• Title, Summary, Keyword: Water sampling

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A Study on Measuring the Similarity Among Sampling Sites in Lake (저수지 수질조사 지점간 유사성 분석)

  • Lee, Yo-Sang;Koh, Deuk-Koo;Lee, Hyun-Seok
    • Proceedings of the Korea Water Resources Association Conference
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    • pp.957-961
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    • 2010
  • Multivariate statistical approaches to classify sampling sites with measuring their similarity by water quality data. For empirical study, data of two years at the 9 sampling sites with the combination of 2 depth levels and 7 important variables related to water quality is collected in reservoir. The similarity among sampling sites is measured with Euclidean distances of water quality related variables and they are classified by hierarchical clustering method. The clustered sites are discussed with principal component variables in the view of the geographical characteristics of them and reducing the number of measuring sites. Nine sampling sites are clustered as follows; One cluster of 5, 6, and 7 sampling sites shows the characteristic of low water depth and main stream of water. The sites of 2 and 4 are clustered into the same group by characteristics of hydraulics which come from that of main stream. But their changing pattern of water quality looks like different since the site of 2 is near to dam. The sampling sites of 3, 8, and 9 are individually positioned due to the different tributary.

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SPATIAL AND TEMPORAL INFLUENCES ON SOIL MOISTURE ESTIMATION

  • Kim, Gwang-seob
    • Water Engineering Research
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    • v.3 no.1
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    • pp.31-44
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    • 2002
  • The effect of diurnal cycle, intermittent visit of observation satellite, sensor installation, partial coverage of remote sensing, heterogeneity of soil properties and precipitation to the soil moisture estimation error were analyzed to present the global sampling strategy of soil moisture. Three models, the theoretical soil moisture model, WGR model proposed Waymire of at. (1984) to generate rainfall, and Turning Band Method to generate two dimensional soil porosity, active soil depth and loss coefficient field were used to construct sufficient two-dimensional soil moisture data based on different scenarios. The sampling error is dominated by sampling interval and design scheme. The effect of heterogeneity of soil properties and rainfall to sampling error is smaller than that of temporal gap and spatial gap. Selecting a small sampling interval can dramatically reduce the sampling error generated by other factors such as heterogeneity of rainfall, soil properties, topography, and climatic conditions. If the annual mean of coverage portion is about 90%, the effect of partial coverage to sampling error can be disregarded. The water retention capacity of fields is very important in the sampling error. The smaller the water retention capacity of the field (small soil porosity and thin active soil depth), the greater the sampling error. These results indicate that the sampling error is very sensitive to water retention capacity. Block random installation gets more accurate data than random installation of soil moisture gages. The Walnut Gulch soil moisture data show that the diurnal variation of soil moisture causes sampling error between 1 and 4 % in daily estimation.

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A Study on Measuring the Similarity Among Sampling Sites in Lake Yongdam with Water Quality Data Using Multivariate Techniques (다변량기법을 활용한 용담호 수질측정지점 유사성 연구)

  • Lee, Yosang;Kwon, Sehyug
    • Journal of Environmental Impact Assessment
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    • v.18 no.6
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    • pp.401-409
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    • 2009
  • Multivariate statistical approaches to classify sampling sites with measuring their similarity by water quality data and understand the characteristics of classified clusters have been discussed for the optimal water quality monitering network. For empirical study, data of two years (2005, 2006) at the 9 sampling sites with the combination of 2 depth levels and 7 important variables related to water quality is collected in Yongdam reservoir. The similarity among sampling sites is measured with Euclidean distances of water quality related variables and they are classified by hierarchical clustering method. The clustered sites are discussed with principal component variables in the view of the geographical characteristics of them and reducing the number of measuring sites. Nine sampling sites are clustered as follows; One cluster of 5, 6, and 7 sampling sites shows the characteristic of low water depth and main stream of water. The sites of 2 and 4 are clustered into the same group by characteristics of hydraulics which come from that of main stream. But their changing pattern of water quality looks like different since the site of 2 is near to dam. The sampling sites of 3, 8, and 9 are individually positioned due to the different tributary.

