Assimilation Of Organic Matter Research Articles

Substrate uptake patterns shape niche separation in marine prokaryotic microbiome.

Marine heterotrophic prokaryotes primarily take up ambient substrates using transporters. The patterns of transporters targeting particular substrates shape the ecological role of heterotrophic prokaryotes in marine organic matter cycles. Here, we report a size-fractionated pattern in the expression of prokaryotic transporters throughout the oceanic water column due to taxonomic variations, revealed by a multi-"omics" approach targeting ATP-binding cassette (ABC) transporters and TonB-dependent transporters (TBDTs). Substrate specificity analyses showed that marine SAR11, Rhodobacterales, and Oceanospirillales use ABC transporters to take up organic nitrogenous compounds in the free-living fraction, while Alteromonadales, Bacteroidetes, and Sphingomonadales use TBDTs for carbon-rich organic matter and metal chelates on particles. The expression of transporter proteins also supports distinct lifestyles of deep-sea prokaryotes. Our results suggest that transporter divergency in organic matter assimilation reflects a pronounced niche separation in the prokaryote-mediated organic matter cycles.

New direction in organic fertilizer production

Our analysis of existing methods of production of organic fertilizers does not allow us to effectively solve the problem of reproduction of soil fertility. Computer simulation of the mixing process in the burts by various aggregates showed the extreme unevenness of the distribution of particles of the resulting compost. The assimilation of organic matter in the soil is less than 2%. The recently widespread method of composting in rotating drums leads to the release of ammonia, which indicates the ongoing process of ammonification, which means that the decomposition of organic matter under the influence of putrefactive, moldy and other microorganisms. The resulting compost causes some damage to the soil and crop. A new direction in the production of organic fertilizers is proposed, based on the cultivation of soil microorganisms in special rooms of the microbiological community. These microorganisms, in turn, produce enzymes that significantly accelerate the biochemical processes in the formation of soil humus.

Weak seasonality in benthic food web structure within an Arctic inflow shelf region

The Arctic Ocean is characterized by pronounced seasonality in the quantity and quality of organic matter exported from the surface ocean. While it is well established that changes in food availability can alter the abundance, biomass and function of benthic organisms, the impact on food web structure is not well studied. We used bulk carbon and nitrogen stable isotope analysis to assess the quantity and quality of sediment organic matter and structure of the benthic food web in four seasons within the Northern Barents Sea (76°N − 82 °C). Despite a highly seasonal vertical flux, we found that the organic carbon and chlorophyll-a content of surface sediments was seasonally stable, suggesting a lack of seasonality in food availability at the seafloor. However, organic biomarkers indicate that the quality of sediment organic matter increased to a maximum in August and December, up to 6 months after the spring bloom. The seasonal stability of food quantity was mirrored in food-web structure (e.g., total isotopic range, number of trophic levels) which did not change significantly across sampling periods. We expected that suspension and deposit feeders would respond more readily to seasonal changes in food quality compared to predators. However, we observed no significant seasonal changes in the trophic levels or isotopic niche areas of benthic functional groups. The centroids of isotopic niches of all benthic functional groups shifted seasonally by <2 ‰ along the δ13C-axis, suggesting minimal shifts in carbon resource use. Because the northern Barents Sea experiences significant changes in seasonal sea ice cover, we expected that stable-isotope ratios of benthic organisms would show an increased consumption of sympagic-derived organic matter through less negative δ13C values in early spring and summer. However, only two taxa (the soft coral Gersemia spp. and bivalves in the family Yoldiidae) showed 13C-enrichment in spring or summer consistent with the assimilation of sympagic-derived organic matter, despite previous evidence suggesting widespread use of this carbon source. Overall, our results show that there is an apparent de-coupling in time between pelagic processes and benthic food-webs in which the accumulation and assimilation of high-quality organic matter occurs for benthos during the fall and early winter months when there is little to no fresh organic matter generated at the surface. This temporal mismatch highlights the importance of considering the timescales over which components of the marine ecosystem respond to short-term environmental changes and the methods employed to assess seasonality.

