Occupational dosimetric assessment (inhalation pathway) from the application of phosphogypsum in agriculture in South West Spain

Phosphogypsum (PG) has been traditionally applied as Ca-amendment in saline marsh soils in SW Spain, where available PG has 710 ± 40 Bq kg−1 of 226Ra. This work assesses the potential radiological risk for farmers through 222Rn exhalation from PG-amended soils and by inhalation of PG-dust during its application. A three-year field experiment was conducted in a commercial farm involving two treatments: control and 25 t PG ha−1 with three replicates (each 0.5 ha plots). The 222Rn exhalation rate was positively correlated with potential evapotranspiration, which explained 67% of the variability. Statistically significant differences between the control and PG treatments were not found for 222Rn exhalation rates, and mean values were within the lowest quartile of the typical range for 222Rn exhalation from soils. Airborne dust samples were collected during the application of PG and sugar-beet sludge amendments. The highest PG-attributable 226Ra concentration in the dust samples was 3.3 × 102 μBq m−3, implying negligible dose increment for exposed workers.Junta de Andalucía IFAPA-C03

Phosphogypsum amendments and irrigation with acidulated water affect tomato nutrition in reclaimed marsh soils from SW Spain

Phosphogypsum (PG) is a by-product of the P fertilizer industry usually valorised as amendment for acidic and sodic soils. This work was aimed to study the effects of PG on nutrient uptake by industrial tomato plants in an originally sodic soil. A completely randomized experiment was performed involving two factors: (i) acidification with nitric acid (mimics cleaning techniques in drip irrigation), and (ii) PG rate (equivalents to 0, 20, 60, and 200 Mg ha–1). The highest PG rate resulted in an increased dry matter yield, which can be ascribed at least in part to an increased water use efficiency. PG decreased K, Mg and P concentrations in shoots, and P and Cu concentrations in fruits. At the highest rate, PG increased B concentration in shoots and total B content in the aerial parts of plants when acid was applied. The highest PG rate also increased Ca concentration in fruits, which can be considered positive in view of reducing the incidence of blossom end rot. The total content of Ni and Mo in aerial parts increased with PG, probably related to a decreased adsorption of these nutrients in soils. Acid application increased the concentration of all micronutrients in shoots and the concentration of Fe, Cu and B in fruits. In conclusion, PG promoted positive effects on B, Ni, Mo, and Ca nutrition, and some negative nutritional effects through antagonisms or affecting nutrient cycling in the soils, which however did not result in decreasing yields, even at a large dose which mimics the cumulative application during 20-30 years. Acid treatments resulted in improved micronutrient nutrition of tomato plant

Transfer of Cd, Pb, Ra and U from Phosphogypsum Amended Soils to Tomato Plants

About 170 million tons of phosphogypsum (PG) are annually generated worldwide as a by-product of phosphoric acid factories. Agricultural uses of PG could become the main sink for this waste, which usually contains significant radionuclide (from the 238U-series) and toxic metals concentrations. To study PG effects on pollutant uptake by crops, a completely randomised greenhouse experiment was carried out growing Lycopersicum esculentum Mill L. on a reclaimed marsh soil amended with three PG rates (treatments), corresponding to zero (control without PG application), one, three and ten times the typical PG rates used in SW Spain (20 Mg ha−1). The concentrations of Cd, Pb, U (by inductively coupled plasma mass spectroscopy) and 226Ra and 210Po (by γ-spectrometry and α-counting, respectively) were determined in soil, vegetal tissue and draining water. Cadmium concentrations in fruit increased with PG rates, reaching 44 ± 7 μg kg−1 formula weight with ten PG rates (being 50 μg kg−1 the maximum allowed concentration by EC 1881/2006 regulation). Cd transfer factors in non-edible parts were as high as 4.8 ± 0.5 (dry weight (d.w.)), two orders of magnitude higher than values found for lead, lead, uranium and radium concentrations in fruit remained below the corresponding detection limits—0.5 and 0.25 mg kg−1 and 0.6 mBq kg−1, respectively (in a d.w. basis). 238U (up to 7 μg kg−1 d.w.) and 210Po (up to 0.74 Bq kg−1 d.w.) could be measured in some fruit samples by α-spectrometry. Overall, the concentrations of these metals and radionuclides in the draining water accounted for less than 1% of the amount applied with PGJunta de Andalucía IFAPA-C03

Microwave-based digestion method for extraction of 127I and 129I from solid material for measurements by AMS and ICP-MS

