Skudai River Research Articles

Magnetotactic Bacteria from Skudai River in Johor, Malaysia: Isolation and Characterization

Isolation of Magnetotactic Bacteria (MTB) has gained significant interest in multidisciplinary fields. In this study, MTB sample was harvested from the Skudai River in Johor Bahru, Malaysia. Subsequently, the isolated pure MTB cell was cultured with enrichment growth media in agar plates, and identified by Biochemical tests and 16S rRNA. Based on the results, the sequence gene of the MTB is related to Alcaligenes sp strain SUM 123, which is a Gram-negative bacterium in the Betaproteobacteria class. The size and shape of isolated bacterium and the magnetosomes produced were observed under Transmission Electron Microscope (TEM). The Field Scanning Electron Microscope-X-ray Energy Diffraction (FESEM-EDX) analysis was used to determine the metals accumulation of intracellular magnetosomes in Alcaligenes sp. strain SUM 123.

Distribution of Silver (Ag) and Silver Nanoparticles (AgNPs) in Aquatic Environment

Nanomaterials, classified as emerging pollutants that are toxic to the environment, are known to bioaccumulate across different trophic levels in the aquatic ecosystem. This study therefore investigates the distribution of silver and silver nanoparticles (AgNPs) in the aquatic environment of Skudai River, Johor, Malaysia. Water, sediment, plant, and fish samples were collected seasonally along four sites along Skudai River between May 2018 and April 2019. All samples were subjected to Ag analysis using an inductively coupled plasma mass spectrometer (ICP-MS). The analysis demonstrated that the concentration of Ag detected in water samples ranging from 0.001 to 0.505 mg/L was the lowest, whereas in the plants, 0.235 to 4.713 mg/kg of Ag was quantified. The upper sediments contained 0.036 to 28.115 mg/kg of Ag, whilst fish samples presented the highest accumulation of Ag, averaging between 9.144 and 53.784 mg/kg of Ag. Subsequently, the formation of silver nanoparticles was further proven by TEM-EDX analysis, where the detected size of AgNPs ranged from 20 nm to 35 nm. The overriding conclusion implied by bioaccumulation factor (BAF) and biota–sediment accumulation factor (BSAF) calculations suggested that Skudai River was indeed polluted by Ag and AgNPs. The values obtained stipulated that silver accumulation is occurring at an alarming rate and could therefore endanger fish consumers.

Trend Analysis on Water Quality Index Using the Least Squares Regression Models

River water pollution requires continuous water quality monitoring that promotes the improvement of water resources. Therefore, the trend analysis on water quality data using mathematical model is an important task to determine whether the measured data increase or decrease during the time period. This paper is intended to highlight the applicability of the least squares regression models to fit the WQI data of the Skudai River, Tebrau River and Segget River located in Johor, Malaysia. As per the 12 years of trend analysis, the data of WQI are collected from the Environmental Quality Reports 2009-2020. The least squares method is utilized to estimate the unknown constants of the linear, quadratic, cubic, polynomial of degree four and degree five regression models. The advantage of using proposed models is that it can be implemented easily even on relatively low computational power systems. The results show that the higher degree polynomial model fits the data reasonably well, in which the polynomials of degree 4 and 5 have lowest average error. Assessment of actual and predictable values of WQI shows that the trends in WQI for all study areas are downward year after year.

Modelling the effects of urbanization on nutrients pollution for prospective management of a tropical watershed: A case study of Skudai River watershed

Nutrient pollution is considered as a primary factor of water quality deterioration in urban-dominated watersheds in which an informed decision on the management strategies are required to improve the water quality condition. The Hydrological Simulation Program Fortran (HSPF) model is used to evaluate the impacts of pollution by these nutrients using the Skudai River watershed in Malaysia as a case study. A developed land-use/land-cover (LU/LC) scenarios were used to evaluate these impacts. Statistical methods were employed to assess the extent of these impacts and their significance in shifting the trophic state of the rivers in the watershed. The study shows that when urban development increases from 18.2 to 49.2%, the total nitrogen (TN) and total phosphorus (TP) loads increase from 3.08 to 4.56 × 10 3 kg/yr and from 0.13 to 0.27 × 103 kg/yr, respectively. Streamflow and stream concentrations (NH3N, NO3N, and PO4-P) produce varying responses as the watershed land-use changes (from 1989 to 2039). As the rivers in the watershed shift their trophic state with respect to the level of anthropogenic disturbance within their catchments, the TN and TP concentrations at the estuaries are likely to change from oligotrophic to eutrophic state. This is an indication that the Johor Strait and the coastal rivers will be exposed to eutrophication, subsequently resulting in harmful algal bloom. This condition can be prevented by integrating water quality management alongside urban development because it is observed that a control of non-point source (NPS) pollutants from 1% of the urban development will decrease TN and TP concentration in Skudai River by 0.023 mg/L and 0.004 mg/L respectively.

Occurrence of Emerging Pollutants in Skudai River in Johor Bahru Region of Malaysia

Increase in landuse development and human activities have significant influence on the occurrence of emerging pollutants (EPs) in water bodies such as rivers. As rivers are the main source of water supply in Malaysia, a study was conducted to determine the occurrence of EPs in one of the drinking water sources, namely Skudai River. Samples were collected five times at eight sampling points from the upstream up to the water intake of the river. Sample pre-treatment was performed by solid-phase extraction (SPE), whereas the analyses of the EPs were performed by Liquid Chromatography-Mass Spectrometry (LCMS-MS QTOF). Results showed that about 50 compounds were detected and fall into categorise as pharmaceuticals, Personal Care Products (PCPs), and Endocrine Disrupting Chemical (EDC). The most prevalent (75-100%) compounds detected were of these categories, whereas the least (less than 40%) were mainly pharmaceuticals. The concentration of styrene, a health-hazards EPs ranged from 45.11 to 203.48 µg/L with increasing trend towards downstream of the river. Based on the landuse data of Skudai River Basin, the study concluded that human activity, landuse, and environmental factors could possibly contribute to the presence of the EPs in the river.

Scenario-based pollution discharge simulations and mapping using integrated QUAL2K-GIS

Malaysia is a tropical country that is highly dependent on surface water for its raw water supply. Unfortunately, surface water is vulnerable to pollution, especially in developed and dense urban catchments. Therefore, in this study, a methodology was developed for an extensive temporal water quality index (WQI) and classification analysis, simulations of various pollutant discharge scenarios using QUAL2K software, and maps with NH3–N as the core pollutant using an integrated QUAL2K-GIS. It was found that most of the water quality stations are categorized as Class III (slightly polluted to polluted). These stations are surrounded by residential areas, industries, workshops, restaurants and wet markets that contribute to the poor water quality levels. Additionally, low WQI values were reported in 2010 owing to development and agricultural activities. However, the WQI values improved during the wet season. High concentrations of NH3–N were found in the basin, especially during dry weather conditions. Three scenarios were simulated, i.e. 10%, 50% and 70% of pollution discharge into Skudai river using a calibrated and validated QUAL2K model. Model performance was evaluated using the relative percentage difference. An inclusive graph showing the current conditions and pollution reduction scenarios with respect to the distance of Skudai river and its tributaries is developed to determine the WQI classification. Comprehensive water quality maps based on NH3–N as the core pollutant are developed using integrated QUAL2K-GIS to illustrate the overall condition of the Skudai river. High NH3–N in the Skudai River affects water treatment plant operations. Pollution control of more than 90% is required to improve the water quality classification to Class II. The methodology and analysis developed in this study can assist various stakeholders and authorities in identifying problematic areas and determining the required percentage of pollution reduction to improve the Skudai River water quality.

