E. P. Achterberg

GEOMAR Helmholtz Centre for Ocean Research Kiel · Division of Chemical Oceanography

Plain Language Summary Primary production in aquatic environments relies on supplies of bio‐accessible nitrogen and phosphorus in addition to light availability. Glacier melt and permafrost degradation have accelerated worldwide over the past two decades, inducing changes in these resources with ensuing ecological impacts. The potential ecological...

Trichodesmium spp. is a colonial diazotrophic cyanobacterium found in the oligotrophic (sub)tropical oceans, where its distribution is strongly regulated by the availability of phosphorus and iron. The bulk carbon : nitrogen : phosphorus elemental composition of phytoplankton has previously been shown to depart from classical “Redfield” values unde...

The January 2022 eruption of the Hunga Tonga-Hunga Ha’apai (HTHH) volcano discharged 2,900 teragrams of ejecta, most of which was deposited in the South Pacific Ocean. Here we investigate its impact on the biogeochemistry of the South Pacific Gyre (SPG) using samples collected during the GEOTRACES cruise GP21 in February-April 2022. Surface water n...

Nutrient limitation regulates phytoplankton growth throughout much of the global ocean and its assessment is important for our understanding of future changes in ocean productivity. The South Pacific Ocean represents a vast region where limiting nutrients have so far been investigated with only a handful of experiments. Here we report the results o...

Glaciers are a source of fine‐ground rock flour to proglacial and coastal marine environments. In these environments, suspended rock flour may affect light and (micro)nutrient availability to primary producers. Due to high loads of glacier rock flour, the particulate metal load of glacier runoff typically exceeds the dissolved metal load. As glacie...

The water column distributions of the alkaline earth metals strontium (Sr) and barium (Ba) were studied along a transect from Hawaii to Alaska. Despite similarity in the chemical properties of Sr and Ba, we find that changes in their concentrations along the transect are governed by different chemical and biological processes, meaning that these el...

The oligotrophic Adriatic Sea is characterized during a typical summer by low productivity caused by strong water column stratification, which inhibits vertical mixing and nutrient supply to the euphotic zone. These conditions can be disrupted by transient physical forcing, which enhances nutrient fluxes and creates localized hotspots of relatively...

We developed a Target Plastic Model (TPM) to estimate the critical plastic burden of organic toxicants in five types of plastics, namely, polydimethylsiloxane (PDMS), polyoxymethylene (POM), polyacrylate (PA), low-density polyethylene (LDPE), and polyurethane ester (PU), following the Target Lipid Model (TLM) framework. By substituting the lipid–wa...

Photodegradation of plastic consumer products is known to accelerate weathering and facilitate the release of chemicals and plastic particles into the aquatic environment. However, these processes are complex. In our presented pilot study, eight plastic consumer products were leached in distilled water under strong ultraviolet (UV) light simulating...

The need for more knowledge concerning warfare materials in the Baltic Sea and their effects on humans and the marine environment is supported by several HELCOM Contracting Parties. The understanding of the issue has grown as a result of national, regional and international scientific research as well as numerous recommendations on how to tackle th...

Aluminum (Al) may play a role in the ocean's capacity for absorbing atmospheric CO2 via influencing carbon fixation, export, and sequestration. Aluminum fertilization, especially in iron (Fe)‐limited high‐nutrient, low‐chlorophyll ocean regions, has been proposed as a potential CO2 removal strategy to mitigate global warming. However, how Al additi...

Concentrations of bioavailable inorganic nitrogen (N) and phosphorus (P) are simultaneously depleted in the (sub)tropical North Atlantic Ocean, but it remains unclear if phytoplankton growth rates are N limited or N–P co‐limited. Here we present findings from three bottle‐scale experiments using a four‐by‐four matrix of low‐level N and P additions,...

Physical and chemical trace metal speciation are important for our understanding of metal cycling and potential toxicity to marine life. Trace metals can behave differently in diffusion processes or particle-solution interactions and have different bioavailabilities depending on their physical and chemical forms, which often depend on redox conditi...

Marginal seas influenced by large rivers are characterized by complex hydrodynamic and organic matter cycling processes. However, the impacts of hydrodynamics on the composition and reactivity of particulate organic matter (POM) remain unclear. Here we conducted a comprehensive study on the bulk, molecular and biological properties of suspended POM...

The marine barium (Ba) cycle is closely connected to the short-timescale carbon cycle, and Ba serves as a valuable paleo proxy for export production, ocean alkalinity, and terrestrial inputs. However, the marine Ba budget is poorly constrained, particularly regarding the fluxes of hydrothermally sourced Ba, which hinders our understanding of the Ba...

Plain Language Summary The Congo River has the second largest freshwater discharge volume globally and creates an extensive near‐equatorial plume into the Atlantic Ocean. The Congo plume constitutes an important source of trace metals (TMs) to the ocean, which impacts biogeochemical cycles in the tropical and subtropical ocean. However, existing wo...

