References

We would like to thank the editor and the reviewers for their comments that have helped us to prepare this final version. All suggestions have been taken into account and all raised issues are answered one by one. References have been included as proposed. The section related to sea-water solubility has been exempted from the manuscript as suggested. Minor comments have been also taken into account. Below is a point by point answer to the reviewer’s comments (by Italics).


Introduction
The Mediterranean Sea has one of the most oligotrophic surface wasters in the world with Low Nutrient and Low Chlorophyll (LNLC). The average annual productivity in the Mediterranean Sea is almost half that of the ultra-oligotrophic Sargasso Sea (Krom et al., 2004;Pitta et al., 2005). The main reason for this ultra-oligotrophic status is that 5 the Mediterranean has an anti-estuarine (reverse thermohaline) circulation in which nutrient poor surface waters incoming from the Atlantic is balanced by outgoing relatively nutrient rich deep waters of the Mediterranean Sea through the Strait of Gibraltar, (Krom et al., 1991;Turley, 1999). As a result of this peculiarity, most of the nutrient inputs to the Mediterranean Sea are mainly originated from the atmosphere (including 10 dry and wet depositions) and riverine runoff. Over the last four decades, the freshwater discharge from rivers to the Mediterranean rivers has suffered a substantial decrease owning to both climate change and dam constructions (Ludwig et al., 2009) therefore the relative importance of atmospheric inputs of nutrients to the Mediterranean surface waters will have increased. 15 The Eastern Mediterranean Sea has a uniquely high N/P ratio raging from 25 to 28, higher values compare to the Western Mediterranean (22) and the "normal" oceanic Redfield ratio of 16 (Krom et al., 1991;Yılmaz and Tugrul, 1998). Thus the primary productivity in the Eastern basin is phosphorus limited . In their recent study, Krom et al. (2004) budgeted fluxes of N and P for the Eastern Mediter- 20 ranean and concluded that the high N/P ratio is due primarily to the high biologically available N/P ratio in all the input sources but for those particularly from the atmosphere (117:1). Ludwig et al. (2009) suggested that decreases in the dissolved Silica concentrations were due to a substantial reduction in the fresh water discharges. These authors have hypnotized that Si may not necessarily reduce the productivity in 25 the Mediterranean however it can provoke a switch from diatom dominated communities to non-siliceous populations.
Atmospheric inputs of nutrients to the coastal system and the open ocean can take place through dry and wet (i.e. rain) deposition. According to Guerzoni et al., (1999), the atmospheric input of inorganic nitrogen represents 60% of the total nitrogen en- 10 tering the Mediterranean from continental origin, 66% of which is via wet deposition. Kouvarakis et al. (2001) suggest that the input of inorganic N species in atmospheric deposition is enough to explain nitrogen needs in the eastern Mediterranean Sea. Unlike N compounds which have dominant anthropogenic sources (Spokes and Jickells, 2005) the aerosol P content and Si are of continental/natural origin (e.g rock and soil) 15 Markaki et al., 2003;Baker et al., 2007).
The present study is based on a long term aerosol, rainwater and riverine data collection in the Northern Levantine Basin of the Eastern Mediterranean. The main aim of the current study is to enhance our knowledge of atmospheric (dry and wet) to the surface waters of the Northern Levantine Basin. The extensive library of aerosol, rain-20 water and riverine samples collected from the region, will allow to (i) define temporal variability of nutrient concentrations in aerosol and rainwater, (ii) assess the influence of air masses back trajectories on nutrient composition, (iii) compare sea-water and pure-water solubilities of nutrients for selected aerosol samples and (iv) assess and compare the atmospheric and riverine inputs of nutrients to the Northern Levantine 25 Basin.

