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Local Changes of Salinity and Nutrients and Processes Contributing to the Nutrient Distribution off the Evros River, in the North Aegean Sea
Published in J. Rose, Water and the Environment, 2017
Three cruises were carried out in the Alexandroupolis Gulf; two of them in late winter (March 1981, 1982) and the third one in summer (August, 1981). The bathymetry and station locations are shown in Figure 1. Samples of water were collected from 1, 5, 10, 20 and 30 m depth using Nansen water bottles of capacity 1.51. Temperatures were obtained with reversing thermometers attached to Nansen bottles. Dissolved oxygen was measured on board using the Winkler method as modified by Carritt and Carpenter (1966). The salinity samples were collected in 300 ml glass bottles and measured in the laboratory with an Autolab Mk III 601 inductive salinometer of precision ± 0.003‰. A secchi disc was used for transparency measurements. The water samples for nutrient analyses were collected in 100 ml plastic bottles to which a few drops of 0.04MHgCl2 have been added for preservation and kept under deep freeze. After thawing and filtering the samples through Millipore HA they were analysed with a Technikon CSM-6 auto-analyser. Nitrites, nitrates and silicates were determined with the method of Armstrong et al. (1967) and phosphates with the method of Murphy and Riley (1962). The above methods were adapted to the Technikon by Hager et al. (1968). Ammonia was measured after Koroleff (1970) as adapted by Slawyk and Mclsaac (1972).
Tidal Measurement and Analysis
Published in S.N. Ghosh, Tidal Hydraulic Engineering, 2017
The salinometer is now the most frequently used instrument for salinity determination. This instrument measures water conductivity and temperature from which salinity can be computed. The electrical conductivity of water is the inverse of its resistance and is expressed in units of ohm−1 cm−1 or mho cm−1. The relation between salinity and electrical conductivity/temperature is not a simple one [1].
Spatial and seasonal characteristics of dissolved heavy metals in the aquaculture areas of Beibu Gulf, South China
Published in Human and Ecological Risk Assessment: An International Journal, 2020
Guoqiang Liu, Qibin Lao, Qizhong Su, Youli Shen, Fajin Chen, Shangmin Qing, Chunlei Wei, Chunhua Zhang
The surface seawater pH was measured in situ with a pH meter (PHS-3C, Shanghai, China), and salinity was measured with a salinometer (SYA2-2). DO was immediately determined using the Winkler titration method (Strickland and Parsons 1969), with a precision of 0.07 mg L−1. Water samples were filtered by GF/F for Chlorophyl a (Chla) analysis. Chla was extracted with 90% acetone and determined spectrophotometrically (Lorenzen, 1967). For metal analysis, the pretreatment in seawater samples were carried out according to the method of Zhang et al. (2015) with a minor modification. Cd, Zn, Pb and Cu concentrations were determined by Anodic stripping voltammetry (797 VA Computrace, Wantong, Switzerland), Cr was determined by atomic absorption spectrometry (ZEENH700P, Jena, Germany), and Hg and As were determined by atomic fluorescence spectrometry (AFS-9530, Beijing Haiguang Instrument, China). The detection limits for Cu, Pb, Zn, Cd, Cr, Hg and As were 0.6 μg L−1, 0.1 μg L−1, 1.0 μg L−1, 0.01 μg L−1, 0.1 μg L−1, 0.007 μg L−1 and 0.5 μg L−1, respectively.