Quantification and evaluation of soil organic carbon and its fractions: case study from the Classical Karst, SW Slovenia

 Soil organic carbon (SOC) is a critical measure of soil organic matter (SOM) content. SOM plays a vital role in ecosystem services, soil fertility, soil water retention capacity, and carbon cycling. SOC can be partitioned into various carbon fractions, which exhibit diverse stability and chemical compositions that are influenced variably by lithology as well as biological and cli­matic processes. A better understanding of SOC and the influ­ence of different bedrock types on carbon fractions could facili­tate the evaluation of the fate and stability of SOC. The present study is focused on the concentrations and characteristics of different SOC fractions (e.g., Labile organic carbon, LOC; Re­calcitrant organic carbon, ROC; Calcium-bound organic car­bon, Ca-SOC; Iron/aluminium-bound organic carbon, Fe/Al-SOC) in forest soils associated with different bedrock lithology under similar climate conditions in the centre of the ‘Classical Karst’, and evaluates influence of the geological environment on SOC. SOC and SOC fraction concentrations decreased with an increase in depth in all profiles, indicating stabilized soil profiles. SOC values (9.7–45.5 g∙kg-1) were consistent with the findings of other studies on soils in the region. ROC and Fe/Al-SOC (51.5–65.8 % and 68.0–73.3 %, respectively) were the ma­jor SOC fractions, while Ca-SOC accounted for a considerably lower proportion (6.4–7.4 %) of the SOC contents. Key factors influencing SOC contents were calcite (expressed as calcium oxide) and clay contents, which represent mineral complexes stabilizing SOC. Overall Fe2O3 and Al2O3 concentration did not explain differences in SOC nor its fractions, potentially due to the importance of chemical/mineral forms of Fe- and Al-related minerals (reactivity). Soils on carbonate rocks, which are richer in clay and CaO, had 6.35 g∙kg-1 (28 percentage points) higher concentrations of SOC average when compared with soils on siliciclastic rock, due to higher concentrations of stabilized SOC fractions. The results demonstrate that bedrock lithology and pedogenesis are key factors influencing SOM stabilization.Key words: karst soil, soil organic carbon, labile organic carbon, recalcitrant organic carbon, calcium-bound organic carbon, iron/aluminium-bound organic carbon.Kvantifikacija in vrednotenje organskega ogljika in njegovih frakcij v tleh: primer s Klasičnega Krasa, JZ SlovenijaZ meritvami organskega ogljika v prsteh (SOC) izražamo vsebnost organskih snovi v prsteh (SOM). SOM igra ključno vlogo pri ekosistemskih storitvah, rodovitnosti, zmogljivosti zadrževanja vode in kroženju ogljika. SOC lahko razdelimo na različne ogljikove frakcije, ki kažejo različno stabilnost in kemično sestavo, na katero različno vplivajo litološka zgradba, biološki in podnebni procesi. Boljše razumevanje SOC in vpliv različnih vrst matične podlage na ogljikove frakcije bi lahko olajšala oceno stabilnosti SOC. Ta študija preučuje koncentracije in dinamiko različnih frakcij SOC (npr. labilni organski ogljik, LOC; rekalcitrantni organski ogljik, ROC; organski ogljik, vezan na kalcij; organski ogljik, vezan na železo/aluminij, Fe/Al-SOC) v gozdnih prsteh in povezanost z različno litološko zgradbo v podobnih podnebnih razmerah. Prostorsko se študija osredotoča na območje klasičnega krasa. Koncentracija SOC in njegove frakcije so se z naraščajočo globino v vseh profilih zmanjšale, kar kaže na relativno uravnotežene profile prsti. Vrednosti SOC (9,7–45,5 g∙kg-1) so skladne z ugotovitvami drugih raziskav prsti v regiji. ROC in Fe/Al-SOC (51,5–65,8 % oziroma 68,0–73,3 %) sta bili glavni komponenti SOC, medtem ko je za Ca-SOC značilen bistveno nižji delež (6,4–7,4 %). Ključna dejavnika, ki vplivata na vsebnost SOC, sta vsebnost kalcita (izražen kot kalcijev oksid) in gline; tadva s SOC tvorita mineralne komplekse, ki stabilizirajo SOC. Vrednosti Fe2O3 in Al2O3 ne pojasnjujejo razlik SOC niti njegovih frakcij, kar je lahko posledica različnega vpliva kemičnih/mineralnih oblik železovih oz. aluminijevih spojin na reaktivnost. Prsti na karbonatnih kamninah, ki so bogatejše z delci velikosti glin in CaO, so imele zaradi višjih koncentracij stabiliziranih SOC frakcij za 6,35 g∙kg-1 (28 odstotnih točk) višje povprečne vrednosti SOC v primerjavi prstmi na siliciklastičnih (flišnih) kamninah. Rezultati kažejo, da sta osnovna dejavnika, ki vplivata na stabilizacijo SOM, litološka zgradba in pedogeneza.Ključne besede: kraške prsti, organski ogljik v tleh, labilni organski ogljik, rekalcitrantni organski ogljik, organski ogljik, vezan na kalcij, organski ogljik, vezan na železo/aluminij.

The Ginger-shaped Asteroid 4179 Toutatis: New Observations from a Successful Flyby of Chang'e-2

On 13 December 2012, Chang'e-2 conducted a successful flyby of the near-Earth asteroid 4179 Toutatis at a closest distance of 770 $\pm$ 120 meters from the asteroid's surface. The highest-resolution image, with a resolution of better than 3 meters, reveals new discoveries on the asteroid, e.g., a giant basin at the big end, a sharply perpendicular silhouette near the neck region, and direct evidence of boulders and regolith, which suggests that Toutatis may bear a rubble-pile structure. Toutatis' maximum physical length and width are (4.75 $\times$ 1.95 km) $\pm$10$\%$, respectively, and the direction of the +$z$ axis is estimated to be (250$\pm$5$^\circ$, 63$\pm$5$^\circ$) with respect to the J2000 ecliptic coordinate system. The bifurcated configuration is indicative of a contact binary origin for Toutatis, which is composed of two lobes (head and body). Chang'e-2 observations have significantly improved our understanding of the characteristics, formation, and evolution of asteroids in general.Comment: 21 pages, 3 figures, 1 tabl

Mutations of genes in synthesis of the carotenoid precursors of ABA lead to pre-harvest sprouting and photo-oxidation in rice

Pre-harvest sprouting (PHS) or vivipary in cereals is an important agronomic trait that results in significant economic loss. A considerable number of mutations that cause PHS have been identified in several species. However, relatively few viviparous mutants in rice (Oryza sativa L.) have been reported. To explore the mechanism of PHS in rice, we carried out an extensive genetic screening and identified 12 PHS mutants (phs). Based on their phenotypes, these phs mutants were classified into three groups. Here we characterize in detail one of these groups, which contains mutations in genes encoding major enzymes of the carotenoid biosynthesis pathway, including phytoene desaturase (OsPDS), ζ-carotene desaturase (OsZDS), carotenoid isomerase (OsCRTISO) and lycopene β-cyclase (β-OsLCY), which are essential for the biosynthesis of carotenoid precursors of ABA. As expected, the amount of ABA was reduced in all four phs mutants compared with that in the wild type. Chlorophyll fluorescence analysis revealed the occurrence of photoinhibition in the photosystem and decreased capacity for eliminating excess energy by thermal dissipation. The greatly increased activities of reactive oxygen species (ROS) scavenging enzymes, and reduced photosystem (PS) II core proteins CP43, CP47 and D1 in leaves of the Oscrtiso/phs3-1 mutant and OsLCY RNAi transgenic rice indicated that photo-oxidative damage occurred in PS II, consistent with the accumulation of ROS in these plants. These results suggest that the impairment of carotenoid biosynthesis causes photo-oxidation and ABA-deficiency phenotypes, of which the latter is a major factor controlling the PHS trait in rice

Structural and mechanistic insights into the biosynthesis of CDP-archaeol in membranes