This work presents a microwave-based digestion method followed by a radiochemical extraction procedure to extract iodine from environmental matrices that provides iodine in a form suitable for the measurement of 129I by AMS, with shorter preparation times, small sample sizes and higher automation than previous methods. Samples were digested by a microwave digestion method in closed vessels using HNO3 as oxidizing agent. Following chemical iodine extraction consisted in an organic compound extraction followed by an aqueous solution extraction and iodine precipitation. Prepared samples were used to measure 127I by ICP-MS and 129I by AMS. The method was validated by ICP-MS measuring 127I content in standard reference materials covering a wide variety of biological, soil and sediment matrices: 1547 Peach Leaves, 1537a Tomato Leaves, 1549 Non-Fat Milk Powder, 2704 Buffalo River Sediment, 2711 Montana Soil and 1648 Urban Particulate Matter from the National Institute of Standards and Technology, IAEA-375 Soil and IAEA SL-1 Lake Sediment from the International Atomic Energy Agency and 186 Pig Kidney from Community Bureau of Reference. The recoveries with respect to the reference values were about 90%. Iodine losses during chemical extraction could be due to its volatilization as HI or I2 in acid means. Accurate results for determination in certified materials and good recoveries.Ministerio de Ciencia y Tecnología FIS2008-01149Junta de Andalucía EXC/2005/RNM-41

Drain flow and related salt losses as affected by phosphogypsum amendment in reclaimed marsh soils from SW Spain

Phosphogypsum (PG), a by-product of the P industries, has been widely applied as an amendment to reduce Na saturation in soils. However, some concern arises due to its content of some metals and radionuclides. Thus, it is necessary to optimize the PG rates to avoid excessive accumulation of such pollutants in soil. To evaluate the effects of PG on drain flow and on the displacement of Na by Ca in soils, a three-year field experiment was conducted in a commercial farm located in a reclaimed marsh area from SW Spain. It involved two treatments (control — without PG — and 25 Mg ha−1 of PG, applied in April 2003 and again in September 2004), done in triplicate in 250 ×20 m plots, following a randomized block design. Drainage flows were monitored, and drain-water samples were analyzed for Na and Ca concentrations. The recorded hydrographs revealed unexpected high lateral flows of water within these soils. No statistically significant differences were found in drained volumes, nor in Na and Ca losses through drainage, between both treatments in each of the three growing seasons (Gossypium hirsutum L. in 2003 and 2005; Beta vulgaris L. in 2003–2004). Losses of Na and Ca in each irrigation event were linearly related to the drainage to irrigation volume ratio (p b 0.001); Ca, however, showed significantly different slopes for both treatments. Cation concentration, Na adsorption ratio (SAR), and electrical conductivity (EC) in the saturation extract of soil at different depths were significantly affected by PG and by the oscillation of saline water table during the experiment. The efficiency of PG in displacing Na by Ca was estimated to be about 30%, with the PG attributable changes in Ca and SAR also appearing in deeper soil layers and in adjacent control plots.Junta de Andalucía Proyecto IFAPA-C039Comisión Interministerial de Ciencia y Tecnología (CICYT) AGF97-1102-CO2-01Comisión Interministerial de Ciencia y Tecnología (CICYT) AGL2000-0303-P4-

Development of a recording water flow meter using ultrasonic measurement of water levels in a slotted U-pipe

The accurate measurement and recording of water flow rates is necessary in the perfor-mance of field experiments in irrigation, overland flow or drainage studies. There is a lack of reliable, low-cost commercial flow meters that are able to operate under ‘‘non-pressure’’ conditions. This work describes a simply designed recording meter based on the ultrasonic measurement of water levels in a slotted U-pipe. A three-width slot design allows accurate flow measurements in the range 0–3 L s 1 and the ultrasonic probe allows for high resolu-tion measurements. Six replications of the instrument have been performed and calibrated (water levels against water flows) in laboratory experiments. After that, they have been successfully tested under field conditions, monitoring water flows which were recorded by using a data logger in the drainage system of an experimental farm in southwest Spain during several irrigation episodes in summer 2005.Junta de Andalucía IFAPA-C03-02

First-order ion-optics calculations for an Accelerator Mass Spectrometry system using SRIM and S3M

