Assessment of Radionuclides, Trace Metals and Radionuclide Transfer from Soil to Food of Jhangar Valley (Pakistan) Using Gamma-Ray Spectrometry

The gamma spectrometric analysis of soil and essential foodstuffs, e.g., wheat, millet, potato, lentils and cauliflower, which form the main component of the daily diet of the local public, was carried out using high purity germanium (HpGe) detector coupled with a computer based high-resolution multi-channel analyzer. The activity concentration in soil samples for ²²⁶Ra, ²³²Th and ⁴⁰K ranged from 30.0 Bq kg^?1 to 81.2 Bq kg^?1, 31.4 Bq kg^?1 to 78.25 Bq kg^?1 and 308.8 Bq kg^?1 to 2177.6 Bq kg^?1, with mean values of 56.2, 58.5 and 851.9 Bq kg^?1, respectively. The average activity measured for ²²⁶Ra, ²³²Th and ⁴⁰K in soil samples was found higher than the world average. The major radionuclide found in the food items studied was ⁴⁰K, while ²²⁶Ra, ²³²Th and ¹³⁷Cs were detected in very nominal amounts. The results clearly indicate that these radionuclides have no health hazard to human beings, as they are well below the annual limit of intake (ALI) for these radionuclides. The transfer factors of these radionuclides from soil to food were also studied. The mean transfer factors of ⁴⁰K, ²²⁶Ra, ²³²Th and ¹³⁷Cs from soil to food were estimated to be about 0.17, 0.07, 0.16 and 0.23, respectively. An artificial radionuclide, ¹³⁷Cs, was also present in detectable amount in all samples. The internal and external hazard indices were measured and had mean values of 0.70 and 0.55, respectively. Absorbed dose rates and effective dose have been determined in the present study. Concentration of trace metals, such as Cr, Pb, Ni and Zn, was also determined in the soil samples. The concentrations of radionuclides and trace metals found in these samples during the present study were nominal and do not pose any potential health hazard to the general public.     

Transfer of radiocesium from hydroponic medium to potherb mustard and tomato plants

Abstract

Potherb mustard (Brassica rapa var. nipposinica) and tomato plants (scion, ‘CF Momotaro haruka’; rootstock, ‘Dokutar K’; Solanum lycopersicum) were cultured in hydroponic medium containing cesium-137 (¹³⁷Cs) at three different concentrations (0.03, 0.13 and 1.03 Bq L^?1), and uptake of ¹³⁷C into the plants was determined. When the ¹³⁷Cs radioactivity concentration in the medium was 1.03 Bq L^?1, the ¹³⁷Cs radioactivity concentrations in the edible portions of the plants were 4.80 Bq kg^?1 fresh weight for the potherb mustard plants and 3.60 Bq kg^?1 fresh weight for the tomato plants. In both species, the ¹³⁷Cs radioactivity concentration in the edible portions decreased with decreasing ¹³⁷Cs radioactivity concentration in the culture medium. When the ¹³⁷Cs radioactivity concentration in the medium was 0.03 Bq L^?1, a concentration observed in many streams and in tap water in Fukushima Prefecture after the accident at the Fukushima Daiichi Nuclear Power Plant, the ¹³⁷Cs radioactivity concentrations in the edible portions of the plants were 0.50 and 0.15 Bq kg^?1 fresh weight for potherb mustard and tomato plants, respectively. These values are less than the Japanese allowable limit for radiocesium in food. For both species, the transfer factors for ¹³⁷Cs uptake from the culture media to the edible portions and the average transfer rates over the cultivation period were calculated.     

Transfer factor of radioactive cesium to forage corn (Zea mays L.) from soil to which contaminated farmyard manure had been applied

