Nitrite regeneration in the oligotrophic Atlantic Ocean
<p>The recycling of scarce nutrient resources in the sunlit open ocean is crucial to ecosystem function. Nitrification directs ammonium (<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M1" display="inline" overf...
| Main Authors: | , , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2022-03-01
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| Series: | Biogeosciences |
| Online Access: | https://bg.copernicus.org/articles/19/1355/2022/bg-19-1355-2022.pdf |
| Summary: | <p>The recycling of scarce nutrient resources in the sunlit
open ocean is crucial to ecosystem function. Nitrification directs ammonium
(<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M1" display="inline" overflow="scroll" dspmath="mathml"><mrow class="chem"><msubsup><mi mathvariant="normal">NH</mi><mn mathvariant="normal">4</mn><mo>+</mo></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="24pt" height="15pt" class="svg-formula" dspmath="mathimg" md5hash="8aeb386a576ed6c8280ae774099f80e4"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="bg-19-1355-2022-ie00001.svg" width="24pt" height="15pt" src="bg-19-1355-2022-ie00001.png"/></svg:svg></span></span>) derived from organic matter decomposition towards the
regeneration of nitrate (<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M2" display="inline" overflow="scroll" dspmath="mathml"><mrow class="chem"><msubsup><mi mathvariant="normal">NO</mi><mn mathvariant="normal">3</mn><mo>-</mo></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="25pt" height="16pt" class="svg-formula" dspmath="mathimg" md5hash="4c315b3ea451cf26923ad12993612b33"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="bg-19-1355-2022-ie00002.svg" width="25pt" height="16pt" src="bg-19-1355-2022-ie00002.png"/></svg:svg></span></span>), an important resource for
photosynthetic primary producers. However, the technical challenge of making
nitrification rate measurements in oligotrophic conditions combined with the
remote nature of these environments means that data availability, and the
understanding that provides, is limited. This study reports nitrite
(<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M3" display="inline" overflow="scroll" dspmath="mathml"><mrow class="chem"><msubsup><mi mathvariant="normal">NO</mi><mn mathvariant="normal">2</mn><mo>-</mo></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="25pt" height="16pt" class="svg-formula" dspmath="mathimg" md5hash="77e75b8e3421a260344892322cb22e26"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="bg-19-1355-2022-ie00003.svg" width="25pt" height="16pt" src="bg-19-1355-2022-ie00003.png"/></svg:svg></span></span>) regeneration rate (<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M4" display="inline" overflow="scroll" dspmath="mathml"><mrow class="chem"><msub><mi mathvariant="normal">R</mi><mrow><msub><mi mathvariant="normal">NO</mi><mn mathvariant="normal">2</mn></msub></mrow></msub></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="25pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="bdcdb6773c80e521977273c3fa58b8fa"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="bg-19-1355-2022-ie00004.svg" width="25pt" height="14pt" src="bg-19-1355-2022-ie00004.png"/></svg:svg></span></span> – the first product of
nitrification derived from <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M5" display="inline" overflow="scroll" dspmath="mathml"><mrow class="chem"><msubsup><mi mathvariant="normal">NH</mi><mn mathvariant="normal">4</mn><mo>+</mo></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="24pt" height="15pt" class="svg-formula" dspmath="mathimg" md5hash="68d940fa21d9c6691de36bd82f3e56d8"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="bg-19-1355-2022-ie00005.svg" width="24pt" height="15pt" src="bg-19-1355-2022-ie00005.png"/></svg:svg></span></span> oxidation) over a 13 000 km
transect within the photic zone of the Atlantic Ocean. These measurements,
at relatively high resolution (order 300 km), permit the examination of
interactions between <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M6" display="inline" overflow="scroll" dspmath="mathml"><mrow class="chem"><msub><mi mathvariant="normal">R</mi><mrow><msub><mi mathvariant="normal">NO</mi><mn mathvariant="normal">2</mn></msub></mrow></msub></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="25pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="d4106037c9765bb30f11f9d226356ad5"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="bg-19-1355-2022-ie00006.svg" width="25pt" height="14pt" src="bg-19-1355-2022-ie00006.png"/></svg:svg></span></span> and environmental conditions that may warrant
explicit development in model descriptions. At all locations we report
