The SAR has the ability of all-weather and all-time data acquisition, it can penetrate the cloud and is not affected by extreme weather conditions, and the acquired images have better contrast and rich texture information. This paper aims to investigate the use of an object-oriented classification approach for flood information monitoring in floodplains using backscattering coefficients and interferometric coherence of Sentinel-1 data under time series. Firstly, the backscattering characteristics and interference coherence variation characteristics of SAR time series are used to analyze whether the flood disaster information can be accurately reflected and provide the basis for selecting input classification characteristics of subsequent SAR images. Subsequently, the contribution rate index of the RF model is used to calculate the importance of each index in time series to convert the selected large number of classification features into low dimensional feature space to improve the classification accuracy and reduce the data redundancy. Finally, the SAR image features in each period after multi-scale segmentation and feature selection are jointly used as the input features of RF classification to extract and segment the water in the study area to monitor floods' spatial distribution and dynamic characteristics. The results showed that the various attributes of backscatter coefficients and interferometric coherence under time series could accurately correspond with the actual flood risk, and the combined use of backscattering coefficient and interferometric coherence for flood extraction can significantly improve the accuracy of flood information extraction. Overall, the object-based random forest method using the backscattering coefficient and interference coherence of Sentinel-1 time series for flood extraction advances our understanding of flooding's temporal and spatial dynamics, essential for the timely adoption of adaptation and mitigation strategies for loss reduction.
This study proposes the concept of duration (D) and severity (S) measures, which were derived from unhealthy air pollution events. In parallel with that, the application of a copula model is proposed to evaluate unhealthy air pollution events with respect to their duration and severity characteristics. The bivariate criteria represented by duration and severity indicate their structural dependency, long-tail, and non-identically marginal distributions. A copula approach can provide a good statistical tool to deal with these issues and enable the extraction of valuable information from air pollution data. Based on the copula model, several statistical measurements are proposed for describing the characteristics of unhealthy air pollution events, including the Kendall's τ correlation of the copula, the conditional probability of air pollution severity based on a given duration, the joint OR/AND return period, and the conditional D|S and conditional S|D return periods. A case study based on air pollution data indices was conducted in Klang, Malaysia. The results indicate that a copula approach is beneficial for deriving valuable information for planning and mitigating the risks of unhealthy air pollution events.
Microplastic pollution is widely recognised as a global issue, posing risks to natural ecosystems and human health. The combination of rapid industrial and urban development and relatively limited environmental regulation in many tropical countries may increase the amount of microplastic entering rivers, but basic data on contamination levels are lacking. This is especially the case in tropical South East Asian countries. In this paper, the abundance, composition and spatio-temporal variation of microplastic in the Langat River, Malaysia, were assessed, and the relationship between microplastic concentration and river discharge was investigated. Water samples were collected over a 12-month period from 8 sampling sites on the Langat, extending from forested to heavily urbanised and industrial areas. All 508 water samples collected over this period contained microplastic; mean concentration across all sites and times was 4.39 particles/L but extended up to 90.00 particles/L in some urban tributaries. Most microplastics were secondary in origin, and dominated by fibres. Microplastic counts correlated directly with river discharge, and counts increased and decreased in response to changes in flow. A time-integrated assessment of the microplastic load conveyed by the Langat suggested that the river is typically (50 % of the time) delivering around 5 billion particles per day to the ocean. The positive correlation between the concentration of microplastics and suspended sediments in the Langat suggested that continuously logging turbidity sensors could be used to provide better estimates of microplastic loads and improve assessment of human and ecological health risks.
The present study examines historical perspectives of the macrobenthic community in response to different phases of anthropogenic perturbations in Kakinada Bay, a tropical embayment on the east coast of India. Multivariate analysis of the snapshot data (1958-2017) revealed considerable changes in the Bay environment following a breakwater construction across the Bay mouth in 1997. Subsequently, port expansion activities, industrialization, urbanization, and geomorphic alterations in the Godavari delta brought deterrent changes in the Bay. The fluctuations over the years in hydrographical and sediment characteristics increased environmental heterogeneity and caused significant spatio-temporal shifts in the macrobenthic community between 1995-1996 and 2016-2017. The observed variabilities were suggestive of anthropogenic perturbations of the system with future repercussions on Bay ecosystem functioning. Overall, this study provides evidence on the long-term impact of anthropogenic activities on coastal marine communities and stresses the importance of macrobenthos as bioindicators of such changes in tropical systems.