Abstract

Radioactive cesium (Cs) deposited after the Fukushima Daiichi Nuclear Power Station accident contaminated farmyard manure (FYM) in the wide area surrounding the plant. We conducted a field trial to determine the transfer factor of radioactive Cs to forage corn (Zea mays L.) from soil to which the contaminated FYM had been applied. The main purpose of this experiment was to examine the behavior of the radioactive Cs from contaminated FYM that was incorporated in agricultural fields. Application of FYM containing 3900 Bq kg^?1 dry matter (DM) of cesium-137 (¹³⁷Cs) at a rate of 4.3 kg m^?2 increased the ¹³⁷Cs concentration in the soil by 64 Bq kg^?1 dry soil, and in the forage corn by 9.2 Bq kg^?1 DM. Therefore, we calculated the transfer factor to corn plants from the soil after application of contaminated FYM to be 0.14. This value is lower than that observed for soil to which uncontaminated FYM had been applied as a control, and it is within the range of reported soil-to-plant transfer factors of 0.003–0.49 listed in the recent parameter handbook by International Atomic Energy Agency. The increase in the radioactive Cs concentration in the corn plants, expressed as the sum of ¹³⁷Cs and cesium-134 (¹³⁴Cs), was only 3% of the 2012 provisional tolerance level for cattle roughage in Japan. Even though the application of contaminated FYM did not cause a large change in the radioactive Cs concentration in the corn plants in this trial, such application should be carefully controlled because it increased radioactive Cs concentrations in both soil and forage corn.     

Spatial and vertical distribution of <Superscript>137</Superscript>Cs in soils in the erosive area of southeastern Serbia (Pčinja and South Morava River Basins)

Purpose

The area of southeastern Serbia, the P?inja and South Morava River Basins, is under the influence of very strong erosion, and the aim of this study was to investigate the vertical and spatial distribution of the ¹³⁷Cs in the eroded soils of this area.

Materials and methods

Vertical soil profiles were collected with 5-cm increments from the uppermost layer down to 20, 25, 30, 40, and 50 cm of depth, depending on the thickness of the soil layers, i.e., down to the underlying parent rocks. Measurements of ¹³⁷Cs activity concentration were performed by using the HPGe gamma-ray spectrometer ORTEC-AMETEK (34 % relative efficiency and high resolution 1.65 keV at 1.33 MeV for ⁶⁰Co), from its gamma-ray line at 661.2 keV.

Results and discussion

The mean ¹³⁷Cs activity concentration across all 18 soil profiles (for all soil layers) was found to be 20 Bq kg^?1. In the greatest number of soil profiles, the ¹³⁷Cs activity concentration was generally highest in the first soil layer (0–5 cm) and decreased with soil depth, while in a few soil profiles, the peak of either the ¹³⁷Cs activity concentration occurred in the second soil layer (5–10 cm) or the ¹³⁷Cs activity concentration was almost equal throughout the entire soil profile. The mean ¹³⁷Cs activity concentration in the first soil layer (0–5 cm) was found to be 61 Bq kg^?1, and the high coefficient of variation of 92 % pointed out high spatial variability and large range of the ¹³⁷Cs activity concentrations in the study area.

Conclusions

The obtained results indicate that in the greatest number of soil profiles, ¹³⁷Cs is present in the upper layers, with concentration decreasing with depth, as is typical in uncultivated soil. Its spatial distribution was very uneven among the surface soil layers of the investigated sites. One of the main reasons for such pattern of ¹³⁷Cs in the study area may be soil erosion. Additional investigations which would support this hypothesis are required.

     

Impact of Tropical Ecosystem on the Migrational Behavior of K-40, Cs-137, Th-232 U-238 in Perennial Plants

A comprehensive study was conducted to determine the soil to plant transfer factor (TF_S–P) of K-40, Cs-137, Th-232 and U-238 in perennial plants from accessible areas of Mumbai, using high-resolution γ spectrometry. A total of 50 soil and 150 plants samples were collected from all over the Mumbai region where lithology is dominated by basaltic rocks. The mean concentration values for K-40, Cs-137, Th-232 and U-238 in soil was 170.06?±?65.36, 5.19?±?1.20, 25.72?±?6.262 and 10.21?±?2.82 Bq kg^?1 respectively, whereas in case of plants the mean concentration values were determined to be 181.82?±?18.50, 0.44?±?0.14, 0.84?±?0.19 and 0.79?±?0.22 Bq kg^?1 respectively. The mean activity ratio of Th-232/U-238 in plants is 1.06 while in soil the ratio is 2.5. The soil to plant transfer factor (TF_S–P) calculated for K-40, Cs-137, U-238 and Th-232 are 1.05, 0.076, 0.071 and 0.031 respectively. Higher value of TF_S–P for K-40, which is an integral part of stable potassium clearly indicates the physiological need of stable potassium, for maintaining the different biological mechanisms of perennial plants under tropical conditions.     