measurable <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M7" display="inline" overflow="scroll" dspmath="mathml"><mrow class="chem"><msub><mi mathvariant="normal">R</mi><mrow><msub><mi mathvariant="normal">NO</mi><mn mathvariant="normal">2</mn></msub></mrow></msub></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="25pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="2f04fa6ccefaeeab34bc5ecc7d03b90b"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="bg-19-1355-2022-ie00007.svg" width="25pt" height="14pt" src="bg-19-1355-2022-ie00007.png"/></svg:svg></span></span> with significant variability between and within
Atlantic provinces. Statistical analysis indicated significant correlative
structure between <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M8" display="inline" overflow="scroll" dspmath="mathml"><mrow class="chem"><msub><mi mathvariant="normal">R</mi><mrow><msub><mi mathvariant="normal">NO</mi><mn mathvariant="normal">2</mn></msub></mrow></msub></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="25pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="d4240575f7d4ba86cccd3a3046a9fbe1"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="bg-19-1355-2022-ie00008.svg" width="25pt" height="14pt" src="bg-19-1355-2022-ie00008.png"/></svg:svg></span></span> and ecosystem variables, explaining
<span class="inline-formula">∼65</span> % of the data variability. Differences between sampling
depths were of the same magnitude as or greater than horizontally resolved differences, identifying distinct biogeochemical niches between depth
horizons. The best overall match between <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M10" display="inline" overflow="scroll" dspmath="mathml"><mrow class="chem"><msub><mi mathvariant="normal">R</mi><mrow><msub><mi mathvariant="normal">NO</mi><mn mathvariant="normal">2</mn></msub></mrow></msub></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="25pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="c5a9928ef970c56928fd055f2369af9f"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="bg-19-1355-2022-ie00009.svg" width="25pt" height="14pt" src="bg-19-1355-2022-ie00009.png"/></svg:svg></span></span> and environmental
variables combined chlorophyll-<span class="inline-formula"><i>a</i></span> concentration, light-phase duration, and silicate concentration (representing a short-term tracer of water column physical instability). On this basis we hypothesize that <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M12" display="inline" overflow="scroll" dspmath="mathml"><mrow class="chem"><msub><mi mathvariant="normal">R</mi><mrow><msub><mi mathvariant="normal">NO</mi><mn mathvariant="normal">2</mn></msub></mrow></msub></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="25pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="f74951ffc81a2974b1431ad01b71882c"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="bg-19-1355-2022-ie00010.svg" width="25pt" height="14pt" src="bg-19-1355-2022-ie00010.png"/></svg:svg></span></span> is related to the short-term autotrophic production and heterotrophic
decomposition of dissolved organic nitrogen (DON), which regenerates
<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M13" display="inline" overflow="scroll" dspmath="mathml"><mrow class="chem"><msubsup><mi mathvariant="normal">NH</mi><mn mathvariant="normal">4</mn><mo>+</mo></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="24pt" height="15pt" class="svg-formula" dspmath="mathimg" md5hash="9d8f7ee8bf88d657d75cdcf077dbe3e2"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="bg-19-1355-2022-ie00011.svg" width="24pt" height="15pt" src="bg-19-1355-2022-ie00011.png"/></svg:svg></span></span> and supports <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M14" display="inline" overflow="scroll" dspmath="mathml"><mrow class="chem"><msubsup><mi mathvariant="normal">NH</mi><mn mathvariant="normal">4</mn><mo>+</mo></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="24pt" height="15pt" class="svg-formula" dspmath="mathimg" md5hash="cb88f58b3b25b473f7c5a29ace587a7f"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="bg-19-1355-2022-ie00012.svg" width="24pt" height="15pt" src="bg-19-1355-2022-ie00012.png"/></svg:svg></span></span> oxidation. However, this did not
explain the observation that <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M15" display="inline" overflow="scroll" dspmath="mathml"><mrow class="chem"><msub><mi mathvariant="normal">R</mi><mrow><msub><mi mathvariant="normal">NO</mi><mn mathvariant="normal">2</mn></msub></mrow></msub></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="25pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="65adeac5af3ccdfe2033e0c0be1d916d"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="bg-19-1355-2022-ie00013.svg" width="25pt" height="14pt" src="bg-19-1355-2022-ie00013.png"/></svg:svg></span></span> in the deep euphotic zone was
significantly greater in the Southern Hemisphere compared to the Northern Hemisphere. We present the complimentary hypothesis that observations reflect the
difference in DON concentration supplied by lateral transport into the gyre
interior from the Atlantic's eastern boundary upwelling ecosystems.</p> |
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| ISSN: | 1726-4170 1726-4189 |