Development of sampling device for monitoring micro-organisms in treated ballast water (밸러스트 처리수 미생물 모니터링을 위한 Sampling Device 개발)

  • Park, Sung-Jin;Kim, Ki-Wook;Yoon, Seung-Je;Cho, Dong-Yeon;Kim, Sang-Yong
    • Proceedings of the Korean Society of Marine Engineers Conference
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    • pp.312-312
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    • 2011
  • All ship's ballast water should be inspected by administration after enter into force IMO BWM Convention. The purpose of the sampling device is to concentrate large amount of samples and to improve return rate of samples. It is composed of Concentration and Rinsing Part and optimized by the variety of tests. it is fully automated and therefore efficiently operated in ships.

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Development of a Water Sampling System for Unmanned Probe for Improvement of Water Quality Measurement (수질측정 방법 개선을 위한 무인 탐사체의 채수장치 개발방안)

  • Jung, Jin Woo;Cho, Kwang Hee;Kim, Min Ji
    • Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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    • v.35 no.6
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    • pp.527-534
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    • 2017
  • The purpose of this study is to develop unmanned equipment that can automatically move to the desired point and measure water quality at the correct depth. For this purpose, we constructed a water sampling lift and water sampling container, an unmanned vessel equipped with a VRS-GPS, an acoustic echo sounder, and a water quality sensor. Also, we developed an automatic navigation algorithm and program, an automatic water sampling program, and a water quality map generation program. As a result of the experiment in the detention pond, the unmanned vessel sailed along the planned route with an accuracy of about 93% within the error range of 3m. In addition, the water quality sensor installed in the lift was able to acquire the water quality of the target area in real time and transmit it to the server via wireless Internet, and it was possible to monitor the water quality of each site in real time. Through field experiments, the water sampling lift was able to control the desired length with an accuracy of about 94%. The stretch length accuracy experiment of the water sampling lift was impossible to measure directly in the water, so it was replaced land-based experiment. We also found some unstable problems due to the weight of the water sampling lift and the weight of the air compressor to operate the water container. Except these two problems, we accomplished purpose of this study. An automated water quality measurement method using an unmanned vessel can be used to measure the quality of water in a difficult to access area and to secure the safety of the worker.

Comparison between Head Space Gas Sampling and Purge & Trap Sampling in Water Analysis

  • Nagayanagi, Yutaka;Nakagawa, Katsuhiro;Saito, Yoshihiro;Kim, Poongzag
    • Analytical Science and Technology
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    • v.8 no.4
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    • pp.739-744
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    • 1995
  • The two main methods to prepare water samples for analyzing volatile organic compounds(VOC's) were investigated. One is the purge and trap(PT) method and another is the head space(HS) sampling method. Both methods were effective to transfer the low boiling point components from the water sample onto the capillary column. The cryo-focusing at the top of the main capillary column was an effective way to obtain the sharpness of the chromatographic peaks but could be avoided when a semi-wide bore column was used. The recovery from the same amount of the sample was better in PT than in HS but a larger sample volume in HS method could compensate the lower efficiency. Therefore PT is suitable to the analysis of drinking water where the very low concentration must be determined. HS is suitable to waste water analysis because of the easiness of the operation. The repeatability was good and similar in both methods. For the contamination of the former sample, both methods were tough and could be used without any problems. The matrix effect which could change the equilibrium parameters in HS method was find negligible in many components. The actual samples such as tap water and river water were analyzed with both methods concerning 16 components regulated in Korea.

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Improvement of sampling method for bacteriological test in tap water (수도꼭지에서 미생물 검사 목적의 샘플링 방법 개선 연구)

  • Lee, Eun-Sook;Lee, Dong-Sik;Lee, Mok-Young;Lee, Man-Ho;Han, Sun-Hee
    • Journal of Korean Society of Water and Wastewater
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    • v.25 no.4
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    • pp.519-525
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    • 2011
  • We studied on the effect of faucet cleanliness, faucet conditions (screen, mixing faucet), and flushing time for bacterial detection in tap water. As results, tap water should be left to run to waste for 2 to 3 minutes and if a questionable cleanliness is questionable, disinfect the faucet by using flaming or other methods before sampling. We proposed sampling method to decrease effect of factors associated with bacterial detection in tap water and contributed to be evaluated more accurate water quality.

