Influence Of Geochemistry Research Articles

Influence of geochemistry and topography on vegetation in tropical Nigeria: Geochemistry and soil thickness surpass topographic position

The influence of lithospheric parameters on vegetation varies from one location to another, regardless of the prevailing climatic conditions. Reliable scientific information on the vegetation-environment relationship is crucial to sustainable agriculture and natural resource management. Poignantly, such information is not readily available, particularly in resource-poor countries. In this study, we assemble spatially referenced datasets on vegetation pattern, topography, soil thickness and bedrock geochemistry. We subject the datasets to global and local spatial regression analyses on GeoDa 1.18 and MGWR 2.2.1 platforms. Our intention is to examine the influence of lithospheric parameters on vegetation patterns over a climatically homogenous basin in the rainforest belt, southwestern Nigeria. The results of our study show that the variation in vegetation pattern can be explained by soil thickness, topographic curvature, and bedrock concentrations of major minerals. Bedrocks’ KO2/Fe2O3 enrichment and soil thickness are the main lithospheric parameters that influence vegetation pattern in the study area. Bedrocks’ K enrichment is relatively high and less heterogeneous while P enrichment is very low and highly heterogeneous across the study area. Fe concentration is highly heterogeneous, with the highest enrichment recorded for schist and the lowest for gneiss. While the concentration of K is discriminately high in granitic rocks, the highest concentration of P is recorded for schist. Vegetation index is averagely higher on schist than on granitic rocks. Regression models show that bedrock geochemistry and soil thickness exert the greater influence on vegetation in the study area. Based on the available data, we observe that the study area’s greenery can self-rejuvenate if left undisturbed. Our data show that the study area could support a large pool of forest carbon stocking. This potential makes the study area suitable for the UN REDD + program in Nigeria.

Influence of Geochemistry in the Tropical Hot Springs on Microbial Community Structure and Function.

Thermophiles inhabiting high temperatures are considered primitive microorganisms on early Earth. In this regard, several works have demonstrated microbial community composition in geothermal environments. Despite that, studies on hot springs located in the Indian subcontinent viz., Surajkund in the district Hazaribag, Jharkhand; Bakreshwar in the district Birbhum, West Bengal; Tantloi in the district Dumka, and Sidpur in the district Pakur, Jharkhand are scanty. Nonetheless, the metagenomic analysis of these hot springs showed significant differences in the predominant phyla corresponding to geochemical properties. The Chloroflexi, Proteobacteria, Actinobacteria, Deinococcus-Thermus, and Firmicutes were dominant phyla in all the samples. In contrast, Meiothermus was more in comparatively low-temperature hot springs. In addition, archaeal phyla, Euryarchaeota, Candidatus Bathyarchaeota, and Crenarchaeota were predominant in all samples. The canonical correspondence analysis (CCA) showed the abundance of Deinococcus, Thermus, Pyrobaculum, Kocuria, and Geodermatophilus positively correlated with the aqueous concentration of sulfate, fluoride, and argon in relatively high-temperature (≥ 72°C) hot springs. However, at a lower temperature (≤ 63°C),Thermodesulfovibrio, Caldilinea, Chloroflexus, Meiothermus, and Tepidimonas are positively correlated with the concentration of zinc, iron, and dissolved oxygen. Further, hierarchical clustering exhibits variations in its functional attributes depending on the temperature gradients. Metagenome analysis predicted carbon, methane, sulfur, and nitrogen metabolism genes, indicating a wide range of bacteria and archaea habitation in these hot springs. In addition, identified several genes encode polyketide biosynthesis pathways. The present study described the microbial community composition and function in the tropical hot springs and their relationship with the environmental variables.

