Dy nam ics of Oceanological Pa ram e ters in the Apsheron Ma rine Area of the Cas pian Sea

Ab stract—Pres ented are the re sults of mea sure ments of some oceanological pa ram e ters of the Cas pian Sea car ried out on the ter ri tory of oil and gas pro duc tion in the Apsheron ma rine area in 2007–2012. The re sults are com pared with the data of anal o gous mea sure ments car ried out in pre ced ing years un der dif fer ent re gimes of sea level fluc tu a tions. In recent decades, the level of production of hydrocarbon resources in the Caspian Sea has increased. In view of this, the study of the dynamics of oceanological parameters of the sea water is of great practical importance for erecting technical installations and equipment and for investigating the pollution of the sea shelf zone [2, 5, 7]. For this purpose, synchronous measurements of the following parameters were made: temperature (T, °C), salinity (S, ‰), concentration of hydrogen ions (pH), dissolved oxygen content (O2, mg/l), and oxidation-reduction potential (Eh, mV) of the sea water. The measurements were carried out on the territory of oil and gas production in the Apsheron marine area of the Caspian Sea in 2007–2012. A scheme of location of measurement points is given in the figure, and their coordinates, depth, and measurement time, in Table 1. The min i mum mea sure ment depth var ied within the lim its up to 10 m, and the max i mum depth, up to 25–35 m ex cept sev eral deep ar eas, where the depth reached 200 m. The stud ies were ac com plished in dif fer ent sea sons in 2007–2012 dur ing the ex pe di tions on eco log i cal mon i tor ing by the State Oil Com pany of Azerbaijan Re pub lic (SOCAR). The oceanological pa ram e ters of the sur face and bot tom lay ers of the sea wa ter were mea sured from the an chored ship in the cases of the light wind and calm (the oxidation-reduction po ten tial was mea sured only for the bot tom layer). The mea sure ments were car ried out us ing well-known meth ods and mod ern mea sure ment equip ment 3D-ACM and Multiline P-4. In all, 2542 mea sure ments were made [3, 8, 10]. The ob tained data were pro cessed, and the ranges of their vari a tions and the mean val ues of each pa ram e ter were de ter mined (Tables 2 and 3). The val ues of the vari ables un der study for dif fer ent re gimes of fluc tu a tions of the Cas pian Sea level ac cord ing to the lit er a ture data are also given in the ta ble [4–7, 9]. For ex am ple, the pe riod of 1958–1979 (pe riod I) is char ac ter ized with the de crease in the sea level, the pe riod of 1980–1996 (pe riod II), with its in crease, the pe riod of 1997–2006 (pe riod III), with the high and sta ble wa ter level, and the pe riod of 2007–2012 (pe riod IV) can be de fined as a quasistable re gime of the Cas pian Sea level. The anal y sis of the ob tained data dem on strated that in the area un der study dur ing pe riod IV min i mum val ues of wa ter tem per a ture are big ger than dur ing other pe ri ods in all sea sons (ex cept sum mer). Min i mum val ues of wa ter tem per a ture in sum mer dur ing pe ri ods II and III and its max i mum val ues dur ing pe ri ods I and II are close to each other. Av er age long-term val ues of wa ter tem per a ture dur ing pe ri ods II and III are very sim i lar. The con sid er able dif fer ence in the av er age long-term tem per a ture as com pared with other pe ri ods is ob served for pe riod IV: it reaches 1.5°C. The sa lin ity of the sur face wa ter layer of the Cas pian Sea af ter the dra matic rise of the wa ter level in 1979–1996 de creased to 0.3–0.5‰. On the av er age, the sea wa ter sa lin ity in the area un der study de creases by 1.0–1.5‰ [1–3, 7].