weed Asystasia gangetica was investigated for its potential as a biomonitor and as a phytoremediator of potentially toxic metals (PTMs) (Cd, Cu, Ni, Pb, and Zn) in Peninsular Malaysia owing to its ecological resistance towards unfavourable environments. The biomonitoring potential of PTMs was determined based on the correlation analysis of the metals in the different parts of the plant (leaves, stems, and roots) and its habitat topsoils. In the roots, the concentrations (mg/kg dry weight) of Cd, Cu, Ni, Pb, and Zn ranged from 0.03 to 2.18, 9.22 to 139, 0.63 to 5.47, 2.43 to 10.5, and 50.7 to 300, respectively. In the leaves, the concentrations (mg/kg dry weight) of Cd, Cu, Ni, Pb, and Zn ranged from 0.03 to 1.16, 7.94 to 20.2, 0.03 to 6.13, 2.10 to 21.8, and 18.8 to 160, respectively. In the stems, the concentrations (mg/kg dry weight) of Cd, Cu, Ni, Pb, and Zn ranged from 0.03 to 1.25, 5.57 to 11.8, 0.23 to 3.69, 0.01 to 7.79, and 26.4 to 246, respectively. On the other hand, the phytoremediation potential of the five metals was estimated based on the bioconcentration factor (BCF) and the translocation factor (TF) values. Correlation analysis revealed that the roots and stems could be used as biomonitors of Cu, the stems as biomonitors of Ni, the roots and leaves as biomonitors of Pb, and all three parts of the plant as biomonitors of Zn. According to the BCF values, in the topsoil, the "easily, freely, leachable, or exchangeable" geochemical fractions of the five metals could be more easily transferred to the roots, leaves, and stems when compared with total concentrations. Based on the TF values of Cd, Ni, and Pb, the metal transfer to the stems (or leaves) from the roots was efficient (>1.0) at most sampling sites. The results of BCF and TF showed that A. gangetica was a good phytoextractor for Cd and Ni, and a good phytostabilizer for Cu, Pb, and Zn. Therefore, A. gangetica is a good candidate as a biomonitor and a phytoremediator of Ni, Pb, and Zn for sustainable contaminant remediation subject to suitable field management strategies.
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.
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.
The gravity of the impending threats posed by microplastics (MPs) pollution in the environment cannot be over-emphasized. Several research studies continue to stress how important it is to curb the proliferation of these small plastic particles with different physical and chemical properties, especially in aquatic environments. While several works on how to monitor, detect and remove MPs from the aquatic environment have been published, there is still a lack of explicit regulatory framework for mitigation of MPs globally. A critical review that summarizes recent advances in MPs research and emphasizes the need for regulatory frameworks devoted to MPs is presented in this paper. These frameworks suggested in this paper may be useful for reducing the proliferation of MPs in the environment. Based on all reviewed studies related to MPs research, we discussed the occurrence of MPs by identifying the major types and sources of MPs in water bodies; examined the recent ways of detecting, monitoring, and measuring MPs routinely to minimize projected risks; and proposed recommendations for consensus regulatory actions that will be effective for MPs mitigation.
This study determines the bulk surface water (BSW) dissolved inorganic nutrients of nitrogen (DINi) and phosphate (DIP) during the upwelling season off the east coast of Peninsular Malaysia, South China Sea. BSW samples were analysed for DINi and DIP by using a standard automated colorimetric method. BSW DINi and DIP concentrations varied between 0.11 and 2.55 μM (mean 1.12 ± 0.63 μM), and below detection limit, and 0.29 μM (mean 0.11 ± 0.08 μM), respectively. The spatial distribution of higher concentrations between DINi and DIP was distinct. However, the highest concentrations of DINi and DIP were mostly recorded in the month of peak upwelling (July and August), where colder BSW temperatures were also encountered during field sampling. This study provides new evidence on the presence of BSW nutrients of DINi and DIP during upwelling season peak in July and August before their decline in September.
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.
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.
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.
Despite of our growing understanding of microplastic's implications, research on the effects of fibrous microplastic (FMPs) on the environment is still in its infancy. Some scientists have hypothesized the possibility of natural textile fibres, which may act as one of the emerging environmental pollutants prevalent among microplastic pollutants in the environment. Therefore, this review aims to critically evaluate the toxic effects of emerging FMPs, the presence, and sources of FMPs in the environment, identification and analytical techniques, and the potential impact or toxicity of the FMPs on the environment and human health. About175 publications (2011-2023) based on FMPs were identified and critically reviewed for transportation, analysis and ecotoxicological behaviours of FMPs in the environment. Textile industries, wastewater treatment plants, and household washing of clothes are significant sources of FMPs. In addition, various characterization techniques (e.g., FTIR, SEM, RAMAN, TGA, microscope, and X-Ray Fluorescence Spectroscopy) commonly used for the identification and analysis of FMPs are also discussed, which justifies the novelty aspects of this review. FMPs are pollutants of emerging concern due to their prevalence and persistence in the environment. FMPs are also found in the food chain, which is an alarming situation for living organisms, including effects on the nervous system, digestive system, circulatory system, and genetic alteration. This review will provide readers with a comparison of different analytical techniques, which will be helpful for researchers to select the appropriate analytical techniques for their study and enhance their knowledge about the harmful effects of FMPs.