Measurement of Radionuclides and Gamma-Ray Dose Rate in Soil and Transfer of Radionuclides from Soil to Vegetation, Vegetable of Some Northern Area of Pakistan Using ��-Ray Spectrometry

The analysis of gamma emitters natural radionuclides, i.e., ²²⁶Ra, ²³²Th, and ⁴⁰K, has been carried out in soil, vegetation, vegetable, and water samples collected from some Northern area of Pakistan, using gamma-ray spectrometry. The ??-ray spectrometry was carried out using high-purity Germanium detector coupled with a computer-based high-resolution multi-channel analyzer. The activity concentrations in soil ranges from 24.7 to 78.5 Bq?kg^?1, 21.7 to 75.3 Bq?kg^?1, and 298.5 to 570.8 Bq?kg^?1 for ²²⁶Ra, ²³²Th, and ⁴⁰K with the mean value of 42.1, 43.3, 9.5, and 418.3 Bq?kg^?1, respectively. In the present analysis, ⁴⁰K was the major radionuclide present in soil, vegetation, fruit, and vegetable samples. The concentration of ⁴⁰K in vegetation sample varied from 646.6 to 869.6 Bq?kg^?1 on dry weight basis. However, the concentration of ⁴⁰K in fruit and vegetable samples varied from 34.0 to 123.3 Bq?kg^?1 on fresh weight basis. In vegetation samples, along with ⁴⁰K, ²²⁶Ra, and ²³²Th were also present in small amount. The transfer factors of these radionuclides from soil to vegetation, fruit, and vegetable were also studied. The transfer factors were found in the order: ⁴⁰K?>?²³²Th????²²⁶Ra. The analysis of water samples showed activity concentrations values for all radionuclides below detection limit. The internal and external hazard indices were measured and found less than the safe limit of unity. The mean value of outdoor and indoor absorbed dose rate in air was found 64.61 and 77.54 nGy?h^?1, respectively. The activity concentrations of radionuclides found in all samples during the current investigation were nominal. Therefore, they are not associated with any potential source of health hazard to the general public.     

Cesium-137 concentration of forage corn and Italian ryegrass in a double cropping system under different rates of cattle farmyard manure application after the Fukushima Daiichi Nuclear Power Station accident in 2011

Abstract

Radioactive ¹³⁷Cs concentrations of forage corn (Zea mays L.) and Italian ryegrass (Lolium multiflorum Lam.) in a double cropping system under continuous cattle farmyard manure (FYM) application were observed for more than 2 years after the Fukushima Daiichi Nuclear Power Station accident in 2011. The experiment field is located 110 km southwest of the Fukushima Daiichi Nuclear Power Station, and the soil contains ¹³⁷Cs of 920 Bq kg^?1 on average. For crop cultivation, nitrogen fertilizer was applied in addition to FYM. The ¹³⁷Cs concentrations in corn decreased significantly between 2011 and 2012, but only differed significantly between 2012 and 2013 for the plot with no FYM application. For Italian ryegrass, no significant differences were observed between the harvest in 2012 and 2013 despite the FYM application rate. To minimize corn ¹³⁷Cs concentrations, the FYM application rate should be more than and equal to 30 Mg ha^?1 when FYM is used as the major nutrient source. Exchangeable potassium oxide (K₂O) greater than around 0.3 g kg^?1 was mostly maintained with the FYM application rates. Corn ¹³⁷Cs concentration appeared to increase at exchangeable K₂O levels below 0.15 g kg^?1. These results suggest that continuous FYM application can maintain soil nutrients including K₂O and thereby control radioactive Cs transfer from the soil. FYM application rate of 30 Mg ha^?1 is within the levels recommended by the prefectural governments around Fukushima Prefecture for crop production before the accident. These levels are sufficient to decrease the radioactive Cs concentrations for corn. However, unlike corn, differences in soil chemical properties by FYM application did not affect ¹³⁷Cs concentrations in Italian ryegrass in this study, although low exchangeable K₂O seemed to increase concentrations of stable ¹³³Cs. Further experiments should be conducted to understand the observed differences between corn and Italian ryegrass.     

