Sökning: "diatoms"

Visar resultat 21 - 25 av 85 avhandlingar innehållade ordet diatoms.

  1. 21. A paleolimnological perspective on liming – implications for defining reference conditions in Swedish lakes

    Författare :Matilda Norberg; Ingemar Renberg; Helen Bennion; Umeå universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Acidification; Liming; European Water Framework Directive; Reference condition; Diatoms; Paleolimnology; Monitoring; Lake sediments; Earth sciences; Geovetenskap; Earth Sciences with Specialization Environmental Analysis; geovetenskap med inriktning mot miljöanalys;

    Sammanfattning : Using paleolimnological techniques, I have studied surface-water acidification and the effects of liming in Swedish lakes on a decadal to millennial time-scale. The overall objective was to contribute to the discussion on the fulfilment of goals within the Swedish liming program. LÄS MER

  3. 22. Dansgaard-Oeschger cycles and Heinrich events in western Europe - A diatom perspective

    Författare :Linda Ampel; Barbara Wohlfarth; Jan Risberg; Sherilyn Fritz; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Dansgaard-Oescher cycles; Heinrich events; MIS 3 and 2; diatoms; Les Echets; France; Quaternary geology; Kvartärgeologi; Quarternary Geology; kvartärgeologi;

    Sammanfattning : The last glacial period was characterised by several abrupt climatic shifts referred to as Dansgaard-Oeschger (DO) cycles and Heinrich events. These shifts were most frequent between 60,000 and 20,000 years before present coinciding with Marine Isotope Stages (MIS) 3 and 2. LÄS MER

  4. 23. Utanför gränserna : En vetenskapshistorisk biografi om Astrid Cleve von Euler

    Författare :Kristina Espmark; Christer Nordlund; Bo Sundin; Anders Lundgren; Umeå universitet; []
    Nyckelord :HUMANIORA; HUMANITIES; History of science; biography; women scientists; diatoms; botany; geology; archaeology; popular science; boundary-work; Astrid Cleve; Hans von Euler-Chelpin; Sweden; History Of Sciences and Ideas; idé- och lärdomshistoria;

    Sammanfattning : This dissertation is a scientific biography of Astrid Cleve von Euler. She was Sweden’s first female Ph.D. graduate in the natural sciences (1898) and pursued a scientific career in spite of formal and cultural limitations. LÄS MER

  5. 24. Acidification trends in Swedish lakes : an assessment of past water chemistry conditions using lake sediments

    Författare :Tom Korsman; Umeå universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Palaeolimnology; acidification history; alkalization; acid deposition; land-use; lake sediments; near infrared spectroscopy; diatoms; multivariate calibration; Sweden;

    Sammanfattning : This thesis presents temporal perspectives of lake acidification in Sweden. Sediment records have been used to study timing, trends and causes of acidification, and two different techniques for assessing past lake-water acidity are presented. LÄS MER

  7. 25. The novel sources of the neurotoxin BMAA in aquatic environments

    Författare :Sandra Lage; Sara Jonasson Rydberg; Ulla Rasmussen; Ann-Sofi Rehnstam-Holm; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; β-N-methylamino-L-alanine; diatoms; dinoflagellates; shellfish; cockles; PST; växtfysiologi; Plant Physiology;

    Sammanfattning : Neurotoxinet β -N-metylamino -L-alanin (BMAA) anses vara en potentiell miljöriskfaktor för utvecklingen av den neurodegenerativa sjukdomen amyotrofisk lateralskleros (ALS) och har en potentiell roll i flertalet andra neurodegenerativa sjukdomar. Sedan 2003, då det upptäcktes att BMAA produceras av den symbiotiska cyanobakterien Nostoc punctiforme  har flera andra BMAA producerande cyanobakteriearter identifierats. LÄS MER