Journal of the Persian Gulf (Marine Science)/Vol. 2/No. 5/September 2011/8/27-34

Variations in Nitrate and Phosphate Contents of Waters in the Southwest

Khosropanah, Neda1*; Nejatkhah-Manavi, Parisa1; Koohilay, Sara1; Naseri, Mohammad Taghi2

1- Faculty of Marin Science and Technology, North Tehran Branch, Islamic Azad University, Tehran, IR 2- Faculty of Chemistry, Tarbiat Modares University, Tehran, IR Iran

Received: March 2011 Accepted: July 2011

© 2011 Journal of the Persian Gulf. All rights reserved.

Abstract Science and technological developments provide new opportunities to exploit aquatic resource. Hence, it is important to understand biotic and abiotic conditions of aquatic ecosystems. Objective of this Paper is to report findings of the study of nitrate and phosphate contents of water and effects of other physical- chemical parameters in the southwest regions of the Caspian Sea in the spring and summer of 2008. It focuses on the evaluation of nitrate and phosphate concentrations and compares the variations of these parameters with those of previous surveys. Fourty eight Water samples were collected from 18 stations along 6 transects: Astara, , Anzali, Kiashahr, Chamkhaleh and Chaboksar. Water samples were collected below 10 m depths in western parts of the southern coasts of the Caspian Sea. Temperature, pH and salinity of water were measured and recorded in situ. No significant differences were detected between concentrations of nitrate, phosphate and other parameters studied in the water column at different depths and stations in the six transects. Comparison of results obtained from the present study with those of previous surveys indicated that increasing trends in concentrations of nitrate and phosphate are probably caused by discharge of untreated domestic sewage and the discharge of pesticides from agricultural activities into rivers.

Downloaded from jpg.inio.ac.ir at 9:48 IRST on Thursday September 30th 2021 Keywords: Caspian Sea, Nitrate, Phosphate, Temperature, Salinity

1. Introduction it plays a crucial role in the structure of DNA and RNA, ATP, amino acids and enzymes including phosphatase, The Caspian Sea is divided into three sections as which controls the life of an organism (Ahern et al., follows: Northern, Middle and Southern. The Southern 2007). Phosphorous content varies in various water Caspian Sea has the largest volume of water bodies; for example, it is found at higher concentrations (approximately, 64% of the total volume, with 35% of close to the river mouth due to the destructive effects of the total area of the sea). The southern Caspian is the water waves on the river bank; however, in natural deepest part of the sea with the maximum depth waters which are less polluted, phosphorus reaching 1025 m. The average depth of the southern concentration varies from 0.1 to 1000 μg L-1. In closed Caspian Sea is 300 m (Kasimov, 1987). water bodies, the concentration increases given the type Phosphorus is considered as a chemical material on and degree of pollutants (Mann, 2000). which the life of flora and fauna is dependent, because In aquatic environments, dissolved inorganic * E-mail: [email protected] phosphate is biologically available as orthophosphate Khosropanah et al. / Variations in Nitrate and Phosphate contents of Waters in Southwest Caspian Sea

(Shan et al., 1994). Phytoplankton primary along the southern Caspian Sea coast due to agricultural production in fresh water systems are usually intensification. Nitrates and phosphates are the main controlled by phosphorus availability, whereas in components of most chemical fertilizers used in Iran. marine environments elemental nitrogen (N) is more Entry of pollutants to the Caspian Sea in recent years commonly the limiting nutrient (McCarthy and has affected the water quality and this trend may Carpenter, 1983). According to a research carried out naturally lead to phytoplankton growth and there by by Kasimov (1987) on the distribution of nitrate and mortality of marine resources (CEP, 2002). Increased phosphorus in the Iranian coasts of the Caspian Sea nutrient loads have augmented the proliferation and in various seasons, the western coast contains the increased distribution of harmful algal blooms in maximum levels of total nitrogen and nitrate and estuaries and coastal waters across the world (Anderson their concentrations fluctuates depending on seasonal et al., 2002). Given the circumstances, this study variations. Nitrate and phosphate concentrations attempts to investigate the variations in nitrate and showed seasonal variations and the highest phosphate concentrations in the south-west area of the concentrations for these nutrients in the south Caspian Sea. Caspian Sea basins were reported in the western 2. Materials and Methods coast (Kasimov, 1987).