Climate change impact assessment on a tropical river resilience using the Streeter-Phelps dissolved oxygen model

This paper provides a technical analysis of a river’s current and future resilience in a watershed with intensive agricultural and fishing activities. The study area was the last section of the Culiacan River corresponding to the river mouth over a lagoon system. Dissolved oxygen modeling was performed using the Streeter-Phelps model to evaluate the river self-depuration capability using Biochemical Oxygen Demand, dissolved oxygen, streamflow, and water temperature data from 2013 to 2020. Fieldwork was carried out to establish the geomorphological characteristics of the river by determining stream velocity, width, and depth and the location of nine sources of pollution on the river. The modeling was performed for three groups of months with different temperatures, identified by hierarchical cluster analysis. Estimates were made for future scenarios, assessing the effect of climate change on the Culiacan River’s self-depuration capability. The results showed that most of the year, the degradation rate of the system results in rapid assimilation of organic matter. However, the modeling indicates that the river would lose its resilience capability under climate change. Thus, it is essential to implement wastewater treatment systems to reduce the environmental impact on the aquatic ecosystem in the river and the lagoon system.

Experimentally derived biochemical modelling parameters to improve understanding of aquaculture's effect on marine food webs

To construct robust biogeochemical models for application to marine-based aquaculture settings, careful selection of appropriate model parameters is necessary. This study used an experimental approach to establish biomarkers of farm and marine-derived organic matter, and to derive isotopic turnover rates, and trophic discrimination factors specific to aquaculture associated food webs.A shift towards a farm-derived resource base resulted in consumer tissues more depleted in the carbon-13 isotope (indicated by more negative δ13C values) and a higher proportion of oleic acid, linoleic acid, and alpha-linoleic acid in the fatty acid profile of consumers over time. Measured trophic discrimination factors between dietary sources and consumer tissues demonstrated high variability among species and tissue types, ranging from −0.25‰ to 0.82‰ for Δ13C and from −0.77‰ to 6.8‰ for Δ15N. Stable isotope half-lives were also diverse among species and tissue types, ranging from <7 days to 462 days.Results demonstrated that construction of robust models for tracing assimilation of farm-derived organic matter through marine food webs requires the use of taxa and tissue specific parameters. Turnover rates have applications for understanding assimilative capacity of communities and for managing populations within the ecological footprint of farms.

Mechanism of organic matter assimilation and its role in sulfide saturation of oxidized magmatic ore-forming system: insights from C-S-Sr-Nd isotopes of the Tulaergen deposit in NW China

Mechanism of organic matter assimilation and its role in sulfide saturation of oxidized magmatic ore-forming system: insights from C-S-Sr-Nd isotopes of the Tulaergen deposit in NW China

Organic contaminants in imported salmon feed and their effects on reef ecosystems in New Zealand

Organic matter from salmon farms has been shown to be assimilated by soft sediment and rocky reef communities within the ecological footprint of salmon farms. Given these findings, another question arises – What other chemicals in salmon feed may be assimilated into wild communities via organic waste from salmon farms? Here we measured a suite of organic contaminants in salmon feed, in organisms used in a controlled feeding experiment, and in reef species collected within the depositional footprint of salmon farms. Gas Chromatography-Tandem Mass Spectrometry was used to quantify trace concentrations of polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs) and current-use (CPUs) and historic-use pesticides (HUPs) in salmon feed imported to New Zealand. The effect of assimilation of farm-derived organic matter on contaminant profiles differed among species during the controlled feeding experiment and demonstrated that migration of individuals to a farm-associated site has the potential to increase or decrease organic contaminant concentrations. Concentrations of PCBs in Parapercis colias (blue cod), a highly resident, long-lived fish, were significantly higher at farm sites than at reference sites. While these concentrations were relatively low in a global context, this result presents blue cod as an important candidate for future monitoring of organic contaminants around point sources. PCBs and PBDEs measured in wild marine species were all below limits set by the European Union, whereas concentrations of certain HUPs, specifically dichlorodiphenyltrichloroethane (DDT) and its degradation products and endosulfan, may be of concern as a consequence of alternative anthropogenic activities. Overall, feed imported to New Zealand had relatively low levels of most organic contaminants that, at current levels, are unlikely to result in significant ecological effects to wild communities in adjacent habitats.

