![]() There is no correlation between δ7Li values and uranium activity ratios for the dissolved load for non-glacial rivers, but for glacier-fed rivers there is an increase in δ7Li with increasing (234U/238U), suggesting that where physical comminution of mineral grains by glaciers is high, chemical weathering is suppressed, and vice-versa. ![]() distribution coefficients of the more important active impurity elements in terms of their. δ7Li for the dissolved load decreases with increasing levels of dissolved silicon, and the saturation index of secondary minerals, which suggests that δ7Li decreases with increasing chemical weathering. Laboratory tests show that the membrane is able to remove radionuclides used in the medical field technetium-99m, iodine-123 and gallium-68from water with efficiencies of over 99.8 in just one. By dissolving a radioactive isotope of a given solute in the. In turn, the δ7Li value of the dissolved load is always greater than that of the bedload, ranging from 17.0 to 43.7‰. In contrast, in non-glacial rivers, uranium activity ratios increase with distance downstream due to continued weathering in soils and of bedrock. Activity ratios in glacial rivers decrease with distance from the glacial source due to input from non-glacial tributaries which have high levels of dissolved uranium and lower activity ratios. The highest (234U/238U) values are found in glacier-fed rivers, and can be attributed to α-recoil effects, as grinding by glaciers locally enhances rates of physical weathering. Uranium activity ratios, (234U/238U), are close to secular equilibrium in the suspended and bedloads, but all dissolved load samples show values greater than unity, ranging from 1.13 to 2.41. Chemical erosion rates range from 45 to 91 t/km2/yr, with lower rates being associated with glacier-fed rivers. Physical erosion rates range from 920 to 2084 t/km2/yr, with the higher values associated with glacier-fed rivers. This study presents U and Li isotope and major and trace element data for the dissolved load, suspended particulates and bedload for Icelandic rivers draining predominantly basaltic catchments. Earth and Planetary Science Letters, 251(1-2) pp. Riverine behaviour of uranium and lithium isotopes in an actively glaciated basaltic terrain. Of the first 82 elements in the periodic table, 80 have isotopes considered to be stable.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |