Search

The fluctuation of suspended particulate matter (SPM) is essential to the biogeochemical cycle and ecological health of coastal waters. Anthropogenic activities potentially trigger an increase in SPM, so it needs to be monitored continuously. Spatial and temporal monitoring of SPM can be carried out cost-effectively with broad coverage using a remote sensing application. This study aims to build the SPM algorithm and estimate its temporal variability. The algorithm model in this study is based on an empirical formula between field data and reflectance data with the same acquisition. Water samples were taken from 100 stations in July 2022. Half were used for model building and the other for model validation. Suspended Particulate Matter was determined gravimetrically and estimated their temporal variability was based on Landsat 9 image records from December 2021 - November 2022. The results of the analysis show that the best algorithm for SPM estimation can be built based on coastal aerosol canals (B1), blue canals (B2), and green canals (B3) with the accuracy test result of (R² = 0.68; RMSE = 5.551 mg.L-1; MAPE= 7.07%; Bias= 0.28). The SPM temporal fluctuations were generally higher in the west monsoon and lowered in the east monsoon, ranging from 30 to 70 mg.L-1. On the other hand, the spatial distribution shows a higher magnitude in the estuary than in the offshore waters, with a deviation of about 30 mg.L-1. Regional authorities can use the results obtained to improve the management of coastal water quality and monitoring systems. [ABSTRACT FROM AUTHOR]

A comprehensive investigation was conducted to examine the variations in Chlorophyll-a (Chl-a) levels in the waters located to the south of Java Island throughout the past quarter-century. This study employs satellite data and reanalysis data gathered from multiple sources spanning the period between September 1997 and December 2022. The application of EOF analysis revealed that the most notable elevation in Chl-a contents took place during the seasons of SON (September, October, November) and DJF (December, January, February) in the years 1997/1998 and 2006/2007. It has been determined that this significant increase in Chl-a content in southern Java is contingent upon the fulfillment of a number of circumstances. These conditions are associated with climatic patterns in the Indian Ocean and Pacific Ocean. An elevation in Chl-a content was seen throughout the months of SON and DJF in instances where the Indian Ocean Dipole (IOD) had a positive phase. The concurrent occurrence of a powerful positive IOD and El Niño event in the Pacific Ocean is highly probable to result in a substantial elevation in Chl-a content in the southern region of Java. In addition, our findings indicate that the phenomenon of Kelvin wave upwelling significantly contributes to the elevation of Chl-a levels during the months of June, July, August (JJA), and SON. [ABSTRACT FROM AUTHOR]

A precise quantification of the sea surface partial pressure of carbon dioxide (pCO2(water)) at the water surface is required in order to define the role of the sea in air-sea exchange of CO2. Even though the pCO2(water) can be measured directly, the semi-empirical model has seen numerous application in determining the pCO2(water) due to a time-and cost-efficient. This study aims to compare the pCO2 and FCO2 (Flux of CO2) calculated using Zhai and Zhu algorithm with the underway datasets of pCO2 obtained during the scientific cruise of CISKA-SPICE III in April 2013. The partial pressure of CO2 (pCO2) was measured using a high-accuracy electrochemical instrumentation underway HydroC/CO2 FT (flow through) with an error ±1 μ atm. Furthermore, in order to calculate the pCO2 and the FCO2 employing widely used algorithms, some data were needed including wind speed, sea surface temperature and chlorophyll-a extracted from MODIS (Moderate Resolution Imaging Spectroradiometer). According to the results obtained, the difference between the pCO2 and FCO2 derived from those two algorithms are significant. The underway datasets of pCO2 are ranging from 409.52-544.01 μatm. Meanwhile, the pCO2 derived using the Zhai algorithm and Zhu algorithm are between 405.003-422.79 μatm and 398.94-752.06 μatm respectively. The FCO2 are varied between 0.02-0.06 molC.m-2.day-1 (Zhai algorithm), 0.02-0.57 molC.m-2.day-1 (Zhu algorithm) dan 0.04-0.23 molC.m-2.day-1 (the underway datasets). A comparison of the two results reveals that pCO2 derived using Zhai algorithm is closer with the underway datasets compared with the result of pCO2 calculated using Zhu algorithm with the MRE (Mean Relative Estimation Error) as large as 19.4% and 39% respectively. Taken together, these results suggest that the Zhai algorithm is more appropriate to determine algorithms for estimating the air-sea exchange of carbon dioxide in the Malacca Straits. [ABSTRACT FROM AUTHOR]

