شناسه هاي افزوده :
صفري، رضا ، همكار طرح , نصراله تبار آهنگر، عبداله ، همكار طرح , مخلوق، آسيه ، همكار طرح , كيهان ثاني، عليرضا ، همكار طرح , لالوئي، فرامرز ، همكار طرح , واحدي، فريبا ، همكار طرح , صابري كوچصفهاني، حسين ، همكار طرح , ايري، يوسف ، همكار طرح , احمدنژاد، احد ، همكار طرح , رجبي ساسي، ايرج ، همكار طرح , محسن پور آبكنار، حجت اله ، همكار طرح , يونسي پور، حوريه ، همكار طرح , طهماسبي ليموني، مرتضي ، همكار طرح , شعباني، خداداد ، همكار طرح , دشتي، علي ، همكار طرح , كاردررستمي، محمد ، همكار طرح , داودي، ايوب ، همكار طرح , سجادي، اسداله ، همكار طرح , رضائي، مرضيه ، همكار طرح , رازقيان، غلامرضا ، همكار طرح
چكيده انگليسي :
Ecological monitoring of the sea means describing of situation, examining changes in the marine environment and following up on the effects of actions. This approach not only assesses ecosystem changes but also at the same time provides evidences of the fundamental reasons for changes. The objectives of present research are to study on changes of water and sediments environmental parameters, determine the trophic level and eutrophication and compare the values of environmental parameters of water and sediments with previous years. In this study, samples were collected during different seasons (fall, winter, spring and summer) at eight transects (Astara, Anzali, Sefidrud, Ramsar, Nowshahr, Babolsar, Amirabad and Bandar Turkman) and 5, 10 and 30 meter depths in 2018-2019.
The results showed that the changes of 25-75 percentile of 22 environmental parameters of water such as water temperature, air temperature, transparency, turbidity, salinity, pH, DO, DO%, BOD5, CODMn, TN/N, DIN/N, NH4/N, NO2/N, NO3/N, DON/N, TP/P, DIP/P, DOP/P, DSi, Chl-a, TRIXcs and UNTRIX were observed 12.20-24/45, 12.20-24.50 C, 1.500-3.00 m, 6.03-12.60 NTU, 1070-11.30 g/l, 8.50-8.61, 4.93-6.29 ml/l, 77-98 %, 2.87-5.03, 3.08-5.73 mg/l, 54-81, 3.03-5.28, 1.34-3.12, 0.60-0.20, 1.11-2.14, 50.78, 0.72-1.19, 0.48-0.98, 5.0-9.0 µM, 1.39-3.04 mg/l, 4.98-5.81 and 3.61-4.37, respectively.
The results showed that the changes of 25-75 percentile of differet forms of phosphorous such as Loosely-P, Fe-P, Al-P, Bioava.-P, Ca-P, TIP, Res.-P, TP were obtained 3.60-5.80, 31-61, 36-83, 88-135, 914-1381, 0-38 and 985-1578 µg/g.dw, respectively. The results showed that inorganic phosphorus (TIP) was higher at different seasons, so that the annual mean of organic and non-degradable phosphorus (Res.-P) was less than 5%. Among the inorganic phosphorus in sediments, the percentage of Ca-P reached more than 90% and the available phosphorus (Bioava.-P) was less than 10%. Also, among the three forms of available phosphorus (Bioava.-P), Al-P and Loosely-P had the highest and lowest percentages, respectively. The order of different forms of phosphorus were found Ca-P>Al-P>Res.-P>Fe-P>Loosely-P. In addition, the results showed that the changes of 25-75 percentile of differet forms of nitrogen such as NH4/N, NO2/N, NO3/N, TIN/N, DON/N and TN/N were detected 14-28, 0.09-0.17, 0.48-1.18, 15-29, 25-67 and 53-94 µg/g.dw, respectively.The annual percentage of organic nitrogen (DON) is almost two folds than inorganic nitrogen (DIN). Among the inorganic nitrogen form (DIN) in sediments, the percentage of NH4/N (94%) was recorded several times as much as NO3/N (5%). Changes in pH, oxidation and reduction potential (Eh) and organic carbon content (TOC %) and ratio of C/P and C/N changes were found 8.35-8.65, (-63)-(-85) mv, 1.26-2.58%, 2.3-5.3 and 16-48, respectively.
As a conclusion, variations in the trend line of surface water temperature mean (degrees Celsius) from 1994 to 2019 based on field and satellite data (SST) have been gentle and little. Long-term annual fluctuations (1994-2019) of water transparency (SDD) was declining and have a significant inverse correlation with turbidity (r=-0.45). The trend of long-term variations of salinity was slow, but the amount of pH, DO and DO% were increasing due to increased abundance of organisms and high production. The ratio of BOD/COD in the study area is ≤ 2:1; these values indicate that the water of the study area has a biodegradable nature.The gradual offshore dilution of nutrients can be visualised in plots showing nutrient concentrations versus the salinity. This information can be compared with the spatial salinity patterns to give a picture of the area affected by eutrophication. The relation between NH4, NOx, DIP, DSi and salinity follows a hyperbolic function rather than a linear one. This kind of relationship clearly shows that two processes (at least) lower the nutrients concentration: mixing and consumption within the system. Also, the trend of long-term changes of different forms of nitrogen in water was increasing, but these changes were recorded for different forms of phosphorus decreasing. The DIN/DIP and DSi/DIP molar ratios were increasing but the DSi/DIN ratio was decreasing. Fluctuations of DIN/DIP, DSi/DIN, and DSi/DIP molar ratios caused changes in diatoms growth and biomass, species composition, nutrient dynamics, and nutrient recycling processes. The trend of trophic level and eutrophication risk changes showed that in the 1990s, this area was in an oligotrophic state and without eutrophication risk. But in the 2000s, with the arrival of the ctenophore, the Caspian ecosystem came even closer to eutroph status, So that in 2005 with algal bloom, it was completely in the state of eutroph. However, in the early 2010s, the ecosystem was amendmented and was in mesotrophic condition and at risk of eutrophication.
The mian role of the rate of absorption and release of Loosely-P, Fe-P and Al-P adsorbed and desorbed were temperature, Eh and pH, respectively. Rate tranportaion of TINsed. and TIPsed.into the water column was higher than TONsed. and TOPsed.becuase of high ratio of TINsed./TINwat. and TIPsed./TIPwat. as compared with TONsed./TONwat. and TOPsed./TOPwat.
Comparing the percentage of total organic carbon (TOC%) with the threshold, the surface sediments of this region are in the group of moderate effects. Results of this study showed that TOC/TN was very high which represented to excitance of organic matter with almost non-degrediable (wood compounds such as lignin). Whereas, TOC/TP was low which showed that organic phophorous was not related to proteins and phospholipids therefore sources of org-P were belong to other compounds. Low ratio of TOC/TP also indicates the preference of organic phosphorus decomposition over organic carbon at the time of sedimentation.
