scholarly journals Coastal primary productivity changes over the last millennium: a case study from the Skagerrak (North Sea)

2018 ◽  
Vol 15 (19) ◽  
pp. 5909-5928 ◽  
Author(s):  
Anna Binczewska ◽  
Bjørg Risebrobakken ◽  
Irina Polovodova Asteman ◽  
Matthias Moros ◽  
Amandine Tisserand ◽  
...  
Keyword(s):  
Organic Matter ◽  
Human Impact ◽  
Primary Productivity ◽  
Industrial Development ◽  
Variable Temperature ◽  
Nutrient Content ◽  
Atlantic Water ◽  
Ice Age ◽  
14C Dating ◽  
Climate Conditions

Abstract. A comprehensive multi-proxy study on two sediment cores from the western and central Skagerrak was performed in order to detect the variability and causes of marine primary productivity changes in the investigated region over the last 1100 years. The cores were dated by Hg pollution records and AMS 14C dating and analysed for palaeoproductivity proxies such as total organic carbon, δ13C, total planktonic foraminifera, benthic foraminifera (total assemblages as well as abundance of Brizalina skagerrakensis and other palaeoproductivity taxa) and palaeothermometers such as Mg∕Ca and δ18O. Our results reveal two periods with changes in productivity in the Skagerrak region: (i) a moderate productivity at ∼ CE 900–1700 and (ii) a high productivity at ∼ CE 1700–present. During ∼ CE 900–1700, moderate productivity was likely driven by the nutrients transported with the warm Atlantic water inflow associated with a tendency for a persistent positive NAO phase during the warm climate of the Medieval Climate Anomaly, which continues into the LIA until ∼ CE 1450. The following lower and more variable temperature period at ∼ CE 1450–1700 was likely caused by a reduced contribution of warm Atlantic water, but stronger deep-water renewal, due to a generally more negative NAO phase and a shift to the more variable and generally cooler climate conditions of the Little Ice Age. The productivity and fluxes of organic matter to the seafloor did not correspond to the temperature and salinity changes recorded in the benthic Melonis barleeanus shells. For the period from ∼ CE 1700 to the present day, our data point to an increased nutrient content in the Skagerrak waters. This increased nutrient content was likely caused by enhanced inflow of warm Atlantic water, increased Baltic outflow, intensified river runoff, and enhanced human impact through agricultural expansion and industrial development. Intensified human impact likely increased nutrient transport to the Skagerrak and caused changes in the oceanic carbon isotope budget, known as the Suess effect, which is clearly visible in our records as a negative shift in δ13C values from ∼ CE 1800. In addition, a high appearance of S. fusiformis during the last 70 years at both studied locations suggests increased decaying organic matter at the sea floor after episodes of enhanced primary production.

scholarly journals Coastal primary productivity changes over the last millennium: a case study from the Skagerrak (North Sea)

2018 ◽  
Author(s):  
Anna Binczewska ◽  
Bjørg Risebrobakken ◽  
Irina Polovodova Asteman ◽  
Matthias Moros ◽  
Amandine Tisserand ◽  
...  
Keyword(s):  
Human Impact ◽  
Primary Productivity ◽  
River Runoff ◽  
Industrial Development ◽  
Sediment Cores ◽  
Nutrient Content ◽  
Atlantic Water ◽  
Ice Age ◽  
14C Dating ◽  
Climate Conditions

Abstract. A comprehensive multi-proxy study on two sediment cores from western and central Skagerrak was performed in order to detect the variability and causes of marine primary productivity changes in the investigated region over the last 1100 years. The cores were dated by Hg pollution records and AMS 14C dating and analysed for palaeoproductivity proxies such as total organic carbon, δ13C, total planktonic foraminifera, benthic foraminifera (total as well as abundance of Brizalina skagerrakensis and other palaeoproductivity taxa) and palaeothermometers such as Mg / Ca and δ18O. Our results reveal three periods with changes in productivity in the Skagerrak region: (i) moderate productivity at ~ CE 900–1200; (ii) low to moderate productivity at ~ CE 1200–1600 and (iii) high productivity at ~ CE 1600–present. During ~ CE 900–1200, moderate productivity was likely driven by the nutrients transported with the warm Atlantic water inflow associated with a tendency for a persistent positive NAO phase during the warm climate of the Medieval Climate Anomaly. The following low productivity period at ~ CE 1200–1600 was likely caused by a lower contribution of nutrient-rich Atlantic water due to a generally more negative NAO phase and a shift to the more variable and generally cooler climate conditions of the Little Ice Age. At that time the nutrient supply was largely sustained by the Baltic Sea outflow and river runoff associated with land-use changes. Since ~ CE 1600 towards present day our data point to an increased nutrient content in the Skagerrak waters. This increased nutrient content was likely caused by enhanced inflow of warm Atlantic water, increased Baltic outflow, intensified river runoff and enhanced human impact through agriculture expansion and industrial development. Intensified human impact likely increased nutrient transport to the Skagerrak and caused changes in the oceanic carbon isotope budget, known as the Suess effect, which is clearly visible in our records as a negative shift in δ13C values from ~ CE 1750. In addition, a higher benthic foraminiferal Mn / Ca suggests slightly decreased bottom water oxygen conditions between ~ CE 1050 and 1400 in the central Skagerrak and in the last 70 years at both studied locations.