Due to accelerated anthropogenic activity, a significant amount of pollutants has been directly or indirectly discharged into coastal estuaries of Kampar. Nutrient pollution along the river to the estuary that adversely affects coastal and estuary ecosystem mainly originates from inland such as industrial effluent, household, and agricultural waste as well as a naturally derived pollutant from biogeochemical cycle, which is controlled by the propagation of undular bore (Bono). The purpose of this study is to determine the environmental impact of distribution of nutrients caused by the mechanism of Bono. This research employed a purposive quantitative method, the concentration of dissolved phosphate, nitrate, nitrite and ammonia was analyzed using a spectrophotometer, tidal data retrieval was measured for 30 days' near the estuarine area, while, current flow was measured for 24 hours' measurement. Phosphate concentrations ranged from 0.02-0.1 mg.L-1, nitrate concentrations ranged from 0.76-5.73 mg.L-1, ammonia concentrations ranged from 0.2-0.41 mg.L-1, nitrate concentrations ranged from 0.001-0.03 mg.L-1. The tidal type is mixed tide prevailing semidiurnal with tidal range reach 4.2 m during spring tide condition. At the time of Bono propagate, drastically enhance the surface elevation and directly increase the drift of velocity with the flow direction from estuary into the river upstream, that mechanism affects the nutrient distribution in Kampar river. [ABSTRACT FROM AUTHOR]

The distribution of organic matter and nutrients in the estuary can be influenced by tidal current. The presence of organic matter and nutrients can determine the water quality. However, the exceed amount of organic matter and nutrient in the water could lead to eutrofication that caused the depletion of dissolved oxygen. The research was aimed to determine the distribution of organic matter and nutrients (i.e. phophate and nitrate) due to the tidal current in Demaan estuary, Jepara. The titration method with permanganate was used to measure the organic matter concentration in the samples. Meanwhile, the spectrophotometric method was used to measure nitrate and phosphate concentration in the samples. Tidal current was simulated by Surface water Modelling System (SMS) software, and the distribution of organic matter, nitrate and phosphate was plotted using ArGIS software. The result showed that the concentration of organic matter and nutrients is higher at ebb tide than flood tide. The distribution of organic matter and phosphate followed the tidal current, flowing to the north at ebb tide and back to south at flood tide. It is concluded that organic matter and phosphate sourced from the rivers. [ABSTRACT FROM AUTHOR]

Numerous chemical substances are used for daily life activities have an effect on the endocrine system and are frequently classed as endocrine-disrupting chemicals (EDCs). The present study investigated the fact and distribution of EDCs type (estrogen, plasticizer, and preservative). In particular, EDCs such as estriol, 1,2,4 triazole, 17α-ethinylestradiol, methyl paraben, estrone, 3,4,4 trichlorocarbanilide, 17β-estradiol, and bisphenol A (BPA) were selected as the target EDCs for the detection in the Bengawan Solo and Brantas rivers located in Indonesia. Among the targeted EDCs, BPA is found to be highest in the water samples of Bengawan Solo (1070 ng/L and mean at 219 ng/L) and Brantas (556 ng/L and mean at 222 ng/L) rivers. The EDCs concentration is higher in both rivers during the dry season compared to the wet season due to the dilution effect caused by heavy rainfall. The entry of municipal wastewater is the primary sources of EDCs contamination in both rivers. Finally, this study suggests that the contamination level of EDCs in river water could pose an environmental threat, particularly during dry seasons. [Display omitted] • The presence of EDCs in Bengawan Solo and Brantas rivers in Indonesia is investigated. • BPA is the highest EDC found in both river water samples. • All estrogens detected in both rivers sample found to less than 10% of total EDCs. • The EDCs level at Bengawan Solo and Brantas rivers is higher during the dry season. [ABSTRACT FROM AUTHOR]

The southern coast of South Sulawesi-Indonesia is known as an upwelling area occurring during dry season, which peaks in August. This upwelling area is indicated by high chlorophyll-a (Chl-a) concentrations due to a strong easterly wind-induced upwelling. However, the investigation of Chl-a variability is less studied along the western coast of South Sulawesi. By taking advantages of remote sensing data of Chl-a, sea surface temperature, surface wind, and precipitation, the present study firstly shows that along the western coast of South Sulawesi, there are two areas, which have high primary productivity occurring during the rainy season. The first area is at 119.0° E–119.5° E; 3.5° S–4.0° S, while the second area is at 119.0° E–119.5° E; 3.5° S–4.0° S. The maximum primary productivity in the first (second) area occurs in April (January). The generating mechanism of the high primary productivity along the western coast of South Sulawesi is different from its southern coast. The presence of river runoff in these two areas may bring anthropogenic organic compounds during the peak of rainy season, resulting in increased Chl-a concentration. [ABSTRACT FROM AUTHOR]