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Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | 2 Materials and methods

Sites description and sample collection
Aerosol and rain water sampling was carried out at a rural site located on the coastline of the Eastern Mediterranean, Erdemli (36 • 33 54 N and 34 • 15 18 E), Turkey (Fig. 1). The sampling site is not under direct influence of any industrial activities. The samplers 5 were positioned on a sampling tower (at an altitude of ∼22 m) which is situated at the Institute of Marine Sciences, Middle East Technical University (for more details see Kubilay and Saydam, 1995;Koçak et al., 2004b

Sample analysis
The pH in rain waters was measured immediately using a Microprocessor pH meter (WTW-Model pH537) after each specific event. Calibration of the pH meter was carried out using N.B.S buffers at pH values of 4.00 and 7.00. The soluble nutrient measurements in aerosols, rain waters and river samples were 5 carried out by a Technicon Model, four-channel Autoanalyzer (for more details see Yılmaz and Tugrul, 1998 (18.2 Ω) and 50 µL chloroform. In order to compare solubilities, the same extraction procedure was adopted using Northeastern Mediterranean surface Seawater (filtered with 0.2 µm, Herut et al., 2002) as the extraction medium. Samples were immediately analyzed for nutrients after centrifuging at 3500 rpm for 15 min. 20 Air masses back trajectories arriving at the sampling site were computed by the Hysplit Dispersion Model (Hybrid Single Particle Langrangian Integrated Trajectory; Draxler and Hess, 1998) and were illustrated by one-hour endpoint locations in term of latitude and longitude. Daily back trajectories between January 1999 and December 2007 were evaluated for 3 days for three different heights above the starting point at ground 25 level (1, 2 and 3 km a.g.l.). Cluster analysis was applied to categorize air masses back trajectories using the method described by Cape et al. (2000). 5086

Air mass back trajectories and cluster analysis
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Calculation of nutrient fluxes
The wet and dry atmospheric fluxes of nutrients were calculated according to the procedure explained in Herut et al. (1999Herut et al. ( , 2002. The wet atmospheric deposition fluxes (F w ) were calculated from the annual amount of precipitation (P ) and the volume weighted mean concentration (C w ) of the substance of interest (Eq. 1).
The dry deposition (F d ) of nutrients can be calculated as the product of atmospheric mean nutrient concentrations (C d ) and their settling velocities (V d ), where F d is given in units of µmol m −2 yr −1 , C d in units of µmol m −3 and V d in units of m yr −1 (for more details see Sect. 3.5.1).
Annual riverine fluxes (F r , Eq. 4) were calculated by the product of C dw and Q annual (Karakatsoulis and Ludwig, 2004).
The discharge weighted mean concentration (C dw , Eq. 3) was determined on the basis of n samples of instantaneous concentrations (C i , C i +1 ) and discharge values (Q i ,  3 and NH + 4 in rainwater samples were found to be 0.7, 1.9, 44 and 46 µmol L −1 , respectively. Table 2 shows the soluble nutrient concentrations in aerosol and rainwater samples obtained from different sites located around the Mediterranean. Although the values from this study and those in the literature cover different collection periods (and might 15 have different sampling and analytical methodologies), comparison will be useful to evaluate spatial trends.
To our knowledge, no data of water soluble Si diss in the aerosol over the Mediterranean and Si diss in rainwater over the Eastern Mediterranean have been reported previously. Since Bartoli et al. (2005) reported only wet deposition inputs of Si diss for the 20 Western Mediterranean and hence would not be appropriate to compare these with the present Si diss values. The mean aerosol phosphate concentration at Erdemli was comparable to levels reported for Eliat, Israel (Chen et al., 2007). Although phosphate concentrations were measured in seawater, highest levels over the Eastern Mediterranean was reported for Tel Shikmona and this might be attributed to the closer proximity of 25 the sampling site to arid regions (Koçak et al., 2004a). Aerosol nitrate and ammonium concentrations are in agreement with the values reported for Erdemli (Koçak et al., Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | 2004b). Observed mean aerosol nitrate and ammonium concentrations were found to be two to four times higher than those reported for Finokalia, Crete (Kouvarakis et al., 2001;Markaki et al., 2003) and Eliat, Israel (Chen et al., 2007) whereas values were comparable levels reported for Tel Shikmona, Israel (Herut et al., 2002) and Cap Ferrat (Loÿe-Pilot et al., 1993). It should be noted that Erdemli and Tel Shikmona 5 aerosol samples were collected on Whatman 41 cellulose fiber filters whilst Finokalia and Eliat aerosol were collected on Teflon and polycarbonate filters, respectively. It has been reported that positive nitrate and ammonium artifact can result the adsorption of gaseous HNO 3 and NH 3 on filter surfaces (mainly glass fiber and cellulose) or on already collected particles (Wieprecht et al., 2004 and references therein). For 10 instance, Keck and Wittmaack (2005) showed that the retention efficiencies of HNO 3 and NH 3 are very high up to 100%, if the gases are presented in equimolar concentrations. In order to clarify this difference, aerosol samples were simultaneously collected on Whatman 41 and polycarbonate filters (n=158; Koçak, 2006). Comparing nitrate and ammonium results from different substrates it has been shown that NO − 3 and NH + 4 15 values for Whatman 41 were 42% and 50% higher than those concentrations observed for polycarbonate filters. Therefore, it can be assumed that the measured nitrate and ammonium concentrations for the current study are equivalent to be those of total inorganic NO − 3 and NH + 4 plus gaseous HNO 3 and NH 3 . Rainwater volume weighted mean phosphate, nitrate and ammonium concentrations 20 at Erdemli were found to be comparable to values reported for Israeli coastal sites  whereas lowest values were observed at Finokalia (Markakie et al., 2003) since this site is categorized by natural background (distance from large pollution sources >50 km) and its proximity to arid regions located at the Middle East/Arabian Peninsula.  1988;Herut et al., 1999Herut et al., , 2002Markaki et al., 2003). Concentrations of nutrient species were highly variable on a daily time scale and their concentrations may change an order of magnitude from day to day (see