In this study, a polluted site at Kg. Pasir Puteh was assessed for heavy metal pollution by using
transplanted caged mussel (Perna viridis) from a relatively clean population, Sg. Melayu; both are located in the Strait of Johore. For control purposes, the P. viridis from Kg. Pasir Puteh were also simultaneously transplanted in Sg. Melayu at the same time. It was found that Zn was the metal which got accumulated fastest in the transplanted mussel while Cd was the slowest. This study indicated that the byssus of Perna viridis was most effective for biomonitoring of Cd, Ni, Pb and Zn, while the shell could be used for the biomonitoring of Cu, Ni and Pb and the total soft tissue for the biomonitoring of Ni since they were able to accumulate and eliminate the respective metals well. By using mussel as a biomonitor, the present study found that Kg. Pasir Puteh, which is located in the eastern part of the Strait of Johore, had significantly higher contamination and bioavailabilities of Cd, Cu, Fe, Ni, Pb and Zn. Therefore, the use of the transplanted caged mussels is very useful for heavy metal assessment purposes since it can increase the validity of data interpretation by minimizing ecological factors.
For more than two decades, biodosimetry has been used in biomonitoring of occupational and envir onmental exposure to ionising radiation. Chromosome aberration analysis is a method used to dete ct unstable aberrations in the lymphocytes of irradiated personnel. The Malaysian National Biodosi metry Laboratory is a referance centre for activity relating to biodosimetry in the country. This pap er aims at presenting dicentric assay technique for the assessment of whole body dose to low LET ra diation at the Malaysian National Biodosimetry Laboratory.
Analyses activities of 226 Ra and 228 Ra were conducted at ten stations of Pulau Redang, Malaysia. Dissolved radium isotopes such as 226 Ra and 228 Ra had shown enrichment at coastal area stations. Meanwhile, activities of both nuclides in the suspended particle matters were slightly in equilibrium with the activity ratio ranging from 0.88 – 1.86. The calculated distribution coefficient values (Kd) of 226 Ra and 228 Ra were in the range of 0.78 x 10 5 L g -1 to 5.56 x 10 5 L g -1 and 0.21 x 10 5 L g -1 to 1.86 x 10 5 L g -1 , respectively, indicate that most of the radium nuclides in the study area are strongly absorbed into the particulate phases. Therefore, low concentrations of suspended particles matter in the water column (< 10 mg L -1 ) have insignificant effects on the Kd values.
Anthropogenic pressures are causing substantial degradation to the freshwater ecosystems globally and Malaysia has not escaped such a bleak scenario. Prompted by the predicament, this study's objective was to pioneer a river assessment system that can be readily adopted to monitor, manage and drive improvement in a wholesome manner. Three sets of a priori metrics were selected to form the Ichthyofaunal Quality Index (IQI: biological), Water Quality Index (WQI: chemical) and River Physical Quality Index (RPQI: physical). These indices were further integrated on equal weighting to construct a novel Malaysian River Integrity Index (MyRII). To test its robustness, the MyRII protocol was field tested in four eco-hydrological zones located in the Kampar River water basin for 18 months to reveal its strengths, weaknesses, and establish the "excellent", "good", "average", "poor" and "impaired" thresholds based on the "best performer" reference site in an empirical manner. The resultant MyRII showed a clear trend that corresponded with different levels of river impairment. Test site zone A which was a reference site with minimal disturbance achieved the highest MyRII (88.95 ± 4.29), followed by partially disturbed zone B (61.95 ± 5.90) and heavily disturbed zone C (50.00 ± 4.29). However, the MyRII in zone D (59.9 ± 6.39), which was a heavily disturbed wetland that was disjointed from the river, did not conform to such trend. Also unveiled and recognized, however, are some unexpected nuances, limitations and challenges that emerged from this study. These are critically discussed as precautions when interpreting and implementing the MyRII protocol. This study adds to the mounting body of evidence that water resource stakeholders and policymakers must look at the big picture and adopt the "balanced ecosystem" mind-set when assessing, restoring and managing the rivers as a freshwater resource.