Nitrate and phosphate levels are of crucial 2.1. Sampling importance and any changes in their concentrations may entail changes in phytoplankton population and Six transects vertical to the Caspian Sea coastline consequently long term effects in the food chain. were selected (Fig.1) in the area located between the Chemical fertilizers and pesticides are widely used cities of Astara and Chaboksar (Table 1). Downloaded from jpg.inio.ac.ir at 9:48 IRST on Thursday September 30th 2021

Fig. 1. Map showing transects and location of sampling stations studied during March-September 2008.

28 Journal of the Persian Gulf (Marine Science)/Vol. 2/No. 5/September 2011/8/27-34

Table 1- Geographical location of transects of sampling stations 2.2. Sample Analyses in the southwest Caspian Sea in 2008. Transects Location Latitude(N ) Longitude (E) 1 Astara 38º 25' 32" 48º 54' 45" The concentration of phosphate was analyzed by 2 Lisar 37º 59' 47" 49º 00' 16" 3 Anzali 37° 52′ 23″ 49° 35′ 16″ the ascorbic acid method as outlined in APHA 4 Chamkhale 37º 29' 07" 49º 59' 31" (1989) and nitrate by the sulfanilamide method 5 Kiashahr 37º 13'07" 50º 18' 17" 6 Chaboksar 37° 00′29″ 50° 33′47″ described in MENVIQ (1992). The concentrations of Three sampling stations were identified in each nitrate and phosphate in the samples were transect.Water samples were colllected in triplicate determined using spectrophotometer (HACH DR- (surface, 5 and 10 m below surface) using a Niskin 2500) and reported in terms of mg L-1. Other sampler. Sampling was carried out on a monthly basis parameters including water salinity rate (ATAGO during the spring and summer of 2008. Transects were s/mill-E) and pH (pH Tester 30) were also measured Astara, Lisar, Anzali, Kiashahr, Chamkhaleh and using portable kits. Data obtained were analyzed by Chaboksar. The collected samples were filtered in One- Way ANOVA and SPSS software. Statistical the field (Whatman filter paper, 0. 45 micron), the summary of environmental and biological parameters samples were kept in a cool place over ice and collected from waters in the southern Caspian Sea- transported to laboratories for analysis (APHA, 1989). Iranian coast during 2008 is shown in Table 2.

