Hagi BucknWise: Created page with "{{BreadcrumbsPrimaryProduction}} * Page authors: PRIMO * Responsible curator: Hagen Buck-Wiese ---- TOC
{| class="model-ib" style="float:right; margin-left:1em; margin-bottom:1em;" ! Phytoplankton nitrogen content |- | '''Approach:''' elemental analysis (CHN), Redfield assumption, or ¹⁵N incorporation |- | '''Context:''' environmental, lab |- | '''Spatial scale:..."

2026-05-11T23:36:56Z

Created page with "{{BreadcrumbsPrimaryProduction}} * Page authors: PRIMO * Responsible curator: Hagen Buck-Wiese ---- __TOC__ <div class="model-box"> {| class="model-ib" style="float:right; margin-left:1em; margin-bottom:1em;" ! Phytoplankton nitrogen content |- | '''Approach:''' elemental analysis (CHN), Redfield assumption, or 15N incorporation |- | '''Context:''' environmental, lab |- | '''Spatial scale:..."

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{{BreadcrumbsPrimaryProduction}}

* [[Page authors|Page authors]]: [[PRIMO]]
* [[Responsible curator|Responsible curator]]: [[User:Hagi BucknWise|Hagen Buck-Wiese]]
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<div class="model-box">
{| class="model-ib" style="float:right; margin-left:1em; margin-bottom:1em;"
! Phytoplankton nitrogen content
|-
| '''Approach:''' elemental analysis (CHN), Redfield assumption, or 15N incorporation
|-
| '''Context:''' environmental, lab
|-
| '''Spatial scale:''' point sample; single cell
|-
| '''Temporal scale:''' snapshot
|-
| '''Units:''' µg N L-1; pg N cell-1
|-
| '''Community captured:''' group and bulk
|-
| '''Co-measurements:''' cell abundance
|}
</div>
<div style="clear:both"></div>

== Method Overview ==

Particulate organic nitrogen (PON) is measured by CHN elemental analysis of GF/F-filtered seawater samples. Group- or species-specific nitrogen content is obtained by flow cytometric sorting followed by CHN analysis. Alternatively, PON can be estimated from particulate organic carbon (POC) by applying the Redfield C:N ratio (6.6 by atoms), or derived from 15N tracer incubations by tracking the enrichment of 15N in the particulate fraction. Cell-specific N content can also be estimated from cell biovolume combined with taxon-specific C:N:volume relationships.

Nitrogen content is used to normalize N uptake rates, to calculate cellular N:C ratios as an indicator of nutrient status, and as a co-measurement alongside carbon content and primary production rate data.

=== Scale of measurement ===

Bulk PON measurements provide a community-level point estimate. Single-cell measurements (sorted CHN or nanoSIMS) provide cellular resolution.

=== Data generated ===

Bulk PON (µg N L-1) or per-cell nitrogen content (pg N cell-1). N:C ratios characterize the nutrient status of the phytoplankton community (Redfield ratio = 0.15 mol N mol-1 C).

=== Units & currency ===

Units are µg N L-1 (bulk) or pg N cell-1. The currency is nitrogen.

=== Sample size ===

Sample volumes range from single-cell to liters, depending on the approach.

=== Repositories & databases ===

== Limitations ==

Bulk PON includes detrital and non-living nitrogen; phytoplankton-specific estimates require cell sorting. The Redfield ratio assumption introduces uncertainty in nutrient-stressed communities where N:C deviates strongly from the canonical 6.6. CHN analysis requires careful blank correction and GF/F pre-combustion. As with POC, detection limits can be a constraint in oligotrophic waters.

== Example Applications & Protocols ==

=== Classic examples ===
*

=== Recent applications ===
*

=== Common calculations/conversions ===
* Redfield-based PON estimate: PON (µmol N L-1) = POC (µmol C L-1) / 6.6.
* Nutrient status index: N:C ratio vs. Redfield; N:C < 0.15 indicates nitrogen limitation.

== References ==

[[Category:Main Pages|Model types]]

Nitrogen content - Revision history