Various nutrient sources in the upper waters of oceanic subtropical gyres, which are the Earth's largest oligotrophic ecosystems, play a crucial role in governing the sequestration of atmospheric CO2.

Compound‐specific isotope analysis has opened up a new realm for resolving the sources and transformation processes of marine organic matter. However, the stable carbon isotope patterns of amino sugars remain unknown. We examined δ ¹³ C of amino sugars in marine phytoplankton and heterotrophic bacteria, and the variations in amino sugar δ ¹³ C duri...

Geochemical analyses of trace elements in the ocean water column have suggested that pelagic clay‐rich sediments are a major source of various elements to bottom‐waters. However, corresponding high‐quality measurements of trace element concentrations in porewaters of pelagic clay‐rich sediments are scarce, making it difficult to evaluate the contri...

Biological nitrogen fixation is a key process balancing the loss of combined nitrogen in the marine nitrogen cycle. Its relevance in upwelling or high nutrient regions is still unclear, with the few available studies in these regions of the ocean reporting rates that vary widely from below detection limit to > 100 nmol N L ⁻¹ d ⁻¹ . In the eastern...

Higher than expected concentrations of dissolved lead (dPb) have been consistently observed along glaciated coastlines and it is widely hypothesized that there is a net release of dPb from glacier‐derived sediments. Here we further corroborate that dPb concentrations in diverse locations around west Greenland (3.2–252 pM) and the Western Antarctic...

Mercury (Hg) fulminate was used as a primary fuse in World War (WW) munitions, and may consequently be a Hg source for impacted environments. Mercury is a conspicuous and persistent pollutant, with methylmercury (MeHg) acting as a notorious neurotoxin. Considerable amounts of munitions were intentionally dumped in the North Sea and Baltic Sea follo...

Projected responses of ocean net primary productivity to climate change are highly uncertain¹. Models suggest that the climate sensitivity of phytoplankton nutrient limitation in the low-latitude Pacific Ocean plays a crucial role1–3, but this is poorly constrained by observations⁴. Here we show that changes in physical forcing drove coherent fluct...

Atmospheric aerosol deposition into the low latitude oligotrophic ocean is an important source of new nutrients for primary production. However, the resultant phytoplankton responses to aerosol deposition events, both in magnitude and changes in community composition, are poorly constrained. Here, we investigated this with 19 d of field and satelli...

Subtropical gyres cover 26%–29% of the world's surface ocean and are conventionally regarded as ocean deserts due to their permanent stratification, depleted surface nutrients, and low biological productivity. Despite tremendous advances over the past three decades, particularly through the Hawaii Ocean Time‐series and the Bermuda Atlantic Time‐ser...

Nutrients supplied via seabird guano increase primary production in some coastal ecosystems. A similar process may occur in the open ocean. To investigate this directly, we first measured bulk and leachable nutrient concentrations in guano sampled in the North Atlantic. We found that guano was strongly enriched in phosphorus, which was released as...

The oligotrophy of the southern Adriatic Sea is characterized by seasonal stratification which enables nutrient supply to the euphotic layer. A set of interdisciplinary methods was used to elucidate the diversity and co-dependency of bacterio- and phytoplankton of the water column during the stratification period of July 2021. A total of 95 taxa we...

Plain Language Summary Bacteria transform a large fraction of the organic matter made by primary producers and contribute to long‐term oceanic carbon sequestration with bacterial detritus, thereby contributing to ocean uptake of atmospheric carbon dioxide. The abundance and reactivity of bacterial organic matter are critical to consider in this car...

An insufficient supply of the micronutrient iron (Fe) limits phytoplankton growth across large parts of the ocean. Ambient Fe speciation and solubility are largely dependent on seawater physico‐chemical properties. We calculated the apparent Fe solubility (SFe(III)app) at equilibrium for ambient conditions, where SFe(III)app is defined as the sum o...

Plastic pollution has become a widespread problem affecting multiple environmental compartments, with associated chemicals having harmful effects on living organisms. Here, we developed a Target Plastic Model (TPM) to estimate the critical plastic burden of various toxicants in five types of plastics, namely polydimethylsiloxane (PDMS), polyoxymeth...

The Peruvian upwelling system is a highly productive ecosystem with a large oxygen minimum zone (OMZ) close to the surface. In this work, we carried out a mesocosm experiment off Callao, Peru, with the addition of water masses from the regional OMZ collected at two different sites simulating two different upwelling scenarios. Here, we focus on the...

Isolation and detection of microplastics (MP) in marine samples is extremely cost- and labor-intensive, limiting the speed and amount of data that can be collected. In the current work, we describe rapid measurement of net-collected MPs (net mesh size 300 µm) using a benchtop near-infrared hyperspectral imaging system during a research expedition t...