Tracing Nutrients and Organic Matter Changes in Eutrophic Wenchang (China) and Oligotrophic Krka (Croatia) Estuaries: A Comparative Study

Estuaries modify the concentration and composition of riverine nutrients and organic matter (OM), which eventually determine the riverine flux effect to coasts. Nutrients, organic carbon (OC), pigments, and amino acids (AAs) from the samples collected in the eutrophic Wenchang River Estuary (WRE) in China and the oligotrophic Krka River Estuary (KRE) in Croatia were analyzed in order to have a better understanding of how estuaries regulate terrestrial materials. We found a clear increase of dissolved inorganic nitrogen (DIN) concentration and its subsequent decrease due to the removal of DIN (over 100 μM) in the WRE, whereas DIN showed minor variation lengthwise in the KRE, i.e., with the salinity changes, ranging between 1.0 and 5.8 μM. The elevated algae-derived OC, dissolved organic nitrogen, and particulate AAs nitrogen suggest that the OM assimilation may explain approximately one-third of the DIN removal in the WRE, whereas in the oligotrophic KRE, such inorganic to organic transformation is not likely to be significant. Due to the prominent estuarine nitrogen removal/assimilation process, DIN/dissolved inorganic phosphorus (DIP) ratio was as high as 425 in the upper WRE under strong riverine influence, but it declined to as low as 5.4 at the mouth of WRE, that is even lower than DIN/DIP ratio at the mouth of oligotrophic KRE (12). When compared with other rivers worldwide, the Wenchang River showed high nutrients and organic carbon yields. Given the contrasting estuarine process (e.g., DIN removal) between the KRE and the WRE, apparent high nutrient yield from eutrophic rivers should be viewed with caution in ocean studies as the final impact to coastal zone could be similar to the oligotrophic rivers like the KRE.

Significant but short time assimilation of organic matter from decomposed exotic Spartina alterniflora leaf litter by mangrove polychaetes

Leaf litter is an important nutrient source for benthic communities within mangrove ecosystems and in adjacent areas. Exotic Spartina alterniflora invasion to the eastern coastlines of China has been shown to alter trophic relationship of benthos in mangrove wetlands, but little is known about potential effect of exotic litter decomposition on food sources of benthic macrofauna. We took the advantage of significant differences in the δ13C values of exotic S. alterniflora (C4 plant) from a native mangrove species Kandelia obovata (C3 plant) to investigate leaf carbon assimilation by polychaetes during litter decomposition. We found that exotic S. alterniflora leaf litter decomposed more slowly than that of native mangrove species at the mangrove site (P = 0.003), but there was no significant difference between them at the salt marsh site (P = 0.270). The polychaetes assimilated major organic matter from K. obvata and the particulate organic matter (> 90%) at the mangrove site. But the polychaetes assimilated major organic matter from S. alterniflora (> 60%) at the salt marsh site. However, after adding S. alterniflora leaf litter at the mangrove site, polychaetes assimilated more carbon from S. alterniflora (> 45%) than that from K. obovata (< 25%). Furthermore, the significant carbon assimilation only occurred within a short period time (1–2 months) during decomposition. Our results suggested that Spartina invasion can change food sources of local mangrove polychaetes through utilizing the organic matter released from litter decomposition, but such assimilation of exotic foods is of short time nature.

The redox conditions and C isotopes of magmatic Ni-Cu sulfide deposits in convergent tectonic settings: The role of reduction process in ore genesis

Reduction process might play a critical role in the genesis of magmatic Ni-Cu sulfide deposits in convergent tectonic settings. To test this hypothesis, we have determined the oxygen fugacities (fO2) and C isotopes of several typical magmatic Ni-Cu sulfide deposits in convergent tectonic settings in western China. Two popular spinel-olivine-orthopyroxene (Spl-Ol-Opx) oxybarometers, one from Wood (1990) and the other from Ballhaus et al. (1991), are evaluated for their accuracy for this type of deposit by comparing the results with those from an independent method, the olivine-sulfide (Ol-Sul) oxybarometer of Barnes et al. (2013). We find that only the results from the Spl-Ol-Opx oxybarometer of Wood (1990) are consistent with those from the independent method. The fO2 of the sulfide-mineralized samples from the selected deposits, estimated using these two methods, are from QFM–0.56 to QFM+1.84 (quartz-fayalite-magnetite buffer). Using the Spl-Ol-Opx oxybarometer of Wood (1990), the estimated fO2 values of the sulfide-unmineralized ultramafic rocks from primitive arc cumulates in the same region, which have higher olivine Fo contents than the sulfide-mineralized rocks, are significantly higher (~QFM+2.42). The decrease of fO2 from the sulfide ore-barren to ore-bearing magmatic systems indicates that reduction process indeed played a critical role in the genesis of the studied magmatic sulfide deposits. The δ13C values of the sulfide-bearing ultramafic rocks are from –16.5 to –37.2‰ (n = 52), which are significantly lower than the primitive arc cumulates (−7.1 to −9.6‰) but similar to those of organic matter in sedimentary rocks worldwide (–15 to –35‰). The isotope data indicate assimilation of organic matter from the country rocks by the parental magmas for the studied magmatic Ni-Cu sulfide deposits, supporting the interpretation that sulfide saturation in the parental magmas were mainly induced by the reduction process associated with the addition of organic matter to the magmas.