Varietal difference in radiocesium uptake and transfer from radiocesium deposited soils in the genus Amaranthus

Abstract

Within Amaranthaceae, 33 different varieties, including local varieties from Japan, were grown in 2012 in a field in the town of Iino in the Fukushima prefecture, which is located approximately 51 km north of Tokyo Electric Power Company, Fukushima Daiichi Nuclear Power Plant (FDNPP). The contamination level of the soil was 2770 ± 140 Bq kg^?1 dry weight (¹³⁴Cesium (Cs) + ¹³⁷Cs, average ± SE), and the field was also cultivated in 2011. There was a significant varietal difference in the dry weight production, radiocesium accumulation and transfer factor (TF) of radiocesium from the soil to the plant. The ratio of the lowest TF to the highest TF was approximately 3. Because the ratio of ¹³⁷Cs to ¹³³Cs was significantly positive, radiocesium seems to be absorbed in a manner similar to that of ¹³³Cs. It is suggested that the varietal difference in the behavior of radiocesium uptake mainly depends on its genetic background rather than on environmental factors.     

Pilot-scale counter-current acid leaching process for Cu,Pb, Sb,and Zn from small-arms shooting range soil

Purpose

The main objective of this study was to evaluate the potential of a counter-current leaching process (CCLP) on 14 cycles with leachate treatment at the pilot scale for Pb, Cu, Sb, and Zn removal from the soil of a Canadian small-arms shooting range.

Materials and methods

The metal concentrations in the contaminated soil were 904?±?112 mg Cu kg^–1, 8,550?±?940 mg Pb kg^–1, 370?±?26 mg Sb kg^–1, and 169?±?14 mg Zn kg^–1. The CCLP includes three acid leaching steps (0.125 M H₂SO₄?+?4 M NaCl, pulp density (PD)?=?10 %, t?=?1 h, T?=?20 °C, total volume?=?20 L). The leachate treatment was performed using metal precipitation with a 5-M NaOH solution. The treated effluent was reused for the next metal leaching steps.

Results and discussion

The average metal removal yields were 80.9?±?2.3 % of Cu, 94.5?±?0.7 % of Pb, 51.1?±?4.8 % of Sb, and 43.9?±?3.9 % of Zn. Compared to a conventional leaching process, the CCLP allows a significant economy of water (24,500 L water per ton of soil), sulfuric acid (133 L H₂SO₄ t^–1), NaCl (6,310 kg NaCl t^–1), and NaOH (225 kg NaOH t^–1). This corresponds to 82 %, 65 %, 90 %, and 75 % of reduction, respectively. The Toxicity Characteristic Leaching Procedure test, which was applied on the remediated soil, demonstrated a large decrease of the lead availability (0.8 mg Pb L^–1) in comparison to the untreated soil (142 mg Pb L^–1). The estimated total cost of this soil remediation process is 267 US$ t^–1.

Conclusions

The CCLP process allows high removal yields for Pb and Cu and a significant reduction in water and chemical consumption. Further work should examine the extraction of Sb from small-arms shooting range.     

Zinc,Copper, Boron and Iron Requirement of Upland Rice Grown on a Brazilian Oxisol

Deficiency of micronutrients increasing in field crops, including upland rice in recent years. The objective of this study was to determine requirement of zinc (Zn), copper (Cu) boron (B) and iron (Fe) for upland rice grown on a Brazilian Oxisol. The levels used were: Zn (0, 10, 20, 40, and 80 mg kg^?1), Cu (0, 5, 10, 20 and 40 mg kg^?1), B (0, 5, 10, 20 and 40 mg kg^?1) and Fe (0, 250, 500, 1000, and 2000 mg kg^?1). Plant height, straw yield, grain yield, panicle number and grain harvest index (GHI) were significantly improved with the addition of these micronutrients. Root growth was also improved with the application of micronutrients, except with the addition of B. Maximum grain yield was obtained with the addition of 51 mg Zn, 24 mg Cu, 5 mg B kg^?1, and 283 mg Fe kg^?1 soil. Similarly, maximum straw yield was obtained with the addition of 38 mg Zn, 17 mg Cu, 6 mg B kg^?1, and 1500 mg Fe kg^?1 soil. Maximum plant height was obtained with the addition of 54 mg Zn, 10 mg B kg^?1, and 1197 mg Fe kg^?1 soil. Copper did not affect plant height significantly. Maximum panicle number was obtained with the addition of 22 mg Cu kg^?1, 3 mg B kg^?1, and 1100 mg Fe kg^?1 soil. Zinc did not affect panicle number significantly. Maximum GHI was obtained with the addition of 61 mg Zn kg^?1, and 8 mg B kg^?1. Zinc was had a linear increase in GHI in the range of 0 to 80 mg kg^?1, and Fe showed a negative relationship with GHI.     