Autonomous on-site monitoring of orthophosphate (PO4 3−), an important nutrient for primary production in natural waters, is urgently needed. Here, we report on the development and validation of an on-site autonomous electrochemical analyzer for PO4 3− in seawater. The approach is based on the use of flow injection analysis in conjunction with a du...

Tropical peat swamps are essential ecosystems, which provide numerous services, and also serve as a rich source of dissolved organic carbon (DOC), hydrogen ions and trace elements to peat draining rivers. However, not much is known about trace element export from tropical peat swamps. We investigated trace element dynamics in rivers and estuaries d...

Mercury fulminate (HgFu) was used as an initial detonator for World War I and II munitions. Its presence in previously discarded and dumped munitions could potentially supply mercury pollution into coastal ecosystems where bygone weaponries reside. There is evidence that historical munitions have already contributed mercury pollution in coastal env...

We present high‐resolution profiles of dissolved, labile, and total particulate trace metals (TMs) on the Northeast Greenland shelf from GEOTRACES cruise GN05 in August 2016. Combined with radium isotopes, stable oxygen isotopes, and noble gas measurements, elemental distributions suggest that TM dynamics were mainly regulated by the mixing between...

Biological nitrogen fixation is a key process balancing the loss of combined nitrogen in the marine nitrogen cycle. Its relevance in upwelling or high nutrient regions is still under debate, with the few available studies in these regions of the ocean reporting rates that vary widely from below detection limit to as high as 127nmol L−1d−1. In the e...

We present labile (L‐pTM) and refractory (R‐pTM) particulate trace metal distributions of Fe, Mn, Al, Ti, Co, Zn, Cd, Ni, Pb, Cu, and P for a transect along the southwest African shelf and an off‐shore section at 3°S of the GEOTRACES GA08 section cruise. Particle sources and biogeochemical cycling processes are inferred using particle‐type proxies...

Plain Language Summary Lead (Pb) is a toxic element. Hundreds of thousands of tons have historically been emitted into the atmosphere through use of leaded gasoline, ore‐smelting and coal‐combustion which led to large‐scale deposition of Pb into the ocean and onto the Greenland Ice Sheet. Since the phase‐out of leaded gasoline, concentrations of di...

The Peruvian upwelling system is a highly productive ecosystem that could be altered by ongoing global changes. We carried out a mesocosm experiment off Peru, with the addition of water masses from the regional oxygen minimum zone (OMZ) collected at two different sites simulating two different upwelling scenarios. Here we focus on pelagic remineral...

The abundance of plastic debris (PDs) and its correlation with phthalic acid esters (PAEs), a class of pollutants associated with plastics, is not well understood, although PDs have been reported in relation to the release and distribution of aquatic pollutants such as PAEs. Few studies have linked the distribution of these pollutants in seawater....

Iron (Fe) is an essential micronutrient for primary production, and Fe isotopic composition (δ⁵⁶Fe) has become a widely used oceanographic tool for determining sources and evaluating the biogeochemical cycling of dissolved Fe (dFe) in the oceans. Here, we present dFe concentrations and δ⁵⁶Fe from three unique oceanographic settings (a river dominat...

Carbon capture and storage is a key mitigation strategy proposed for keeping the global temperature rise below 1.5 °C. Offshore storage can provide up to 13% of the global CO2 reduction required to achieve the Intergovernmental Panel on Climate Change goals. The public must be assured that potential leakages from storage reservoirs can be detected...

Glacial freshwater discharge is a source of trace elements and micronutrients to shelf waters. Approximately half of freshwater discharge from the Greenland and Antarctic Ice Sheets enters the marine environment subsurface beneath large floating ice tongues or ice shelves. Yet, due to the inaccessibility of these subglacial cavities, only few studi...

Dissolved organic matter (DOM) is a distinct component of Earth’s hydrosphere and provides a link between the biogeochemical cycles of carbon, nutrients, and trace metals (TMs). Binding of TMs to DOM is thought to result in a TM pool with DOM-like biogeochemistry. Here, we determined elemental stoichiometries of aluminum, iron, copper, nickel, zinc...

High quality pH measurements are required in estuarine and coastal waters to assess the impacts of anthropogenic atmospheric CO2 emissions on the marine carbonate system, including the resulting decrease in pH. In addition, pH measurements are needed to determine impacts on carbonate chemistry of phytoplankton blooms and their breakdown, following...

The Arctic Ocean is considered a source of micronutrients to the Nordic Seas and the North Atlantic Ocean through the gateway of Fram Strait (FS). However, there is a paucity of trace element data from across the Arctic Ocean gateways, and so it remains unclear how Arctic and North Atlantic exchange shapes micronutrient availability in the two ocea...

Accurate, on-site determinations of macronutrients (phosphate (PO43−), nitrate (NO3−), and silicic acid (H4SiO4)) in seawater in real time are essential to obtain information on their distribution, flux, and role in marine biogeochemical cycles. The development of robust sensors for long-term on-site analysis of macronutrients in seawater is a grea...