Pollutants Release from Sediments in Estuarine Reservoir

Abstract

Sediment pollutants have been considered an important source for the eutrophication of estuarine reservoir. In this study, the effects of pollutants released from bottom sediment to water column were investigated. Sediment samples were collected each two station from Namyang and Sukmoon estuarine reservoirs in August 2013. The fractionation result of sediment phosphorus indicated that Adsorbed-P (36.7±8.84 %) and Nonapatite-P (29.3±12.50 %) are the two dominant phosphorus groups in the sediments. For sediment release test, eight sets of acrylic chamber (0.3 m diameter×1 m high, with 0.15 m sediment depth) were used with aerobic and anaerobic environment. Under anaerobic conditions, rates of NH4-N release from the sediments were highly variable, with final concentrations of NH4-N in the overlying water varying from between about 0.69～1.04 in Namyang and 2.58～4.23 mg/L in Sukmoon reservoir. The NH4-N release was active at the upstream around the confluence of tributary compared to downstream near the embankment. The PO4-P release was more obvious than NH4-N in anaerobic condition. The final PO4-P concentrations were approximately from two-fold to eight-fold higher than initial concentration. In terms of reservoir water quality management, not only tributary pollutants but also sediment nutrient loading is necessary to consider the water quality contribution.

Evaluation of Sentinel-2 Based Chlorophyll-a Estimation in a Small-Scale Reservoir: Assessing Accuracy and Availability

“…The reservoir has a watershed area of 209 km 2 , with a maximum river width of 900 m, effective water storage capacity of 20.4 × 10 6 m 3 , and a water surface area of 7.67 km 2 (Figure 2). The blockage of the estuary has altered the aquatic environment by causing eutrophication in which organic matter from the upper basin is decomposed into inorganic matter, and inorganic nutrients such as nitrogen and phosphorus are accumulated [24]. In addition, urbanization and industrialization in the surrounding areas pose a risk of water pollution from urban runoff, agriculture, and livestock farming.…”

“…In the field, water quality parameters such as water temperature, dissolved oxygen (DO), conductivity, chlorophylla, phycocyanin, and fDOM were measured using a YSI EXO-1 instrument. In the The blockage of the estuary has altered the aquatic environment by causing eutrophication in which organic matter from the upper basin is decomposed into inorganic matter, and inorganic nutrients such as nitrogen and phosphorus are accumulated [24]. In addition, urbanization and industrialization in the surrounding areas pose a risk of water pollution from urban runoff, agriculture, and livestock farming.…”

“…It was determined that the influx of TSS and organic matter due to precipitation affect algae growth. In winter, TN showed a high correlation coefficient of 0.864 (p < 0.001), suggesting its significant contribution to algal growth in late autumn and winter, likely associated with the upwelling of organic and inorganic sediments from the bottom layer [24,57]. Examining the influence of water quality factors on reflectance, various wavelength bands such as 440, 550, 665, and 700 nm (B1, B3, B4, B5) were usually used to estimate Chl-a.…”