Chemical Weathering of Deposits from the 1980 Mount St. Helens Eruption and its Effect on Stream Water Chemistry

Chemical weathering is an ongoing natural phenomenon that aids in the breakdown of solid rocks and contributes to the chemistry of natural waters and soils. Therefore, studying chemical weathering in a given area may provide a better understanding of the natural influencers on nearby water chemistry. The eruption of Mount St. Helens (MSH) in 1980 provides a unique opportunity to study the chemical weathering of young rocks which typically weather more rapidly than older rocks. The aim of the study was to determine the relative resistance of the volcanic rocks from the 1980 MSH eruption to chemical weathering by using a sequential leaching process. Sediments were collected from the streams and leached with the following solutions to simulate chemical weathering: ultra-pure water (H2O), 1 N acetic acid (CH3COOH), and 1 N nitric acid (HNO3). The leaches were analyzed for Ca, Na, K, Fe, Mg, and Al using an inductively coupled plasma optical emission spectrotrometer (ICP-OES). Results show that each successive leach was capable of breaking down more resistant minerals. Future research includes interpreting the composition of the leaches to determine which minerals each removed from the stream sediments

Trace metal fluxes to the ocean: The importance of high‐standing oceanic islands

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/94592/1/grl16149.pd

Seasonal melting and the formation of sedimentary rocks on Mars, with predictions for the Gale Crater mound

A model for the formation and distribution of sedimentary rocks on Mars is proposed. The rate-limiting step is supply of liquid water from seasonal melting of snow or ice. The model is run for a O(10^2) mbar pure CO2 atmosphere, dusty snow, and solar luminosity reduced by 23%. For these conditions snow only melts near the equator, and only when obliquity >40 degrees, eccentricity >0.12, and perihelion occurs near equinox. These requirements for melting are satisfied by 0.01-20% of the probability distribution of Mars' past spin-orbit parameters. Total melt production is sufficient to account for aqueous alteration of the sedimentary rocks. The pattern of seasonal snowmelt is integrated over all spin-orbit parameters and compared to the observed distribution of sedimentary rocks. The global distribution of snowmelt has maxima in Valles Marineris, Meridiani Planum and Gale Crater. These correspond to maxima in the sedimentary-rock distribution. Higher pressures and especially higher temperatures lead to melting over a broader range of spin-orbit parameters. The pattern of sedimentary rocks on Mars is most consistent with a Mars paleoclimate that only rarely produced enough meltwater to precipitate aqueous cements and indurate sediment. The results suggest intermittency of snowmelt and long globally-dry intervals, unfavorable for past life on Mars. This model makes testable predictions for the Mars Science Laboratory rover at Gale Crater. Gale Crater is predicted to be a hemispheric maximum for snowmelt on Mars.Comment: Submitted to Icarus. Minor changes from submitted versio

High elevation watersheds in the southern Appalachians: Indicators of sensitivity to acidic deposition and the potential for restoration through liming

Southern Appalachian high elevation watersheds have deep rocky soils with high organic matter content, different vegetation communities, and receive greater inputs of acidic deposition compared to low elevation sites within the region. Since the implementation of the Clean Air Act Amendment in the 1990s, concentrations of acidic anions in rainfall have declined. However, some high elevation streams continue to show signs of chronic to episodic acidity, where acid neutralizing capacity (ANC) ranges from 0 to 20 µeq L-1. We studied three 3rd order watersheds (North River in Cherokee National Forest, Santeetlah Creek in Nantahala National Forest, and North Fork of the French Broad in Pisgah National Forest) and selected four to six 1st order catchments within each watershed to represent a gradient in elevation (849–1526 m) and a range in acidic stream ANC values (11–50 leq L-1). Our objectives were to (1) identify biotic, physical and chemical catchment parameters that could be used as indices of stream ANC, pH and Ca:Al molar ratios and (2) estimate the lime required to restore catchments from the effects of excess acidity and increase base cation availability. We quantified each catchment’s biotic, physical, and chemical characteristics and collected stream, O-horizon, and mineral soil samples for chemical analysis seasonally for one year. Using repeated measures analysis, we examined variability in stream chemistry and catchment characteristics; we used a nested split-plot design to identify catchment characteristics that were correlated with stream chemistry. Watersheds differed significantly and the catchments sampled provided a wide range of stream chemical, biotic, physical and chemical characteristics. Variability in stream ANC, pH, and Ca:Al molar ratio were significantly correlated with catchment vegetation characteristics (basal area, tree height, and tree diameter) as well as O-horizon nitrogen and aluminum concentrations. Total soil carbon and calcium (an indicator of parent material), were significant covariates for stream ANC, pH and Ca:Al molar ratios. Lime requirement estimates did not differ among watersheds but this data will help select catchments for future restoration and lime application studies. Not surprisingly, this work found many vegetation and chemical characteristics that were useful indicators of stream acidity. However, some expected relationships such as concentrations of mineral soil extractable Ca and SO4 were not significant. This suggests that an extensive test of these indicators across the southern Appalachians will be required to identify high elevation forested catchments that would benefit from restoration activities