Is the Period of 18 Years Sufficient for an Evaluation of Changes in Soil Organic Carbon under a Variety of Different Soil Management Practices?

The influence of differing soil management practices on changes seen in soil organic carbon (SOC) content of loamy Haplic Luvisol was evaluated. The field experiment included two types of soil tillage: 1. conventional tillage (CT) and 2. reduced tillage (RT) and two treatments of fertilization: 1. crop residues with nitrogen, phosphorus, and potassium (NPK) fertilizers (PR+NPK) and 2. NPK fertilizers (NPK). The results of SOC fluctuated from 9.8 to 14.5 g kg^?1 and the tillage systems employed and fertilization status did not have a statistically significant influence on SOC. The SOC content was higher in RT (12.4 ± 0.86 g kg^?1) than in CT (12.2 ± 0.90 g kg^?1). On average, there was a smaller higher value of SOC in PR+NPK (12.4 ± 1.02 g kg^?1) than in NPK (12.3 ± 0.88 g kg^?1). During a period of 18 years, reduced tillage and application of NPK fertilizers together with crop residues build up a SOC at an average speed of 7 and 16 mg kg^?1 year^?1, respectively, however conventional tillage and NPK fertilizer applications caused a SOC decline at an average speed of 104 and 40 mg kg^?1 year^?1, respectively.     

Potassium fertilization and soil diagnostic criteria for forage corn (Zea mays L.) production contributing to lower potassium input in regional fertilizer recommendation

Abstract

Effective soil diagnostic criteria for exchangeable potassium (Ex-K) combined with inorganic potassium (K) application rates were developed to lower K input in forage corn (Zea mays L.) production using experimental fields with different application rates and histories of cattle manure compost. Two corn varieties, ‘Cecilia’ as a low K uptake variety and ‘Yumechikara’ as a high K uptake variety, were selected from among 20 varieties and tested to make diagnostic criteria for K fertilization applicable to varieties with different K uptakes. The K uptakes increased from 96 to 303 kg K ha^?1 for ‘Cecilia’ and from 123 to 411 kg K ha^?1 for ‘Yumechikara’ with increasing Ex-K content on a dry soil basis from 0.11 to 0.92 g kg^?1 with no inorganic K fertilizer application. The K uptake by corn for achieving the target dry matter yield of 18 Mg ha^?1 was estimated to be approximately 200 kg K ha^?1 in common between the two varieties. Yields of both varieties achieved the target yield at an Ex-K content of approximately 0.30 g kg^?1 with no K fertilization, although ‘Yumechikara’ reached the target yield at a lower Ex-K content. At the low Ex-K content of 0.1 g kg^?1, inorganic K fertilizer application at 83 kg K ha^?1 was needed to gain the target yield, and apparent K recovery rate for K fertilizer was calculated to be 70% for both varieties. The K uptakes for gaining the target yield by the K fertilization were lower than that by soil K supply. Based on these results, diagnostic criteria of Ex-K and inorganic K application rates were set up as follows: at an Ex-K content of < 0.15 g kg^?1, inorganic K fertilizer is applied at 83 kg K ha^?1 (100 kg ha^?1 as potassium oxide (K₂O) equivalent); at an Ex-K content of 0.15–0.30 g kg^?1, the application rate is reduced to 33 kg K ha^?1 (40 kg K₂O ha^?1); at an Ex-K content of ≥ 0.30 g kg^?1, inorganic K fertilizer is not applied because of sufficient K in the soil. Additionally, we propose that cattle manure compost be used to supplement soil K fertility.     

Radioactive cesium distribution in bamboo [Phyllostachys reticulata (Rupr) K. Koch] shoots after the TEPCO Fukushima Daiichi Nuclear Power Plant disaster