Variations in bacterial taxonomic profiles and potential functions in response to the gut transit of earthworms (Eisenia fetida) feeding on cow manure

Earthworms play an important role in the organic matter decomposition in terrestrial ecosystems. Earthworms interact directly with the microorganisms to affect the organic matter decomposition via gut transit, i.e., the digestion and assimilation of organic matter in the foregut and midgut and its excretion by the hindgut. However, how the microbial community ingested by earthworms respond to the transit processes in different gut segments of earthworms is not clear. We used composted cow manure to feed earthworms and sampled vermicompost and the contents of foregut, midgut and hindgut for bacterial 16S rRNA gene sequencing analysis. We observed that earthworm gut transit decreased the abundances of the dominant phyla Proteobacteria and Bacteroidetes but increased Actinobacteria, Chloroflexi and Acidobacteria. The alpha diversity of bacterial community in midgut was the lowest of the different gut segments, and the bacterial community structure of the foregut was significantly different from the midgut and hindgut. The enrichment analysis results revealed different selective stimulatory and inhibitory effects on the ingested bacterial community in the different gut segments, which extended to vermicompost. The FAPROTAX data indicated that C and N metabolic microbes were enriched in the earthworm gut. Microbes involved in fermentation and methanogenesis were enriched in the hindgut, and denitrification microbes were enriched in the foregut. The N metabolism microbes in vermicompost were significantly enriched after the stimulation of earthworm gut transit (P < 0.05), and the pathogenic microbes of animals and plants were inhibited. Combined with the results of subsequent correlation and biochemical analyses, earthworm gut transit significantly altered the structure and function of the bacterial community to accelerate the degradation and mineralization of organic matter and the enrichment of phosphorus and potassium. Our study suggests that the gut transit process of earthworms plays an important role in regulating organic matter dynamics in terrestrial ecosystems.

A quantitative analysis of organic matter inputs to soft sediment communities surrounding salmon farms in the Marlborough Sounds region of New Zealand

Local differences in trophic structure and composition of organic matter subsidies can influence the capacity of soft sediment communities to assimilate recycled organic matter from processes such as salmon farm enrichment. The present study combines biochemical analysis with biomass density information on soft sediment taxa collected within the depositional footprint of salmon farms and at reference sites in the Marlborough Sounds, New Zealand. Distinct biochemical signatures confirmed that the flux of organic matter from salmon farms was an important subsidy for soft sediment communities. Isotopic modelling demonstrated that the proportion of biomass supported by farm-derived organic matter did not change in a consistent pattern along the 300 m gradient from each farm site, whereas the average trophic level of communities decreased with increasing proximity to farms. High variability in both the total biomass and the distribution of biomass across trophic levels occurred among sites downstream of farms and among individual farms. Consequently, estimates of basal organic matter assimilation per unit area by communities differed by several orders of magnitude among sites. Total organic matter assimilation tended to decrease with increasing proximity to farms due to a shift towards a more detrital based community. Differences in basal organic matter assimilation among farms did not appear to be directly related to local flow regime, but instead was closely linked to differences in the soft sediment community composition likely influenced by an array of anthropogenic and environmental factors. The results presented here highlight the importance of considering local variability in basal organic matter source pools, and the potential for synergistic and cumulative effects to drive changes in food web trophodynamics when assessing the impacts of aquaculture on soft sediment communities.

