A long record of atmospheric 14 C concentration, from 45 to 11 thousand years ago (ka), was obtained from a stalagmite with thermal-ionization mass-spectrometric 230 Th and accelerator mass-spectrometric 14 C measurements. This record reveals highly elevated Δ 14 C between 45 and 33 ka, portions of which may correlate with peaks in cosmogenic 36 Cl and 10 Be isotopes observed in polar ice cores. Superimposed on this broad peak of Δ 14 C are several rapid excursions, the largest of which occurs between 44.3 and 43.3 ka. Between 26 and 11 ka, atmospheric Δ 14 C decreased from ∼700 to ∼100 per mil, modulated by numerous minor excursions. Carbon cycle models suggest that the major features of this record cannot be produced with solar or terrestrial magnetic field modulation alone but also require substantial fluctuations in the carbon cycle.

The Fukushima nuclear accident in March 2011 has released a large amount of radioactive pollutants to the environment. Of the pollutants, iodine-129 is a long-lived radionuclide and will remain in the environment for millions of years. This work first report levels and inorganic speciation of (129)I in seawater depth profiles collected offshore Fukushima in June 2011. Significantly elevated (129)I concentrations in surface water were observed with the highest (129)I/(127)I atomic ratio of 2.2 × 10(-9) in the surface seawater 40 km offshore Fukushima. Iodide was found as the dominant species of (129)I, while stable (127)I was mainly in iodate form, reflecting the fact that the major source of (129)I is the direct liquid discharges from the Fukushima NPP. The amount of (129)I directly discharged from the Fukushima Dai-ichi nuclear power plant to the sea was estimated to be 2.35 GBq, and about 1.09 GBq of (129)I released to the atmosphere from the accident was deposited in the sea offshore Fukushima. A total release of 8.06 GBq (or 1.2 kg) of (129)I from the Fukushima accident was estimated. These Fukushima-derived (129)I data provide necessary information for the investigation of water circulation and geochemical cycle of iodine in the northwestern Pacific Ocean in the future.

Evidence for basin scale brine migration and clay mineral diagenesis in the northern Appalachian Basin was investigated using elemental and isotope ( 129 I/I, 87 Sr/ 86 Sr) geochemistry of formation waters collected from the Middle to Upper Devonian section of the northern basin margin in western New York, northwest Pennsylvania, and eastern Kentucky. One sample from each of the Mississippian Berea sandstone and the Silurian Medina sandstone were analyzed for comparison. Measured iodine ratios range between 28 to 1,890 ؋ 10 ؊15 and are anomalously high compared to cosmogenic iodine sourced from Devonian age organic matter. Iodine-129 in the waters was largely derived from fissiogenic sources, the spontaneous fission of 238 U to produce 129 I, with estimated 129 I/I values up to 270 ؋ 10 ؊15 , which occur locally in the organic-rich shales. There are three water samples that have values of 490 ؋ 10 ؊15 , 860 ؋ 10 ؊15 , and 1,890 ؋ 10 ؊15 , which are above the range for local fissiogenic 129 I and may be accounted for by topographically driven, basin scale fluid flow through a regionally high fissiogenic source. Relatively large uranium occurrences lie along the structural front of the Appalachian Basin in the Blue Ridge Province and are situated within hypothesized flow paths parallel to the main compressional direction of the Alleghanian orogeny. Estimated 129 I/I values for these uranium occurrences are in excess of 55,000 ؋ 10 ؊15 . The strontium isotope composition and Sr concentration of brines display a mixing trend between a highly radiogenic endmember (0.7210) with low Sr (51 mg/L) and a non-radiogenic (0.7100), high Sr (4789 mg/L) end-member. Potassium and boron concentrations are notably depleted relative to evaporated Paleozoic seawater, the hypothesized source of Appalachian Basin brines. The K/Rb values of formation waters are depleted relative to seawater values, but in some cases are well above values indicative of water-rock reactions. The Sr isotopic composition, K and B depletion, and intermediate K/Rb ratios are consistent with smectite diagenesis and paleo-temperatures that are likely greater than approximately 150 °C. These temperatures may be high given the burial history of the study area and support the flow of formation waters from deeper within the basin. The combined isotopic and elemental results of formation waters provide compelling evidence for basin scale fluid migration in the northern Appalachian Basin and are consistent with previously published evidence documented from the rock record, including clay mineral diagenesis and ore deposition.