Aerosol
Although, particles are efficiently scavenged by wet deposition (26% of the annual amount, 39% of the total events, one rain event per 5 day) PO 3− 4 and Si diss demonstrated higher concentrations and larger variations during the transitional period (spring 10 and autumn). As documented in the literature (Kubilay and Saydam, 1995;Avila et al., 1998;Moulin et al., 1998;Koçak et al., 2004a) intense sporadic dust events occur over the Eastern Mediterranean during the transitional period when the air mass trajectories originate predominantly from North Africa (but rarely from the Middle East/Arabian Peninsula). Higher concentrations and variations might be attributed to transport of  The lowest values for aerosol nutrient species were observed during the winter. Lower values of aerosol nutrients in winter can be attributed to efficient removal of particles from the atmosphere via frequent rain events (70% of the annual amount, 55% of the total events, one rain event per 3 day). Aerosol NO − 3 and NH + 4 showed 10 higher values in summer. This variability has mainly been attributed to the absence of precipitation and active photochemical formation under prevailing summer conditions in Mediterranean region (Mihalopoulos et al., 1997;Bardouki et al., 2003;Koçak et al., 2004b).

15
In general, PO 3− 4 and Si diss showed higher concentrations in the transition periods due to dust transport from arid desert regions (e.g. North Africa and Middle East/Arabian Peninsula). It has been demonstrated that the pH of Western Mediterranean rains is strongly affected by the type of material scavenged from the atmosphere (Loÿe-Pilot et al., 1986). For instance, rain samples associated with air masses from North Africa and 20 which had a red "mineral dust" had pH values as high as 7 as a result of the dissolution of calcium carbonate originated from dust. The distribution of the pH at Erdemli indicated that the largest fraction ∼70% of all events had a pH greater than 5.6 whereas acidic rain events (pH<5.6; Guerzoni et al., 1997)