Biogeochemical Stoichiometry of Antarctic Dry Valley Ecosystems

Among aquatic and terrestrial landscapes of the McMurdo Dry Valleys, Antarctica, ecosystem stoichiometry ranges from values near the Redfield ratios for C:N:P to nutrient concentrations in proportions far above or below ratios necessary to support balanced microbial growth. This polar desert provides an opportunity to evaluate stoichiometric approaches to understand nutrient cycling in an ecosystem where biological diversity and activity are low, and controls over the movement and mass balances of nutrients operate over 10–10⁶ years. The simple organisms (microbial and metazoan) comprising dry valley foodwebs adhere to strict biochemical requirements in the composition of their biomass, and when activated by availability of liquid water, they influence the chemical composition of their environment according to these ratios. Nitrogen and phosphorus varied significantly in terrestrial and aquatic ecosystems occurring on landscape surfaces across a wide range of exposure ages, indicating strong influences of landscape development and geochemistry on nutrient availability. Biota control the elemental ratio of stream waters, while geochemical stoichiometry (e.g., weathering, atmospheric deposition) evidently limits the distribution of soil invertebrates. We present a conceptual model describing transformations across dry valley landscapes facilitated by exchanges of liquid water and biotic processing of dissolved nutrients. We conclude that contemporary ecosystem stoichiometry of Antarctic Dry Valley soils, glaciers, streams, and lakes results from a combination of extant biological processes superimposed on a legacy of landscape processes and previous climates

Mineral weathering in soil as a function of landscape position, vegetation and fungi at the Hubbard Brook Experimental Forest, New Hampshire.

Mineral weathering provides nutrients to vegetation, neutralizes acid deposition, and controls soil water composition. In the northeastern USA, acid deposition has leached exchangeable calcium, an essential plant nutrient, from soil. This dissertation investigates factors that affect the replenishment of exchangeable calcium by mineral weathering, especially landscape position, vegetation type and fungi, at the Hubbard Brook Experimental Forest (HBEF), New Hampshire. Long-term mineral weathering rates, calculated from changes in soil chemical composition compared to parent material, are twice as rapid at higher elevations where conifers are abundant than at lower elevations where deciduous trees are dominant. The average weathering rate is 35 meq (Ca+Na+Mg+K) m -2 yr-1 - one-third the current rate of base cation loss from the watershed via stream flow. This confirms that the pool of exchangeable base cations in HBEF soil is being diminished. The relative availability of different Ca-bearing minerals to the plant-available pool was investigated. A sequential extraction method was developed to identify the following soil pools of Ca: exchangeable pool, easily-weathered minerals and weathering-resistant minerals. The weathering of apatite [Ca5(PO 4)3(F,Cl,OH)], a trace mineral in HBEF soil, was found to account for ∼20% of Ca loss from HBEF during the last 14,000 years. To explore the distribution of apatite in soils across the northeastern USA, the sequential extraction procedure was performed on several types of soil parent material collected from 18 locations. Apatite, identified by a Ca:P ratio of 5:3 in a 1M HNO3 extract, is present in soils developed on crystalline-silicate rocks. Soils developed on sedimentary rocks do not contain appreciable amounts of apatite. Fungal response to Ca- and P-bearing minerals in soil was also examined. Mesh bags containing apatite or wollastonite (CaSiO3) were buried in HBEF soils for two growing seasons. Fungal biomass, quantified as phospholipid fatty acid content, increased in bags containing apatite beneath beech stands. Fungi in a mixed spruce-fir stand showed no response to either Ca-bearing mineral. Fungal biomass in sugar maple decreased in wollastonite-amended bags relative to a control.Ph.D.BiogeochemistryEarth SciencesGeochemistryUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/126245/2/3238042.pd