Study on the sampling rate for the purpose of use in water distribution network data (상수도 관망 데이터의 사용목적에 관한 수집 주기 연구)

  • Lee, Kyounghwan;Suh, JungChul;Cha, Hunjoo;Song, Kyosin;Choi, Junemo
    • Journal of Korean Society of Water and Wastewater
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    • v.27 no.2
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    • pp.233-239
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    • 2013
  • Sampling rate of Hydraulic pressure data, depending on the intended use of the water distribution system is an important factor. If sampling interval of hydraulic data is short, that will be more useful but it demand a lot of expense for maintenance. In this study, based on simulation of water distribution system 2 khz data, statistical techniques of student t distribution, non-exceedance probability using the optimal sampling rate for research.

Applications of Cryogenic Method to Water Vapor Sampling from Ambient Air for Isotopes Analysis (수증기 동위원소 측정을 위한 저온채집법에 대한 연구)

  • Kim, Songyi;Han, Yeongcheol;Hur, Soon-Do;Lee, Jeonghoon
    • Ocean and Polar Research
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    • v.38 no.4
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    • pp.339-345
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    • 2016
  • Stable water vapor isotopes have been utilized as a tracer for studying atmospheric global circulations, climate change and paleoclimate with ice cores. Recently, since laser spectroscopy has been available, water vapor isotopes can be measured more precisely and continuously. Studies of water vapor isotopes have been conducted over the world, but it is the early stage in south Korea. For vapor isotopes study, a cryogenic sampling device for water vapor isotopes has been developed. The cryogenic sampling device consists of the dewar bottle, filled with extremely low temperature material and impinger connected with a vacuum pump. Impinger stays put in the dewar bottle to change the water vapor which passes through the inside of impinger into the solid phase as ice. The fact that water vapor has not sampled completely leads to isotopic fractionation in the impinger. To minimize the isotopic fractionation during sampling water vapor, we have tested the method using a serial connection with two sets of impinger device in the laboratory. We trapped 98.02% of water vapor in the first trap and the isotopic difference of the trapped water vapor between two impinger were about 20‰ and 6‰ for hydrogen and oxygen, respectively. Considering the amount of water vapor trapped in each impinger, the isotopic differences for hydrogen and oxygen were 0.33‰ and 0.06‰, respectively, which is significantly smaller than the precision of isotopic measurements. This work can conclude that there is no significant fractionation during water vapor trapping.

Application Assessment of Passive Sampling to Monitor Polybrominated Diphenyl Ethers in Water Environment as Alternative Sampling Method for Grab Sampling (수계 중 폴리브롬화 디페닐에테르 모니터링을 위한 Passive Sampling 적용 및 그랩 시료채취법의 대체 활용가능성 평가)

  • Kim, Un-Jung;Seo, Chang Dong;Im, Tae-Hyo;Oh, Jeong-Eun
    • Journal of Korean Society of Environmental Engineers
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    • v.37 no.1
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    • pp.45-51
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    • 2015
  • PBDEs (polybrominated diphenyl ehters) are rarely dissolved in water due to their strong hydrophobicity and large molecular mass so not many researches were done in aqueous environment compared to other environmental compartments. However, the mass loading from wastewater treatment plant into aquatic environment, re-suspension from bottom sediment and partitioning from floating particles and colloids may not be negligible. It is, therefore, important but also difficult to investigate PBDEs in water environment. Recent overcoming resolution towards this barrier to monitor hydrophobic organic compounds in aquatic environment is using passive sampling technique like semipermeable membrane device. By using passive sampling, it might be possible to obtain long-term reproducible monitoring result and detect the trace amounts of PBDEs, with controlling fluctuation of surrounding environmental factors during the sampling event. So therefore, this study is purposed to confirm the possibility of using SPMD (semi-permeable membrane device) as water monitoring tool. Grab samples, composite samples and SPMDs were applied in river bank to evaluate the concentration difference and temporal fluctuation by various water sampling method, and to assess the water concentration prediction capability of SPMD for the PBDEs.