scholarly journals Last millennium environmental changes and climate inferences in the Southeastern Atlantic forest, Brazil

2010 ◽  
Vol 82 (3) ◽  
pp. 717-729 ◽  
Author(s):  
Luiz C.R. Pessenda ◽  
Soraya E.M.G. Saia ◽  
Susy E.M. Gouveia ◽  
Marie-Pierre Ledru ◽  
Abdelfettah Sifeddine ◽  
...  
Keyword(s):  
Organic Matter ◽  
Environmental Changes ◽  
Ice Age ◽  
Southeastern Brazil ◽  
C3 Plants ◽  
14C Dating ◽  
Data Set ◽  
The Core ◽  
Arboreal Pollen ◽  
Made In

This study presents paleoenvironmental data based on pollen, elemental and isotopic compositions of organic matter (TOC, N, d13C and d15N) and 14C dating of 170 cm lake sediment record. Samplings have been made in Lagoa Grande at Parque Estadual Turístico do Alto Ribeira - PETAR, Southern São Paulo State, Southeastern Brazil. The variations in relative frequencies (in percentage) of arboreal pollen along the core range between 40 and 80%. The d13C values ranged from -23‰ to -30‰ and C/N of ~10 to 15, indicating the contribution of terrestrial C3 plants and algae in the sediment organic matter. The d15N results presented values from 3 to 4.5‰, also suggesting a mixture of algae and terrestrial C3 plants. The 14C dating indicates modern age for the shallow horizons to ~1030 BP at the base of the core. A probable wetter climate in the period of ~370 BP to ~340 BP was inferred from the data set, which corresponds to a part of the period covered by the Little Ice Age (LIA).

Is volcanic ash responsible for the enrichment of organic carbon in shales? Quantitative characterization of organic-rich shale at the Ordovician-Silurian transition

2020 ◽  
Author(s):  
Ke Zhao ◽  
Xuebin Du ◽  
Yongchao Lu ◽  
Fang Hao ◽  
Zhanhong Liu ◽  
...  
Keyword(s):  
Organic Matter ◽  
Organic Carbon ◽  
Primary Productivity ◽  
Volcanic Ash ◽  
Trace Element Analysis ◽  
Nutrient Content ◽  
Major Elements ◽  
Redox Conditions ◽  
Element Analysis ◽  
High Productivity

Subaerial volcanism and atmospheric volcanic ash deposition have been recognized as factors that can greatly affect the nutrient content of the surface ocean and the redox conditions of the water column. Black siliceous, organic-rich mudstone and shale containing numerous volcanic ash layers were deposited in the South China Block during the Ordovician-Silurian transition. Although this association has been observed in other regions, whether there is a relationship between volcanic ash and the organic carbon contents and the effect of volcanic ash remains unclear. Based on analysis of the concentrations of major elements, trace elements, and total organic carbon in the volcanic ash and shale, we found that anoxic and high-productivity environments existed during the Ordovician-Silurian transition and that organic matter was preferentially preserved under these conditions. For the volcanic ash, we quantitatively estimated the depletion of the nutrient elements Fe, Si, and P (in percentages). The calculated results show that leaching removed 25−75% of the Fe, Si, and P in most of the ash samples in the study area, potentially leading to high marine primary productivity in the surface water. Redox conditions also played a major role in the preservation of organic matter. The trace element analysis results show that although productivity was high during the Ordovician-Silurian transition, organic matter was preferentially preserved in the Lower Silurian strata. Therefore, high organic matter flux and good preservation conditions both contributed to the formation of the organic-rich shale, and volcanic ash was the dominant source of nutrients for primary productivity.