Table 2. Physical and chemical parameters in the southern Caspian Sea, Iranian coast during 2008 Nitrate (mg L-1) Phosphate (mg L-1) pH Salinity Temprature (°C) Surface Surface Surface Surface Surface season Transects 10m 5m water 10m 5m water 10m 5m water 10m 5m water 10m 5m water Mean 0.17 0.16 0.18 0.069 0.068 0.073 8.6 8.5 8.6 10.8 10.9 10.8 22.6 22.1 22.7 Astara STDV 3.1 0.28 0.55 3.08 0.177 0.16 0.023 0.099 0.035 1.94 1.64 1.2 3.93 3.03 2.51 Mean 0.41 0.4 0.038 0.072 0.06 0.235 8.59 8.6 8.5 10.8 10.8 10.2 23 23.5 25.3 Lisar STDV 0.16 0.13 0.26 0.01 2.1 0.06 0.062 3.08 0.056 2.2 3.1 1.32 4.7 6.9 4.7 Anzali Mean 0.26 0.2 0.14 0.032 0.045 0.16 8.6 8.6 8.5 11.1 10 8.83 22.8 23.3 26.1 Spring STDV 0.27 0.16 0.064 0.13 0.041 0.075 0.57 0.055 0.076 0.022 2.87 2.29 3.5 4.07 4.06 Mean 0.58 0.66 0.29 0.048 0.19 0.166 8.6 8.6 8.6 9.9 9.5 9 21.2 21.7 22.6 Chamkhale STDV 0.08 0.4 0.18 0.01 0.238 0.04 0.05 0.049 0.05 0.95 0.99 3.5 2.63 5.03 5.04 Mean 0.31 0.33 0.33 0.06 0.028 0.038 8.6 8.6 8.6 10.2 10.5 10.6 22.1 22.7 23.3 Kiashahr STDV 0.19 0.2 0.36 0.09 0.03 0.03 1.91 2.35 0.03 0.03 0.03 2.7 2.74 3.2 3.8 Chaboksar Mean 0.4 0.38 0.53 0.1 0.11 0.44 8.6 8.5 8.6 12 10.5 9.88 22.7 20.6 22.1 STDV 0.13 0.28 0.57 0.1 0.08 0.1 0.44 0.19 0.04 0.038 0.75 0.6 3.34 4.07 3.53 Mean 0.3 0.36 0.37 0.061 0.114 0.185 8.6 8.6 8.6 8.33 8.3 8.2 29.3 29.3 29.6 Astara STDV 0.2 0.3 0.35 0.047 0.163 0.23 0.063 0.03 0.039 0.12 0.57 0.33 1.34 0.86 1.18 Mean 0.52 0.61 0.82 0.148 0.211 0.241 8.6 8.6 8.6 9.1 9 8.2 29.9 30.1 30.6 Lisar STDV 0.3 0.7 1.01 0.13 0.24 0.2 0.09 0.08 0.06 0.24 1.3 0.83 1.4 1.9 2.3 Mean 0.42 0.46 0.48 0.34 0.45 0.42 8.7 8.7 8.7 8.7 8.3 8.8 30.3 30.8 31.8 Anzali STDV 0.24 0.432 0.07 0.3 0.59 0.2 0.44 0.047 0.06 0.04 0.5 0.92 0.62 1.03 1.72 Downloaded from jpg.inio.ac.ir at 9:48 IRST on Thursday September 30th 2021 Summer Mean 0.81 0.86 0.87 0.16 0.128 0.283 8.7 8.7 8.7 8.6 8.5 8 29.9 29.8 31.6 Chamkhale STDV 0.31 0.075 0.078 0.06 0.15 0.28 0.043 0.043 0.04 0.25 0.57 0.51 1.63 0.59 2.05 Mean 0.76 0.86 0.81 0.288 0.27 0.30 8.7 8.7 8.7 9.8 9.8 9.7 29.7 30.1 30.9 Kiashahr STDV 0.14 0.28 0.41 0.43 0.26 0.31 0.007 0.05 0.047 0.51 0.5 0.52 0.422 0.76 1.47 Mean 0.74 0.74 0.8 0.45 0.49 0.61 8.7 8.7 8.7 7.6 7.6 7.1 29.1 29.6 28 Chaboksar STDV 0.14 0.17 0.12 0.35 0.14 0.5 0.06 0.051 0.169 0.4 0.44 0.55 0.45 1.76 3.63

3. Results and Discussion

The highest concentration of phosphate (0.61 mg L-1) was detected in the surface waters of the Chaboksar station in summer, while the lowest concentration (0.028 mg L-1) was reported in the water sample collected from 5 m depths of Kiashahr station, in spring (Table 2). The distribution of inorganic phosphate during spring and summer was higher in the surface layers as compared to the other layers (Fig. 2). However, no significant differences (P>0.05) were detected in the phosphate concentrations in the various Fig. 2: Mean variations in phosphate concentrations at depths less than 10 m in the southwest Caspian Sea during the spring and water depths studied. summer of 2008 (bars show standard error).