Incenvites in Turkey

Ülke ekonomisinin kalkınmasında girişimciler önemli paya sahiptir. Girişimciler mevcut pazarların yanında potansiyel pazarların yarattığı boşluğunu doldurmaktadır. Özellikle gelişmemiş ve gelişmekte olan ülkelerin ekonomilerini etkilemektedir. Girişimcilerin ekonomiye yaptığı katkının bilincinde olan devlet girişimcileri desteklemektedir. Ülkemizde girişimcilere destek ve teşviklerde en büyük paya sahip olan KOSGEB'dir. KOSGEB tarafından verilen eğitim ve destekler sayesinde girişimcilik kültürünün yaygınlaştırılması, nitelikli girişimcilerin arttırılması ve sürdürülebilir işletmelerin oluşturulması hedeflenmektedir. Girişimcilik faaliyetleri insanlık tarihinin ilk yıllarından beri takas yolu ile varlığını sürdürmektedir. Bireyler ihtiyaçlarını karşılayabilmek için her dönem çeşitli faaliyetlerde bulunmuşlardır. Zaman içerisinde ihtiyaç ve isteklerin değişmesiyle ticaretin şeklide değişiklik göstermiştir. Bireylerin ihtiyaçlarını karşılayabilmek için çeşitli faaliyetlerde bulunmasına girişimcilik olarak tanımlanabilir. Girişimcilik günümüzde işsizlik sorununun azalmasına yardımcı olmaktadır. İşsizliğin azaltılması ülkeler için önemlilik arz etmesinden kaynaklı ülke ekonomisinde yer kaplamaktadır. Ülkeler ekonomik politikalarını ve stratejilerini oluştururken girişimciliği göz önüne almaktadırlar. Bundan dolayı ülkeler girişimciler için teşvik ve destek programları gibi birçok destekleme programını girişimcilere sunmaktadır. Verilen destek programları ile potansiyel girişimcilerin ekonomiye katkıda bulunması sağlanmıştır. Çalışmamızda ülkelerin değişen ekonomik ve stratejik planları sonucu girişimcilere verilen teşvik ve destekler incelenmiştir. Yapılan araştırmayla girişimcilere verilen güncel destekler araştırılmıştır. Böylece girişimcilerin ihtiyacı olan destek ve teşviklere kolayca ulaşabilmektedirler.Entrepreneurs play a significant role in any country's development, filling the gap created by potential markets as well as the current ones. Entrepreneurs influence especially undeveloped and developing countries' economies. Aware of how entrepreneurs may contribute in the country's economy, governments, therefore, offer incentives for entrepreneurs, the primary provider of which is KOSGEB (Small and Medium Enterprises Development Organization of Turkey) in Turkey. KOSGEB, through intensive training and incentives, aims to popularize the entrepreneurship culture, increase the number of qualified entrepreneurs and facilitate establishment of sustainable enterprises. Entrepreneurship has existed since the creation of human beings through exchange. People were involved in various activities to meet their needs in every age. These needs and demands, however, keep changing, which also leads to changes in manners of exchange. These activities involving human beings seeking to meet their vital demands are called 'entrepreneurship', which helps reduce unemployment today. Unemployment is directly linked to country economy, since it is of utmost importance to every country to keep it under control. Countries take entrepreneurship into consideration when it comes to determining their economic policies and strategies - they, therefore, offer entrepreneurs many support programs, including incentives. These programs have so far made it possible to take advantage of potential economic contributions offered by potential entrepreneurs. Our study addresses incentives and supports offered to entrepreneurs as a result of the changing economic and strategic plans of countries. The study lists current incentives available to entrepreneurs to have a clearer view of the incentives and supports entrepreneurs seek

Growth, recovery and bioaccumulation of alfalfa (Medicago sativa) and spinach (Spinacia oleracea) exposed to cyanotoxins in agricultural environments

2020 Spring.Includes bibliographical references.Harmful algal blooms (HABs) are a growing concern for surface water resources around the globe. With increasing pressure on our limited fresh water resources due to climate change, the risk of contamination from HABs and the cyanobacterial toxins that accompany blooms, exacerbates the problem. Adverse health effects from cyanotoxin exposure has been documented in human and animal mortality and morbidity cases worldwide. Nationally, the presence and severity of HABs has prompted multiple cyanotoxins, including cylindrospermopsin (CYN) and microcystins (MCLR), to be listed on the USEPA Drinking Water Contaminant Candidate List-4 (CCL4) requiring many public systems to monitor for cyanotoxin presence. Recognizing this risk, the World Health Organization (WHO) has long established guidelines to acceptable levels in surface waters based on exposure pathways and use. Further concerns have arisen as our understanding about cyanotoxins has been expanded by research. The purpose of this experiment was to determine 1) effects of toxin exposure during germination, 2) the effects of CYN and MCLR on agricultural crops exposed to toxins during vegetative and mature growth stages, 3) crops ability to recover from toxin exposure and 4) to quantify amount of cyanotoxin accumulated within crop tissue after exposure to cyanotoxins. Germination results indicated exposure to CYN and MCLR did not decrease the rate of germination of alfalfa or spinach. Further, alfalfa and spinach had increased primary root growth for seeds exposed to cyanotoxins. During early vegetative exposure, spinach showed increased biomass and larger leaf area when exposed to MCLR and CYN. After a recovery period spinach plants exposed to CYN showed increased biomass compared to controls. Alfalfa plants exposed to MCLR in vegetative stages had significantly more biomass when compared to controls and this trend was observed after the recovery period. Results of alfalfa exposed during mature growth stages to CYN and MCLR indicated it was more sensitive to CYN, however both toxin treatments resulted in increased biomass production. After one- and two-weeks of recovery the MCLR treated alfalfa biomass remained higher than controls. Bioaccumulation of CYN and MCLR was observed in alfalfa exposed early to the toxins and detectable levels were observed after the one-week recovery period. Spinach accumulated MCLR during early exposures and had detectable levels in the stems after one-month recovery. During mature exposure, alfalfa initially only had detectable levels of MCLR, which decreased over the recovery periods. However, the presence of CYN was not detected until one-week prior to the final toxin exposure. These findings support the growing concern that use of cyanotoxin contaminated irrigation water can be an additional exposure route for ingestion of toxins and increased risk of adverse health effects. Further studies into the subsurface fate of cyanotoxins will further increase the understanding of their bioavailability and persistence in soil