scholarly journals Analisis Kandungan Bahan Organik, Nitrat dan Fosfat pada Sedimen Mangrove Jenis Avicennia dan Rhizophora di Desa Tapak Tugurejo, Semarang The Analysis of Organic Content, Nitrate, Phosphate in the Sediment of Mangrove Rhizophora dan Avicennia at Tapak Village, Tugurejo Semarang

2020 ◽  
Vol 9 (2) ◽  
pp. 107-114
Author(s):  
Lalik Salistia Citra ◽  
Supriharyono Supriharyono ◽  
Suryanti Suryanti
Keyword(s):  
Organic Matter ◽  
Primary Productivity ◽  
Random Sampling ◽  
Sampling Method ◽  
Organic Matter Content ◽  
Nutrient Content ◽  
Organic Content ◽  
Matter Content ◽  
Nitrate Content ◽  
Sediment Sampling

ABSTRAKKawasan Tugu merupakan kawasan pesisir yang ditanami mangrove yang bermanfaat untuk menanggulangi dampak abrasi dan memiliki produktivitas yang tinggi, sehingga  perlu untuk dikaji kandungan nutriennya. Tujuan penelitian ini untuk mengkaji perbedaan kandungan nutrien pada sedimen antar stasiun dan antar  tegakan Avicennia dan Rhizophora. Penelitian ini dilaksanakan pada Bulan November 2019 di Desa Tapak Tugurejo, Semarang dengan menggunakan metode purposive random sampling. Pengambilan sampel sedimen dilakukan pada empat stasiun pengamatan. Hasil penelitian menunjukkan rata-rata kandungan bahan organik pada tegakan Avicennia dan Rhizophora di keempat stasiun berturut-turut adalah 10,67% dan 13,21%.  Rata-rata kandungan nitrat pada tegakan Avicennia dan Rhizophora di keempat stasiun berturut-turut adalah 5,42 mg/100 g dan 5,6 mg/100 g. Rata-rata kandungan fosfat pada tegakan Avicennia dan Rhizophora di keempat stasiun berturut-turut adalah 1,16 mg/100 g dan 1,74 mg/100 g. Berdasarkan analisis kandungan bahan organik, nitrat dan fosfat antar tegakan mangrove tidak berbeda nyata (P>0,05), artinya kandungan nutrien tidak dipengaruhi oleh jenis mangrove Avicennia ataupun Rhizophora. ABSTRACTTugu area is a coastal area planted by mangroves that is useful to overcome the impacf of abration and has high primary productivity so it needs to be reviewed. This study aims to examine the differences of nutrient content in sediments between stations and between Avicennia and Rhizophora grounds. The study was conducted in November 2019 at Tapak Tugurejo Village, Semarang using a purposive random sampling method. Sediment sampling at four observation stations with the specified point, namely Avicennia and Rhizophora. The results showed the average organic matter content in Avicennia and Rhizophora stands at the four stations are 10,67% and 13,21% respectively. The average nitrate content in Avicennia and Rhizophora grounds in the four stations are 5,42 mg/100 g and 5,6 mg/100 g respectively. The average phosphate content in Avicennia and Rhizophora grounds in the four stations are 1,16 mg/100 g and 1,74 mg/100 g respectively. Based on result of the analysis organic matter content, nitrate and phosphate between mangrove stands was not significantly different (P>0,05). It means that the nutrient content was not influenced by the types of Avicennia or Rhizophora mangroves.   

scholarly journals Ocean acidification of a coastal Antarctic marine microbial community reveals a critical threshold for CO<sub>2</sub> tolerance in phytoplankton productivity

2018 ◽  
Vol 15 (1) ◽  
pp. 209-231 ◽  
Author(s):  
Stacy Deppeler ◽  
Katherina Petrou ◽  
Kai G. Schulz ◽  
Karen Westwood ◽  
Imojen Pearce ◽  
...  
Keyword(s):  
Organic Matter ◽  
Ocean Acidification ◽  
Primary Productivity ◽  
Phytoplankton Community ◽  
Bacterial Abundance ◽  
Critical Threshold ◽  
Bacterial Productivity ◽  
High Co2 ◽  
Chl A ◽  
Antarctic Marine

