Distribution of authigenic and allogenic fractions in recent lake sediment: Isotopic and chemical compositions

Recent sediments in Lake Kozjak, in the Plitvice Lakes National Park, Croatia, were used to study the impact of the material delivered to the lake sediment via Rječica Brook. Sediment cores, top 40 cm, were taken near the mouth of the Rječica Brook at three locations in the lake at different distances from the shore, water depth 2-9 m and analyzed using different isotopic and chemical methods. Sediment depth profiles of the following parameters were obtained: organic and carbonate fraction, C/N analyses of organic fraction, 14C activity (a14C) and d13C values of carbonate (d13Ccarb) and organic fraction (d13Corg) and d15N of total nitrogen. The results were compared with sediment core collected in the middle of Lake Kozjak, water depth 21 m. Distribution of organic matter, C/N values, d13Corg and d13Ccarb in sediment profiles showed strong influence of terrestrial organic and carbonate fraction run-off via Rječica Brook which decreased rapidly in the direction of the open lake. The sedimentation rate as well as the ratio of allogenic and authigenic fraction in sediments was estimated. Lower d13Corg values in surface sediments might be a consequence of the increase in algal productivity but might also be a contribution of fossil fuel combustion. The anthropogenicaly induced 14C in the atmosphere in 1963/64 is visible though shadowed in sediments

Application of Stable Isotopes and Tritium in Hydrology

The Special Issue (SI) of the MDPI journal Water, entitled “Application of stable isotopes and tritium in hydrology” addresses the current state-of-the-art applications of stable isotopes and tritium in studies of hydrological processes in various compartments of the water cycle. It can be considered as a sequel of the previous SI, “Use ofWater Stable Isotopes in Hydrological Process”. However, this SI is the only (closed) special issue of the journal Water—Hydrology and Hydrogeology Section that in the title explicitly mentions “tritium”, the radioactive isotope of hydrogen of both natural (cosmogenic) and anthropogenic origin. A total of nine papers were submitted for publication and they have undergone a scrutinized review process. Eventually, six papers passed the rigorous review by at least two recognized international reviewers and extensive editorial checks. The papers compiled in this SI show a wide variety of topics: isotope distribution in precipitation and groundwater on regional scales, the relation between isotopes in precipitation and ground and drip water in a karst area, effects of evapotranspiration, and farming activities on water isotope composition. Three out of six papers describe isotope studies in a karst area of Croatia, while the other papers consider the Iberian Peninsula, the United States of America, and China