scholarly journals Geologic controls on phytoplankton elemental composition

2021 ◽  
Author(s):  
Shlomit Sharoni ◽  
Itay Halevy
Keyword(s):  
Organic Matter ◽  
Nutrient Enrichment ◽  
Nutrient Content ◽  
Geologic History ◽  
Marine Fauna ◽  
Average Temperature ◽  
Marine Organic Matter ◽  
Phosphate Availability ◽  
Redfield Ratios

Abstract Although the nutrient content of planktonic organic matter (C:N:Porg) plays a crucial role in marine metazoan evolution and global biogeochemistry (1–3), its geologic history is poorly constrained, and it is often regarded as a constant “Redfield” ratio of C:N:Porg~106:16:1. We calculate C:N:Porg through the Phanerozoic by including nutrient- and temperature-dependent C:N:Porg parameterizations (4–6) in a model of long-term biogeochemical cycles (7). We infer a decrease from high Paleozoic C:Porg and N:Porg to present-day Redfield ratios. This gradual nutrient enrichment of marine organic matter stems from a decrease in the global average temperature and an increase in seawater phosphate availability, which are driven by various Phanerozoic events, mainly the middle to late Paleozoic emergence and expansion of land plants and the Triassic breakup of the supercontinent Pangaea. The nutrient enrichment of planktonic organic matter likely impacted the evolution of marine fauna and global biogeochemistry.

scholarly journals Geologic controls on phytoplankton elemental composition

2021 ◽  
Vol 119 (1) ◽  
pp. e2113263118
Author(s):  
Shlomit Sharoni ◽  
Itay Halevy
Keyword(s):  
Organic Matter ◽  
Nutrient Content ◽  
Geologic History ◽  
Temperature Dependent ◽  
Marine Fauna ◽  
Growth Environment ◽  
Marine Food Web ◽  
Average Temperature ◽  
Phosphate Availability ◽  
History Of

Planktonic organic matter forms the base of the marine food web, and its nutrient content (C:N:Porg) governs material and energy fluxes in the ocean. Over Earth history, C:N:Porg had a crucial role in marine metazoan evolution and global biogeochemical dynamics, but the geologic history of C:N:Porg is unknown, and it is often regarded constant at the “Redfield” ratio of ∼106:16:1. We calculated C:N:Porg through Phanerozoic time by including nutrient- and temperature-dependent C:N:Porg parameterizations in a model of the long-timescale biogeochemical cycles. We infer a decrease from high Paleozoic C:Porg and N:Porg to present-day ratios, which stems from a decrease in the global average temperature and an increase in seawater phosphate availability. These changes in the phytoplankton’s growth environment were driven by various Phanerozoic events: specifically, the middle to late Paleozoic expansion of land plants and the Triassic breakup of the supercontinent Pangaea, which increased continental weatherability and the fluxes of weathering-derived phosphate to the oceans. The resulting increase in the nutrient content of planktonic organic matter likely impacted the evolution of marine fauna and global biogeochemistry.

scholarly journals Geologic controls on phytoplankton elemental composition

2021 ◽  
Vol 119 (1) ◽  
pp. e2113263119
Author(s):  
Shlomit Sharoni ◽  
Itay Halevy
Keyword(s):  
Organic Matter ◽  
Nutrient Content ◽  
Geologic History ◽  
Temperature Dependent ◽  
Marine Fauna ◽  
Growth Environment ◽  
Marine Food Web ◽  
Average Temperature ◽  
Phosphate Availability ◽  
History Of

Planktonic organic matter forms the base of the marine food web, and its nutrient content (C:N:Porg) governs material and energy fluxes in the ocean. Over Earth history, C:N:Porg had a crucial role in marine metazoan evolution and global biogeochemical dynamics, but the geologic history of C:N:Porg is unknown, and it is often regarded constant at the “Redfield” ratio of ∼106:16:1. We calculated C:N:Porg through Phanerozoic time by including nutrient- and temperature-dependent C:N:Porg parameterizations in a model of the long-timescale biogeochemical cycles. We infer a decrease from high Paleozoic C:Porg and N:Porg to present-day ratios, which stems from a decrease in the global average temperature and an increase in seawater phosphate availability. These changes in the phytoplankton’s growth environment were driven by various Phanerozoic events: specifically, the middle to late Paleozoic expansion of land plants and the Triassic breakup of the supercontinent Pangaea, which increased continental weatherability and the fluxes of weathering-derived phosphate to the oceans. The resulting increase in the nutrient content of planktonic organic matter likely impacted the evolution of marine fauna and global biogeochemistry.

scholarly journals Amplification and dampening of soil respiration by changes in temperature variability

