Results of investigations into cyclic salts on the east coast of the Adriatic (Split)
Abstract
The content of chlorides in rainwater was investigated into during a period of time extending over more than thirteen months (in 1948 and 1949). The content of sulphate in rain water was also the subject of those investigations. The data thereon are given in tables covering days and months. The lowest content of Cl' was 1.38 Cl/l, and the highest one was 156.4 mg Cl/l.
December 1948 showing 21.58 mg Cl/l and March 1949 showing 21.2 mg Cl/l were the rainy months with the highest concentration of chlorides in rain water. Among the months with rain October 1949 showing 3.29 mg Cl/l and June 1949 showing 5.72 mg Cl/l were the ones with the lowest content of chlorides in rain water. The yearly average, as resulting from 72 analyses, was 9.65 mg Cl/l.
The amount of Cl, precipitated on 1 m2 of surface during a day's period was 7.7 x10-4 mg Cl/cm2 (24. V. 1949), and the greatest one was 7.04 x 10-2 mg Cl/cm2 (8. XI. 1949). The year's average precipitation was 6.58 x 10-1 mg Cl/cm2. Expressed in a year's total of (dry) salts a height is reached amounting to 5.49 µ.
A regularity has been stated consisting in the fact that in cases of rain water belonging to rainfalls occurring during several subsequent days, in absence of winds being over 4-6 degrees Beaufort strong, the concentration of Cl/l decreases regularly with time. (R u l e o f s e v e r a l d a y s' p e r i o d).
It has been stated further that the points, resulting from data on mm of rain water and mg Cl/l of all the rainfalls which occurred during a year, if placed into a system of coordinates, will produce almost a hyperbolic curve. There results that the product obtained by multiplying mm of rain water by mg Cl/l represents one, to some extent constant, quantity (K). This is the R e g u l a r i t y o f l o n g e r t i m e p e r i o d s.
The opinion has been expressed that K might possibly be a c h a r a c t e- r i s t i c o f s i n g l e c l i m a t i c regions.
By dealing with the data on Cl and mm of fractions of a single rainfall lasting for 4¼ hours there has been found that t h e a m o u n t o f m g C l p r e c i p i t a t e d o n t h e g r o u n d (mg Cl/l x l of rain water) d e c r e a s e s w i t h t i m e f o l l o w i n g t h e l a w o f t h e e x p o- n e n t i a l f u n c t i o n.
Data are also given on the content of SO4 found in several rain waters at different season of the year, the average content of Cl/SO4" amounting to 0.314.
The possibility of an influence of cyclic salts upon the salinity of the Vrana Lake water was also dealt with.
Approximate values of the amounts of salts precipitating during a year on the 5 km wide coastal belt of the Yugoslav Adriatic Littoral are given. The total quantity of salts amounts to 2.4 x 105 tons.
The probable influence of some compounds of the rain water salts on the living world of the coastal belt has also been considered.
