Examination of reactive phosphate fluxes in an eutrophicated coastal area

PubMed ID: 21713465Reactive phosphate (RP) fluxes over sediment in an eutrophic bay were obtained under different conditions. The results were assessed together with water column, sediment solid, and liquid-phase parameters. The RP fluxes ranged from 0 to 1,300 µgatP × m -2d -1 day depending on the sediment site and other variables. At stations with relatively high net RP fluxes, the clay fraction was >3% and disproportionate with salinity, which explained why the RP effluxes decreased by inhibition of the organic coating on particulate matter with increased SO 4 -2 ions and good competition of RP anions with SO 4 -2. The RP flux in Fe/RP ratios >2 in surface water decreased to approach a minimum asymptotically, which was thus defined with a hyperbolic curve to determine the maximum rate of the RP flux (JRP). The [RPporewater]initial/[RPambient] initial ratios were suggested to govern the net RP flux regionally, so the critical value where the RP flux turns positive could indicate eutrophication with Chl-a values <500 µg/g. So, this study investigated the phosphate fluxes between sediment and water column and determined the factors influencing the RP fluxes in the inner bay of Izmir. © Springer Science+Business Media B.V. 2011

Geochemical and statistical approach for assessing heavy metal accumulation in the Southern Black Sea sediments [Güney Karadeniz Sedimentlerinde agi{dotless}r metal birikiminin jeokimyasal ve İstatistiksel yönden degerlendirilmesi]

The assessment of heavy metal pollution in the sediment of the Southern Black Sea requires knowledge of pre-anthropogenic metal concentrations. The effects of anthropogenic activities on the accumulation of heavy metals, elements, and other compounds in the sediment were examined. The objective of this study is to investigate the levels of metals, organic carbon, carbonate, and chlorophyll degradation products in order to assess the extent of environmental pollution and to discuss the origin of these contaminants in the sediments of the Southern Black Sea. The heavy metals, metalloid, and elements were assessed by factor analysis. The results of the factor analysis have shown positive and/or negative correlations among Mo, Cu, Pb, Zn, Ni, Co, Mn, Fe, As, Sr, Cd, Sb, Bi, V, Ca, P, Cr, Mg, Ba, Ti, Zr, Sn, S, Y, Hg, organic carbon, carbonate, and chlorophyll degradation products and has indicated that heavy metals in the sediments of the Southern Black Sea have different anthropogenic and natural sources. Also, a sediment pollution assessment was carried out using the enrichment factor and geoaccumulation index. The Igeo accumulation index shows that the surface sediment of the Southern Black Sea is not contaminated with respect to Cu, Pb, Zn, Mn, Fe, As, Sr, Bi, V, Cr, Mg, Zr, Y, Sb, Sn, and Ni, but is moderately contaminated with respect to Hg and Cd, and moderately to strongly polluted with respect to S and Mo. Despite total sedimentary concentrations above their pre-industrial background levels, Igeo shows that the surface sediments are unpolluted with respect to P, Ba, and Ti. The 14C age determinations have shown that surface sediments in stations KD2A and KD5A belong to AD 130-350 and AD 1000 respectively, indicating undersea landslides and turbidity fluxes in the Southern Black Sea are not rare because of the sharp slope in the topography of this region and high bottom transportation in certain places. The requirement of age determination is of great importance to assess the extent of the anthropogenic contribution to pollution

Nutrient dynamics between sediment and overlying water in the inner part of Izmir Bay, Eastern Aegean

PubMed ID: 17926138The nutrient flux experiments for the sediments of Inner Izmir Bay were performed for the first time during January 2004-August 2004. The flux rates ranged between -27.9 and 358.2 µg at N m-2 day-1 for NH4+, -47.88 and 320.9 µg at N m-2 day-1 for NO2-, -62.96 and 121.3 µg at N m-2 day-1 for NO3-, -64.1 and 528 µg atP m-2 day-1 for reactive phosphate (RP) and between -168.44 and 284.19 µg at Si m-2 day-1 for reactive silicate (RSi). Negative values were obtained from core incubations in winter except for nitrite (flux from water to sediment). The positive flux in all the core incubations during spring and summer (except nitrite in August) at least revealed that the sediment might be partially anoxic and/or included H2S. The turnover times obtained from water column nutrient inventory and flux rates indicated that Si and NH4+ possessed a rapid cycle in water column. It was argued that NO3- would be more influenced by the removal processes within the sediment, therefore the water column would provide an additional contribution to the N limitation and the short turnover time of RP could rapidly supply RP to the water column. The continuous increase of pore water nutrient concentrations from January to August does not explain whether this nutrient reserve attains the next year with higher background levels or it is released back to environment at the end of autumn. © Springer Science+Business Media B.V. 2007

Effects of biogeochemical processes on spatial distribution of iron, manganese, reactive phosphates and nitrates in the Black Sea

