Surface water quality and eutrophication dataset from the Semarang-Demak coastal
Description
This dataset contains integrated surface-water quality observations collected from 17 coastal sampling stations distributed across Semarang City and Demak Regency, Central Java, Indonesia. Field sampling was conducted on 8 July 2025 in Semarang and 15 July 2025 in Demak. The stations represent coastal environments influenced by urban drainage, river mouths, port activities, fishing settlements, aquaculture areas, and shallow sediment-rich coastal waters. All data are provided in a single Microsoft Excel workbook organized into four worksheets: Insitu, laboratory, Phytoplankton, and TRIX. The Insitu worksheet contains direct field measurements of water temperature, pH, total dissolved solids, salinity, and dissolved oxygen. Measurements were obtained using an OEM EZ-9909 multiparameter Water Quality Meter and a YSI Xylem Pro20 dissolved oxygen meter. The laboratory worksheet contains nitrate, nitrite, phosphate, total suspended solids, and chlorophyll-a measurements. Nitrate, nitrite, and phosphate were determined using a Hach DR3900 VIS Spectrophotometer. Chlorophyll-a was determined using an Agilent Technologies Cary 60 UV-Vis Spectrophotometer with a wavelength range of 190-1100 nm. Total suspended solids were determined gravimetrically using filtration and drying to constant mass. The Phytoplankton worksheet contains phytoplankton identification, cell counts, and calculated abundance. A 20,000 mL original water volume was concentrated to 50 mL using a 20 µm plankton net. Concentrated samples were preserved with 1% acidic Lugol's solution. A 1 mL aliquot was analyzed using a Sedgwick-Rafter counting chamber and microscopic identification. The TRIX worksheet contains derived trophic variables, including dissolved inorganic nitrogen, dissolved inorganic phosphorus, dissolved oxygen saturation deviation, chlorophyll-a, TRIX values, and trophic classifications. The four worksheets are linked through Station ID, allowing direct integration of physical, chemical, and biological observations. The dataset can be reused for coastal water-quality assessment, eutrophication analysis, nutrient stoichiometry, phytoplankton assessment, TRIX recalculation, comparison with satellite-derived chlorophyll-a, spatial interpolation, environmental modelling, and coastal management studies in tropical urbanized coastal waters.
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Steps to reproduce
The dataset was generated from field measurements and laboratory analyses conducted at 17 coastal stations in Semarang-Demak, Central Java, Indonesia. The raw measurements are organized in a single Excel workbook containing four worksheets: Insitu, laboratory, Phytoplankton, and TRIX. The Insitu worksheet contains direct measurements of pH, temperature, salinity, TDS, and dissolved oxygen. The laboratory worksheet contains nutrient concentrations, total suspended solids, and chlorophyll-a obtained from laboratory analysis. The Phytoplankton worksheet contains identification and abundance data calculated from concentrated plankton samples. The TRIX worksheet contains derived variables calculated from measured parameters, including DIN, DIP, dissolved oxygen saturation deviation, and trophic index values. Users can reproduce the derived dataset by linking all worksheets using Station_ID and applying the calculation procedures described in the associated Data in Brief manuscript.
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Funders
- Ministry of Education and CultureJakarta, JakartaGrant ID: Ministry of Higher Education, Science, and Technology of the Republic of Indonesia;BIMA Fundamental Research Program; Award number: 100/C3/DT.05.00/PL-MULTITAHUNLANJUTAN/2026