The declining water level in Lake Urmia has become a significant issue for Iranian policy and decision makers. This lake has been experiencing an abrupt decrease in water level and is at real risk of becoming a complete saline land. Because of its position, assessment of changes in the Lake Urmia is essential. This study aims to evaluate changes in the water level of Lake Urmia using the space-borne remote sensing and GIS techniques. Therefore, multispectral Landsat 7 ETM+ images for the years 2000, 2010, and 2017 were acquired. In addition, precipitation and temperature data for 31 years between 1986 and 2017 were collected for further analysis. Results indicate that the increased temperature (by 19%), decreased rainfall of about 62%, and excessive damming in the Urmia Basin along with mismanagement of water resources are the key factors in the declining water level of Lake Urmia. Furthermore, the current research predicts the potential environmental crisis as the result of the lake shrinking and suggests a few possible alternatives. The insights provided by this study can be beneficial for environmentalists and related organizations working on this and similar topics.
Functional classification of phytoplankton could be a valuable tool in water quality monitoring in the eutrophic riverine ecosystems. This study is novel from the Bangladeshi perspective. In this study, phytoplankton cell density and diversity were studied with particular reference to the functional groups (FGs) approach during pre-monsoon, monsoon, and post-monsoon at four sampling stations in Karatoya River, Bangladesh. A total of 54 phytoplankton species were recorded under four classes, viz. Chlorophyceae (21 species) Cyanophyceae (16 species), Bacillariophyceae (15 species), and Euglenophyceae (2 species). A significantly higher total cell density of phytoplankton was detected during the pre-monsoon season (24.20 × 103 cells/l), while the lowest in monsoon (9.43 × 103 cells/l). The Shannon-Wiener diversity index varied significantly (F = 16.109, P = 000), with the highest value recorded during the post-monsoon season. Analysis of similarity (ANOSIM) identified significant variations among the three seasons (P
Microplastic ingestion has been documented in various aquatic species. This causes physical damage, and additionally contaminated microplastics transfer attached pollutants and microbial pathogens to ingesting organisms. Continued metal accumulation can lead to toxicity and adverse health effects; attached microbial pathogens can cause dysbiosis - which lowers host immunity and promotes infections. Catfish, Clarias gariepinus, are a major food source in Southeast Asia, a hotspot of plastic pollution. This study aimed to quantify the transfer of the trace metals copper (Cu) and lead (Pb) -at environmentally relevant concentrations-from microplastics (polyamide 12, PA12, and polylactic acid, PLA) to catfish. Fish were reared for three months and exposed to seven different combinations of feed, supplemented with plastics and metals. At monthly intervals, fish gills, intestines, liver, and edible muscles were analysed for Cu and Pb concentrations using ICP-OES, and the intestines content assessed for Vibrio sp.. Our results showed that biodegradable PLA transferred higher amounts of metals to catfish than expected and also led to increased Vibrio counts in the intestines compared to PA12. Trace metal accumulation was significantly different in varying tissues, with highest concentrations observed in the gills, followed by liver, intestines, and lastly edible muscles. The results of this study further support the existing evidence that microplastics act as efficient shuttles to concentrate and transfer metals. They also indicate that their uptake can cause dysbiosis (increased numbers of Vibrio sp.). Most importantly, however, our study highlights that biodegradable polymers, such as PLA, could actually pose a greater environmental threat when ingested compared to the more common polymers such as PA12.