Organic matter assimilation by hard substrate fauna in an offshore wind farm area: a pulse-chase study

AbstractThe installation of offshore wind farms (OWFs) adds artificial hard substrates into naturally soft-bottom areas, changing the local biodiversity. The turbine foundations are rapidly colonized by colonizing organisms, mainly consisting of suspension feeders that can potentially reduce the local primary producer standing stock. In this study, we estimated the amount of organic matter processed by colonizing assemblages of OWFs. We conducted a laboratory pulse-chase experiment, by offering 13C-labelled fragmented microalgae to PVC panels colonized by OWF colonizing fauna. The blue mussel Mytilus edulis showed the highest biomass-specific carbon assimilation, while the high densities of the amphipod Jassa herdmani resulted in the highest total carbon assimilation. By upscaling our results to the total number of the installed offshore wind turbines in the Belgian part of the North Sea, we estimate that these species can reduce the local primary producer standing stock in the area by ca. 1.3%. Mytilus edulis and J. herdmani communities colonizing offshore wind turbine foundations significantly increase carbon assimilation compared to natural soft sediment macrofauna inhabiting the same surface area (i.e. footprint of the turbines).

Feeding selectivity of Holothuria atra in different microhabitat in Panjang Island, Jepara (Java, Indonesia)

Abstract. Hartati R, Zainuri M, Ambariyanto A, Widianingsih W. 2020. Feeding selectivity of Holothuria atra in different microhabitat in Panjang Island, Jepara (Java, Indonesia). Biodiversitas 21: 2233-2239. Particle selectivity by deposit feeder sea cucumber Holothuria atra was an important concept in its feeding ecology. This species utilized the organic matter that coated sediment and detrital particles as food. Thus, particle size, organic matter, and microalgal biomass had been proposed as variables food resources along which niche separation could occur in optimal foraging strategy. This study was conducted in five microhabitats of different coverage of seagrass bed (P1-P4) up to the rubble area (P5) over a tidally variable depth range of 0,5-5m in Panjang island, Jepara. Twenty samples of sea cucumber H. atra were taken from defined microhabitat, along with samples of sediment underneath the sea cucumber. Granulometry of the particles ingested by sea cucumbers, total organic matter, and microphytobenthic biomass (as chlorophyll-a) found throughout their digestive tract (alimentary canal) and in the sediments was analyzed. Comparison of the contents and the rates of organic matter assimilation of the digestive tract with those of the microhabitat sediment were carried out. The results showed that H. atra fed on sediment underneath their body and it was revealed that there were strong (ƿ=0.833-0.876) to very strong (ƿ=0.945) positive relationship between grain size in the sediment and in their alimentary canal which showed their feeding selectivity of the sediment. H. atra also found to have efficiency in feeding by taking advantage of the high TOM content and high abundance of microphytobenthic organisms (presented as chlorophyll-a) in their natural microhabitats.

Linking extracellular enzymes to phylogeny indicates a predominantly particle-associated lifestyle of deep-sea prokaryotes.

Heterotrophic prokaryotes express extracellular hydrolytic enzymes to cleave large organic molecules before taking up the hydrolyzed products. According to foraging theory, extracellular enzymes should be cell associated in dilute systems such as deep sea habitats, but secreted into the surrounding medium in diffusion-limited systems. However, extracellular enzymes in the deep sea are found mainly dissolved in ambient water rather than cell associated. In order to resolve this paradox, we conducted a global survey of peptidases and carbohydrate-active enzymes (CAZymes), two key enzyme groups initiating organic matter assimilation, in an integrated metagenomics, metatranscriptomics, and metaproteomics approach. The abundance, percentage, and diversity of genes encoding secretory processes, i.e., dissolved enzymes, consistently increased from epipelagic to bathypelagic waters, indicating that organic matter cleavage, and hence prokaryotic metabolism, is mediated mainly by particle-associated prokaryotes releasing their extracellular enzymes into diffusion-limited particles in the bathypelagic realm.

Spatio-Temporal Changes in Basal Food Source Assimilation by Fish Assemblages in a Large Tropical Bay in the SW Atlantic Ocean

Understanding food pathways in estuarine communities is essential to improve our ability to cope with the increasing effects of man-made activities and climate variability on the biodiversity of coastal systems. Herein, we analyzed carbon and nitrogen isotope ratios of food web components in a large tropical bay in the southwestern Atlantic, in order to investigate spatial and temporal changes in the assimilation of basal food sources by fishes. Two hypotheses were evaluated: (i) continental-derived organic matter assimilation and isotopic niches of fish trophic guilds will increase during higher rainfall conditions and (ii) relative mangrove and macroalgae-derived nutrients assimilation will be directly proportional to their relative availability at each location. Our results did not corroborate our first hypothesis, while only partially corroborating the second one. As expected, macroalgae was one of the main assimilated basal food sources (especially by omnivore and zooplanktivore fishes) at the site where this primary producer was highly abundant. In contrast, only negligible amounts of mangrove-derived nutrients were assimilated by most trophic fish guilds at the site harboring an extensive mangrove area. Bayesian mixing models also revealed a substantial contribution of seagrass to herbivore and detritivore fishes. Some mechanisms like water divergence diminishing organic matter transport into the bay and the refractory characteristics of mangrove-derived detritus could partially explain these findings.

