Radionuclide Analysis on Bamboos following the Fukushima Nuclear Accident

In response to contamination from the recent Fukushima nuclear accident, we conducted radionuclide analysis on bamboos sampled from six sites within a 25 to 980 km radius of the Fukushima Daiichi nuclear power plant. Maximum activity concentrations of radiocesium 134Cs and 137Cs in samples from Fukushima city, 65 km away from the Fukushima Daiichi plant, were in excess of 71 and 79 kBq/kg, dry weight (DW), respectively. In Kashiwa city, 195 km away from the Fukushima Daiichi, the sample concentrations were in excess of 3.4 and 4.3 kBq/kg DW, respectively. In Toyohashi city, 440 km away from the Fukushima Daiichi, the concentrations were below the measurable limits of up to 4.5 Bq/kg DW. In the radiocesium contaminated samples, the radiocesium activity was higher in mature and fallen leaves than in young leaves, branches and culms

Osiguranje kvalitete u gama-spektrometriji morskih sedimenata

This article brings the results of a method for quality assurance in gamma-ray spectrometry of seabed sediments. Sediments were collected in selected locations of the South and Middle Adriatic Sea using grab and corer tools. Using our own experimental design, we determined the self-attenuation factors of selected samples. The article also discusses sources of uncertainty in gamma-ray spectrometry, which is another important issue in quality assurance. Together with self-attenuation correction sources of uncertainty are used to calculate the activity concentration for a given sample. The presented procedure demonstrates how a gamma-ray spectrometry experiment should be approached in order to properly account for errors and uncertainties specifi c to a particular sample.U ovom radu predstavljena je metoda za osiguranje kvalitete u gama-spektrometriji sedimenata s morskog dna, skupljenih s pomoću grabila i gravitacijske udarne sonde iz odabranih područja srednjeg i južnog dijela Jadranskog mora. Uzorci za gama-spektrometriju pripremljeni su prema standardnim metodama. Eksperimentalnom metodom razvijenom u našem laboratoriju odredili smo samoatenuacijske koeficijente odabranih uzoraka. Također raspravljamo o izvorima nesigurnosti u gama-spektrometriji kao važnom čimbeniku u osiguranju kvalitete. Zajedno sa samoatenuacijskim koeficijenima, ostali izvori nesigurnosti nužni su za dobivanje potpunog izračuna koncentracije aktivnosti za određeni uzorak. Ovdje predstavljena metoda prikazuje način pristupanja gama-spektrometrijskomu mjerenju, kako bismo pravilno objasnili nesigurnosti i korekcije koje potječu iz jedinstvenosti svakog uzorka

Increase in African dust flux at the onset of commercial agriculture in the Sahel region

The Sahara Desert is the largest source of mineral dust in the world1. Emissions of African dust increased sharply in the early 1970s (ref. 2), a change that has been attributed mainly to drought in the Sahara/Sahel region2 caused by changes in the global distribution of sea surface temperature3,4. The human contribution to land degradation and dust mobilization in this region remains poorly understood5-11, owing to the paucity of data that would allow the identification of long-term trends in desertification12. Direct measurements of airborne African dust concentrations only became available in the mid-1960s from a station on Barbados2 and subsequently from satellite imagery since the late 1970s: they do not cover the onset of commercial agriculture in the Sahel region ∼170 years ago11,13,14. Here we construct a 3,200-year record of dust deposition off northwest Africa by investigating the chemistry and grain-size distribution of terrigenous sediments deposited at a marine site located directly under the West African dust plume. With the help of our dust record and a proxy record for West African precipitation15 we find that, on the century scale, dust deposition is related to precipitation in tropical West Africa until the seventeenth century. At the beginning of the nineteenth century, a sharp increase in dust deposition parallels the advent of commercial agriculture in the Sahel region. Our findings suggest that human-induced dust emissions from the Sahel region have contributed to the atmospheric dust load for about 200 years