A Geochemical Comparison of Three Terrestrial Sites of Serpentinization: The Tablelands, the Cedars, and Aqua de Ney

AbstractAlthough the Earth's subsurface hosts an abundance of microbial life, the influence of geochemistry on these communities remains poorly constrained. Ophiolites, sites where oceanic ultramafic minerals can be hydrated to serpentine minerals and metal oxides, create unique conditions capable of sustaining life. The fluid geochemistry of the Tablelands (NL, CAN), The Cedars (CA, USA), and Aqua de Ney (CA, USA), were studied to better characterize the range of fluid compositions observed at terrestrial sites of serpentinization. Fluids from these sites shared many commonalities including being ultra‐basic and reducing as well as having elevated levels of Cl−, Na+, K+, and Br− and depleted concentrations of Mg2+. They also exhibited a wide range of geochemistry. Isotopic and compositional data suggested the CH4 from The Cedars was a mixture of microbial and non‐microbial sources while the CH4 from the Tablelands was non‐microbial in origin. Aqua de Ney was the only site where the CH4 plotted in the abiogenic field. Despite being a known product of serpentinization, no H2 was detected at Aqua de Ney, likely due to the formation of abiogenic CH4 as well as the reaction of H2 and SO42− in the system to produce H2S. These unique sites of terrestrial serpentinization help to better understand the range of geochemistry at sites of serpentinization and its influence on the microbial communities in the subsurface.

Influence of environmental conditions on the mercury levels of the sediment along the Balbina Reservoir, Brazilian Amazon.

Mercury dynamics in hydroelectric reservoirs have been studied worldwide. In tropical reservoirs, especially in those of the Amazon, the influence of geochemistry on Hg levels along this aquatic system is not well understood. The main objective of the present study was to assess the influence of environmental conditions (physical and chemical water parameters, trace element concentrations of sediment and sediment geochemistry) on mercury levels of sediment along the Balbina Reservoir (Amazon basin, Brazil). Sediment was collected along the reservoir and in the main tributaries in May 2015 (n= 10). These samples were assessed for labile iron (LFe), manganese (LMn), aluminum (LAl) and mercury (LHg) concentrations, total mercury (THg) concentrations, organic matter (OM) content, and granulometry. Concentrations in the sediment were 4-212 (LFe), 2-460 (LAl), 180-613 (LMn), < detection limit-256 (LHg), and 12-307μgkg-1 dry weight (THg). In general, these concentrations decreased along the reservoir from upstream to downstream, reaching the lowest concentrations in the middle of the lake, and they increased in the sampling points near the dam. The lability and concentrations of mercury were influenced by the concentrations of LFe, LMn, LAl, and the granulometry and OM content of the sediment. Altogether, THg concentrations of sediments of the Balbina Reservoir encompass the range of concentrations of other reservoirs or natural lakes in the Amazon basin (from ten to a few hundred μg kg-1 dry weight).

The influence of geochemistry on health risks to animals and humans in geographically localised livestock production systems

Extracted from text ... The influence of geochemistry on health risks to animals and humans ingeographically localised livestock production systemsJ.A. Meyer1, N.H. Casey1and J. Myburgh21 Dept of Animal and Wildlife Sciences, University of Pretoria, South Africa; 2 Dept of Community Herd Health, Faculty ofVeterinary Science, University of Pretoria, South AfricaIntroductionResearch conducted for the Water Research Commission and the National Research Foundation concerninggeochemistry related risk factors, and health implications, within communal livestock production systems in selectedcommunities, revealed a high number of potentially hazardous constituents to occur within both surface andsubterranean water sources. As a consequence of this, livestock may, both indirectly and directly, pose significanttoxicological ..

Protist biogeography.

Autecology (cellular organelles and secretions, encystment and dispersal abilities), environmental conditions (physiological tolerances and interaction with other organisms), and evolutionary history contribute to protist biogeography, which manifests ecological and historical aspects. Ecological biogeography is seen in the influence of geochemistry on the distribution of fresh-water phytoflagellates and algae, and of moisture and vegetation type on soil-litter protists. A temporal feature is often present because many protists encyst and respond only to certain ranges of temperature and organic content. Historical biogeography has occurred by radiative host evolution on symbiotic protozoa (e.g., termite flagellates and rumen ciliates), and by the isolating effects of water currents, temperature, and density gradients on oceanic protists (coccoliths, dinoflagellates, foraminifera, radiolaria, and tintinnines). These two aspects combine in protists living on animal surfaces. Humans affect protist biogeography by increasing parasite ranges through human migrations and by water pollution. They can diminish these situations by disease control and exploiting appropriate ciliates in sewage disposal. Many free-living protozoa appear to be cosmopolitan, but mating types and isoenzyme studies suggest that speciation with its geographic connotations may be more widespread than presently appreciated.