The 210Po and 210Pb levels in surface sediment samples in the Izmir Bay (Aegean Sea-Turkey)

Bottom sediments reflect in general the relative contamination of a sea area. Therefore, a great deal of monitoring work has been dedicated to the analysis of bottom sediments. Izmir Bay is a very important pollution centre in Turkish Aegean coast region due to a densely populated community, industrial complex and maritime transportation, and there are many streams flowing into the bay that pass through a number of industrial and agricultural areas. It had received the majority of domestic and industrial wastewaters until the wastewater treatment plant was constructed. It is well known that sediments play an important role as reservoirs of a fraction of the pollution in aquatic systems. Therefore, sediment samples were collected monthly from three stations which are located in the inner part of the bay during the period January to December 2003. Temporal variations and seasonal changes on their ²¹⁰Po and ²¹⁰Pb contents were examined, and the activity concentrations of ²¹⁰Po and ²¹⁰Pb were found to vary from 43±6 to 132±12 and 27±5 to 91±9 Bq kg^???1 dry wt, respectively. The highest values of those natural radionuclides were measured at Kar??yaka Station because of the current systems of the bay. Seasonally, the ²¹⁰Pb levels were found to increase during the winter time for all the stations.     

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

In this article a concept is described in order to predict and map the occurrence of benthic communities within and near the German Exclusive Economic Zone (EEZ) of the North Sea. The approach consists of two work steps: (1) geostatistical analysis of abiotic measurement data and (2) calculation of benthic provinces by means of Classification and Regression Trees (CART) and GIS-techniques. From bottom water measurements on salinity, temperature, silicate and nutrients as well as from punctual data on grain size ranges (0–20, 20–63, 63–2,000 μ) raster maps were calculated by use of geostatistical methods. At first the autocorrelation structure was examined and modelled with help of variogram analysis. The resulting variogram models were then used to calculate raster maps by applying ordinary kriging procedures. After intersecting these raster maps with punctual data on eight benthic communities a decision tree was derived to predict the occurrence of these communities within the study area. Since such a CART tree corresponds to a hierarchically ordered set of decision rules it was applied to the geostatistically estimated raster data to predict benthic habitats within and near the EEZ.     

Spatio-temporal variations of organic carbon and chlorophyll degradation products in the surficial sediments of Izmir Bay (Aegean Sea/Turkey)

The aim of this research is to determine the effects of Izmir Big Channel Waste Water Treatment Project on the sediment quality of Izmir Bay. Wastewater treatment improves the water quality. However, sediment does not respond to this treatment as fast as water column. Monitoring of bottom water and sediment quality is necessary for identification of the recovery of the whole ecosystem. For this purpose, bottom water and sediment samples were collected from three stations which are located in the middle and inner parts of the Izmir Bay on a monthly basis between January 2003 and December 2003. Values measured at stations ranged between; 0.54-12.82 microg/L for chlorophyll-a, 0.09-9.32 microg/L for phaeopigment, 0.05-1.91 mg/L for particulate organic carbon in bottom waters, 11.88-100.29 microg/g for chlorophyll degradation products and 1.12-5.39% for organic carbon in sediment samples. In conclusion, it was found that grazing activity explained carbon variations in sediment at station 2, but at station 1 and station 3 carbon variations in sediment were not related to autochthonous biological processes.     

The relationship between zooplankton community and environmental factors of Ghrib Dam in Algeria

Environmental Science and Pollution Research - The effect of environmental factors on zooplankton diversity, abundance, and distribution in the Ghrib Dam water body was investigated for...     

Examination of reactive phosphate fluxes in an eutrophicated coastal area

Reactive 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 SO₄ ⁻² ions and good competition of RP anions with SO₄ ⁻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 (J_RP). The [RP_porewater]_initial/[RP_ambient] _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.