Influence of airflow on nutrients
During the application of cluster analysis daily air mass back trajectories (n>3100) for 1 km altitude were used covering the whole sampling period (1999)(2000)(2001)(2002)(2003)(2004)(2005)(2006)(2007). First two clusters (Cluster 1 and 2; EU) shows north-westerly air flows: The first cluster includes trajectories with high wind speeds (long fetch) passing through Europe and accounting 20 for 2.1% of the airflow whereas the second cluster denotes relatively slower air flow and contributing to 9.1% of the trajectories. The third and fourth clusters show short trajectories originating from the north-west (Cluster 3; NWT) and northern Turkey (Cluster 4; NT) and they represent 41.4% and 19.6% of the airflow, respectively. The fifth cluster represents trajectories traveling at high speeds, being maritime air masses from 25 the western Mediterranean Sea, representing 7.1% of the airflow (hereafter MEDS).

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Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Air masses originating from the Middle East/Arabian Peninsula (Cluster 6; MEAP) and Eastern Saharan (Cluster 7: SAH) represent 10.1% and 10.6% of the trajectories. The Kruskal-Wallis (K-W) test was applied to test for the presence of significant differences in nutrient concentrations. Consequently, if the nutrient concentrations are considered for each of the six air flow categories (Table 3) the following general obser-5 vations might be made: (a) The K-W test showed that there was a significant difference in the concentrations of PO 3− 4 and Si diss (p<0.01). PO 3− 4 and Si diss concentrations for aerosol and rain samples were found to be higher in the SAH and MEAP than those observed for remaining air flows. For instance, mean concentrations of PO 3− 4 and Si diss for 10 aerosol (rain) were found approximately 1.5 (1.6) and 3 (2) times higher than remaining air flows, respectively. These two air flows are mainly affected by crustal aerosol population associated with dust events originating from North Africa and Middle East/Arabian arid regions occurring particularly during the transitional period. 15 (b) The K-W test indicated that there was a significant difference in the concentrations of NO − 3 (p<0.01). Aerosol nitrate concentrations were found to be lower when air flow origination from Europe (EU) and Mediterranean Sea (MEDS) whereas concentrations for the remaining air masses were found to be comparable. For aerosol ammonium concentrations were found statistically higher when air flows 20 originating from Turkey (NWT and NT) and this might be mainly attributed to intense usage of ammonium containing fertilizers (Koçak et al., 2004b). Rainwater weighted mean values of nitrate and ammonium were found approximately two times lower when air flow originated from Mediterranean Sea than those observed for remaining air flows. It can be suggested that relatively cleaner air masses as-