29 Khosropanah et al. / Variations in Nitrate and Phosphate contents of Waters in Southwest Caspian Sea

Nitrate concentrations in the south Caspian Sea The maximum temperature recorded was 31.8 °C in fluctuated between 0.14 and 0.66 mg L-1 in spring and summer in the surface waters of Anzali, while the between 0.3 and 0.87 mg L-1 in summer (Fig. 3). No minimum water temperature during the study was significant differences were reported in nitrate recorded as 21.2 °C in spring at 10m depths in concentrations in the various water depths studied in Chamkhale (Fig. 5). the study area (P>0.05).

Fig. 3: Mean variations in nitrate concentrations at depths less than 10 m in the southwest Caspian Sea during the spring and summer of 2008 (bars show standard error). Fig. 5: Mean variations in temperature at depths less than 10 m in the southwest Caspian Sea during the spring and summer of 2008 Other parameters in water were determined in situ (bars show standard error). using portable instruments. Water salinity fluctuated Mean water temperature during spring and summer between 7.1 and 12 ppt in the study area (Table 2). of 2002 in depths of 0-10 meters are reported as 21.2 Highest salinity was recorded at 10 m depths in and 31.8 °C, respectively (Table 2). The highest pH Chaboksar in spring, while the lowest salinity was (8.7) was recorded in the surface waters of Anzali in reported in surface water samples collected from the summer, while the lowest pH (8.1) was recorded at 5 m Chaboksar station in summer (Fig.4). Results depths in Chaboksar, in March (Fig. 6).

Downloaded from jpg.inio.ac.ir at 9:48 IRST on Thursday September 30th 2021 indicated that except for the surface waters in Anzali and Kiashahr which are influenced by the rivers flowing into them, salinity was high in the other water depths in all the stations studied (Fig. 4).

Fig. 6: Mean variations in pH at depths less than 10 m in the southwest Caspian Sea during the spring and summer of 2008 (bars show standard error). No significant differences (P>0.05) were detected in the concentrations of nitrate and phosphate and Fig. 4: Mean variations in salinity at depths less than 10 m in the southwest Caspian Sea during the spring and summer of 2008 other parameters studied in the different depths in the (bars show standard error). six transects.

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Major parts of the southern coasts of the Caspian Sea beginning of summer inorganic nitrogen levels increase are less than 10 meters in depth. The shallow regions significantly compared to that of spring which may be are of prime significance due to the ecological due to the increase in agricultural activities. conditions prevailing, higher productivity, as well as Variations in salinity levels showed minor increases higher life span of fish fingerlings and for tourist form the surface to greater depths in the study area. attractions in summer. Marine waters possess almost all Kideys et al. (2001) stated that such variations (0.1 – kinds of chemical materials some of which are of great 0.2 ppt) from the surface to the depths in the Caspian significance for marine resources. For example, nitrate Sea are insignificant. On the other hand, with regard to and phosphate which are highly essential for the the geographical location and prevailing climatic synthesis of organic matter, play a key role in their life conditions of the Caspian Sea, water vapour in the and growth (Laloei, 2004). region increases and reaches saturation (CEP, 2002). The findings of this study revealed that the This results in a decrease in evaporation thereby, highest phosphate concentration (0.44 mg L-1) in increasing salinity during summer to a maximum level the south-west part of the sea was recorded in of 9.1 ppt in the Lisar region, due to the influence of Chaboksar in spring, which was probably due to the fresh water flowing into this region through the effects of northern cold waters of the Volga River navigational canals at the estuary. and the entry of the Sepidrud River, but the highest The temperature regime in the Caspian Sea is one of phosphate concentrations in summer time were the main factors for the circulation of water in this sea. recorded in Anzali, Chamkhale and Chaboksar. No significant differences (P>0.05) were detected in the Phosphate and nitrate concentrations in Astara were vertical variations in water temperature in the sampling reported to be the lowest as compared to the other stations in the six transects. This is because the water areas (Table 2). Previous studies indicated that the depth at the stations studied was less than 10 m and highest rate of nutrient transferred annually through thermal stratification had not set in these depths. the Sepidrud River is 1840 tons per year and 171 Statistical comparison of data pertinent to pH revealed tons per year through the Challus River. The lowest that the lowest values belonged to the pelagic waters of nutrient loading rate was recorded in the far west the first station in each transects. This may be attributed

