Highest 14C Research Articles

Phytoavailability of bound residue of Carbendazim to Chinese cabbage (Brassica campestris ssp.chinensis) coexisted with Superabsorbent polymers

Understanding the bioavailability and phytotoxicity of Carbendazim (MBC) bound residues (BR) in soils incubated with different Superabsorbent polymer (SAP) amendment on succeeding crops is essential to assess their environmental fate and risks. In our research, we studied the morphological characteristics and 14C-accumulation of Chinese cabbage and released BR in three typical cultivated soils. The plant dry weight was in order of superabsorbent-hydrogels formulations (HMBC) > MBC > MBC and SAP (MBC-SAP) at 35 d in basic soil 3 (S3), with 675.40 ± 29.07 mg/plant.d.w, 575.93 ± 25.35 mg/plant.d.w and 427.86 ± 18.79 mg/plant.d.w. The whole plant accumulated 2-fold more BR when grew in neutral soil 2 (S2) treated with SAP than MBC at 7 d. The root accumulated a greater proportion of 14C-MBC residue than shoot, with order of MBC-SAP > MBC > HMBC at 21d. The results indicate MBC-BR could be released and accumulated in plant. HMBC promoted the Chinese cabbage growth with lowest 14C accumulation, while MBC-SAP inhibited plant growth with the highest 14C uptake. The released BR rate was 61.43 ± 3.75% of initial BR in MBC-SAP, with 2-fold higher than MBC and HMBC. It is assumed HMBC could be a potential environmentally friendly measure for rational use of pesticides in future.

Local variance of atmospheric 14C concentrations around Fukushima Dai-ichi Nuclear Power Plant from 2010 to 2012

Radiocarbon (14C) has been measured in single tree ring samples collected from the southwest of the Fukushima Dai-ichi Nuclear Power Plant. Our data indicate south-westwards dispersion of radiocarbon and the highest 14C activity observed so far in the local environment during the 2011 accident. The abnormally high 14C activity in the late wood of 2011 ring may imply an unknown source of radiocarbon nearby after the accident. The influence of 14C shrank from 30 km during normal reactor operation to 14 km for the accident in the northwest of FDNPP, but remains unclear in the southwest.

Distribution characteristics of 14C and 3H in spent resins from the Canada deuterium uranium-pressurized heavy water reactors (CANDU-PHWRs) of Korea

It is regarded that the spent resins from the water purification systems of moderator (MOD) and the primary coolant of the Canada deuterium uranium-pressurized heavy water reactor (CANDU-PHWR) are a unique waste, owing to their high 14C and gamma-emitting nuclides. In this work, 14C and 3H contents, anion and cation fractions and the predominant gamma-emitting nuclides of the spent resins from 4 units of CANDUPHWRs, were investigated. Also the chemical species of 14C of the spent resins were determined. For a simultaneous separation of 14C and 3H from the spent resins, the wet oxidation-16 wt% H2SO4 stripping process was utilized. The 14C and 3H activity concentration range of the spent resins of the nuclear power plant (NPP), 4 units of all CANDU-PHWR types, was 2.48E5 Bq/g ∼5.33E6 Bq/g, 1.29E5 Bq/g and ∼2.33E5 Bq/g, respectively. Among the analyzed spent resins, the highest 14C and 3H activity concentration was detected in units 4 and 3, respectively. It was found that more than 92% of the 14C activity concentration was retained on the anion resin and the predominant chemical species was inorganic 14C. It was revealed that the anion resin fraction of the spent resins from unit 1 and unit 2, was about 40% and that of unit 3 and unit 4 was around 60%. More than 80% of the total gamma-radioactivity concentration was associated with the cation fraction of the spent resin. The predominant gamma-emitting nuclide of the spent resin for unit 2 was 137Cs, a fission product, and that for unit 4 was 60Co, a corrosion product.

Growth, flowering and partitioning of 14C-assimilate in oriental lily ‘Star Gazer’ as affected by light level and flower removal

SummaryOriental hybrid lily ‘Star Gazer’ plants were forced in a greenhouse during winter months under natural conditions or with artificial lighting. Supplemental lighting improved plant quality expressed as greater plant fresh weight, longer flower buds and earlier flowering. Lilies grown with supplemental lighting were shorter than control plants. To determine how light conditions and the presence of buds affect growth, whole lily shoots were exposed to 14CO2 at flowering time. Removing lily buds two weeks before flowering in conjunction with higher light level significantly increased the specific 14C radioactivity in mother and daughter scales in lily bulbs when harvested 24 h after exposure. The specific radioactivity in the upper leaves and stems was always higher than in the bottom parts. Bottom leaves showed lower specific 14C radioactivity in the presence of buds but it was not influenced by light level. The highest 14C radioactivity in the bottom and upper parts of the stem was observed in non-irradiated plants without buds. Sink activity of the anthers of irradiated plants was 14 times lower than that of non-irradiated plants. These results demonstrate that the maturation of pollen grains was not completed due to insufficient light level in greenhouse during forcing. Regardless of the light treatment, the specific 14C radioactivity in perianth segments was not affected but the relative sink strength (RSS) was four times higher on plants grown with supplementary lighting than in the control.

Fosamine Absorption and Translocation in Multiflora Rose (Rosa multiflora)

In a 2-yr field study, selective application of a 2.5% (v/v) solution of the ammonium salt of fosamine [ethyl hydrogen(aminocarbonyl)phosphonate] plus 0.5% (v/v) nonionic surfactant to multiflora rose (Rosa multiflora Thunb. # ROSMU) demonstrated leaves to be the major site of uptake for suppressing growth. In greenhouse studies, 14C-fosamine was absorbed in decreasing order by axillary bud, leaf, and stem treatments, respectively. 14C was rapidly translocated throughout multiflora rose plants when applied to leaf, stem, or bud tissue. The highest 14C concentration always occurred at the site of uptake. In a 32-day study, the treated leaf, the treated bud, and treated stem had the highest 14C concentration when 14C-fosamine was leaf, bud, or stem applied, respectively.

The Influence of a Short Period of Evaporative Cooling on the Distribution of 14C in Potato Plants1

Abstract Potato plants (Solarium tuberosum L. cv. Irish Cobbler) which were intermittently misted fixed more 14CO2 than nonmisted plants. Most of the 14C was found in the sugar fraction with the greatest activity translocating to the top of the plant. The highest 14C in the nonvolatile organic acid fraction was found in the leaf which was fed 14CO2. The radioactivity of the free amino acid fraction was highest in tubers of misted plants, but was highest in the 14CO2 fed leaf of the nonmisted plants.