Abstract. High-latitude oceans are anticipated to be some of the first regions affected by ocean acidification. Despite this, the effect of ocean acidification on natural communities of Antarctic marine microbes is still not well understood. In this study we exposed an early spring, coastal marine microbial community in Prydz Bay to CO2 levels ranging from ambient (343 µatm) to 1641 µatm in six 650 L minicosms. Productivity assays were performed to identify whether a CO2 threshold existed that led to a change in primary productivity, bacterial productivity, and the accumulation of chlorophyll a (Chl a) and particulate organic matter (POM) in the minicosms. In addition, photophysiological measurements were performed to identify possible mechanisms driving changes in the phytoplankton community. A critical threshold for tolerance to ocean acidification was identified in the phytoplankton community between 953 and 1140 µatm. CO2 levels  ≥ 1140 µatm negatively affected photosynthetic performance and Chl a-normalised primary productivity (csGPP14C), causing significant reductions in gross primary production (GPP14C), Chl a accumulation, nutrient uptake, and POM production. However, there was no effect of CO2 on C : N ratios. Over time, the phytoplankton community acclimated to high CO2 conditions, showing a down-regulation of carbon concentrating mechanisms (CCMs) and likely adjusting other intracellular processes. Bacterial abundance initially increased in CO2 treatments  ≥ 953 µatm (days 3–5), yet gross bacterial production (GBP14C) remained unchanged and cell-specific bacterial productivity (csBP14C) was reduced. Towards the end of the experiment, GBP14C and csBP14C markedly increased across all treatments regardless of CO2 availability. This coincided with increased organic matter availability (POC and PON) combined with improved efficiency of carbon uptake. Changes in phytoplankton community production could have negative effects on the Antarctic food web and the biological pump, resulting in negative feedbacks on anthropogenic CO2 uptake. Increases in bacterial abundance under high CO2 conditions may also increase the efficiency of the microbial loop, resulting in increased organic matter remineralisation and further declines in carbon sequestration.

scholarly journals Late Holocene environmental reconstructions and their implications on flood events, typhoon, and agricultural activities in NE Taiwan

2014 ◽  
Vol 10 (5) ◽  
pp. 1857-1869 ◽  
Author(s):  
L.-C. Wang ◽  
H. Behling ◽  
T.-Q. Lee ◽  
H.-C. Li ◽  
C.-A. Huh ◽  
...  
Keyword(s):  
Little Ice Age ◽  
Southern Oscillation ◽  
Phase 1 ◽  
Warm Pool ◽  
Ice Age ◽  
Agricultural Activities ◽  
Flood Events ◽  
Climate Conditions ◽  
Hydrological Conditions ◽  
Enso Events

Abstract. We reconstructed paleoenvironmental changes from a sediment archive of a lake in the floodplain of the Ilan Plain of NE Taiwan on multi-decadal resolution for the last ca. 1900 years. On the basis of pollen and diatom records, we evaluated past floods, typhoons, and agricultural activities in this area which are sensitive to the hydrological conditions in the western Pacific. Considering the high sedimentation rates with low microfossil preservations in our sedimentary record, multiple flood events were. identified during the period AD 100–1400. During the Little Ice Age phase 1 (LIA 1 – AD 1400–1620), the abundant occurrences of wetland plant (Cyperaceae) and diatom frustules imply less flood events under stable climate conditions in this period. Between AD 500 and 700 and the Little Ice Age phase 2 (LIA 2 – AD 1630–1850), the frequent typhoons were inferred by coarse sediments and planktonic diatoms, which represented more dynamical climate conditions than in the LIA 1. By comparing our results with the reconstructed changes in tropical hydrological conditions, we suggested that the local hydrology in NE Taiwan is strongly influenced by typhoon-triggered heavy rainfalls, which could be influenced by the variation of global temperature, the expansion of the Pacific warm pool, and the intensification of El Niño–Southern Oscillation (ENSO) events.

scholarly journals Multidecadal to millennial marine climate oscillations across the Denmark Strait (~ 66° N) over the last 2000 cal yr BP

2014 ◽  
Vol 10 (1) ◽  
pp. 325-343 ◽  
Author(s):  
J. T. Andrews ◽  
A. E. Jennings
Keyword(s):  
North Atlantic ◽  
Low Frequency ◽  
Atlantic Water ◽  
Ice Age ◽  
The North ◽  
Denmark Strait ◽  
Water Stratification ◽  
The North Atlantic Oscillation ◽  
Frequency Variations ◽  
Marine Climate

