Diatom carbon export enhanced by silicate upwelling in the North East Atlantic.

Diatom carbon export enhanced by silicate upwelling in the northeast Atlantic John T. Allen1,2, Louise Brown1,3, Richard Sanders1, C. Mark Moore1, Alexander Mustard1, Sophie Fielding1, Mike Lucas1, Michel Rixen4, Graham Savidge5, Stephanie Henson1 and Dan Mayor1 Top of pageDiatoms are unicellular or chain-forming phytoplankton that use silicon (Si) in cell wall construction. Their survival during periods of apparent nutrient exhaustion enhances carbon sequestration in frontal regions of the northern North Atlantic. These regions may therefore have a more important role in the 'biological pump' than they have previously been attributed1, but how this is achieved is unknown. Diatom growth depends on silicate availability, in addition to nitrate and phosphate2, 3, but northern Atlantic waters are richer in nitrate than silicate4. Following the spring stratification, diatoms are the first phytoplankton to bloom2, 5. Once silicate is exhausted, diatom blooms subside in a major export event6, 7. Here we show that, with nitrate still available for new production, the diatom bloom is prolonged where there is a periodic supply of new silicate: specifically, diatoms thrive by 'mining' deep-water silicate brought to the surface by an unstable ocean front. The mechanism we present here is not limited to silicate fertilization; similar mechanisms could support nitrate-, phosphate- or iron-limited frontal regions in oceans elsewhere.

Michael Allen: Close Readings: Essays on Irish Poetry

The late Michael Allen was a member of the famous Belfast Group, and one of the most authoritative critical voices on poetry from Northern Ireland, intimately part of the North’s poetic movement since the early 1960s. He taught at Queen’s University, where he was a colleague of Seamus Heaney and tutor to poets such as Paul Muldoon and Medbh McGuckian. Seamus Heaney called him ‘the reader over my shoulder’. Close Readings brings together interlinked critical writings which have crucially influenced approaches to Irish poetry during the last forty years. The book ends with an extended essay, hitherto unpublished: ‘Doubles, Twins and the Feminine: Development in the Poetry of Michael Longley’.

Close Readings contains a Foreword by Fran Brearton, which relates Michael Allen’s essays to continuing critical and cultural debates. Edna Longley’s Afterword offers a personal view of Allen’s involvement with poetry in Belfast.