• 한국농공학회논문집
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• 제65권1호
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• pp.73-81
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• 2023

To understand salinity status of fresh water and paddy soils and the susceptibility of rice to salinity stress of Gunnae reclaimed tidelands, salinity monitoring was conducted in rainy and dry seasons. For fresh water, a high salinity was observed at the sampling location near the sluice gate and decreased with distance from the gate. This spatial pattern of fresh water salinity indicates the necessity of spatial distribution of salinity in the assessment of salinity status of fresh water. Interestingly, there was significant correlation between rainfall amount and salinity, implying that salinity of fresh water varies with rainfall and thus it may be possible to predict salinity of water using rainfall. Soil salinity also higher near the gate, reflecting the influence of high saline water. In addition, the groundwater salinity also high to threat rice growth. Though soil salinity status indicated low possibility of sodium injury, there was changes in soil salinity status during the course of rice growth, suggesting that more intensive monitoring of soil salinity may be necessary for soil salinity assessment. Our study suggests the necessity of intensive salinity monitoring to understand the spatio-temporal variations of salinity of water and soil of reclaimed tideland areas.

• Fisheries and Aquatic Sciences
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• 제12권3호
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• pp.209-218
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• 2009

We examined physiological and histological responses related to the survival, oxygen consumption, excretion, and O/N ratio of the ark shell, Scapharca subcrenata, as a result of salinity changes. The 20-day $LS_{50}$ (median lethal salinity) at $15^{\circ}C$ was 13.87 practical salinity units (psu; confidence limits 10.30-18.74 psu), whereas the 14-day $LS_{50}$ at $25^{\circ}C$ was 12.59 psu (confidence limits 8.03-18.16 psu). In conditions of decreasing salinity, the osmolarity of individuals acclimated within 5 h above 26.4 psu but required more than 60 h below 13.2 psu. Oxygen consumption and ammonia excretion rates varied irregularly as salinity decreased. The O/N ratio was 19 and 27 at water temperatures of $15^{\circ}C$ and $25^{\circ}C$, respectively, but decreased to 1-10 as salinity declined. The effects of decreasing salinity were observed in the histological changes to each organ of S. subcrenata. As salinity decreased, cilia fell off, the epithelial layer underwent necrosis and vacuolation, the connective tissue layers of the mantle and visceral mass were destroyed, and hemocytes increased in the gills. The results of this study could prove important in investigating causes of mass mortality and managing shellfish aquaculture farms.

• 한국해양공학회지
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• 제32권5호
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• pp.361-366
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• 2018

The present study analyzed the variation factors in inducing a salinity change using the existing observation network in the section between the Nakdong River Estuary Barrage and Changnyeong-Haman Weir, and also examined the seasonal changes in precipitation, salinity, and discharge. Furthermore, this study analyzed the causes of a salinity increase by collecting observational data during a period when abnormal salinity occurred, and further investigated the salinity transfer time in a section of approximately 5.3 km from the Nakdong River Estuary Barrage to Nakdong River Bridge to understand the behavioral characteristics of the salinity moving upstream. The study results would make it possible to control the increase in salinity and block salt water from moving upstream by understanding the salinity variation characteristics according to the discharge amount. This will provide stability in collecting water from various residential, agricultural, and industrial sources through water intake facilities scattered near the Nakdong River Estuary Barrage.

• 한국해안·해양공학회논문집
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• 제20권3호
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• pp.310-320
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• 2008

조간대가 발달한 강화도 남단 여차리, 동막리, 동검도에서의 정점 CTD 관측 자료를 이용하여 수온 및 염분변동 양상 및 원인 분석을 수행하였다. 조간대 관측 자료는 조간대의 침수기간동안의 자료만을 이용하였다. 침수기간동안의 기온자료와 수온자료를 비교분석한 결과 상관관계가 매우 작은 것으로 파악되었으며, 수온변화는 조위의 상승하강과 반대되는 양상을 뚜렷하게 보여 주었다. 반면, 장기적인 지하수 유입의 영향으로 조석주기 동안 해수에서의 염분경사는 해안선에서 바다방향으로 갈수록 증가하는 경향(수온의 경우에는 해안선에서 바다방향으로 갈수록 수온이 감소)이 있기 때문에 수온과는 반대되는 변화양상을 보이고 있다. 즉 조석의 침수기간동안의 염분변화는 침수시점을 기준으로 조위가 상승하여 고조에 도달할 때 까지 증가하고, 조위가 감소하여 노출되는 시점까지 다시 염분이 감소하는 뚜렷한 양상을 보이고 있는 것으로 파악되었다.