###EgeUn###The aim of this study was to identify differences in the distribution of Mn (Manganese), Fe (Iron), NO3 - (Nitrates) and reactive phosphates (RP) in the water columns of the eastern and western basin of the Black Sea region. Accordingly, the selected sampling area covered offshore waters from west to east including Istanbul (station KD01), Ereğli (KD2A, 2B, and 2C), Inebolu (KD03), Sinop (KD04), Ordu (KD5A, 5B, 5C) and Trabzon (KD06). The B and C codes for stations 2 and 5 indicate that the stations are towards the basin centers of the Black Sea. At all the stations of the study area, the Mn values were below the limit of detection (5 µg/L) up to 100 m depth. The Mn concentration reached maximum at 200 m depth of stations KD2B, KD5B, KD5C and KD06. This situation could be due to mobilization of Mn from the continental slope sediments (Mn pump). Also, it was observed that relatively high values of nitrates were associated with low RP concentration in the deep waters of the eastern basin. If nitrate is present in the suboxic zone, bacteria prefers nitrate and reduce it as N2 (g). Then, the FeOOH?RP (ferric oxyhydroxides?reactive phosphate) particulates sink into deeper layers without reduction by bacteria and cause the upper layers to become poor in phosphates. In case of low values of nitrate in suboxic zone, FeOOH?RP particulates are reduced to dissolved Fe+2 by the bacteria. Significantly higher levels of nitrate concentrations were observed at station KD06. In conclusion, the eastern basin center is characterized by relatively higher nitrate concentrations in water columns compared to those in the western basin center. Therefore, the eastern basin contains lower RP concentrations and this limits the phytoplankton growth. It is concluded that where nitrate concentrations are higher than 2 µM, the bacteria preferred to reduce the nitrates. On the other hand, particulate Fe can be reduced chemically with H2S in the deeper layers, where there is lower nitrate concentration. © 2019, National Institute of Science Communication and Information Resources (NISCAIR). All rights reserved.TUBITAK-CAYDAG-107Y182This research was funded by the Technical and Scientific Research Council of Turkey (TUBITAK-CAYDAG-107Y182). In addition, this text was edited and proof-read by Tim J Egginton. -

Growth kinetics of Cylindrotheca closterium (Ehrenberg) Reimann and Lewin isolated from aegean sea coastal water (Izmir Bay/Türkiye)

The aim of this research was to reveal the detailed information on growth kinetics of Cylindrotheca closterium (Ehrenberg) Remann and Lewin from the results of nutrient enrichment experiments under batch culture conditions. C. closterium was isolated from Izmir Bay. The present study were performed under optimum light and nutrient saturated conditions except the nutrient, which was investigated. An exponential growth rate was obtained by using each growth curves. The exponential growth rates were plotted against corresponding each nutrient concentrations. The parameters of Monod curve were calculated with the least square method by using transformations to linear form. Half Saturation Constant (Ks) was calculated for only silicate as 9.58 µM maximum growth rate were found as 4.32 day -1 . © 2006 Asian Network for Scientific Information

TOXICITY-CHEMISTRY RELATIONSHIPS IN SEDIMENTS COLLECTED FROM BLACK SEA

Abstract This research investigated the spatial distribution of chemical contamination and toxicity of marine surfacial sediments collected from six sites along the Turkish coast in Black Sea. Sediment toxicity to sea urchin (Paracentrotus lividus) embryonic development was evaluated with whole sediment specimens. Concurrently, sediment samples were analyzed for their chemical characterisation to evaluate toxicity data

Gulluk lagoon (Aegean Sea, Turkey) ecosystems [Gulluk lagunu (Ege Denizi, Turkiye) ekosistemi]

Gulluk Lagoon has an area of 2500 decares with a depth of 0.5-5.0 m and is connected to Gulluk Bay by a channel. In this study, samplings of phytoplankton and benthos were taken and physico-chemical parameters were recorded monthly during 1993 at 5 stations. The temperature reached a minimum of 10.42°C in January and a maximum of 26.9°C in July, with a mean annual temperature of 19.53±1.511. The salinity in the lagoon ranged from 7.48‰ to 13.92‰ in January and March, respectively with a mean annual salinity of 10.65 ± 0.555. Dissolved oxygen in the sub-surface (0.25 m) water was 5.56 mg 1-1 in June and 9.06 mg 1-1 in February, with an annual mean 7.31 ± 0.331. The Secchi-disk depth was 1.12 m in May and 2.40 m in October. Nutrient measurements revealed moderately high levels of ammonia (ranging from 4.39 to 29.70 µg-at 1-1), low nitrate (0.81 to 17.87 µg-at 1-1), nitrite (0.19 to 1.35 µg-at 1-1), phosphate (0.01 to 0.45 µg-at 1-1), and silicon (0.26 to 6.00 µg-at 1-1). Chlorophyll a distribution generally indicated that productivity was highest in May (21.49 mg 1-1) and lowest in September (0.77 mg 1-1). Melosira moniliformis was the predominant phytoplankton species. All of the stations were characterized by high species diversity. Identification of the benthic species was carried out with 60 samples collected from 5 stations in a of one year period. As result 68 benthi species belonging to 7 taxa (Nemertina, Polychaeta, Oligochaeta, Crustacea, Mollusca, Insecta, Echinodermata) were identified. The polychaetae were numerically dominated by Notomastus latericeus (3737 individuals), followed by Hediste diversicolor (1524 individuals), and Spionidae (sp) (1361 individuals). Economically important fish species in Gulluk Lagoon consist of mullets (Mugil cephalus, M. capito, Chelon labrosus, Liza saliens), Sparus aurata (gilthead sea bream), Dicentrarchus labrax (sea bass), Solea solea (sole), Anguilla anguilla (eel) and Cyprinus carpio (carp), with an annuall yield varying from 10 to 69 tonnes