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.
Even though Pacific - Indian Ocean exchange [Indonesian Throughflow (ITF)] has been measured for the last three decades, the measurements of microplastic in the region is very limited. This study was the initial investigation of the vertical distribution of microplastic in the deep-sea areas across the ITF Pathway. Niskin water samples were utilized to obtain the samples from a water column in a range of 5 to 2450 m. A total of 924 microplastic particles with an average abundance of 1.062 ± 0.646. n/L were found in the water column. Our findings indicate that water temperature and water density are the most significant factors correlated to the microplastic concentration. This study will be the first report discussing the distribution of microplastics in the deep-sea water column that could be highly significant in determining the fate and transport of microplastic within Indonesian waters that exits into the Indian Ocean.
Benthic foraminifera, single-celled marine organisms, are known for their wide distribution, high abundance and species diversity, test (i.e., shell) preservation in the sedimentary (e.g., historical) record, and sensitivity to environmental changes. Because of these characteristics, they have been widely used as bioindicators in environmental monitoring and, more recently, as Biological Quality Elements (BQEs) in the Ecological Quality Status (EcoQS) evaluation. The global scientific literature on benthic foraminifera as bioindicators was gathered from the Scopus database (overall 966 papers from 1973 to 2022) and explored with scientometric software. The outcomes highlight that the investigation of benthic foraminiferal response to pollutants started over 50 years ago. Indeed, not only the number of published documents has recently peaked (i.e., 2021 and 2022) but there has been also a growth in the percentages of papers falling within the Decision Sciences category that deals with the application of foraminiferal indices for the EcoQS assessment.
Surface sediments along the Southern Terengganu coast (≤7 km from the coast) were analyzed for polycyclic aromatic hydrocarbons (PAHs). The concentrations of 16 USEPA priority polycyclic aromatic hydrocarbons (ΣPAH16) ranged from 2.59 to 155 ng g-1 and their respective alkylated ranged between 8.80 and 24.90 ng g-1. Traces of acephenanthrylene, benzo[c]phenanthrene, thiophenic PAH, and benzonaphthofuran were identified. PAH diagnostic ratios and cross-plots revealed that these sedimentary PAH compounds are derived mainly from pyrogenic sources, primarily from biomass burning and petroleum combustion residues with minor petrogenic input. The high correlations between pyrogenic PAHs to total PAHs (r >0.73, p <0.5), and the Bap/Bep ratio to total PAHs (r = 0.88, p <0.5), suggest that atmospheric deposition and urban runoff are the main deposition pathways. The concentrations of the PAHs in the southern South China Sea fall in the moderate contamination range of 100-1000 ng g-1.
Seagrass is a valuable marine ecosystem engineer. However, seagrass population is declining worldwide. The lack of seagrass research in Malaysia raises questions about the status of seagrasses in the country. The seagrasses in Lawas, which is part of the coral-mangrove-seagrass complex, have never been studied in detail. In this study, we examine whether monthly changes of seagrass population in Lawas occurred. Data on estimates of seagrass percentage cover and water physicochemical parameters (pH, turbidity, salinity, temperature, and dissolved oxygen) were measured at 84 sampling stations established within the study area from June 2009 to May 2010. Meteorological data such as total rainfall, air temperature, and Southern Oscillation Index were also investigated. Our results showed that (i) the monthly changes of seagrass percentage cover are significant, (ii) the changes correlated significantly with turbidity measurements, and (iii) weather changes affected the seagrass populations. Our study indicates seagrass percentage increased during the El-Nino period. These results suggest that natural disturbances such as weather changes affect seagrass populations. Evaluation of land usage and measurements of other water physicochemical parameters (such as heavy metal, pesticides, and nutrients) should be considered to assess the health of seagrass ecosystem at the study area.
Forests and agricultural lands are the main resources on the earth's surface and important indicators of regional ecological environments. In this paper, Landsat images from 1990 and 2017 were used to extract information on forests in Malaysia based on a remote-sensing classification method. The spatial-temporal changes of forests and agricultural lands in Malaysia between 1990 and 2017 were analyzed. The results showed that the natural forests in Malaysia decreased by 441 Mha, a reduction of 21%. The natural forests were mainly converted into plantations in Peninsular Malaysia and plantations and secondary forests in East Malaysia. The area of agricultural lands in Malaysia increased by 55.7%, in which paddy fields increased by 1.1% and plantations increased by 98.2%. Paddy fields in Peninsular Malaysia are mainly distributed in the north-central coast and the Kelantan Delta. The agricultural land in East Malaysia is dominated by plantations, which are mainly distributed in coastal areas. The predictable areas of possible expansion for paddy fields in Peninsular Malaysia's Kelantan (45.2%) and Kedah (16.8%) areas in the future are large, and in addition, the plantations in Sarawak (44.7%) and Sabah (29.6%) of East Malaysia have large areas for expansion. The contradiction between agricultural development and protecting the ecological environment is increasingly prominent. The demand for agriculture is expected to increase further and result in greater pressures on tropical forests. Governments also need to encourage farmers to carry out existing land development, land recultivation, or cooperative development to improve agricultural efficiency and reduce the damage to natural forests.