2010 ◽  
Vol 7 (6) ◽  
pp. 8979-9008 ◽  
Author(s):  
C. A. Sierra ◽  
M. E. Harmon ◽  
E. Thomann ◽  
S. S. Perakis ◽  
H. W. Loescher
Keyword(s):  
Organic Matter ◽  
Soil Respiration ◽  
Anthropogenic Activities ◽  
Temperature Variability ◽  
Average Temperature ◽  
Carbon Release ◽  
Mean And Variance ◽  
Future Warming ◽  
Climatic System

Abstract. Accelerated release of carbon from soils is one of the most important feedbacks related to anthropogenically induced climate change. Studies addressing the mechanisms for soil carbon release through organic matter decomposition have focused on the effect of changes in the average temperature, with little attention to changes in temperature variability. Anthropogenic activities are likely to modify both the average state and the variability of the climatic system; therefore, the effects of future warming on decomposition should not only focus on trends in the average temperature, but also variability expressed as a change of the probability distribution of temperature. Using analytical and numerical analyses we tested common relationships between temperature and respiration and found that the variability of temperature plays an important role determining respiration rates of soil organic matter. Changes in temperature variability, without changes in the average temperature, can affect the amount of carbon released through respiration over the long-term. Furthermore, simultaneous changes in the average and variance of temperature can either amplify or dampen the release of carbon through soil respiration as climate regimes change. These effects depend on the degree of convexity of the relationship between temperature and respiration and the magnitude of the change in temperature variance. A potential consequence of this effect of variability would be higher respiration in regions where both the mean and variance of temperature are expected to increase, such as in some low latitude regions; and lower amounts of respiration where the average temperature is expected to increase and the variance to decrease, such as in northern high latitudes.

Effect of N deposition on decomposition of plant litter and soil organic matter in forest systems

1997 ◽  
Vol 5 (1) ◽  
pp. 1-25 ◽  
Author(s):  
B Berg ◽  
E Matzner
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Nutrient Content ◽  
N Deposition ◽  
Feedback Mechanism ◽  
Plant Litter ◽  
Natural Organic Compounds ◽  
Degradation Rates ◽  
Positive Feedback Mechanism

The effects of nitrogen (N) deposition on plant litter and soil organic matter decomposition differ depending on the stage of decomposition (early, late, and final stages). The effects can be divided further into direct and indirect ones. Direct effects: additions of ammonium and nitrate to fresh, newly shed litter stimulate the initial decomposition of celluloses and solubles. By contrast, addition of the same compounds to humus (final stages) clearly suppresses activity. This was seen in all studies reviewed and for several types of humus. Indirect effects: long-term deposition leads to increases in litter concentrations of N and other nutrients. This N in litter forms "natural" organic compounds and the resulting effects are similar to those resulting from natural variation among litter types. Thus, initial decomposition is generally higher for N (nutrient) rich plant litters than for litters with a lower N (nutrient) content. In later stages, at which lignin-degradation rates regulate litter decomposition, N has a retarding effect on decomposition. Significant negative correlations have also been found between N concentrations in humus and respiration rate. There probably is a sink for deposited N in the humus. We may conclude that N storage in humus is regulated by a positive feedback mechanism. Raised levels of N resulting from N deposition cause more humus to be left in the system, and the resulting lower levels of Mn further retards humus decomposition, thus leading to an increased storage of N in humus. Thus, when calculating critical loads it would be incorrect to assume that N pools in the humus remain at a steady state.

scholarly journals Amplification and dampening of soil respiration by changes in temperature variability

2011 ◽  
Vol 8 (4) ◽  
pp. 951-961 ◽  
Author(s):  
C. A. Sierra ◽  
M. E. Harmon ◽  
E. Thomann ◽  
S. S. Perakis ◽  
H. W. Loescher
Keyword(s):  
Organic Matter ◽  
Soil Respiration ◽  
Anthropogenic Activities ◽  
Temperature Variability ◽  
Average Temperature ◽  
Carbon Release ◽  
Mean And Variance ◽  
Future Warming ◽  
Climatic System

Abstract. Accelerated release of carbon from soils is one of the most important feedbacks related to anthropogenically induced climate change. Studies addressing the mechanisms for soil carbon release through organic matter decomposition have focused on the effect of changes in the average temperature, with little attention to changes in temperature variability. Anthropogenic activities are likely to modify both the average state and the variability of the climatic system; therefore, the effects of future warming on decomposition should not only focus on trends in the average temperature, but also variability expressed as a change of the probability distribution of temperature. Using analytical and numerical analyses we tested common relationships between temperature and respiration and found that the variability of temperature plays an important role determining respiration rates of soil organic matter. Changes in temperature variability, without changes in the average temperature, can affect the amount of carbon released through respiration over the long-term. Furthermore, simultaneous changes in the average and variance of temperature can either amplify or dampen the release of carbon through soil respiration as climate regimes change. These effects depend on the degree of convexity of the relationship between temperature and respiration and the magnitude of the change in temperature variance. A potential consequence of this effect of variability would be higher respiration in regions where both the mean and variance of temperature are expected to increase, such as in some low latitude regions; and lower amounts of respiration where the average temperature is expected to increase and the variance to decrease, such as in northern high latitudes.