The World Health Organization noted that there is a growing need to determine the occurrence of microplastics in bottled water and its potential risks to human health. Thus, present study analyzes microplastics in eight major bottled water brands available in Malaysia and estimates the potential human exposure. Membrane filtration method followed by visual and polymer identifications were utilized to identify microplastics particles in these eight major bottled water brands. Microplastic concentrations in bottled water samples ranged from 8 to 22 particles/L, with an average of 11.7 ± 4.6 particles/L. Particle sizes ranging between 100 and 300 μm were dominant and accounted for approximately 31% in these bottled water brands. Fragments were the most identified microplastics in bottled water with transparent color being the most prevalent. The polyethylene terephthalate (PET) and polypropylene (PP) polymer types found in this study are consistent with prior results in that microplastics in bottled water are mainly derived from packaging materials and bottle caps. The Estimated Dietary Intake (EDI) for adults was between 0.068 and 0.19 particle/kg/day, while the EDI for children was between 0.089 and 0.25 particle/kg/day. Although consumption of bottled water was estimated to have low EDI values, the potential risks to human health should be heeded due to the presence of numerous plastic additives and residual monomers in these particles, which have the potential to increase inflammatory reactions and cytotoxicity in human body. Future studies should concentrate on understanding microplastics particles less than 1.5 μm and other associated factors (bottled material quality, consumption behaviour, bottled water storage conditions, and the frequency of bottle opening and closing) to further understand the effects of these microplastics particles on human toxicological aspects.
Microplastics have been considered as contaminants of emerging concern due to ubiquity in the environment; however, the occurrence of microplastics in river estuaries is scarcely investigated. The Klang River estuary is an important ecosystem that receives various contaminants from urbanised, highly populated areas and the busiest maritime centre in Selangor, Malaysia. This study investigates the abundance and characteristics of microplastics in surface water of the Klang River estuary. The abundance of microplastics ranged from 0.5 to 4.5 particles L-1 with a mean abundance of 2.47 particles L-1. There is no correlation between the abundance of microplastics and physicochemical properties, while there is a strong correlation between salinity and conductivity. The microplastics were characterised with a stereomicroscope and attenuated total reflection-Fourier transform infrared spectroscopy to analyse size, shape, colour, and polymer composition. The microplastics in the surface water were predominantly in the 300-1000 μm size class, followed by > 1000 μm and
Miri city has a dynamic coastal environment, mainly influenced by intensive sedimentation from the Baram River and excessive trace metal loading by the Miri River, which are significant environmental concerns. As the mobility, bioavailability, and toxicity of the trace metals in the sediments are largely controlled by their particulate speciation, the modified BCR sequential extraction protocol was applied to determine the particulate speciation of trace metals in the coastal sediments of Miri, to unravel the seasonal geochemical processes responsible for known observations, and to identify possible sources of these trace metals. The granulometric analysis results showed that littoral currents aided by the monsoonal winds have influenced the grain size distribution of the sediments, enabling us to divide the study area into north-east and south-west segments where the geochemical composition are distinct. The Cu (>84%) and Zn (82%) concentrations are predominantly associated with the exchangeable fraction, which is readily bioavailable. Pb and Cd are dominant in non-residual fractions and other metals viz., Fe, Mn, Co, Ni, and Cr are dominant in the residual fraction. Using Pearson's correlation and factor analysis, the major mechanisms controlling the chemistry of the sediments are identified as association of Cu and Zn with fine fraction sediments, sulphide oxidation in the SW segment of the study area, atmospheric fallout of Pb and Cd in the river basins, precipitation of dissolved Fe and Mn supplied from the rivers and remobilization of Mn from the coastal sediments. Based on various pollution indices, it is inferred that the coastal sediments of NW Borneo are contaminated with Cu and Zn, and are largely bioavailable, which can be a threat to the local aquatic organisms, coral reefs, and coastal mangroves.