Abstract

Radioactivity levels of cesium (Cs)-134 and ¹³⁷Cs in bamboo [Phyllostachys reticulata (Rupr) K. Koch] sprouts grown from April to June 2011 over a wide area (including Fukushima Prefecture) were elevated (max. 3100 Bq kg^?1 fresh weight) after the Tokyo Electric Power Company, Inc. (TEPCO) Fukushima Daiichi Nuclear Power Plant disaster in March 2011. Bamboo sprouts in 2012 also contained high radioactivity levels. Radioactivity imaging analysis of bamboo sprouts harvested in 2012 showed increasing concentration gradients of radioactivity from the lower parts to the top of the sprouts. The peels were individually separated from the sprouts, and the inner edible part (trunk) was cross-sectioned at the internodal sections from the top to the lower parts. Each segmented trunk and its corresponding peel were analyzed for radioactive cesium (¹³⁴Cs and ¹³⁷Cs) and stable cesium (¹³³Cs). The concentrations of ¹³⁴Cs and ¹³⁷Cs showed significant increases from the lower part to the top, whereas ¹³³Cs showed an almost constant value in the trunk and peel except in the peel of the top node. We speculated that ¹³⁴Cs and ¹³⁷Cs in newly emerging bamboo sprouts in 2012 were translocated mainly from various plant tissues (where the fallout was layered on the bamboo tissues) in older bamboo, while ¹³³Cs was translocated from the soil through the roots of the new bamboo sprouts and was present in the roots and stems.     

Enhanced sorption and fixation of radiocaesium in soils amended with K-bentonites, submitted to wetting–drying cycles

The use of bentonites as soil amendment has met with little success in reducing plant uptake of radiocaesium. However, bentonites exchanged with K⁺ have pronounced Cs⁺ binding capacity when subjected to wetting–drying cycles. Fifty‐four different bentonites were collected and characterized for cation exchange capacity and chemical composition. The radiocaesium interception potential (RIP) increased up to 160‐fold (mean 25) when the bentonites were converted to the K‐form and subjected to wetting–drying cycles. This increase in radiocaesium sorption was ascribed to a collapse of the clay sheets into an illite‐like structure, and was most pronounced in bentonites with a high layer charge. The RIP values of K‐bentonites subjected to 25 wetting–drying cycles ranged from 0.22 to 44.3 mol kg^?1. The RIP yields, i.e. the RIP in soil–bentonite mixtures expressed per unit bentonite added, were even higher and ranged up to 99 mol kg^?1. This upper limit is about 10‐fold higher than the RIP value of illite (～ 10 mol kg^?1), the principal ¹³⁷Cs sorbent in soils of temperate climates. Wetting–drying also promoted fixation of radiocaesium in soils amended with K‐bentonites. About 30% of added ¹³⁷Cs could be desorbed with 1 m ammonium acetate (NH₄Ac) from an unamended soil after 25 wetting–drying cycles, while only between 8 and 21% of ¹³⁷Cs could be desorbed from a soil amended with bentonite and a K‐salt. These findings support the proposition that addition of K‐bentonite may be effective in reducing availability of ¹³⁷Cs in soils.     

Effects of organic material amendment and water content on NO, N2O, and N2 emissions in a nitrate-rich vegetable soil

Amending vegetable soils with organic materials is increasingly recommended as an agroecosystems management option to improve soil quality. However, the amounts of NO, N₂O, and N₂ emissions from vegetable soils treated with organic materials and frequent irrigation are not known. In laboratory-based experiments, soil from a NO ₃ ^? -rich (340 mg N?kg^?1) vegetable field was incubated at 30°C for 30 days, with and without 10 % C₂H₂, at 50, 70, or 90 % water-holding capacity (WHC) and was amended at 1.19 g?C kg^?1 (equivalent to 2.5 t?C ha^?1) as Chinese milk vetch (CMV), ryegrass (RG), or wheat straw (WS); a soil not amended with organic material was used as a control (CK). At 50 % WHC, cumulative N₂ production (398–524 μg N?kg^?1) was significantly higher than N₂O (84.6–190 μg N?kg^?1) and NO (196–224 μg N?kg^?1) production, suggesting the occurrence of denitrification under unsaturated conditions. Organic materials and soil water content significantly influenced NO emissions, but the effect was relatively weak since the cumulative NO production ranged from 124 to 261 μg N?kg^?1. At 50–90 % WHC, the added organic materials did not affect the accumulated NO ₃ ^? in vegetable soil but enhanced N₂O emissions, and the effect was greater by increasing soil water content. At 90 % WHC, N₂O production reached 13,645–45,224 μg N?kg^?1 from soil and could be ranked as RG?>?CMV?>?WS?>?CK. These results suggest the importance of preventing excess water in soil while simultaneously taking into account the quality of organic materials applied to vegetable soils.     