Downloaded from jpg.inio.ac.ir at 9:48 IRST on Thursday September 30th 2021 region of the Caspian Sea (CEP, 2002).The study to the effects of the remains of marine organisms and conducted by Kasimov in 1987 on the phosphorous organic matter which are deposited close to the coastal variations in the Caspian Sea suggested that its region (Duxbury et al., 2000). distribution in the southern Caspian Sea was more pH in the Caspian Sea has seasonal and spatial heterogeneous or amorphous than the other areas and variations. In summer, the increase in phytoplankton

its highest transfer rate was recorded in the west production results in the absorption of (CO2) and a coast. Meanwhile, its volume varied depending on chain reaction that take the free Hydrogen ion from the seasonal variations (Kasimov, 1987). sea water, reduce the acidity and increase pH Nitrate concentrations follow similar trends. (Hajizadeh and Eghtesadi, 2008). In this study, the Phytoplanktons first consume inorganic nitrogen maximum value for pH was observed 8.7 at the water when they are in the early stages of growth. Then, surface in summer. Nasrollahzadeh et al. (2008) they convert organic nitrogen in various water layers reported that the maximum pH value for the Caspian into inorganic nitrogen for consumption. The present Sea was 8.6 in summer. study showed that nitrogen levels in the south-west Comparison of data collected in this study and those coast lines in spring were characterised by related to 2002 in the southwestern zone of the sea fluctuations from 0.16 to 0.66 mg L-1. With the (CEP, 2002) indicated an increasing trend in nitrate and

31 Khosropanah et al. / Variations in Nitrate and Phosphate contents of Waters in Southwest Caspian Sea

phosphate concentrations. On the basis of CEP reports bloom is highly significant as it is an indication of an nitrate concentrations ranged between 0.03-0.41 mg L-1 environmental alert for the Caspian Sea. Therefore, and that of phosphate ranged between 0.03 and 0.15 mg identifying the causes of such developments and L-1. In the present, study a significant increase was their impacts on the marine resources are of great recorded compared to that of 2002, which can be significance. attributed to the discharge of household wastes as well as discharge of fertilizers and pesticides into the rivers Acknowledgements during agricultural activities. Leonov et al. (2000) reported that the Sepidrud The authors wish to thank Dr. Hoseinali Rostami in River is the main source of pollution that enters the Fisheries Department of Iran for Material and Caspian Sea on the Iranian coastline. Dumont (1998) Instrumental support. This work was supported by stated that the main part of nutrients in the Caspian grants from the Department of Environment, Marine Sea was supplied through Volga River, but their Environment Division, Tehran, Iran. levels in the Caspian Sea were generally low. Phosphorus as well as nitrate levels during spring References and summer are low in the south Caspian Sea. It was in 1970 that agricultural and domestic waste Ahern, K.S., Ahern, C.R. and Udy, J., 2007. In situ materials led to an increase in nutrient levels field experiment shows Lyngbya majuscule growth (Dumont, 1998). According to investigations carried stimulated by added iron, phosphorus and nitrogen. out by Shiganova et al. (2001) in the Black Sea Harmful Algae. Vol. 21, pp.34-50. increase in water temperature in summer resulted in Anderson, D.M., Gilbert, P.M. and Burkholder J.M., an increase in the biomass of ctenophores. Increase 2002. Harmful algae blooms and eutrophication: in feeding intensity of ctenophore ultimately led to a nutrient sources, composition, and consequences. decrease in the population of zooplanktons and an Eustuaries. Vol. 25, pp.704-726. increase in that of phytoplanktons. Krupatkina (1991) APHA, 1989.Standard methods for the examination attributed nutrient accumulation (phosphorous, nitrogen of water and wastewater, 17th ed,. American Public