Changes in carbon cycling across the OAE 1b cluster (Aptian-Albian transition): New insights from the Vocontian Basin

2020 ◽  
Author(s):  
Mickaël Charpentier ◽  
Clemens V. Ullmann ◽  
Arka Rudra ◽  
Hamed Sanei ◽  
Stéphane Bodin
Keyword(s):  
Organic Matter ◽  
Carbon Cycling ◽  
Carbon Isotope ◽  
Stable Carbon Isotope ◽  
Abrupt Onset ◽  
Oceanic Anoxic Event ◽  
Marine Organic Matter ◽  
Isotope Record ◽  
Stratigraphic Interval

<p>The Aptian-Albian transition is marked by the unfolding of the Oceanic Anoxic Event (OAE) 1b, a protracted environmental perturbation characterized by occurrence of several sub-events out of which the Kilian and Paquier events are the most well-known ones. So far, the conditions leading to the unfolding of the OAE 1b cluster and its sub-events, as well as their consequences, remain elusive as most of the studies have focussed on the Paquier level, thereby precluding a broader perspective on this event. In this study, we focus on an extended stratigraphic interval from the Brier section (Vocontian Basin, SE France) spaning the Kilian to Paquier levels interval. Our goal is to better understand the processes having led to organic matter (OM) accumulation across this stratigraphic interval as well as to constrain the exogenic carbon cycle framework in which these changes are inscribed. For this purpose, we have performed high-resolution bulk-rock pyrolysis analyses, paired stable carbon isotope measurements on both bulk carbonate and organic matter, and handheld XRF analyses.</p><p>Measured total organic contents (TOC) average 1.5% with peaks reaching 3% in the Paquier level. Apart for the Kilian, Paquier and HN 12 levels, which are characterized by the dominance of marine organic matter, the remainder of the studied interval is characterized by the accumulation of continental organic matter. Moreover, there is a good correlation between changes in the long-term TOC content and detrital input as inferred from changes in element concentration such as aluminium and thorium. A preservation model therefore best explains the long-term OM accumulation across the studied interval. Sporadic episodes of enhanced marine OM productivity account only for the deposition of the Kilian, Paquier and HN 12 levels.</p><p>Carbon isotope analyses shows that the Kilian and Paquier levels are both associated with a 0.5 – 1‰ negative excursion in the bulk carbonate record. In the bulk OM record, the C-isotope signal is however different. The Kilian level is hence characterized by a 3‰ negative excursion whereas the Paquier level is characterized by a 4‰ positive excursion. This discrepancy is due to the fact that the bulk OM C-isotope record is strongly influenced by the mixing of different types of organic matter. By applying a correction factor tacking into account the type of organic matter, as characterized by the pyrolysis analyses, both OM and carbonate C-isotope records can be reconciled.</p><p>Importantly, our paired C-isotope record shows that in between the Kilian and Paquier levels, two others episodes of similar negative C-isotope excursion occur, with an abrupt onset and a total amplitude of 1‰. These episodes likely correspond to the Monte Nerone level observed in Italy.  The unfolding of OAE 1b cluster is thus thightly tied to a very dynamic exogenic carbon cycling, characterized by repeated injections into the oceans-atmosphere of light isotopic carbon, potentially similar to the Early Eocene scenario.</p>

Effect of NPK fertilization on the yield of winter wheat and maize and on the nutrient content of the soil in a long-term experiment network in Hungary

2013 ◽  
Vol 62 (2) ◽  
pp. 311-330
Author(s):  
Jakab Loch ◽  
János Lazányi
Keyword(s):  
Winter Wheat ◽  
Nutrient Content ◽  
Term Experiment ◽  
Long Term Experiment ◽  
Npk Fertilization