In this paper, we describe the transport of a simulated beam, created with the S 3M beam generation module, along the real beam line of the Accelerator Mass Spectrometry (AMS) facility located at Centro Nacional de Aceleradores (CNA, Seville, Spain). The beam transport through the optical system was determined using the transfer-matrix method, which can easily calculate the beam envelopes without having to track all individual particles, evaluating the ability of such systems and saving computation time. The beam size results given by S 3M were compared to the real beam size in three of the four image points that the system has (P1, P2 and P3), corresponding with the position of Faradays Cups where the 127I current was measured, obtaining a good agreement between them. This suggests that the first order approximation model is enough to simulate the optical behavior of the system. It is shown that the beam line has a focusing behavior, minimizing the beam size from ±3 mm at the exit of the ion source to ±1.09 mm at the detector's entrance window. Using the beam emittance diagram simulations, it is shown that when ions pass through the stripper, the angles of their trajectories are altered by scattering with the gas molecules and the geometrical emittance enlarges, according to Liouville's Theorem. The study presented in this work gives confidence and open new perspectives in simulations with S 3M in AMS facilities contributing to the understanding of their optical behavior. © 2012 Elsevier B.V. All rights reserved.This work has been financed through the projects FIS2008-01149 of the Spanish Ministry of Science and Technology, and EXC/2005/RNM-419 of the Junta de Andalucía.Peer Reviewe

The cumulative effect of three decades of phosphogypsum amendments in reclaimed marsh soils from SW Spain: 226Ra, 238U and Cd contents in soils and tomato fruit

Phosphogypsum (PG), a by-product of the phosphate fertiliser industries, has been applied as soil amendment to reduce Na saturation in soils, as in the reclaimed marsh area from SW Spain, where available PG has a typical fingerprint of 710 ± 40 Bq kg− 1 of 226Ra, 165 ± 15 Bq kg− 1 of 238U and 2.8 ± 0.4 mg kg− 1 of Cd. This work was focussed on the cumulative effects of PG amendments on the enrichment of these pollutants in cultivated soils and plants (Lycopersicum esculentum Mill L.) from the area studied, where PG has been applied since 1978 at recommended rates of 20–25 Mg ha− 1 every 2–3 years. A field experiment was conducted over three years to compare activity concentrations of 226Ra ( 214Pb) and 238U ( 234Th) in non-reclaimed soils, reclaimed soils with no additional PG application, and reclaimed soils with two additional PG applications. A non-significant effect of two PG amendments (in three years) was observed when compared with non-amended reclaimed plots. Nevertheless, a significant (p b 0.05) enrichment of 226Ra was observed in the surface horizon (0–30 cm) of reclaimed plots relative to deeper horizons and also when compared with the surface horizon of non reclaimed soil (p b 0.05), thereby revealing the cumulative effect of three decades of PG applications. Furthermore, the effect of a continuous application of PG was studied by analysing soils and tomato fruits from six commercial farms with different cumulative rates of PG applied. Cadmium concentrations in tomatoes, which were one order of magnitude higher than those found in tomatoes from other areas in South Spain, were positively correlated (r = 0.917⁎) with 226Ra-concentration in soils, which can be considered an accurate index of the cumulative PG rate of each farm.Junta de Andalucía IFAPA-C03

Anthropogenic 129I concentration and 129I/127I ratio in rainwater from Seville (Spain) in the period 2005–2008 as affected by airborne releases from Sellafield and La Hague facilities

129I is a very long-lived radionuclide (T1/2 = 15.7 × 106 years) that is present in the environment both because of natural and anthropogenic sources. In this work 129I concentration and 129I/129I ratio have been determined in rainwater samples collected at Seville (south-western Spain) during the period 2005–2008. Typical 129I concentration range from (0.26–8.86)×108 atoms/L, while 129I deposition are normally in the order of 107–108 atoms/m2d. Variability in the isotopic ratio 129I/129I indicates a range of (0.17–8.71) × 10−8. Temporal evolution of the 129I deposition seem to be related with the history of the 129I gaseous releases from the European reprocessing facilities at Sellafield and La Hague. The results obtained in this work are lower than the reported in previous works for the same location during the period 1996–1999, probably due to the reduction of the total gaseous 129I releases emitted by Sellafield and La Hague. The study of the dependence of the 129I deposition with some atmospheric parameters suggests that deposition seems to be more important in wet than in dry periods and that also depends in the wind direction, being more important for winds with north to south component. The agreement between the 129I concentration and the 129I/129I ratio suggest that the gaseous 129I emitted by the reprocessing plants has enough time to equilibrate with the 127I present in the atmosphere before arriving to southern Spain, probably due to the distance between Seville and these reprocessing plants.Ministerio de Ciencia y Tecnología FIS2008-01149Junta de Andalucía EXC/2005/RNM-41