Comparison between sea-water and pure-water solubility of nutrients
There are few studies which have directly compared the dissolution of nutrients in seawater and pure-water. For instance, Markaki et al. (2003) compared sea-water (SW) and pure-water (PW) solubility of P after extracting samples from Finokalia for 45 min. Results from the comparison did not reveal any statistical difference for solubility of P in 5 sea-water and pure-water (slope = 0.99, R 2 =0.80). Similarly, Chen et al. (2006) studied the dissolution of PO 3− 4 , NO − 3 and NH + 4 in sea-water and pure-water, after extracting aerosol samples from Gulf of Aqaba for 30 min. Dissolution of NO − 3 and NH + 4 was found to be statistically not different while PO 3− 4 was found to be 11% lower in sea-water than those observed for pure-water. were found to 43% and 67% lower than those for pure-water (0.31 and 3.48 nmol m −3 ), respectively. This difference might be attributed to pH and ionic strength of sea water and association of phosphate (Chen et al., 2006), silicate aerosols with less soluble compounds (such as calcium phosphate, kaolinite, opal and quartz) and origin of the aerosol species (Koçak et al., 2007a;Baker et al., 2007). 20 In order to assess influence of the origin of the aerosol species, air mass back trajectories were simply classified into three categories namely Turkey (T: NT+NWT) and Europe (E) and Southerly (S: SAH+MEAP) flows. Mean concentrations of PO 3− 4 and Si diss in pure-water and sea-water for the three air flow categories are presented in Table 4. As expected, highest concentrations of PO 3− 4 and Si diss for pure-water and 25 sea-water were found to be associated with Southerly air flow, being 1.5 to 3 times higher than those observed for air flow from Europe and Turkey. The SW/PW (%) ratio for PO 3− 4 and Si diss showed values decreasing in the order E (80%)>T (57%)>S (48%) and T (48%)>S∼E (25%), respectively. Observed difference for PO 3− 4 might be attributed to higher anthropogenic character of the aerosol particles originating from Europe and Turkey compare to arid/semi-arid source regions. On the other hand, highest Si solubility were identified in air masses originating from Turkey, two time higher than 5 those calculated for remaining air flows. It is possible that local and/or region crustal dust particles have a different solubility character compared to European and Southerly crustal material. Further studies (such as solid state speciation) are required to investigate the solubility of Si originating from different crustal materials.
To test the influence of pH on PO spectively. In addition to pH observed solubility difference of PO 3− 4 for sea-water and pure-water might be affected by ionic strength.
NO − 3 and NH + 4 : Fig. 4b exhibits concentrations of NO − 3 and NH + 4 in pure and sea water. The mean concentrations of NO − 3 and NH + 4 (63.2 and 115.7 nmol m −3 ) in sea-water were found to be similar to values obtained for pure-water (63.9 and 111.9 nmol m −3 ). 25 Unlike PO 3− 4 and Si diss there were no statistical differences for nitrate and ammonium solubilities in pure and sea water. Therefore, obtained results for nitrate and ammonium implies that sea water does not influence the solubilites of these nutrients considering 5095 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | high pH and ionic strength of sea water. This peculiarity suggests that aerosol nitrate and ammonium are almost exclusively associated with highly soluble chemical forms such as NH 4 NO 3 , Ca(NO 3 ) 2 , NaNO 3 (NH 4 ) 2 SO 4 and NH 4 HSO 4 (Bardouki et al., 2003;Koçak et al., 2007b).

Atmospheric nutrient fluxes
Dry deposition of the particles is size dependent; therefore, 20 samples were collected by stack filter unit in two size fraction namely coarse (10-2.5 µm; <d<2.5 µm) and fine (d<2.5 µm) (for more details see Koçak et al., 2007c). Water-soluble PO 3− 4 , NO − 3 and Si diss were associated predominantly with coarse particles (>75%) whereas NH + 4 was 10 mainly found in the fine mode (>97%). An Approach adopted by Spokes et al. (2001), after Ottley and Harrison (1993) were used to estimate the settling velocities of nutrients. The V d 's of nutrients for the current study was based on assumption of V d 's are 0.1 cm s −1 and 2.0 cm s −1 for fine and coarse particles (Duce et al., 1991). Settling velocities of nutrient for Eastern and Western Mediterranean are presented in Table   15 5. Generally the V d 's value of 2 was applied to estimate dry deposition of PO 3− 4 in the Eastern Mediterranean. Migon et al. (2001) applied settling velocity values between 0.1 and 0.5 cm s −1 for dry deposition fluxes of P in the Western Mediterranean since 90% of the P was found to be associated with anthropogenic particles.
V d values between 1 to 2 and 0.1 to 0.6 were applied to calculate the dry deposition 20 fluxes of NO − 3 and NH + 4 in the Mediterranean, respectively. Nitrate at Erdemli and Finokalia sites were mainly associated (>70%) with the coarse fraction due to reactions with alkaline sea salt and dust particles, whilst ammonium was almost exclusively found in fine fraction in the form of (NH 4 )HSO 4 (Bardouki et al., 2003 andKoçak et al., 2007b). Based on our knowledge, there is no reported V d value for Si diss in the literature for the 25 Mediterranean region. Estimated mean V d value of 1.59 cm s −1 would be logical for Si diss since it was found to be associated mainly in coarse fractions and predominantly originated from crustal material. However, it should be noted that the settling velocities used in the present study will still be a sources of uncertainty in the dry deposition calculations and the estimation might be subject to a bias of a factor of two (Duce et al., 1991;Herut et al., 2002). The atmospheric dry and wet deposition fluxes calculated for each nutrient are pre-5 sented in Table 6. The dry deposition flux of PO 3− 4 (0.35 mmol m −2 yr −1 ) was found to be comparable with the wet deposition flux (0.34 mmol m −2 yr −1 ). Whereas the Si diss and NH + 4 fluxes were found to be dominated by wet deposition (0.92 and 23 mmol m −2 yr −1 ) with dry deposition contributed amounting to 35% (0.51 mmol m −2 yr −1 ) and 40% (15 mmol m −2 yr −1 ) of their total deposition, respectively. In contrast dry deposition 10 accounted for 83% (103 mmol m −2 yr −1 ) of the total nitrate flux. In addition, fluxes of nitrate and ammonium via wet deposition were found to be similar whilst dry deposition flux of nitrate was an order of magnitude higher than those for ammonium owning to differences in their particle sizes and hence settling velocities.