Az Országos Műtrágyázási Tartamkísérletek (OMTK) tizenkét NPK kezeléskombinációjában, kilenc termőhelyen vizsgáltuk az NPK-trágyázás hatását az őszi búza és a kukorica termésére és a talajok 0,01 M CaCl2-oldható tápelemtartalmára. A termőhelyek: Bicsérd (BI), Hajdúböszörmény (HA), Iregszemcse (IR), Karcag (KA), Keszthely (KE), Kompolt (KO), Mosonmagyaróvár (MO), Nagyhörcsök (NA), Putnok (PU). Az NPK kezelések: 000, 101, 111, 121, 201, 220, 221, 222, 331, 341, 421, 441. A N- és P-kezelések a kódoknak megfelelően 50 kg N, ill. P2O5·ha−1, a K-adagok 100 kg K2O·ha−1 hatóanyag-mennyiséggel növekszenek. Az őszi búza termésadatok a 23., 24., 27., 28. és 31. évi kísérletekből, a kukoricatermések a 25., 26., 29. és 30. évből származnak.Az NPK-kezelések jelentősen növelték az őszi búza és a kukorica öt-, illetve négyéves átlagtermését, szignifikáns különbségek jöttek létre a termőhelyek átlagában. Az NPK-kezelések különböző érvényesülése az egyes termőhelyeken az eltérő ökológiai viszonyok, köztük a különböző eredeti tápelemtartalom és szolgáltató képesség következménye.Az NPK-kezelések hatására a talajok 0,01 M CaCl2-oldható tápelemtartalma is jelentősen változott. A növények tápelemigényét meghaladó kezelések tartamhatásaként tápelem-felhalmozódás igazolható mindhárom tápelem esetében. A növények szükségletét meghaladó N-adagok, a karbonátos talajokat és a nagy agyagtartalmú kompolti (KO) talajt kivéve csökkentették a talaj pH-t. A másodfokú görbék az őszi búza ötéves termésátlaga és a 0,01 M CaCl2-ban mért összes-N, P- és K-tartalom közötti összefüggéseket szemléltetik termőhelyenként.A legnagyobb kezeléshatások azokon a talajokon igazolhatók, melyeken a kontroll 0,01 M CaCl2-oldható összes-N értéke kisebb, mint 5–10 mg·kg−1. A 15,0 mg·kg−1 érték felett altalaban nem érvényesült a nitrogén termésnövelő hatása. Kivételt képez a tápanyagban gazdag, hajdúböszörményi nem karbonátos réti talaj. A foszfor termésnövelő hatása 2,0 mg P·kg−1 érték felett — a karbonátos réti talaj kivételével — általában nem érvényesül. Az összefüggéseket jellemző R2 meghatározottsági tényezők a legkisebbek az őszi búza és a talaj 0,01 M CaCl2-oldható K-tartalma között, ami az egyéb tényezők nagyobb szerepére utal.A bemutatott eredmények igazolják, hogy a 0,01 M CaCl2-oldható N-, P- és Kfrakciók alkalmasak a tápanyaghiány és -felesleg jellemzésére. Egyben igazolják, hogy az eltérő ökológiai viszonyok között nagyobb terméskülönbségek jöhetnek létre, mint a kezelések hatására. A környezetkímélő tápanyag-gazdálkodás megköveteli a tápanyagok eltérő érvényesülésének figyelembevételét.A termésadatok átengedéséért köszönet az OMTK Hálózati Tanács elnökének, titkárának, és valamennyi kísérletfelelősnek.

Influence of long-term fertilization on soil microbial biomass and dehydrogenase activity in relation to crop productivity in an acid Inceptisols

2019 ◽  
Vol 56 (3) ◽  
pp. 305-311
Author(s):  
Debasis Purohit ◽  
Mitali Mandal ◽  
Avisek Dash ◽  
Kumbha Karna Rout ◽  
Narayan Panda ◽  
...  
Keyword(s):  
Microbial Biomass ◽  
Dehydrogenase Activity ◽  
Nutrient Content ◽  
Crop Productivity ◽  
Maturity Stage ◽  
Microbial Biomass Nitrogen ◽  
Biological Potential ◽  
Initiation Stage ◽  
The Impact

An effective approach for improving nutrient use efficiency and crop productivity simultaneously through exploitation of biological potential for efficient acquisition and utilization of nutrients by crops is very much needed in this current era. Thus, an attempt is made here to investigate the impact of long term fertilization in the soil ecology in rice-rice cropping system in post kharif - 2015 in flooded tropical rice (Oryza sativa L.) in an acidic sandy soil. The experiment was laid out in a randomized block design with quadruplicated treatments. Soil samples at different growth stages of rice were collected from long term fertilizer experiment.The studied long-term manured treatments included 100 % N, 100% NP, 100 % NPK, 150 % NPK and 100 % NPK+FYM (5 t ha-1) and an unmanured control. Soil fertility status like SOC content and other available nutrient content has decreased continuously towards the crop growth period. Comparing the results of different treatments, it was found that the application of 100% NPK + FYM exhibited highest nutrient content in soils. With regards to microbial properties it was also observed that the amount of microbial biomass carbon (MBC) and microbial biomass nitrogen ( MBN) showed highest accumulation in 100 % NPK + FYM at maximum tillering stage of the rice. The results further reveal that dehydrogenase activity was maximum at panicle initiation stage and thereafter it decreases. Soil organic carbon content, MBC, MBN and dehydrogenase activity were significantly correlated with each other. Significant correlations were observed between rice yield and MBC at maturity stage( R2 = 0.94**) and panicle initiation stage( R2 = 0.92**) and available nitrogen content at maturity stage( R2 = 0.91**).

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