Setiu Wetland is rapidly developing into an aquaculture and agriculture hub, causing concern about its water quality condition. To address this issue, it is imperative to acquire knowledge of the spatial and temporal distributions of pollutants. Consequently, this study applied combinations of hydrodynamic and particle tracking models to identify the transport behaviour of pollutants and calculate the residence time in Setiu Lagoon. The particle tracking results indicated that the residence time in Setiu Lagoon was highly influenced by the release location, where particles released closer to the river mouth exhibited shorter residence times than those released further upstream. Despite this fact, the pulse of river discharges successfully reduced the residence time in the order of two to twelve times shorter. Under different tidal phases, the residence time during the neap tide was longer regardless of heavy rainfalls, implying the domination of tidal flow in the water renewal within the lagoon.
Stormwater runoff is a major concern in urban areas which is mostly the result of vast urbanization. To reduce urban stormwater runoff and improve water quality, low impact development (LID) is used in urban areas. Therefore, it is vital to find the optimal combination of LID controls to achieve maximum reduction in both stormwater runoff and pollutants with optimal cost. In this study, a simulation-optimization model was developed by linking the EPA Storm Water Management Model (SWMM) to the Multi-Objective Particle Swarm Optimization (MOPSO) using MATLAB. The coupled model could carry out multi-objective optimization (MOO) and find potential solutions to the optimization objectives using the SWMM simulation model outputs. The SWMM model was developed using data from the BUNUS catchment in Kuala Lumpur, Malaysia. The total suspended solids (TSS) and total nitrogen (TN) were selected as pollutants to be used in the simulation model. Vegetated swale and rain garden were selected as LID controls for the study area. The LID controls were assigned to the model using the catchment characteristics. The target objectives were to minimize peak stormwater runoff, TSS, and TN with the minimum number of LID controls applications. The LID combination scenarios were also tested in SWMM to identify the best LID types and combination to achieve maximum reduction in both peak runoff and pollutants. This study found that the peak runoff, TSS, and TN were reduced by 13%, 38%, and 24%, respectively. The optimal number of LID controls that could be used at the BUNUS catchment area was also found to be 25.
The agriculture sector responsible for global food and nutrition security has an urgent need to examine climatic trends so that adaptations can be exercised in advance. Freely available dataset from satellite sources can greatly ease rainfall analysis, especially for smallholder farmers who typically operate under limited resources. Tests to determine their accuracy, however, are so far not deployed in tropical Southeast Asia. We compared in situ observations with dataset from the Global Satellite Mapping of Precipitation (GSMaP) and the Prediction of Worldwide Energy Resources (POWER) in two sites located 180 km apart in the tropical Malay Peninsula for 30 days. We found that in situ precipitation values were markedly overestimated by GSMaP (34.9-67.5%) and POWER (180.5-289.2%), and the possible reasons are discussed. Nonetheless, we conclude that GSMaP remains the best hope for smallholder farmers and its dataset can still be used under the precaution of error margins determined by the practical method described herein.
Decision-makers require useful tools, such as indicators, to help them make environmentally sound decisions leading to effective management of hazardous wastes. Four hazardous waste indicators are being tested for such a purpose by several countries within the Sustainable Development Indicator Programme of the United Nations Commission for Sustainable Development. However, these indicators only address the 'down-stream' end-of-pipe industrial situation. More creative thinking is clearly needed to develop a wider range of indicators that not only reflects all aspects of industrial production that generates hazardous waste but considers socio-economic implications of the waste as well. Sets of useful and innovative indicators are proposed that could be applied to the emerging paradigm shift away from conventional end-of-pipe management actions and towards preventive strategies that are being increasingly adopted by industry often in association with local and national governments. A methodological and conceptual framework for the development of a core-set of hazardous waste indicators has been developed. Some of the indicator sets outlined quantify preventive waste management strategies (including indicators for cleaner production, hazardous waste reduction/minimization and life cycle analysis), whilst other sets address proactive strategies (including changes in production and consumption patterns, eco-efficiency, eco-intensity and resource productivity). Indicators for quantifying transport of hazardous wastes are also described. It was concluded that a number of the indicators proposed could now be usefully implemented as management tools using existing industrial and economic data. As cleaner production technologies and waste minimization approaches are more widely deployed, and industry integrates environmental concerns at all levels of decision-making, it is expected that the necessary data for construction of the remaining indicators will soon become available.