Mangrove‐fringed estuaries are intertidal ecosystems discharging significant amounts of dissolved organic matter (DOM) into coastal oceans. DOM in these ecosystems is derived from autochthonous production, fluvial input, and mangrove porewater outwelling; however, differentiating between these sources remains challenging. Our incomplete understanding of the biogeochemical factors controlling DOM dynamics and its relationship w...

Dissolved black carbon (DBC) is the largest known slow‐cycling organic carbon pool in the ocean; yet, its sources and processing in the coastal seas remain poorly understood. To address this knowledge gap, we conducted a study in the East China Sea and South Yellow Sea to quantify and molecularly characterize DBC using benzene polycarboxylic acids (DBC BPCA ) and ultra‐high resolution mass spectrometry (DBC FT ), respectively....

Subterranean estuaries are connective zones between inland aquifers and the open sea where terrestrial freshwater and circulating seawater mix and undergo major biogeochemical changes. They are biogeochemical reactors that modify groundwater chemistry prior to discharge into the sea. We propose that subterranean estuaries of high-energy beaches are particularly dynamic environments, where the effect of the dynamic boundary con...

Our current knowledge of the chemical composition of ocean dissolved organic matter (DOM) is limited, mainly because of its extreme molecular diversity, low concentration of individual compounds and the elevated ionic strength of ocean waters. As a result, many analytical methods require a previous extraction step. The efficiency and selectivity of the extraction method defines the representativeness of the extracted DOM fract...

Submarine groundwater discharge (SGD) connects fresh groundwater and marine ecosystems and conveys terrestrially derived dissolved organic matter (DOM) and nutrients from land to sea. The connectivity of terrestrial and marine ecosystems via SGD depends strongly on local environmental settings. For example, SGD composition is modified on its transit through the coastal aquifer, with spring-type SGD from highly permeable aquife...

Zooplankton grazing onphytoplankton promotes the release of particulate and dissolved organic matter (DOM) into the water column and therefore plays a key role in organic matter cycling in aquatic systems. Prokaryotes are the main DOM consumers in the ocean by actively remineralizing and transforming it, contributing to its molecular diversification. To explore the molecular composition of zooplankton‐derived DOM and its bioav...

Dissolved organic matter (DOM) is the largest organic carbon reservoir in the ocean and an integral component of biogeochemical cycles. The role of free‐living microbes in DOM transformation has been studied thoroughly, whereas little attention has been directed towards the influence of benthic organisms. Sponges are efficient filter feeders and common inhabitants of many benthic communities circumglobally. Here, we investigat...

Rare earth elements (REEs) are used as powerful proxies for a variety of oceanic processes. The understanding of their biogeochemical behaviour in the marine environment is therefore essential. While the influence of OM-cycling on REE patterns in seawater is considered as insignificant, it has been shown that algae and bacteria provide good sorption surfaces for REEs and that components of the dissolved OM pool are able to com...

Summary In lake ecosystems, changes in eukaryotic and prokaryotic microbes and the concentration and availability of dissolved organic matter (DOM) produced within or supplied to the system by allochthonous sources are components that characterize complex processes in the microbial loop. We address seasonal changes of microbial communities and DOM in the largest Croatian lake, Vrana. This shallow lake is connected to the Adria...

Large quantities of carbon are stored in marine dissolved organic matter (DOM), and its recycling has a major effect on the carbon cycle. Microbes are responsible for turnover of DOM. Little is known about how the complex pool of DOM shapes microbial communities and vice versa, especially in anoxic systems. In this study, we characterized the DOM pool with high‐resolution Fourier transform ion cyclotron resonance mass spectrom...

The temporal dynamics of dissolved organic matter (DOM) are inherently linked with the functioning of aquatic ecosystems. Because DOM represents a complex mixture of millions of different compounds, the statistical analysis of DOM dynamics poses a huge challenge. Here, we present a statistical approach based on hierarchical clustering of time series that groups DOM compounds with synchronous dynamics. We applied this approach...

Advective flows of seawater and fresh groundwater through coastal aquifers form a unique ecohydrological interface, the subterranean estuary (STE). Here, freshly produced marine organic matter and oxygen mix with groundwater, which is low in oxygen and contains aged organic carbon (OC) from terrestrial sources. Along the groundwater flow paths, dissolved organic matter (DOM) is degraded and inorganic electron acceptors are suc...

Climate change is decreasing watershed glacial coverage throughout Alaska, impacting the biogeochemistry of downstream ecosystems. We collected streamwater fortnightly over the glacial runoff period from three streams of varying watershed glacier coverage (0–49%) and a subglacial outflow to assess how glacier recession impacts the relative contributions of glacier and terrestrial plant derived dissolved organic matter (DOM) in...