Development of a Novel DGT Passive Sampler for Measuring Cs-137 In Situ in Marine Environments.

Cs-137 is the most released fission product in the marine environment. It is important to develop a robust in situ technique for its monitoring. The existing diffusive gradients in thin films (DGT) passive sampling techniques for in situ measurement of Cs+ have some limitations due to the ion competition and high pH of seawater. A new DGT sampler based on potassium zinc hexacyanoferrate (KZFCN) as a binding layer has been developed and investigated for the measurement of the time-weighted average concentration of Cs-137 in seawater. This binding layer proved a working pH range of 2-12 and an ionic strength of up to 0.75 M. Two types of diffusive gels were tested and agarose gel (AGE) was chosen for the KZFCN-DGT sampler. The measured Cs+ diffusion coefficient (1.71 × 10-5 cm2·s-1 at 25 °C) in the diffusive gel from seawater was within the expected range published in the literature. The measured concentrations of Cs-137 in seawater obtained by laboratory deployments of the KZFCN-DGT samplers for up to 4 weeks showed good precision (RSD = 13%) and accuracy (relative error = 8.5%) values. The performance test results demonstrated that the KZFCN-DGT sampler is suitable for long-term monitoring of Cs-137 in seawater due to its high capacity and resistance to ion competition and high pH.

Datasets of trace elements in shallow marine sediments along the Egyptian shore of the Mediterranean and Red Seas.

A comprehensive dataset concerning the geochemical composition of unconsolidated shallow marine sediments collected along coastal areas of Northern Nile Delta and Egyptian sector of Red Seas is presented. The sediment samples were analyzed using instrumental neutron activation analysis (INAA) in Frank Laboratory of Neutron Physics FLNP - Joint Institute for Nuclear Research JINR and inductively coupled plasma - mass spectrometer (ICP-MS) in Actlabs - Canada. Data thus collected supported the research published and published articles conducted to evaluate the geochemistry of shallow marine sediments covering mentioned areas [1], [2], [3]. The mass fractions of 43 and 39 trace elements and oxides were determined in the unconsolidated marine sediments of Northern Nile Delta and Egyptian sector of Red Sea, respectively. Final data were expressed in wt.% and mg/kg for major and trace elements, respectively. Different statistical tests such as Shapiro-Wilk, Anderson-Darling, Lilliefors and Jarque-Bera were used to check the normality of data. At the same time, distribution patterns of the rare earth elements (lanthanides) as well as Eu and Ce anomalies were investigated. Quality control of analytical measurements was carried out using certified reference materials. Different univariate and multivariate as well as graphic statistical analyses were performed. Presented data were used in identifying, by means of more pollution indices, the degree of local contamination. The present dataset could be further used in establishing geochemical background for the studied areas and tracking eventually changes posing significant threat to environment and humans.

Characterization of major and trace elements in coastal sediments along the Egyptian Mediterranean Sea.

The present study was conducted to provide a comprehensive picture of marine sediment characterization in terms of geochemistry and the extent of pollution. A total of 99 surface coastal sediments were collected from coastal areas along with the Egyptian Mediterranean Sea. The samples were analyzed by neutron activation analysis (NAA) and the mass fractions in mg/kg of 39 trace elements were determined. The normalized mass fractions show significant amounts of Cl (26.4%), Sn (12%), Zr (7.3%), Hf (5.9%), Ti (4.7%), Cr (4.2%), Ca (3.4%), Si (3.1%), Sr (2.9%). The mass fractions of the rare earth elements REEs (La, Ce, Nd, Sm, Eu, Tb, Dy, Yb, and Lu) are almost double compared to literature data. Principal component analysis PCA and positive matrix factorization PMF were used to decipher the sources of pollutions. Sediment quality was quantified using different pollution indices such as enrichment factor (EF), modified pollution index (MPI), pollution load index (PLI) and the new approach to calculate total pollution index (TPI). The results of the study recognized four locations with significant pollution, namely the coastal area along Al Manzalah Lake, the Nile River estuaries at Ras Elbar and its western coastal area, at the outlet of Elbrullus Lake, and finally the Abu Qir Bay. The obtained result can serve as a geochemical background of the sediments of the study coastal area, which allows following the quality of marine sediments along with the Egyptian Mediterranean Sea.