• 한국수산과학회지
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• 제37권2호
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• pp.116-121
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• 2004

Physiological responses and tolerance limit of hybrid striped bass $(Morone\;Chrysops\;male{\times}\;M.\;saxatilis\;female),$ were investigated on salinity changes from 33 psu to 0 psu and from 0 to psu 33 psu in two separate trials, respectively. In the acute salinity decrease from sea water (33 psu) to fresh water (0 psu), plasma level of cortisol, glucose, total protein, aspartate aminotransferase (AST) and alanine aminotransferase (ALT) were not affected, however, $Na^+,\;Cl^-$ and osmolality significantly decreased. In the acute salinity increase from fresh water to sea water (33 psu), plasma cortisol level did not change. Glucose and total protein concentrations in plasma and hematocrit (Hct) decreased, whereas AST, ALT, $Na^+,\;Cl^-$ and osmolality increased. The hybrid striped bass can overcome the acute changes of salinity, from 0 psu to 33 psu or from 33 psu to 0 psu, But salinity decrease stressed the fish much more than salinity increase.

• 유기물자원화
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• 제8권2호
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• pp.124-129
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• 2000

본 논문은 퇴비화의 분해속도와 처리효율이 염분농도에 따라 어떻게 변화하는가를 조사하기 위해 이루어졌다. 실험에 사용된 음식물쓰레기의 시료는 경기도 포천군에서 채취하였으며 이 시료의 수분함량, pH 및 C/N비를 적정범위로 조정하였다. 염분함량이 1%, 5%및 10%인 3종류의 시료를 조제하여 온도조절과 공기공급량이 조절가능한 반응조에 넣고 호기성 퇴비화가 진행되는 동안 반응조내의 온도, pH, C/N비 및 이산화탄소와 산소 농도 등을 측정하였다. 최고온도는 반응조 1(염분함량 1%)에서 $59^{\circ}C$, 반응조 2(염분함량 5%)에서 $49^{\circ}C$ 및 반응조 3(염분함량 10%)에서 $45^{\circ}C$로 나타났다. 이산화탄소 발생량은 온도상승과 상관관계를 보였으며 낮은 염분함량에서 피크값을 나타냈다. 퇴비화가 진행되는 동안 반응조 1, 반응조 2 및 반응조 3의 pH는 8.9, 8.6 및 7.2로 상승하였으며 C/N비는 18.9, 19.1 및 22.1로 천천히 감소하였다. 반응조 1, 반응조 2 및 반응조 3의 최종함수율은 51.1%, 53.7% 및 55.0%로 나타났다. 퇴비화기간 동안의 염분농도의 증가는 미생물의 분해활동을 지연시키는 원인이 되는 것으로 생각된다. 한편, 효율적인 퇴비화를 위해 시료중의 염분함량은 5% 미만으로 유지되어야 한다.

• 한국가축번식학회지
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• 제16권4호
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• pp.363-376
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• 1993

This study was taken to examine serum components concentrations and electrophoretic patterns of female tilapia(Oreochromis niloticus) living in 0$\textperthousand$, 10$\textperthousand$, 20$\textperthousand$, and 30$\textperthousand$ salt concentrations, respectively. The results obtained in these experiments were summarized as follows. The level of albumin and total protein showed changes in each salinity, but didn't significantly(P<0.05) change in Oreochromis niloticus. The level of BUN didn't significantly(P<0.05) change. When fish were adapted from 0$\textperthousand$ to 10$\textperthousand$, 20$\textperthousand$ and 30$\textperthousand$, each calcium level in every salinity groups showed less than that of control, and didn't significantly change in 10$\textperthousand$, 20$\textperthousand$, 30$\textperthousand$ salinity. The level of calcium didn't significantly(P<0.05) change in each salinity. In 20$\textperthousand$ salinity, the level of cholesterol was at the highest peak. When fish were adapted from 0$\textperthousand$ to 10$\textperthousand$, 20$\textperthousand$ and 30$\textperthousand$, each glucose level gradually decreased. When fish were adapted from 0$\textperthousand$ to 10$\textperthousand$, 20$\textperthousand$ and 30$\textperthousand$, each glucose level gradually decreased. When fish were adapted from 0$\textperthousand$ to 10$\textperthousand$, 20$\textperthousand$ and 30$\textperthousand$. In 30$\textperthousand$ salinity, the level of alkaline phosphatase was at the highest peak. The level of serum enzyme such as SGOT and SGPT was higher in seawater-adapted group than in freshwater group. The level of phosphorus chnage significantly(P<0.05) in each salinity. Correlation coefficient between serum albumin and glucose in 0$\textperthousand$ was ＋0.924. Correlation coefficient between serum SGOT and SGPT of individuals in 0$\textperthousand$ was ＋0.917. Fraction 1 of transferrin patterns of tilapia(Oreochromis niloticus) adapted in seawater was much thicker than that of transferrin patterns of individuals adapted in freshwater. Also fraction No. a wasn't observed in some individuals adapted in freshwater. These results showed that transferrin adapted in seawater relatively increased. Slight differences, that is, showed to be observed in total iron binding capacityand iron saturatin rate between tilapia adapted in freshwater and in seawater. The increase in total iron binding capacity was attributed to a rise in transferrin pressent in the first fraction of serum protein adapted in seawater. Accordingly, the serum iron levles seemed to be related to salinity($\textperthousand$).

