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The Chlorophyll-a Response of Phytoplankton to Ratio N/P in Different Coastal Waters

Maslukah Lilik, Handoyo Gentur, Wulandari Sri Yulina, Sihite Catherine Berliana, Sarjito

Ecological Engineering & Environmental Technology

2023

Vol. 24, iss. 9

121--129

Phytoplankton growth is influenced by the presence of nutrients N (nitrogen) and P (phosphor). Each region has a specific N/P ratio, due to the influence of anthropogenic inputs. This study aimed to assess the response of phytoplankton chlorophyll-a (Chl-a) biomass due to differences in N/P ratio by the influence of river flow in the north coast of Java; Jobokuto Bay (Jepara), the coastal waters of Semarang and the front of the Cisadane river. N-nutrients were analyzed in the form of N-NO3 (nitrate), and N-NH4+ (ammonium ions), and orthophosphate ions (P-PO42-). Nutrient analysis was spectrometric, using the reduction methods (nitrate), ammonium (indophenolblue), and phosphate (molybdenum-blue). Test for site differences using Kruskall-Wallis, followed by a posthoc test. The results showed that Semarang waters had a lower N/P (Stoichiometric) ratio than Jepara and Cisadane, which can be used to predict that P nutrient input is higher than N. This high P input impacts microalgal development (chlorophyll-a). In addition, we also found Semarang waters to have higher speciation of inorganic N in the form of ammonium, which is one of the drivers of eutrophication in these waters. The use of a ratio of N/P is very important in estimating the eutrophication process and can be used to estimate the dominance of nutrients entering the water due to anthropogenic activities in the upstream area.

Distributions and Fluxes of Nitrogen and Phosphorus Nutrients in Porewater Sediments in the Estuary of Jepara Indonesia

Maslukah Lilik, Wulandari Sri Yulina, Prasetyawan Indra Budi, Zainuri Muhammad

Journal of Ecological Engineering

2019

Vol. 20, nr 2

58--64

River is a location that is responsible for the main transport of nutrient flow from land to estuary and oceans. The nutrients that are adsorbed by the solid phase can be deposited and stored in the sediment. Sediments in estuaries and beaches have an important role in storing or removing nutrients from or to the water column. The presence of nutrients in porewater interacts with sediment and water column. In general, the nutrients that have a role as limiting factors for life in the waters are nitrogen (N) and phosphorus (P). The release of N and P elements is very important for the estuary and coastal environment, related to the process of regenerating nutrients into the water column. The release mechanism is determined by a diffusion process, based on the difference of concentration between the water column and the porewater. This study aims to determine the concentration of N and P in the porewater and estimate the value of flux. The sediment samples were taken from the Wiso and Serang estuary, Jepara. The components that were analyzed in the porewater are the concentration of N (nitrate, nitrite) and P (phosphate). Nitrite, nitrate and phosphate were determined by using sulphanilamide method and the molybdenum blue method, respectively. Furthermore, the flux value (F) was calculated based on the Fick’s I Law which was corrected by porosity. The results show that the mean concentrations of nitrate (NO3-), nitrite (NO2-) and phosphate (PO42-) in the sediment water of Serang Estuary are 1.96, 1.41, 3.46 μM and in the Wiso estuary are 3.4, 1.85, 8.22 μM. In general, based on the calculation of flux, the sediments in the Serang and Wiso estuaries have a positive flux. Moreover, the sediment in Jepara acts as a source and releases N and P nutrient into the water column. The Wiso estuary has a higher flux than the Serang estuary.