Comparison between atmospheric and riverine nutrient fluxes
15 Table 7 shows discharge weighted mean nutrient concentrations and discharges for studied Rivers. Annual mean water discharge for Seyhan, Ceyhan, Göksu, Berdan and Lamas were found to be 168, 144, 45, 6 and 3 m 3 s −1 , respectively. Discharges of Rivers show similar seasonality with highest values during spring. Within the annual period three seasons were defined; winter, transitional, and summer. The winter period included the months, December, January, and February, whereas the transitional season included the months March, April, and May. The summer season included the months June, July, August and September. On the basis of annual and seasonal atmospheric and riverine inputs (see Table 8) the following 5 general observation might be made: (a) Seyhan and Ceyhan Rivers were found to be main fresh water sources and more than 85% of the PO 3− 4 , Si diss , NO − 3 and NH + 4 (DIN as well) originated from these two rivers. In addition, the contribution made by the Göksü River was 10,11, , Si diss , NO − 3 and NH + 4 fluxes, respectively. Although, ammonium 10 inputs from rivers showed substantial contribution (15%), nitrate inputs were the primary component of the DIN pool (85%) to the Northern Levantine Basin.
(b) Seasonal riverine inputs of nutrients exhibited a decrease in values in the order of Transitional > Summer > Winter. During the transition period nutrient inputs were found to be two to five times higher than those calculated for winter and summer, 15 respectively. This of course is not unexpected owing to the higher discharges of rivers in transition period.
(c) Dry deposition inputs of PO 3− 4 and Si diss in the transition period were 1.2 to 1.6 times larger than those observed during the winter and summer. NO − 3 and NH + 4 dry deposition inputs were found comparable for the transition period and 20 summer, whilst the lowest input was observed in winter. During the winter period wet (P=357 mm) deposition inputs of nutrients were 1.2 to 2 times higher than those calculated for the transition period (P =133 mm) mainly due to the higher amount of precipitation. In winter, with the exception of nitrate, nutrient inputs were dominated by wet deposition compared to dry deposition. For example, in-25 puts of PO 3− 4 , Si diss and NH + 4 via wet deposition were found to be 2 to 3 times larger than their inputs via dry deposition. In addition, inputs of nutrients were exclusively found to be originated from dry deposition in summer due to the lack of precipitation.
(d) Comparison of the atmospheric and riverine fluxes (annual and seasonal) reveals that inorganic nitrogen species (DIN = NO − 3 +NH + 4 ) fluxes to NLB were dominated by the atmospheric pathway with a mean contribution being more than 90%. 5 Riverine phosphate flux (36%) had a substantial contribution to the phosphate pool in the NLB, however the atmosphere was found to be the main source to the surface waters with a mean contribution of 64%. Unlike inorganic nitrogen and phosphate, the NBL Si pool was almost exclusively dominated by riverine fluxes (90%) and only 10% of the Si was attributed to atmospheric source. 10 (f) Riverine molar N/P ratios ranged from 18 to 279 with a mean value of 28, in contrast the molar Si/N ratios were found to range from 0.8 to 1.7, with a mean value of 1.3. Obtained riverine N/P and Si/N ratios suggested that riverine sources in the region are deficient in phosphate compare to DIN and Si. Atmospheric (dry and wet) molar mean N/P ratios were found to be order of magnitude higher than for-15 mer ratio whereas riverine Si/N ratio was 100 times greater than those observed for atmospheric inputs. It appears that both sources were deficient in phosphorus compared to nitrogen. In other words, the Northeastern Levantine Basin of the Mediterranean Sea receives excessive amounts of DIN; more than is required by autotrophic organisms. Considering N/P ratio it might be suggested that un-20 balanced phosphorus and nitrogen inputs may provoke even more phosphorus deficiency in NLB. Although Si inputs have no effect on phosphorus limitation, total Si/N ratio suggests that Si deficiency relative to nitrogen might cause a switch from diatom dominated phytoplankton population to non-siliceous communities particularly at coastal areas where riverine inputs limited. 25

