Sökning: "silica precipitation"

Visar resultat 1 - 5 av 9 uppsatser innehållade orden silica precipitation.

  1. 1. Mercury accumulation in lake sediments on different time scales – the influence of algal primary production

    Master-uppsats, Umeå universitet/Institutionen för ekologi, miljö och geovetenskap

    Författare :Anne Rebotzke; [2023]
    Nyckelord :mercury; lake sediment; primary productivity; algal scavenging; biogenic silica; diatom proxy; chlorophyll-a; organic matter;

    Sammanfattning : The aim of this work is to test the proposed approach of algal scavenging as a driver of sediment mercury (Hg) on different time scales and to gain a better understanding of the mechanisms of Hg accumulation in lake sediments. A 3000-year sediment record from Nylandssjön in northern Sweden was analysed for this purpose, as well as a 20-year sediment record from the seasonal sediment traps of this lake. LÄS MER

  3. 2. Polymerized Tubular Silicates in Lower Cambrian Carbonates – Biology or Chemistry?

    Kandidat-uppsats, Uppsala universitet/Institutionen för geovetenskaper

    Författare :Scott Green; [2022]
    Nyckelord :biosignature; tubular structures; Lower Cambrian; silica precipitation; bifurcating; biosignatur; rörstrukturer; Kambrium Serie 3; kiseldioxid utfällning; förgrening;

    Sammanfattning : Shallow marine environments from the Lower Cambrian period were very different to shallow marine environments of today. Tubes of what was thought to be silica recovered from a partly dolomitized carbonate sample collected form a site near Indian Springs, Nevada could help further understand the chemistry and characteristics of such environments. LÄS MER

  4. 3. Records of environmental change and sedimentation processes over the last century in a Baltic coastal inlet

    Master-uppsats, Lunds universitet/Geologiska institutionen

    Författare :Hanna Nilsson; [2019]
    Nyckelord :Baltic Sea; eutrophication; coastal areas; archipelago; laminated sediments; nutrient inputs; carbon and nitrogen content; biogenic silica; sedimentation; environmental impact; marine geology; Earth and Environmental Sciences;

    Sammanfattning : The marine ecosystem in the Baltic Sea is affected by multiple stress factors, e.g. eutrophication and deoxygenation, overfishing and anthropogenic pollution. Here we evaluate the short-term trends of dissolved oxygen in bottom waters and changes in the primary productivity within a coastal inlet in the Baltic Sea. LÄS MER

  5. 4. Fällning av kisel från avloppsvatten vid Hellisheidarvirkjun - experimentell studie

    Master-uppsats, KTH/Skolan för kemivetenskap (CHE)

    Författare :VERA SÓLVEIG ÓLAFSDÓTTIR; [2015]
    Nyckelord :Silica; Precipitation; Experiments; waste water; Hellisheiði power plant;

    Sammanfattning : This report is about the experiments with mixing of the separated water and the vacuum pump seal water at Hellisheiði power plant. This is done to prevent silica scaling and clogging in pipes and reinjection wells as well as eliminating vacuum pump seal water from the plant. LÄS MER

  7. 5. Estimating soluble arsenic and phosphorus concentrations under Precambrian oceanic conditions

    Master-uppsats, Stockholms universitet/Institutionen för geologiska vetenskaper

    Författare :Christoffer Hemmingsson; [2014]
    Nyckelord :Arsenic; Phosphorus; Co-precipitation; Precambrian; Oceanic P levels; Ferrihydrite synthesis; Distribution coefficient; Banded iron formation;

    Sammanfattning : Original estimates of phosphorus (P) concentrations in the Precambrian oceans before 1.9 Ga gave a budget of ~10-25% of modern day levels. LÄS MER