• Korean Journal of Fisheries and Aquatic Sciences
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• v.53 no.5
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• pp.773-783
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• 2020

In order to evaluate the recovery of fishing ground environment after the cessation of aquaculture farming, we examined the variation in sediment quality over time using different geochemical factors and investigated whether these factors are indicators of sediment quality recovery. The study area was an oyster Crassostrea gigas, farm in Tongyeong, Geyongsangnam-do, South Korea, where aquaculture activities had been carried out for 20 years, and the changes in water and sediment environment were monitored for 14 months after the abandonment of the farm. The mean water depth was 14 m, with a tidal range of 3 m, and seawater current velocity ranged from 4.7 to 7.0 cm/s. After the abandonment of the farm, total organic carbon and total nitrogen concentrations in the surface sediments decreased significantly over time compared to those in the control site; in particular, immediately after farm abandonment, acid-volatile sulfide concentrations decreased relatively rapidly. Carbohydrate and protein concentrations in the sediments showed no significant changes; however, lipid concentrations markedly decreased. Further studies on other aquaculture taxa and various aquaculture areas are needed to establish new policies for environmental management of fishing grounds, such as relocation of fishing grounds and determination of optimal fallowing periods.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2003.04a
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• pp.115-119
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• 2003

Pollutants from industry, mining, agriculture, and other sources have contaminated sediments in many surface water bodies. Sediment contamination poses a severe threat to human health and environment because many toxic contaminants that are barely detectable in the water body can accumulate in sediment at much higher levels, the purpose of this study was to make convenient sampling method and optimal treatment of sediment for water quality improvement in reservoir or stream based on an evaluation of degree of contamination. Results for analysis of S-reservoir sediments were observed that copper concentration of almost areas were higher than the regulation of soil pollution (50 mg/1) for the riverbed. S-stream sediments were observed that copper, arsenic and TPH concentration of almost areas were exceeded soil pollution concerning levels for factorial areas. We used Remscreen(version. 1.0) program which is contaminated soil recovery program to select optimal treatment method of contaminant sediments. The result was shown in the order of Thermal Calcination > Excavation, Retrieval and Off-site Disposal(comparative less then contaminant) > Low Temperature Thermal Desorption + Solidification/Stabilization.

• Environmental Analysis Health and Toxicology
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• v.22 no.1 s.56
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• pp.49-55
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• 2007

Three kind of ASE (Accelerated Solvent Extraction) and SPMDs (Semi-Permeable Membrane Devices) combined methods (ASE-SPMDs, ASE-accelerated SPMDs and SPMDs without extraction) and general Soxhlet-GPC were compared each other for the analysis of PCDD/FS in sediment. The average recovery rate of three types ASE and SPMDs combined methods (108.1%) were higher than that of the Soxhlet-GPC (79.5%) for three samples in each method using surrogate internal standards. The average coefficient of variation (10%, $2.1{\sim}25.2%$) for each congener of PCDD/Fs shows the reasonable results. Total PCDD/Fs concentrations after SPMDs without extraction were quite low, but those after ASE-SPMDs and ASE-accelerated SPMDs methods were close to the Soxhlet-GPC. Thus, the ASE-SPMDs and ASE-accelerated SPMDs methods are considered as the excellent pre-treatments method because they need less solvent and time without quality degradation.

• Journal of Wetlands Research
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• v.12 no.3
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• pp.15-20
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• 2010

The contamination loadings generated in Changwon City are coming into Masan Bay through the Bongam tidal flat except the loadings collected and transferred by sewer lines to the wastewater treatment plant. The recovery of waterbirds, shellfishes, and fishes has been quite well recognized in recent years after the first implementation of Masan Bay TPLM (Total Pollution Loads Management) in Korea. This tidal flat has been conserved by the cooperation of several stakeholders and utilized as an ecosystem field site for in situ education. A large industrial complex has been operated since 1970's, therefore increasing the level of pollutants in estuary and costal sediments, especially by heavy metals. Zinc, copper, and lesd contamination of sediment was revealed at higher level by Clean-up guideline (MOMAF) or heavily polluted level by SQC (USEPA). There was a significant difference between two sites at the 95% confidence level, which implies no homogeneity in the processes of transport and deposition even at 500 m of distance. The heavy metal concentrations in the Bongam sediments have been gradually decreased with comparing the data of 2006, and 2009.

• Fisheries and Aquatic Sciences
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• v.23 no.6
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• pp.15.1-15.14
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• 2020

Background: Large rivers are ecological treasures with high human value, but most have experienced decades of degradation from industrial and municipal sewage, row-crop agricultural practices, and hydrologic alteration. We reviewed published analyses of long-term fish diversity publications from three intensively managed large river ecosystems to demonstrate the conservation potential of large river ecosystems. Results: We show how the incorporation of recent advances in river concepts will allow a better understanding of river ecosystem functioning and conservation. Lastly, we focus on the Wabash River ecosystem based on high conservation value and provide a list of actions to maintain and support the ecosystem. In the Wabash River, there were originally 66 species of freshwater mussels, but now only 30 species with reproducing populations remain. Although there were multiple stressors over the last century, the largest change in Wabash River fish biodiversity was associated with rapid increases in municipal nutrient loading and invasive bigheaded carps. Conclusions: Like similarly neglected large river systems worldwide, the Wabash River has a surprising amount of ecological resilience and recovery. For instance, of the 151 native fish species found in the 1800s, only three species have experienced local extinctions, making the modern assemblage more intact than many comparable rivers in the Mississippi River basin. However, not all the changes are positive or support the idea of recovery. Primary production underpins the productivity of these ecosystems, and the Wabash River phytoplankton assemblages shifted from high-quality green algae in the 1970s to lower less nutritional blue-green algae as nutrient and invasive species have recently increased. Our recommendations for the Wabash River and other altered rivers include the restoration of natural hydrology for the mainstem and tributaries, nutrient reductions, mechanisms to restore historical hydrologic patterns, additional sediment controls, and improved local hydraulics.

