Volcanically mediated plankton blooms in the Central Belt of the Southern Uplands, Scotland, during the Llandovery

2000 ◽  
Vol 91 (3-4) ◽  
pp. 457-470 ◽  
Author(s):  
S. Rigby ◽  
S. J. Davies
Keyword(s):  
Population Structure ◽  
Trace Metals ◽  
Primary Productivity ◽  
Volcanic Ash ◽  
High Productivity ◽  
Straight Line ◽  
Temporal Continuity ◽  
Plankton Bloom ◽  
Turn Over

ABSTRACTAt Thirlestane Score and at four other localities in the Southern Uplands, graptolites of the Llandovery gemmatus Zone occur in couplets of lithologies immediately above thin ‘high-U’ bentonites. Above the bentonites, abundant graptolites, especially siculae, and a straight-line survivorship trend implies high productivity coupled with environmentally mediated mortality: the population structure expected in the early part of a plankton bloom. In the overlying facies, fewer, larger individuals and a convex survivorship curve suggest reduced productivity and internally mediated mortality. This is consistent with the later stages of a bloom where resources were waning but the ecological structure of the system was better developed. It is likely that the introduction of trace-metals, Fe or Al, to the water column via volcanic ash increased primary productivity, suggesting that macronutrients were available in the Southern Uplands system, allowing a bloom to be stimulated by the addition of volcanic products. This process is observed in modern open oceanic systems and implies a temporal continuity of control on the plankton despite complete faunal turn-over since the Silurian. These interpretations are most consistent with an open ocean geotectonic setting for the region.

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 Preparation and certification of reference materials, brown forest soil (JSAC 0401) and volcanic ash soil (JSAC 0411) for the analysis of trace metals.

2002 ◽  
Vol 51 (4) ◽  
pp. 269-279 ◽  
Author(s):  
Shin-ichi YAMASAKI ◽  
Shoji HIRAI ◽  
Masataka NISHIKAWA ◽  
Yoshinori TAKATA ◽  
Akira TSURUTA ◽  
...  
Keyword(s):  
Trace Metals ◽  
Forest Soil ◽  
Reference Materials ◽  
Volcanic Ash ◽  
Brown Forest Soil ◽  
Volcanic Ash Soil

Population structure, density and biomass of large herbivores in the tropical forests of Nagarahole, India

1992 ◽  
Vol 8 (01) ◽  
pp. 21-35 ◽  
Author(s):  
K. Ullas Karanth ◽  
Melvin E. Sunquist
Keyword(s):  
Population Structure ◽  
Tropical Forests ◽  
Primate Species ◽  
Line Transect ◽  
Large Herbivore ◽  
Large Herbivores ◽  
Transect Sampling ◽  
Structure Density ◽  
Density And Biomass ◽  
Turn Over

ABSTRACTWe studied the population structure, density and biomass of seven ungulate and two primate species in the tropical forests of Nagarahole, southern India, using line transect sampling and roadside/platform counts, during 1986–87. The estimated ecological densities of large herbivore species in the study area are: 4.2 muntjac km−2, 50.6 chital km−2, 5.5 sambar km−2, 0.8 four-horned antelope km−2, 9.6 gaur km−2, 4.2 wild pig km−2, 3.3 elephant km−2, 23.8 hanuman langur km−2and 0.6 bonnet macaque km−2. Most ungulates have female-biased adult sex ratios. Among common ungulate species, yearlings and young of the year comprise about a third of the population, suggesting relatively high turn-over rates. Three species (muntjac, sambar and four-horned antelope) are solitary, while others form groups. The study area supports a wild herbivore biomass density of 14,744 kg km−2. Among the three habitat types within the study area, biomass is lower in dry deciduous forests when compared with moist deciduous or teak plantation dominant forests. Using our results, we have examined the factors that may contribute towards maintenance of high ungulate biomass in tropical forests.