The divergence of archaea, bacteria and eukaryotes was a fundamental step in evolution. One marker of this event is a major difference in membrane lipid chemistry between these kingdoms. Whereas the membranes of bacteria and eukaryotes primarily consist of straight fatty acids ester-bonded to glycerol-3-phosphate, archaeal phospholipids consist of isoprenoid chains ether-bonded to glycerol-1-phosphate. Notably, the mechanisms underlying the biosynthesis of these lipids remain elusive. Here, we report the structure of the CDP-archaeol synthase (CarS) of Aeropyrum pernix (ApCarS) in the CTP- and Mg(2+)-bound state at a resolution of 2.4 Å. The enzyme comprises a transmembrane domain with five helices and cytoplasmic loops that together form a large charged cavity providing a binding site for CTP. Identification of the binding location of CTP and Mg(2+) enabled modeling of the specific lipophilic substrate-binding site, which was supported by site-directed mutagenesis, substrate-binding affinity analyses, and enzyme assays. We propose that archaeol binds within two hydrophobic membrane-embedded grooves formed by the flexible transmembrane helix 5 (TM5), together with TM1 and TM4. Collectively, structural comparisons and analyses, combined with functional studies, not only elucidated the mechanism governing the biosynthesis of phospholipids with ether-bonded isoprenoid chains by CTP transferase, but also provided insights into the evolution of this enzyme superfamily from archaea to bacteria and eukaryotes.Cell Research advance online publication 29 September 2017; doi:10.1038/cr.2017.122

Texture Evolution and Grain Competition in NiGe Film on Ge(001)

National Natural Science Foundation of China [61176092, 61036003, 60837001]; National Basic Research Program of China [2012CB933503, 2013CB632103]; Ph. D. Programs Foundation of Ministry of Education of China [20110121110025]; Fundamental Research Funds for the Central Universities [2010121056]; Natural Science Foundation of Fujian Province of China [2012J01284]; Opened Fund of the State Key Laboratory on Integrated Optoelectronics [2011KFB004]To understand the agglomeration mechanism of NiGe films grown on Ge(001), texture structures of NiGe films are revealed by X-ray pole figure measurement. Two preferred epitaxial orientations of the NiGe grains are identified to be NiGe(4 (5) over bar4) II Ge(001) NiGe[(1) over bar 01] II Ge[110] and NiGe(130) II Ge(001) NiGe[002] II Ge[110]. The component of the first epitaxial alignment becomes dominating and the latter diminishing with increasing annealing temperature. The NiGe grains of the second epitaxial alignment are unstable and diminishing at high temperature due to the relatively higher interface/surface energy. The competition of grains with various epitaxial orientations has made a significant contribution to film agglomeration. (C) 2013 The Japan Society of Applied Physic

Effects of Trade Liberalization on Agriculture in China: Institutional and Structural Aspects

This book analyzes institutional and structural aspects of the effects of trade liberalization on agriculture in China. The study stresses the analysis of trade-related policies, physical infrastructure, institutions and performance in international trade. It discusses such commodities as rice, maize, soybean, peanuts, frozen pork, canned food, raw silk, wheat, vegetable oils, sugar and raw wool. This book gives readers a general view of trade liberalization in China

Effects of Trade Liberalization on Agriculture in China: Commodity Aspects

This book analyzes commodity aspects of the effects of trade liberalization on agriculture in China. The study describes the effects of trade liberalization on selected commodities namely rice, wheat, maize, soybean, sweet potato, potato, other grains, pork, beef, mutton, poultry, egg, milk and fish at the national level and farm level. The analysis included ex-ante and ex-post welfare gain and loss at the national level and profitability at the farm level

Effects of Trade Liberalization on Agriculture in China: Commodity Aspects

This book analyzes commodity aspects of the effects of trade liberalization on agriculture in China. The study describes the effects of trade liberalization on selected commodities namely rice, wheat, maize, soybean, sweet potato, potato, other grains, pork, beef, mutton, poultry, egg, milk and fish at the national level and farm level. The analysis included ex-ante and ex-post welfare gain and loss at the national level and profitability at the farm level.trade liberalization, agricultural products, production, consumption, International Relations/Trade,