Downloaded from jpg.inio.ac.ir at 9:48 IRST on Thursday September 30th 2021 and sometimes silica) to intensive pollution and Health Association. Washington D.C. unfavorable conditions of life including pH, CEP., 2006. A study on the harmful algal bloom in temperature, salinity and even wind during the the south western basin of the Caspian Sea. favorable seasons such as spring and summer in Caspian Environment Programme CEP.15P. particular, which has changed into a problem in the CEP., 2002. Pollution in Caspian Sea. Caspian Caspian Sea region. Environment Programme CEP.24P. Entry of nutrients through agricultural, industrial Dumont, H.J., 1998. The Caspian lake: history, biota, and urban waste discharge results in phytoplankton structure, function, limnology and oceanography. bloom under normal circumstances. Algal blooms Vol. 43, pp. 44-52. were reported between Anzali and Nowshahr in Duxbury, A.B., Duxbury, A.C. and Sverdrup K.A., September 2005 due to an imbalance in nitrate and 2002. Fundamentals of oceanography. McGrahill. phosphate levels. Meanwhile in 2006, algal blooms 344P. caused a change in water colour in the coasts of Hajizadeh- Zaker, N., Eghtesadi-Araghi, P., 2009. Anzali. The occurrence of this bloom is associated to Characteristics and seasonal variation of pH in the flooding from the and entry of southern shelf of the Caspian Sea. Environmental nutrients into the sea (CEP, 2006). Phytoplankton Studies. Vol. 35, pp. 7-9.

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Kasimov, A.G., 1987. The Caspian Sea. Baku. Elm. cycling in near surface waters of the open ocean. (In Russian). Academic Press. New York. 900P. Kideys, A.E., Soydemir, N., Eker, E., Vladmyrov, MENVIQ ,1992. Determination des nitrates et des Soloviev, D. and Melin, F., 2001. Phytoplankton nitrates. Method colorimetrique automatisee avec distribution in the Caspian Sea during March 2001. le sulphanilamide et le N.E.D. 87.06/303-NO3. Hydrobiologia. Vol. 543., pp.159-168. 1.1. Minister de 1′ Environment du Que′bec. 9p. Krupatkina, D.K., Finenko, Z.Z. and Shalapyonok, Nasrollah zadeh, H.S., Din, Z.Z.and Makhlogh, A., A.A., 1991. Primery production and size fractionated 2008. Trophic status of Iranian Caspian Sea based structure of the Black Sea phytoplankton in the on water quality parameters and phytoplankton winter spring period. Marine Ecology Progress diversity. Continental Shelf Research. Vol. 28., Series. Vol. 73, pp. 25-31. pp.1153-1165. Laloei, F., Nasrollahzadeh, H.S., Varedi, E. and Shan, Y., Mckelvie, I. D. and Hart, B.T., 1994. vahedi, F., 2002. Caspian Sea investigation of Determination of alkaline phosphate hydrolysable hydrology and hydrobiology (Iranian Coast, 10 m phosphorus in natural water systems by enzymatic Depth). EACS Publisher. Iran. 315P. flow injection method.Limnology and Oceanography. Leonov, A.V and Nazarov, A.N., 2000. Nutrient input Vol. 39. pp.1993-2000. into the Caspian Sea with river run off. Water Shiganova,A.T., Kamakin, A.M., Zhukora., O.P., Resources. Vol. 28, pp. 656-665. Ushivtser, V.B., Dulimov, A.B and Museava, Mann, K.H., 2000. Ecology of Coastal Waters: With E.I., 2001. The Invader into the Caspian Sea Implications For Management. 2th edition, Wiley- ctenophore Menemiopsis and its initial effect on Blackwell. 406P. the Pelagic Ecosystem .Oceanology. Vol.41., McCarthy, J.J. and Carpenter, E.J., 1983. Nitrogen pp.542-549.

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