ESTIMATION OF HYDROLOGICAL CHANGES IN A TROPICAL WATERSHED USING MULTI-TEMPORAL LAND-USE AND DYNAMIC MODELLING

The response of a watershed due to changes in its physical environment might result in floods, river erosions and siltations, subsequently affecting humans and biotas. Evaluating land-use changes is crucial for better assessment of hydrological conditions in a watershed system. The remote sensing imagery, field data collection, and land change modelling were used to produce the land-use maps of different spatiotemporal scale from 1989 to 2039. The generated maps are integrated into Hydrological Simulation Program-Fortran (HSPF) model, to evaluate the hydrological changes in Skudai River watershed in Malaysia. Total runoff is expected to account for 57% of the rainfall influx by 2039, a change of 2% from 1989 land-use, an indication of the low response of runoff to change in land-use. As built-up land increase by 3.39 %, the average streamflow will increase by 0.05 m3/s. It will further reduce actual evapotranspiration (AET) by 0.39%, groundwater by 0.34% and change in storage by 0.38%. The sensitivity analysis of the hydrological elements to the land-use changes indicates that AET being the most sensitive then change in storage, and total runoff showing the lowest sensitivity. The result of the study provides information on the long-term impact of land-use on the hydrology of the tropical watershed, and it can be a useful tool in the planning and management of a watershed in a different perspective.

Microplastics in sediment from Skudai and Tebrau river, Malaysia: a preliminary study

Plastic debris floating on surface water has now become an environmental issues concerning its abundance and fate. Generally, plastic debris that are fragmented into less than 5 mm in size is known as microplastics (MP). To date, discovery on the occurrence and impacts of MP in marine environments have been reported by many studies. However, less investigation has been carried out in freshwater environments. The occurrence of MP in Malaysia is also unknown. Thus, the present study has characterised the abundance of MP between Skudai and Tebrau River. The quantification of MP levels in these channels are pertinent since both rivers are listed among polluted rivers in Malaysia with high amount of rubbish. Surface sediments were collected with a box corer and MP were extracted via density separation. The inspection of particles was carried out under microscope and were categorized based on shape, colour, and size. Preliminary results showed that the concentration of MP was much higher in Tebrau than of Skudai River. The study demonstrates that the abundance of MPs in both urban rivers may possibly be affected by weathering breakdown of large plastic materials since these locations are well-known for fishing and industrial areas.

RANKING OF SKUDAI RIVER SUB-WATERSHEDS FROM SUSTAINABILITY INDICES – APPLICATION OF PROMETHEE METHOD

In this study, ranking of sub-watersheds in the Skudai River watershed was developed from the sustainability index. The watershed sustainability index (WSI) was developed by considering two important parameters such as potential flood damages (PFD) and potential water quality deterioration (PWQD) parameters. Preference Ranking Organization Method (PROMETHEE), a multicriteria decision making (MCDM) method, was used and WSI scores for 25 Skudai River sub-watersheds were produced. Based on the WSI score, a ranking of sub-watersheds was developed to locate the more problematic areas in the Skudai River watershed. The middle and lower parts of the Skudai River watershed were found to have considerably low sustainability score which suggested the degradation of sub-watersheds from water quality and flood damage parameters. The ranking of sub-watersheds in this study will assist planners and decision makers to identify the problematic areas within the watershed so that priority interventions can be built before the problem gets worse and affects other areas of the Skudai River watershed.

Characterization of Cultured Rod-shaped MagnetotacticBetaproteobacteriafrom Skudai River, Malaysia

Objectives: Magnetotactic bacteria (MTB) represent a widespread group of phylogenetically, physiologically and morphologically aquatic prokaryotes with a distinct ability to migrate along the earth’s geomagnetic field using intracellular magnetic organelles called magnetosomes (MSs). Methods: In this study, a new MTB, AlcaligenesspSUM 123 was successfully isolated from Skudai river in Johor Bahru, Malaysia. The bacterium was cultivated in enrichment growth media (GM) at room temperature 25 º C after isolation using a neodymium magnet. Findings: Phylogenetic analysis using 16S rRNAgenoe sequence revealed that the new strain SUM 123 of Alcaligenesspbelongs to Betaproteobacteria class. The strain SUM 123 contained three or more round shaped, random distributed magnetosomes (MSs) of 80-120 nm in size observed under Scanning Transmission Electron Microscope (STEM). The minerals in MTB were studied by X-ray Energy Diffraction (EDX) analysis. Furthermore, the peaks that are attributed to the 220, 311, and 210 of MS were confirmed using X-ray Diffraction (XRD). Application/Improvement: The band around 580 cm-1 was related to Fe-O functional group of magnetite confirmed by Fourier Transform Infrared (FTIR) Spectroscopy. Keywords: 16S rRNA, Alcaligenes sp., Betaproteobacteria,MagnetotacticBacteria,Magnetosomes