Abstract. In the area of Denmark Strait (~66° N), the two modes of the North Atlantic Oscillation (NAO) and Arctic Oscillation (AO) are expressed in changes of the northward flux of Atlantic water and the southward advection of polar water in the East Iceland current. Proxies from marine cores along an environmental gradient from extensive to little or no drift ice, capture low frequency variations over the last 2000 cal yr BP. Key proxies are the weight% of calcite, a measure of surface water stratification and nutrient supply, the weight% of quartz, a measure of drift ice transport, and grain size. Records from Nansen and Kangerlussuaq fjords show variable ice-rafted debris (IRD) records but have distinct mineralogy associated with differences in the fjord catchment bedrock. A comparison between cores on either side of the Denmark Strait (MD99-2322 and MD99-2269) show a remarkable millennial-scale similarity in the trends of the weight% of calcite with a trough reached during the Little Ice Age. However, the quartz records from these two sites are quite different. The calcite records from the Denmark Strait parallel the 2000 yr Arctic summer-temperature reconstructions; analysis of the detrended calcite and quartz data reveal significant multi-decadal–century periodicities superimposed on a major environmental shift occurring ca. 1450 AD.

scholarly journals Separation and 14C Dating of Pure Pollen from Lake Sediments: Nanofossil AMS Dating

Radiocarbon ◽  
1992 ◽  
Vol 34 (3) ◽  
pp. 557-560 ◽  
Author(s):  
Austin Long ◽  
Owen K. Davis ◽  
Jeanne de Lanois
Keyword(s):  
Organic Matter ◽  
Lake Sediments ◽  
Mono Lake ◽  
Bulk Sediment ◽  
Clean Room ◽  
14C Dating ◽  
Ams Dating

We have developed and tested a practical device for manually separating pollen from pollen concentrates in sufficient quantity for AMS 14C dating. It is a combination of standard, commercially available equipment handled in a clean room by an individual trained to recognize pollen. A typical example requires about 15–20 h of hand-picking under the microscope. We show the usefulness of this procedure with results on a mid-Holocene segment from a core from Mono Lake. Sediments from this hardwater lake contain pollen and finely disseminated organic matter, but no macrofossils. The pollen dated ca. 1000 yr younger than the bulk sediment. The sediment “date” is most likely affected by incorporation of limestone-derived carbon, and is erroneously old.

scholarly journals Climatic variability and human impact during the last 2000 years in western Mesoamerica: evidence of late Classic (AD 600–900) and Little Ice Age drought events

2015 ◽  
Vol 11 (9) ◽  
pp. 1239-1248 ◽  
Author(s):  
A. Rodríguez-Ramírez ◽  
M. Caballero ◽  
P. Roy ◽  
B. Ortega ◽  
G. Vázquez-Castro ◽  
...  
Keyword(s):  
Human Impact ◽  
Little Ice Age ◽  
Climatic Variability ◽  
Seasonal Migration ◽  
Ice Age ◽  
Cultural Tradition ◽  
Late Classic ◽  
High Pressure Cell ◽  
Western Mexico ◽  
The North

Abstract. We present results of analysis of biological (diatoms and ostracodes) and non-biological (Ti, Ca / Ti, total inorganic carbon, magnetic susceptibility) variables from an 8.8 m long, high-resolution (~ 20 yr sample−1) laminated sediment sequence from Lake Santa María del Oro (SMO), western Mexico. This lake lies at a sensitive location between the dry climates of northern Mexico, under the influence of the North Pacific subtropical high-pressure cell and the moister climates of central Mexico, under the influence of the seasonal migration of the intertropical convergence zone and the North American monsoon (NAM). The sequence covers the last 2000 years and provides evidence of two periods of human impact in the catchment, shown by increases in the diatom Achnanthidium minutissimum. The first from AD 100 to 400 (Early Classic) is related to the shaft and chamber tombs cultural tradition in western Mexico, and the second is related to Post-Classic occupation from AD 1100 to 1300. Both periods correspond to relatively wet conditions. Three dry intervals are identified from increased carbonate and the presence of ostracodes and aerophilous Eolimna minima. The first, from AD 500 to 1000 (most intense during the late Classic, from AD 600 to 800), correlates with the end of the shaft and chamber tradition in western Mexico after ca. AD 600. This late Classic dry period is the most important climatic signal in the Mesoamerican region during the last 2000 years, and has been recorded at several sites from Yucatan to the Pacific coast. In the Yucatan area, this dry interval has been related with the demise of the Maya culture at the end of the Classic (AD 850 to 950). The last two dry events (AD 1400 to 1550 and 1690 to 1770) correspond with the onset of, and the late, Little Ice Age, and follow largely the Spörer and Maunder minima in solar radiation. The first of these intervals (AD 1400 to 1550) shows the most intense signal over western Mexico; however this pattern is different at other sites. Dry/wet intervals in the SMO record are related with lower/higher intensity of the NAM over this region, respectively.

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