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Conclusions
In this study, factors controlling nutrient composition in aerosol and rainwater, differences in sea-water and pure-water solubilities of nutrients and atmospheric and riverine nutrient inputs for Northeastern Levantine Basin of the Eastern Mediterranean have been investigated. 5 Nutrient concentrations in aerosol and rainwater samples exhibited substantial temporal variability and their values changed up to an order of magnitude from day to day. PO 3− 4 and Si diss in aerosol and rainwater exhibited higher and larger variations during the transitional period since their concentrations are heavily affected by sporadic dust events originating from North Africa and Middle East/Arabian Peninsula. Their mean 10 concentrations were at least 1.5 times higher during airflows originating from the Saharan and Middle East/Arabian Peninsula than those observed for the remaining air flows. Deficiency of alkaline material were found to be the main reason of acidic rain events whereas, alkaline rain events were observed when air mass back trajectories originated from arid and semi-arid desert regions. Aerosol NO European (80%) and Turkey (57%) compare to Southerly (48%) air flows due to higher anthropogenic character of the aerosol particles originating from former air flows. The highest Si solubility was identified in air masses flowing from Turkey and attributed to different solubility character crustal materials. Solubility of Si was mainly constrained by the pH of the pure-water whereas, PO 3− 4 solubility was found to be less effected by 25 pH of the pure-water.
Dry and wet deposition fluxes were found comparable for PO 3− 4 . Si diss and NH + a main source of nitrate flux (∼80%). Seyhan and Ceyhan were found to be main fresh water sources of the region with nutrient contributions more than 85%. Riverine DIN pool was found to be dominated by nitrate input (75%). Comparison of the atmospheric and riverine fluxes demonstrated that DIN and PO 3− 4 fluxes to NLB were dominated by atmospheric pathway (∼90% and ∼60%). However, the Si pool in the NLB was almost 5 exclusively originated from riverine runoff (∼90%). Considering molar N/P ratios from the atmosphere (236) and riverine (22) sources it is clear that the NLB of the Eastern Mediterranean Sea receives excessive amounts of DIN; more than is required by autotrophic organisms and this unbalanced P and N inputs may provoke even more phosphorus deficiency. Atmospheric and total molar Si/N ratio suggested that Si limi-10 tation relative to N and it might cause a switch from diatom dominated communities to non-siliceous populations particularly at coastal areas where riverine input is limited.
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