• Korean Journal of Ecology and Environment
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• v.47 no.spc
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• pp.1-9
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• 2014

Lake Suwa is a natural lake which is well-known for sightseeing and fisheries. It had suffered severe eutrophication during 1960s and 1970s with the occurrence of cyanobacterial blooms and the extinction of some benthic animals. Since 1980 water quality has been improved due to efforts of local government, scientists, and citizens. Of various methods that were attempted to improve the water quality of Lake Suwa biological methods received much attention, because it can improve the lake ecosystem integrity and fisheries in addition to the water quality. The aim of this paper is to introduce the biological methods for water quality improvement that had been employed in Lake Suwa, Japan, and their contribution to the economic benefit of local residents. Until now a significant restoration of water quality has been achieved, but there are insufficient recovery of the sediment and biota due to anoxic hypolimnion of the lake. This study proposed suspended cage culture of bivalves as a feasible method of water quality improvement. Increased grazing by bivalves will contribute to the improvement of water quality and fisheries production, which will contribute both to the ecological restoration and economy of local residents.

• Journal of the Korean Society for Marine Environment & Energy
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• v.13 no.4
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• pp.249-262
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• 2010

Regulatory test method for Total Petroleum Hydrocarbons (TPHs) in the marine sediment and biota has not still been established even though TPHs are one of the major pollutants in marine environment. Based on the Korean Soil Standard Method (SSM) for TPHs, we considered a new treatment method for determining TPHs in marine environmental samples by using a Gas chromatography coupled with Mass spectrometric detector. We suggested an improved recovery test for quality control procedures and introduced analytical procedures of removing sulfur, polar organic materials, water and saponification for removing neutral lipids in marine bottom sediments and biota.

• Geophysics and Geophysical Exploration
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• v.12 no.2
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• pp.192-198
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• 2009

Side scan sonar and SBP (sub-bottom profiler) play a very important role in the survey for seafloor imaging and sub-bottom profiling. In this study, we have acquired side scan sonar and SBP data from the artificial reef area. We applied digital image processing techniques to side scan sonar data in order to improve an image quality. For the enhancement of data quality and image resolution, we applied the typical seismic data processing sequence including gain recovery, muting, spectrum analysis, predictive deconvolution, migration to SBP data. We could easily estimate if artificial reef structures were settled properly and their distribution on the seafloor from the integrated interpretation of side scan sonar and SBP data. From the sampling analysis of seabed sediments, texture filtering of side scan sonar data and SBP data interpretation, we could evaluate the sediment type, distribution and thickness of seafloor sediments in detail.

• Korean Journal of Ecology and Environment
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• v.44 no.1
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• pp.75-84
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• 2011

We examined the effect of the turbid water on the periphytic diatom community in an artificial stream system. The artificial stream was constructed with transparent acryl and composed of four channels. Each channel ($20\;cm{\times}200\;cm{\times}40\;cm$) was supplied continuously with eutrophic lake water. In order to the freely colonize and grow diatoms, artificial substrate was installed with commercial slide glass soaked in 1% agar. Prior to introducing turbid water, the artificial stream was operated with lake water for 6 days to permit the propagation of diatom community on the substrates. The turbid water prepared with sediment sieved with ${\varphi}$ $64\;{\mu}m$ at $2\;g\;L^{-1}$ (final concentration, 300 NTU) was provided daily for 50 minute duration. The experiment was conducted for 7 days with manipulated experimental condition of light ($50{\sim}80\;{\mu}mol\;m^{-2}s^{-1}$, light:dark=24:0), temperature ($10{\pm}1^{\circ}C$), and flow rate ($0.31\;cm\;s^{-1}$). Sampling and analysis were conducted daily for water quality and diatom. Turbidity of the water varied 162.2~173.2 NTU during the experiment. After introduction of turbid water, DO, pH and TN were decreased, while SS and TP increased significantly. A total of 14 genera and 47 species of diatoms was observed on the artificial substrates during the experimental period. Of these, Navicula appeared to be a most dominant genus with 10 species, followed by Cymbella (6 species), Fragilaria (6 species) and Gomphonema (5 species). Achnanthes minutissima was the most dominant species (>70% of total frequency) in both control and treatment experiments. Increase in diatom abundance lasted for three days since turbid water introduction, after that they gradually decreased by the termination of the experiment. These results suggest that frequent supply of highly-concentrated turbid water significantly decreases the periphytic diatom community, and retard the recovery of the stable food-web within the stream.