Determination of Natural and Artificial Radionuclide Levels in Soils of Western and Southern Coastal Area of Turkey

Soil samples were collected from western and southern region of Turkey in 1995 from 17 sampling stations of different depths. Natural and artificial radionuclide activity levels of soil samples of the western and southern sea in Turkey were previously reported about nine years after the Chernobyl accident. The aim of the study was to collect data for following up of the earlier study and to present result for distributions of radionuclides in soil samples of the western and southern regions of Turkey. ²²⁶Ra is in the range 19–276 Bq kg^?1, 7–173 Bq kg^?1 for ²³⁸U, 8–244 Bq kg^?1 for ²³²Th, 86–1162 Bq kg^?1 (dry wt.) for ⁴⁰K and ¹³⁷Cs activity result varies between 1.8–82 Bq kg^?1 (dry wt.).     

Pine Bark Amendment to Promote Sustainability in Cu-Polluted Acid Soils: Effects on <Emphasis Type="Italic">Lolium perenne</Emphasis> Growth and Cu Uptake

The establishment of a complementary grass cover on vineyard soils can promote sustainability of the affected environment. In this work, we used an acid vineyard soil with total Cu concentration 188 mg kg^?1 to study the influence of pine bark amendment on Lolium perenne growth and Cu uptake. The results indicate that the pine bark amendment did not cause a significant increase in the mass of the shoots of Lolium perenne, but favored the root biomass: 0.034 g for control and 0.061 g for soil samples amended with 48 g kg^?1 of pine bark. Moreover, the pine bark amendment decreased Cu concentration in both, shoots (50 mg kg^?1 for control soil and 29 mg kg^?1 for soil amended with 48 g kg^?1 pine bark) and roots (250 mg kg^?1 for control soil and 64 mg kg^?1 for soil amended with 48 g kg^?1 pine bark). The main factor responsible for these results was a significant decrease of the most mobile fractions of Cu in the soil. Those fractions were extracted using ammonium acetate, ammonium chloride, sodium salt of ethylene-diamine-tetraacetic acid (EDTA-Na), and diethylene-triamine-pentaacetic acid (DTPA).     

Are horticulture-based land uses benign for fertility and health of soils in mid to high hills of the north-western Himalayan region?

ABSTRACT

Soil fertility in many parts of the north?western Himalayan region (NWHR) has declined owing to accelerated nutrient mining under existing crop regime. Therefore, this study aimed to assess effect of the predominant horticulture?based land uses on soil fertility and health in mid and high hills of NWHR. Soil samples (0?20 cm) were collected, analyzed for different soil chemical attributes (pH, electrical conductivity, organic C, available primary-, secondary-, and micro-nutrients), and compared across five key land uses: perennial grass (PG), peach orchard (PO), apple orchard (AO), field vegetable farming (VF), and protected vegetable farming (PV). Soils of the investigated land uses were neutral to near neutral in soil reaction (6.3?6.8) except field vegetable and protected vegetable farming. Amount of soil organic C and labile organic C was significantly higher (p ≤ 0.05) in soils of apple orchards (18.6 g kg^?1 and 687.3 mg kg^?1, respectively) and peach orchards (20.4 g kg^?1 and 731.3 mg kg^?1, respectively) over others. An abrupt and significant increase in Olsen-P was recorded in soils of field vegetable farming (17.1 mg kg^?1) and protected vegetable farming (13.0 mg kg^?1), which shifted their nutrient index (NI) of P in to high category (≥ 2.33). The concentration of mineralizable-N in soil was statistically at par in soils under perennial grass and fruit orchards, while protected vegetable farming showed maximum soil mineralizable-N content (115.5 mg kg^?1) and NI of nitrogen (1.83). The NI was in high category (≥ 2.33) for copper, iron, and manganese in majority of the land uses. In view of the results, temperate fruit?tree based land uses are benign in up?keeping soil fertility and soil health, and needs promotion on large scale. Additionally, policies to create incentives for the build-up of soil organic matter and replenishment of the depleted soil macro and micro nutrients in vegetable-farmed lands are warranted.     