Scavenging of sulphur, halogens and trace metals by volcanic ash: The 2010 Eyjafjallajökull eruption

2013 ◽  
Vol 103 ◽  
pp. 138-160 ◽  
Author(s):  
E. Bagnato ◽  
A. Aiuppa ◽  
A. Bertagnini ◽  
C. Bonadonna ◽  
R. Cioni ◽  
...  
Keyword(s):  
Trace Metals ◽  
Volcanic Ash

Mathematical Model for Face-Hobbed Straight Bevel Gears

2012 ◽  
Vol 134 (9) ◽  
Author(s):  
Yi-Pei Shih
Keyword(s):  
Mathematical Model ◽  
Bevel Gear ◽  
Tooth Contact Analysis ◽  
Rolling Circle ◽  
High Productivity ◽  
Bevel Gears ◽  
Straight Line ◽  
Base Circle ◽  
Straight Line Mechanism ◽  
Straight Lines

Face hobbing, a continuous indexing and double-flank cutting process, has become the leading method for manufacturing spiral bevel gears and hypoid gears because of its ability to support high productivity and precision. The method is unsuitable for cutting straight bevel gears, however, because it generates extended epicycloidal flanks. Instead, this paper proposes a method for fabricating straight bevel gears using a virtual hypocycloidal straight-line mechanism in which setting the radius of the rolling circle to equal half the radius of the base circle yields straight lines. This property can then be exploited to cut straight flanks on bevel gears. The mathematical model of a straight bevel gear is developed based on a universal face-hobbing bevel gear generator comprising three parts: a cutter head, an imaginary generating gear, and the motion of the imaginary generating gear relative to the work gear. The proposed model is validated numerically using the generation of face-hobbed straight bevel gears without cutter tilt. The contact conditions of the designed gear pairs are confirmed using the ease-off topographic method and tooth contact analysis (TCA), whose results can then be used as a foundation for further flank modification.

scholarly journals Effect of fertilization on below-ground plant mass of submontane Polygono-Cirsietum meadow

Beskydy ◽  
2013 ◽  
Vol 6 (1) ◽  
pp. 33-42
Author(s):  
Petr Holub ◽  
Ivan Tůma ◽  
Karel Fiala
Keyword(s):  
Primary Productivity ◽  
Root Biomass ◽  
Net Primary Productivity ◽  
Growing Season ◽  
Dry Mass ◽  
The Czech Republic ◽  
Plant Parts ◽  
Below Ground ◽  
Turn Over ◽  
Different Levels

We assessed below-ground net primary productivity (BNPP) in the wet submontane Cirsium meadow occurred in the highland region of the Czech Republic. Effect of four different fertilization levels on BNPP was estimated in 1992. At the beginning of the growing season (April 29), total dry mass of rhizomes, roots and total below-ground plant parts of unfertilized stand reached 177, 1478 and 1657 g.m-2, respectively. Their living parts formed 42 % of their total dry mass. In comparison with unfertilized stands, however, the greatest accumulation of dry mass of rhizomes (504 g.m-2), roots (1503 g.m-2) and total below-ground dry mass (2008 g.m-2) was reached after application of 90 kgN.ha-1. Similarly, the highest BNPP values for living (435 g.m-2.yr-1) and total below-ground dry mass (351 g.m-2.yr-1) were calculated for the stand affected by the same amount of fertilization. These data show how variable role grasslands can play in accumulation and turn over of root biomass due to different levels of fertilization.

How Can High Animal Diversity Be Supported in Low-Productivity Deserts?: The Role of Macrodetritivory and Habitat Physiognomy

2005 ◽  
Author(s):  
Gary A. Polis ◽  
Yael Lubin
Keyword(s):  
High Temperatures ◽  
Primary Productivity ◽  
Salt Marshes ◽  
Spatial Scales ◽  
General Pattern ◽  
Trophic Levels ◽  
High Productivity ◽  
Number Of Species ◽  
Mechanics Model ◽  
Number Of Individuals

On large spatial scales, species diversity is typically correlated positively with productivity or energy supply (Wright et al. 1993, Huston 1994, Waide et al. 1999). In line with this general pattern, deserts are assumed to have relatively few species for two main reasons. First, relatively few plants and animals have acquired the physiological capabilities to withstand the stresses exerted by the high temperatures and shortage of water found in deserts (reviewed by Noy-Meir 1974, Evenari 1985, Shmida et al. 1986). A second, more ecological mechanism is resource limitation. In deserts, the low and highly variable precipitation levels, high temperatures and high evapotranspiration ratios limit both plant abundance and productivity to very low levels (Noy-Meir 1973, 1985, Polis 1991d). This lack of material at the primary producer level should exacerbate the harsh abiotic conditions and reduce the abundance of animals at higher trophic levels by limiting the types of resources and their availability. Animal abundance should be even further reduced because primary productivity is not only low, but also tends to be sporadic in time and space (MacMahon 1981, Crawford 1981, Ludwig 1986). Herbivores should have difficulties tracking these variations (e.g., Ayal 1994) and efficiently using the available food resources. Hence, herbivore populations in deserts have low densities relative to other biomes (Wisdom 1991) and most of the primary productivity remains unused (Crawford 1981, Noy-Meir 1985). This low abundance of herbivores should propagate through the food web and result as well in lower abundance of higher trophic levels. The number of individuals and the number of species are not always positively correlated; in particular, some examples of low diversity at high productivity with high densities are well documented (e.g., salt marshes, reviewed by Waide et al. 1999). However, several distinct mechanisms have led to the expectation that when productivity and the number of individuals are low, the number of species is also likely to be low. First, within trophic levels, the “statistical mechanics” model of Wright et al. (1993) may operate. In this model, the amount of energy present determines the probability distribution of population sizes for the members of the species pool in a region.

