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《Oceanologia Et Limnologia Sinica》 1960-02
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SOME MORPHOLOGICAL FEATURES OF THE BASIN OF,AND THE PHYSICAL, CHEMICAL AND BIOLOGICAL PROPERTIES OF THE WATER IN THE SOUTHEASTERN PART OF THE LAKE WEISHAN ADJACENT TO THE ISLAND HWANGSHAN

S. P. CHU & Y. WANG(National Hwanghai Fisheries Research Institute)  
The lake Weishan is situated at the southwestern end of a chainof four continuous lakes in the province of Shantung and is the largest in area and lowest in lake bottom level, hence the depth of water is also the greatest in natural conditions. The drainage through a number of rivers on both sides of the lake chain is recieved by the northern three lakes but stored mainly in Lake Weishan. The rivers on the northwestern side of the lake chain are mostly long, washing the large West Shantung Plain of cultivated fields; while those on the southeastern side, washing the mountainous region, are rather short with the exception of the rather long river Seshei. The northern part of Lake Weishan is much shallower than the southern part; and the three northern lakes are even still shallower, mostly with thick growths of higher aquatic plants and a thick layer of nutritious bottom mud. Thus the supply of nutrients of the southern part of Lake Weishan comes not only from its neighbouring land but also related to the system of drainage received by other parts of the lake chain as well as to the internal drainage through the rich marginal area of the northern three lakes.The investigated region is situated near the southeastern corner of the southern part of Lake Weishan with the east bank formed along three steep rocky peninsulas of the Liguoh Iron Mine District. There are four steep rocky islands in the north portion of the investigated region,, which are separated from each other and from the main land by narrow straits (Fig. 1). The neighbouring region of the main land and these four island are all covered with cultivated fields. The lake bottom here is as a whole very flat as shown in Figs. 1-5. The morphological features, here are as a whole very characteristic of a tectonic basin associated with a fault scarp. The deepest portion of Lake Weishan lies on the northwestern side of the region invstigated.Measurements of the morphological features of the lake basin and investigations of physical, chemical and biological properties of water were all carried out mainly in August, 1952, after a long period of summer drought, and hence the water level of the lake was at its lowest. The height of the water level was 31.75 metres (old Yellow River zero point) and the depth of the deepest region investigated, north of Hwangshan and Tungshan islands, was only a little more than 1.25 m, while that between Hwangshan and Funghwangshan, i. e. at the mouth of Hwangshan Bay, a little more than one metre. The shoreline was fixed at between 33 m and 34 m contour lines as judged by the high water marks, though in the year of exceptionally high flood, i.e. 1935, the water level was above the 36 m contour line. As the bottom near the shore is still rather flat, the area between the low water level and the high water mark is usually very large. The lowest water level usually occur in July or August, while the highest, in August or September. The bottom is generally hard and smooth, being covered by only a thin layer of soft mud mostly not more than 7 cm. in thickness.As can be seen from the physical and chemical data in Tab. 2, the pH value and the CaCO3 alkalinity of the lake water were rather high, and the dissolved PO4-P, NO3-N, SiO2 and organic matter were very far from being depleted even after a long summer drought when the phytoplankton growth was very heavy. Chemical data indicate a high fertility of the water and there is reason the believe that the inorganic nutrients was actually continuously replenished by those released from the dissolved organic matter. This is also shown by the amount of oxygen released during photosynthesis of phytoplankton in the experiments with black and white glass bottles submerged one metre beneath the water surface at a place between Tungshan Island and Liwan Peninsula. During an interval of 4 hours and 30 munits, 2.34 mg/L oxygen was released by phytoplankton, and, at the same time, no less than two third of this amount of oxygen was also released by submered higher aquatic plants (see list of species of aquati
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