• 상하수도학회지
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• 제34권6호
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• pp.403-410
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• 2020

The difficulty of securing freshwater sources is increasing with global climate change. On the other hand, seawater is less affected by climate change and regarded as a stable water source. For utilizing seawater as freshwater, seawater desalination technologies should be employed to reduce the concentration of salts. However, current desalination technologies might accelerate climate change and create problems for the ecosystem. The desalination technologies consume higher energy than conventional water treatment technologies, increase carbon footprint with high electricity use, and discharge high salinity of concentrate to the ocean. Thus, it is critical to developing green desalination technologies for sustainable desalination in the era of climate change. The energy consumption of desalination can be lowered by minimizing pump irreversibility, reducing feed salinity, and harvesting osmotic energy. Also, the carbon footprint can be reduced by employing renewable energy sources to the desalination system. Furthermore, the volume of concentrate discharge can be minimized by recovering valuable minerals from high-salinity concentrate. The future green seawater desalination can be achieved by the advancement of desalination technologies, the employment of renewable energy, and the utilization of concentrate.

• 환경생물
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• 제26권3호
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• pp.138-144
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• 2008

본 연구에서는 자바틸라피아(체장 10$\pm$1.0cm, 체중 173$\pm$4.2g)를 사용하여 염분의 변화에 따른 산소소비율, 아가미 호흡수 및 암모니아 배설률을 조사하였다. 담수(0 psu)에서 사육하던 자바틸라피아를 염분 0(대조구), 3, 9. 15, 21 및 32 psu로 이동하였을 때 시간경과에 따른 생존율을 조사하였다. 단계적 인 염분변화는 담수(0 psu, 대조구)로부터 염분을 1일 3psu씩 증가시켜 3, 9, 15, 21 및 32 psu가 되도록 조절하였다. 급격한 변화는 각 사육 염분(0, 9, 15, 21, 32 psu)에서 각각 4개의 다른 염분으로 순화 없이 바로 옮겨 조사하였다. 본 연구결과에서 나타난 갑작스런 염분변화는 96시간 반수치사농도(96 hr-TL$_{50}$)는 23.3 psu로 나타났다. 단계적으로 염분을 옮겼을 때 3 psu로부터 27 psu까지 염분증가에 따라 산소소비율과 호흡수는 높아지는 것으로 나타났으며, 32 psu에서는 0 psu보다 낮아지는 경향을 보였다. 암모니아 배설량은 15 psu에서 가장 높은 배설률을 보이고 21 psu이상에서는 불규칙한 배설률을 보였다. 이러한 결과로 볼 때, 담수에서 15 psu 이상으로 갑작스런 이동은 항상성 유지에 문제가 있는 것으로 나타났으며, 염분에 적응사육한다고 할 때 15 psu 이하에서 단계적인 순화를 거쳐서 사육하는 것이 안전하다고 판단되어진다.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2021년도 학술발표회
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• pp.207-207
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• 2021

The Vietnamese Mekong Delta(VMD) covers an area of 62,250 km² in the lowest basin of the Mekong Delta where more than half of the country's total rice production takes place. In 2016, an estimated 1.29 million tonnes of Vietnam's rice were lost to the country's biggest drought in 90 year and particularly in VMD, at least 221,000 hectares of rice paddies were hit by the drought and related saltwater intrusion from the South China Sea. In this study, 3D numerical simulations using Delft3D hydrodynamic models with calibration and validation process were performed to examine flow characteristics, climate change scenarios, water level changes, and salinity concentrations in the nine major estuaries and coastal zones of VMD during the 21^st century. The river flows and their interactions with ocean currents were modeled by Delft3D and since the water levels and saltwater intrusion in the area are sensitive to the climate conditions and upstream dam operations, the hydrodynamic models considered discharges from the dams and climate data provided by the Coupled Model Intercomparison Project Phase 6(CMIP6). The models were calibrated and verified using observational water levels, salinity distribution, and climate change data and scenarios. The results agreed well with the observed data during calibration and validation periods. The calibrated models will be used to make predictions about the future salinity intrusion events, focusing on the impacts of sea level rise due to global warming and weather elements.