scholarly journals Volcanic ash fuels anomalous plankton bloom in subarctic northeast Pacific

2010 ◽  
Vol 37 (19) ◽  
pp. n/a-n/a ◽  
Author(s):  
Roberta C. Hamme ◽  
Peter W. Webley ◽  
William R. Crawford ◽  
Frank A. Whitney ◽  
Michael D. DeGrandpre ◽  
...  
Keyword(s):  
Volcanic Ash ◽  
Northeast Pacific ◽  
Plankton Bloom

I. Preliminary report to the hydrographer of the admiralty on some of the results of the cruise of H. M. S. 'Challenger' between Hawaii and Valparaiso

1876 ◽  
Vol 24 (164-170) ◽  
pp. 463-470 ◽  
Keyword(s):  
Preliminary Report ◽  
Volcanic Ash ◽  
Summit Crater ◽  
Lava Flows ◽  
Mauna Loa ◽  
Temperature Observations ◽  
Lava Lakes ◽  
Warm Clothing ◽  
The Way

Sir,—I have the honour to report that we left Honolulu on the 11th of August, and on the 12th we sounded in 2050 fathoms, and took a series of temperature observations between the islands of Oahu and Hawaii. At night a crimson reflection was visible in the position of the top of Mauna Loa; but as we understood that the side crater of Kilauea only was in eruption, we supposed that that was some great conflagration of forest on the flank of the mountain. All the following day we steamed against a head wind along the rugged and picturesque coast of Hawaii—headlands of lava and volcanic ash separated by deep wooded ravines or “gulches,” with a rapid hill-stream running in the bottom of each. The top of Mauna Loa was covered with clouds during the day; but at night a splendid crimson glare hung over the mountain, and lit up the clouds to a wide radius, and it became evident that we were fortunate enough, to see one of the rare eruptions of the summit crater. Early on Saturday we cast anchor in Hilo Bay; and a party of us made arrangements to start as early as possible for the volcano of Kilauea thirty miles distant, intending, if the eruption of the summit crater continued and if we found it practicable, to push on to the top of the mountain. We left Hilo in the afternoon, taking magnetic and photographic instruments with us, and rode all night through the forest and over the lava-flows, reaching the rest-house at the side of the crater of Kilauea early in the morning. During the early part of the night the light from the summit crater was very brilliant, but it began to pale soon after midnight; and when we arrived at Kilauea we found that the column of smoke at the top of the mountain had almost entirely disappeared, and that the eruption was virtually over. This was no great disappointment to us; for we had learned that the ascent of the upper peak could not be undertaken with reasonable safety without much greater preparation in the way of provisions and warm clothing than we had had time to make, and we should have been obliged to give up the idea in any case. In the afternoon we went down into the crater and walked for about three miles over the nearly level lava of the eruption of 1868; we then clambered up to the ridge overlooking the two liquid lava-lakes, which have remained nearly in the same condition since 1868. We were greatly struck with the fluidity of the melted lava, which washed about in the basins with very much the appearance and sound of water. The night was perfectly still; and it had a most singular effect to see the two glowing lakes tossing like the sea in a storm, and a red surf dashing against the encircling rocks and springing forty or fifty feet into the air in wreaths of fiery spray. Lieutenant Bromley and I recrossed the lava-bed after nightfall, and our guide missed the ordinary path. In several places on either side of us the surface of the lava was glowing of a dull red, and we could see through the cracks the crust red-hot a couple of inches under our feet, and the liquid lava flowing beneath at the depth of about half a yard. Observations were made by Lieutenant Bromley in the crater and on its rim with the “Fox” dip-circle for inclination and intensity, and with the prismatic compass for declination. Several excellent photographs of the crater were taken during the day. We returned to the ship on the evening of the 16th, and on the 19th we left Hilo and proceeded under sail for Tahiti, 2270 miles distant.

Sign in / Sign up

Export Citation Format

Share Document