Migration path and isotope tracing of 137Cs and 239 + 240Pu in estuary sediments: a case study of Liao River estuary in China

Purpose

Currently, the distribution characteristics and transport processes of the radionuclides ¹³⁷Cs and ^239?+?240Pu in the sediments of estuaries are still a controversial issue. Thus, in the present study, we investigated the distribution characteristics, sources and migration path of ¹³⁷Cs and ^239?+?240Pu in sediment cores of the Liao River estuary (LRE), China, and evaluated the relative contributions of the Pacific Proving Grounds (PPG) and riverine sources of Pu for the sediments in this area. We used ¹³⁷Cs and Pu isotopes for dating the sediments and estimated the sedimentation rates by the two radionuclides in the LRE.

Materials and methods

Seven sediment samples were collected using a box corer from the Liao River estuarine wetland and tidal flat in the LRE in October 2012 and April 2015, respectively. The activities of ¹³⁷Cs in the various samples were determined by γ spectrometry using HP-Ge detectors with 60% relative counting efficiency. Approximately 2–5 g of sediment were spiked with ²⁴²Pu (ca. 1 mBq) as a chemical yield tracer for Pu isotopic analysis at the School of Radiation Medicine and Protection, Soochow University. The measurement of Pu isotopes (²³⁹Pu, ²⁴⁰Pu, ²⁴²Pu) was performed by a sector field ICP-MS. In order to quantitatively differentiate the relative proportions of global fallout and PPG, we employed a two-end member mixing model to estimate their contributions.

Results and discussion

The average values of ¹³⁷Cs, ^239?+?240Pu activity concentrations, and ²⁴⁰Pu/²³⁹Pu atom ratios in the surface sediment samples of the LRE were 6.727?±?0.251 mBq g^?1, 0.294?±?0.024 mBq g^?1, and 0.188?±?0.049 (1σ), respectively. The average ²⁴⁰Pu/²³⁹Pu atom ratios ranged from 0.180?±?0.034 to 0.199?±?0.021 in sediment cores from the east and west sides of the LRE. For core LT-2 values for ¹³⁷Cs and ^239?+?240Pu concentrations were from below the detection limit: 3.380?±?0.414 and 0.036?±?0.007 to 0.105?±?0.007 mBq g^?1. The mean ²⁴⁰Pu/²³⁹Pu atom ratio 0.217?±?0.050 (1σ) in sediment core LT-2 lies between the global fallout and PPG close-in fallout.

Conclusions

We found that atmospheric fallout is the main source of Pu in sediment cores from the east and west sides of the LRE. For core LT-2, atmospheric fallout and riverine input (~?73.4%) are the major sources of Pu with the source of the rest of Pu (~?26.6%) attributed to the PPG via the Tsushima Warm Current and the coastal water of the East China Sea. The sedimentation rates (means 0.62–0.8 cm year^?1) estimated by the two radionuclides were in good agreement and without any statistically significant difference.

     

Tillage system affects fertilizer-induced nitrous oxide emissions

Since the development of effective N₂O mitigation options is a key challenge for future agricultural practice, we studied the interactive effect of tillage systems on fertilizer-derived N₂O emissions and the abundance of microbial communities involved in N₂O production and reduction. Soil samples from 0–10 cm and 10–20 cm depth of reduced tillage and ploughed plots were incubated with dairy slurry (SL) and manure compost (MC) in comparison with calcium ammonium nitrate (CAN) and an unfertilized control (ZERO) for 42 days. N₂O and CO₂ fluxes, ammonium, nitrate, dissolved organic C, and functional gene abundances (16S rRNA gene, nirK, nirS, nosZ, bacterial and archaeal amoA) were regularly monitored. Averaged across all soil samples, N₂O emissions decreased in the order CAN and SL (CAN?=?748.8?±?206.3, SL?=?489.4?±?107.2 μg kg^?1) followed by MC (284.2?±?67.3 μg kg^?1) and ZERO (29.1?±?5.9 μg kg^?1). Highest cumulative N₂O emissions were found in 10–20 cm of the reduced tilled soil in CAN and SL. N₂O fluxes were assigned to ammonium as source in CAN and SL and correlated positively to bacterial amoA abundances. Additionally, nosZ abundances correlated negatively to N₂O fluxes in the organic fertilizer treatments. Soils showed a gradient in soil organic C, 16S rRNA, nirK, and nosZ with greater amounts in the 0–10 than 10–20 cm layer. Abundances of bacterial and archaeal amoA were higher in reduced tilled soil compared to ploughed soils. The study highlights that tillage system induced biophysicochemical stratification impacts net N₂O emissions within the soil profile according to N and C species added during fertilization.