Effectiveness of Water Quality Index for Monitoring Malaysian River Water Quality

The Skudai River has experienced a general decline in water quality over the last several years due to agricultural practices, economic development, and other human activities in the river catchment. The spatial trend of water quality index (WQI) and its sub-indexes are important for determining the locations of major pollutant sources that contribute to water quality depletion in the Skudai and its tributaries. In this study, we have developed WQI for eight sections of the Skudai watershed. Ammonia-nitrogen (NH3-N) was identified as a major pollutant downstream from the Skudai, with the lowest WQI index (i.e. 38). WQI for the Skudai (natural) was 94, i.e., Class I (very clean) category of river water quality. The Senai River has WQI value of 85 and Class II category (slightly polluted). However, the Kempas River, which was in suburban parts of the Skudai watershed, had WQI of 53 (Class III, polluted). The Melana and Danga rivers were also polluted rivers with WQI of 69 and 57, respectively, in Class III (polluted). Overall water quality in the Skudai and its tributaries was downstream of the river. The study also assessed water quality of the Skudai and its tributaries from other water quality parameters such as conductivity, turbidity, temperature, total dissolved solids, total phosphorous, and nitrogen, which were not part of the WQI formula developed by the Department of the Environment (DOE), Malaysia. The study found that Department of Education (DOE) formula for WQI was not effective in water quality assessment as many important parameters such as nutrients, heavy metals, and fecal coliform (or E. Coli) were missing in the WQI formula.

Removal of Bisphenol A (BPA) in Surface Water by Ozone Oxidation Process

The removal of Bisphenol A in river water can be accomplished with the application of ozone. Ozone is widely used to disinfect drinking water due to its strong oxidizing properties. This study was conducted to investigate the removal of Bisphenol A in different areas of Skudai River. Batch experiments were conducted at initial Bisphenol A concentration of 0.5 mg L-1. The concentrations of Bisphenol A and dissolved ozone were measured using Ultra High Performance Liquid Chromatography (UHPLC) and UV-Visible spectrophotometer respectively. Based on the results obtained the stability of ozone in the water were very fast. Ozonewas quickly decomposed in water samples. The results indicated that the depletion of ozone varied from different dissolved organic carbon (DOC) value of water samples. Concentration of dissolved ozone was reducing rapidly after spiked into high DOC value (9.17 mg L-1) of river water. The results of the study have shown that ozonation could be used to effectively remove the Bisphenol A from water. The ozone depletions in river water at 120 seconds were about 87%-99%.

Identification of flood-prone areas by integrated remote sensing model

Flood is one of the main natural hazards that normally occurs every year in Malaysia. Flood causes inconveniences to human as well as life, property and financial losses. Floods cause a range of adverse impacts, including human injuries and fatalities, damages to crop, property, and public infrastructure. In this study, the identification of flood prone area has been done by integrated remote sensing images with the Soil Conservation System-Curve Number (SCS-CN). Johor Bahru city centre and Nusajaya of Iskandar Malaysia were selected as a study area since they are involved with the rapid development. A Landsat-5 image has been used in development of elevation model while the hydrological model was utilized to estimate the peak surface runoff. Based on the result, the flood prone areas for Skudai River and the Plentong River have been identified. The rapid changes in landuse has significantly has caused these area classified as high risk of flood areas. The development of this hazard map could be a used as a guideline in planning any development in this areas.

“Water Quality Management of Skudai River,” by K. K. Chin and T. N. Goh2

“Water Quality Management of Skudai River,” by K. K. Chin and T. N. Goh²

Reply to DISCUSSION1“Water Quality Management of Skudai River”2

Reply to DISCUSSION¹“Water Quality Management of Skudai River”²

WATER QUALITY MANAGEMENT OF SKUDAI RIVER1

ABSTRACT: Urban runoff as well as industrial and agricultural discharges have seriously affected the water quality of the Skudai River, Malaysia. A water quality model is developed for simulating BOD and oxygen relationship. The simulated values agree relatively well with survey data taken during low flow conditions. Survey and simulated values show that a pollution abatement program is needed to prevent further deterioration of the river from organic discharges. A systems approach, involving complete analysis of water quality models and environmental control procedures, considering various water use patterns, water quality criteria, and waste input, is essential for solution.