Development of a new neutron probe for borehole research

Neutronska proba za ispitivanje naftnih bušotina razvijena je na Institutu Ruđer Bošković u okviru HRZZ projekta IP-2018-01-4060 \u27\u27Nove primjene 14 MeV neutrona\u27\u27. U ovom istraživanju ispitane su daljnje mogućnosti redukcije šuma u mjerenju C/O omjera metodom pridružene alfa čestice. Mješavina kvarcnog pijeska i grafitnog praha korištena je kao materijal od interesa , dok su plastične bočice ispunjene dizel gorivom korištene kao šum (smetnja) i predstavljaju tekućinu unutar naftne bušotine (npr. nafta). Podjela alfa detektora na četiri jednaka segmenta, omogućila je podjelu volumena oko osi neutronske probe na četiri kvadranta. Materijal od interesa i dizel smješteni su u različite kvadrante i pokazano je da su C/O vrijednosti u slučajevima kad je smetnja prisutna unutar statističke greške u odnosu na slučaj kada smetnje nema.The neutron probe for testing oil wells was developed at the Ruđer Bošković Institute within the HRZZ project IP-2018-01-4060 "New applications of 14 MeV neutrons". In this study, further possibilities of noise reduction in C/O ratio measurement by the associated alpha particle method were investigated. A mixture of quartz sand and graphite powder was used as the material of interest, while plastic bottles filled with diesel fuel were used as noise (interference) and represent the liquid inside the oil well (e.g. oil). Dividing the alpha detector into four equal segments, allowed portioning the volume around the neutron probe axis into four quadrants. The material of interest and diesel were located in different quadrants and it is shown that the C/O values in cases where interference is present are within statistical errors compared to the case where there is no interference

Could atmospheric carbon be driving sedimentation?

Purpose The objective of this study was to provide insights into the most recent responses of sediments to climate change and their capability to sequester atmospheric carbon (C). Methods Three sediment cores were collected, one from the western Black Sea, and two from the southern Adriatic Sea. Cores were extruded and sectioned into 1 cm or 0.5 cm intervals. Sections were frozen, weighed, freeze-dried, and then weighed again to obtain dry weights. Freeze-dried samples were dated by using lead 210 (Pb-210) and cesium 137/ americium 241 (Cs-137/Am-241). Organic and inorganic C were determined by combustion. Particle size distribution was determined using a Beckman Coulter particle size analyzer (LS 13,320; Beckman Coulter Inc.). Mineralogical analyses were carried out by a Philips X'Pert powder diffractometer. Results Sedimentation and organic and inorganic C accumulation rates increased with time in both the Black Sea and the Adriatic Sea. The increase in accumulation rates continued after the global introduction in the early 1970s of controls on the release of phosphorus (P) into the environment and despite the reduced sediment yield of major rivers (Po and Danube). Therefore, the increased accumulation of organic and inorganic C in the sediments cannot be assigned only to nutrient availability. Instead, we suggest that the increase in organic C is the consequence of the increase in atmospheric C, which has made more carbon dioxide (CO2) available to phytoplankton, thus enabling more efficient photosynthesis. This process known as CO2 fertilization may increase the organic C accumulation in sediments. Simultaneously, the increase of sea temperatures decreases the calcite solubility resulting in increases of the inorganic C accumulation. Conclusion Our results suggest that long-term, general increases in accumulation rates of organic and inorganic C in sediments are the consequence of increases in atmospheric C. This shows that coastal sediments play an important role in C uptake and thus in regulating the Earth's climate.Croatian Science Foundation-Youth Careers Development Project [ESF-DOK-1-2018]; Croatian Science Foundation [IP-01-2018]AV acknowledges the support of the Croatian Science Foundation-Youth Careers Development Project (ESF-DOK-1-2018). JO and TK acknowledge the support of the Croatian Science Foundation project IP-01-2018

Could atmospheric carbon be driving sedimentation?

Purpose: The objective of this study was to provide insights into the most recent responses of sediments to climate change and their capability to sequester atmospheric carbon (C). Methods: Three sediment cores were collected, one from the western Black Sea, and two from the southern Adriatic Sea. Cores were extruded and sectioned into 1 cm or 0.5 cm intervals. Sections were frozen, weighed, freeze-dried, and then weighed again to obtain dry weights. Freeze-dried samples were dated by using lead 210 (210Pb) and cesium 137/ americium 241 (137Cs/241Am). Organic and inorganic C were determined by combustion. Particle size distribution was determined using a Beckman Coulter particle size analyzer (LS 13,320; Beckman Coulter Inc.). Mineralogical analyses were carried out by a Philips X’Pert powder diffractometer. Results: Sedimentation and organic and inorganic C accumulation rates increased with time in both the Black Sea and the Adriatic Sea. The increase in accumulation rates continued after the global introduction in the early 1970s of controls on the release of phosphorus (P) into the environment and despite the reduced sediment yield of major rivers (Po and Danube). Therefore, the increased accumulation of organic and inorganic C in the sediments cannot be assigned only to nutrient availability. Instead, we suggest that the increase in organic C is the consequence of the increase in atmospheric C, which has made more carbon dioxide (CO2) available to phytoplankton, thus enabling more efficient photosynthesis. This process known as CO2 fertilization may increase the organic C accumulation in sediments. Simultaneously, the increase of sea temperatures decreases the calcite solubility resulting in increases of the inorganic C accumulation. Conclusion: Our results suggest that long-term, general increases in accumulation rates of organic and inorganic C in sediments are the consequence of increases in atmospheric C. This shows that coastal sediments play an important role in C uptake and thus in regulating the Earth’s climate