Radionuclide impact of the Fukushima Dai-ichi nuclear power plant accident on the distribution of radionuclides in seawater of the NW Pacific Ocean is compared with global fallout from atmospheric tests of nuclear weapons. Surface and water column seawater samples collected during the international expedition in June 2011 were analyzed for ¹³⁴Cs, ¹³⁷Cs, ¹²⁹I and ³H. The ¹³⁷Cs, ¹²⁹I and ³H levels in surface seawater offshore Fukushima varied between 0.002–3.5 Bq L⁻¹, 0.01–0.8 μ Bq L⁻¹, and 0.05–0.15 Bq L⁻¹, respectively. At the sampling site about 40 km from the coast, where all three radionuclides were analyzed, the Fukushima impact on the levels of these three radionuclides represent an increase above the global fallout background by factors of about 1000, 30 and 3, respectively. The water column data indicate that the transport of Fukushima-derived radionuclides downward to the depth of 300 m has already occurred. The observed ¹³⁷Cs levels in surface waters and in the water column are in reasonable agreement with predictions obtained from the Ocean General Circulation Model, which indicates that the radionuclides have been transported from the Fukushima coast eastward. The ¹³⁷Cs inventory in the water column (the area from 34 to 37° N, and from 142 to 147° E) due to the Fukushima accident is estimated to be about 2.2 PBq. The amount of ¹²⁹I and ³H released and deposited on the NW Pacific Ocean after the Fukushima accident was estimated to be about 7 GBq and 0.1 PBq, respectively. Due to a suitable residence time in the ocean, Fukushima-derived radionuclides will provide useful tracers for isotope oceanography studies on the transport of water masses in the NW Pacific Ocean

Abstract. Radionuclide impact of the Fukushima Dai-ichi nuclear power plant accident on the distribution of radionuclides in seawater of the NW Pacific Ocean is compared with global fallout from atmospheric tests of nuclear weapons. Surface and water column samples collected during the Ka'imikai-o-Kanaloa (KOK) international expedition carried out in June 2011 were analyzed for 134Cs, 137Cs, 129I and 3H. The 137Cs, 129I and 3H levels in surface seawater offshore Fukushima varied between 0.002–3.5 Bq L−1, 0.01–0.8 μBq L−1, and 0.05–0.15 Bq L−1, respectively. At the sampling site about 40 km from the coast, where all three radionuclides were analyzed, the Fukushima impact on the levels of these three radionuclides represents an increase above the global fallout background by factors of about 1000, 50 and 3, respectively. The water column data indicate that the transport of Fukushima-derived radionuclides downward to the depth of 300 m has already occurred. The observed 137Cs levels in surface waters and in the water column are compared with predictions obtained from the ocean general circulation model, which indicates that the Kuroshio Current acts as a southern boundary for the transport of the radionuclides, which have been transported from the Fukushima coast eastward in the NW Pacific Ocean. The 137Cs inventory in the water column is estimated to be about 2.2 PBq, what can be regarded as a lower limit of the direct liquid discharges into the sea as the seawater sampling was carried out only in the area from 34 to 37° N, and from 142 to 147° E. About 4.6 GBq of 129I was deposited in the NW Pacific Ocean, and 2.4–7 GBq of 129I was directly discharged as liquid wastes into the sea offshore Fukushima. The total amount of 3H released and deposited over the NW Pacific Ocean was estimated to be 0.1–0.5 PBq. These estimations depend, however, on the evaluation of the total 137Cs activities released as liquid wastes directly into the sea, which should improve when more data are available. Due to a suitable residence time in the ocean, Fukushima-derived radionuclides will provide useful tracers for isotope oceanography studies on the transport of water masses during the next decades in the NW Pacific Ocean.