Biochar derived from banana peels can be used as an alternative nutrient in the soil that can promote crop growth while reducing fertiliser usage. Biochar stability has proportional relationship to biochar residence time in the soil and potassium is one of the vital nutrients needed for plant growth. This research aims at providing optimum pyrolysis operating conditions like temperature, residence time, and heating rate using banana peels as feedstock. An electrical tubular furnace was used to conduct the pyrolysis process to convert banana peels into biochar. The elemental compositions of biochar are potassium, oxygen (O), and carbon (C) content. The O:C ratio was used as the biochar stability indicator. Analysis of results showed that operating temperature has the most remarkable effect on biochar yield, biochar stability, and biochar's potassium content. In addition, a multilayer feedforward artificial neural network model was developed for the pyrolysis process. Eleven training algorithms were selected to model the multi-input multi-output neural network (MIMO). The most suitable training algorithm was identified through four performance criterions which are root mean square error (RMSE), mean absolute error (MSE), mean absolute percentage error (MAPE), and regression (R2). The results show that the Levenberg-Marquardt backpropagation training algorithm has the lowest error. From the chosen training algorithm, neural network was trained, and optimum operating parameters for banana peel were predicted at 490 °C, 110 min, and 11 °C/min with a high yield of 47.78%, O/C ratio of 0.2393, and 14.04 wt. % of potassium.
Haze has been a major issue afflicting Southeast Asian countries, including Malaysia, for the past few decades. Hierarchical agglomerative cluster analysis (HACA) is commonly used to evaluate the spatial behavior between areas in which pollutants interact. Typically, using HACA, the Euclidean distance acts as the dissimilarity measure and air quality monitoring stations are grouped according to this measure, thus revealing the most polluted areas. In this study, a framework for the hybridization of the HACA technique is proposed by considering the topological similarity (Wasserstein distance) between stations to evaluate the spatial patterns of the affected areas by haze episodes. For this, a tool in the topological data analysis (TDA), namely, persistent homology, is used to extract essential topological features hidden in the dataset. The performance of the proposed method is compared with that of traditional HACA and evaluated based on its ability to categorize areas according to the exceedance level of the particulate matter (PM10). Results show that additional topological features have yielded better accuracy compared to without the case that does not consider topological features. The cluster validity indices are computed to verify the results, and the proposed method outperforms the traditional method, suggesting a practical alternative approach for assessing the similarity in air pollution behaviors based on topological characterizations.
The dynamics of the coastal aquifers are well-expressed by geochemical and isotopic signatures. Coastal regions often exhibit complex groundwater recharge pattern due to the influence of depression in the Bay of Bengal, tidal variations on surface waters, saline water intrusion and agricultural return flows. In this research, groundwater recharge processes occurring in coastal Tamil Nadu, South India were evaluated using major ion chemistry and environmental isotopes. A total of 170 groundwater samples were collected from shallow and deep aquifers during both post-monsoon (POM) and pre-monsoon (PRM) seasons. The isotopic results showed a wide variation in the shallow groundwater, suggesting contribution from multiple recharge sources. But, the deeper groundwater recharge is mainly from precipitation. The northern part of the study area showed more depleted isotopic values, which rapidly changed towards south from -6.8 to -4.4‰. Alternatively, central and southern parts exhibited relatively enriched isotopic content with variation from -0.58 to -2.7‰. Groundwater was discerned to be brackish to saline with chloride content, 600-2060 mgL-1 and δ18O ranging from -5.8 to -4.5‰, suggesting influence of the saline water sources. A minor influence of anthropogenic activities was also observed in the deeper groundwater during PRM, which was confirmed by tritium and Cl- trends. The old groundwater with depleted isotopic content infer recharged by distant sources while modern groundwater with enriched isotopes points to the influence of evaporated recharge.
Macro-sized marine litter (>2.5 cm) was collected, characterized, and enumerated along the Cox's Bazar Coast, Bangladesh. Marine litter abundance was converted to density (number of items/m2). Beach cleanliness was evaluated using the clean-coast index (CCI). Plastic polythene bags were the most abundant litter items, followed by plastic cups. Total marine litter abundance was 54,401 ± 184 items. Major sources of marine litter were from tourism, fishery and residential activities. Of 10 sites surveyed, two were classified as dirty, two were moderate, four were clean and two were very clean using the CCI. Marine litter pollution along the Cox's Bazar Coast represents a potential threat to coastal and marine environments. This baseline study will help to establish mitigation strategies that are urgently required to reduce marine litter pollution along the Cox's Bazar Coast.