Assimilation of shrimp farm sediment by Holothuria scabra: a coupled fatty acid and stable isotope approach

Deposit-feeding sea cucumbers are efficient nutrient recyclers and have the potential to contribute to the limitation of organic matter load in polyculture or integrated aquaculture systems. Assessing how they assimilate organic matter originating from other farmed species is therefore important for the development of such multi-species farming systems. Here, a coupled stable isotope − fatty acid approach was used to characterize the assimilation of organic matter from shrimp (Penaeus stylirostris) farming by Holothuria scabra in an experimental culture system. H. scabra were reared in mesocosms on shrimp farming-originating sediment with and without additional food sources (maize and fish meals). Although fatty acid results did indicate that shrimp-farming sediment was assimilated by holothurids, we found no evidence of maize waste and fish meal contribution to H. scabra organic carbon (no effect on δ13C, no accumulation of meal-specific fatty acids). However, a strong effect of fish meal on H. scabra δ15N was observed, suggesting that this additional food source could represent an alternative source of nitrogen for holothurids. Finally, this study supports the culture of H. scabra as a perspective to reduce sedimentary organic matter excess associated with shrimp farms, and suggest that the addition of selected food sources might contribute to increasing the content in some nitrogen organic compounds in holothurid tissues.

Cellulase activity and stable isotope signature of benthic macroinvertebrates in estuarine habitats: potential assimilation of land-derived organic matter

Cellulase activity and stable isotope signature of benthic macroinvertebrates in estuarine habitats: potential assimilation of land-derived organic matter

Implication of Viral Infections for Greenhouse Gas Dynamics in Freshwater Wetlands: Challenges and Perspectives.

Viruses are non-living, acellular entities, and the most abundant biological agents on earth. They are widely acknowledged as having the capacity to influence global biogeochemical cycles by infecting the bacterial and archaeal populations that regulate carbon and nutrient turnover. Evidence suggests that the majority of viruses in wetlands are bacteriophages, but despite their importance, studies on how viruses control the prokaryotic community and the concomitant impacts on ecosystem function (such as carbon cycling and greenhouse gas flux) in wetlands are rare. Here we investigate virus-prokaryote interactions in freshwater wetland ecosystems in the context of their potential influence on biogeochemical cycling. Specifically, we (1) synthesize existing literature to establish current understanding of virus-prokaryote interactions, focusing on the implications for wetland greenhouse gas dynamics and (2) identify future research priorities. Viral dynamics in freshwater wetlands have received much less attention compared to those in marine ecosystems. However, based on our literature review, within the last 10 years, viral ecology studies on freshwater wetlands have increased twofold. Despite this increase in literature, the potential implication of viral infections on greenhouse gas emission dynamics is still a knowledge gap. We hypothesize that the rate of greenhouse gas emissions and the pool of sequestered carbon could be strongly linked to the type and rate of viral infection. Viral replication mechanism choice will consequently influence the microbial efficiency of organic matter assimilation and thus the ultimate fate of carbon as a greenhouse gas or stored in soils.

Stable isotopes and geochemical indicators in marine sediments as proxies for anthropogenic impact: A baseline for coastal environments of central Chile (33°S)

Stable isotopes and geochemical proxies (TOC/TN and Chla/TOC) in sediments can be used to distinguish organic matter sources (anthropogenic, terrestrial, or marine). This study aims to characterize organic matter (OM) in superficial sediments from three sectors of central Chile (33°S) that are highly influenced by urban and industrial development. Our results show that a substantial fraction of these OM in Quintero Bay is anthropogenic, from industrial and domestic wastewater sources. In contrast, a mixture of terrestrial and anthropogenic OM dominates the isotopic signal of surface sediments from Concón, derived from non-point industrial and agriculture sources associated with the Aconcagua River basin, while Ritoque exhibited a mixture of different OM sources. However, deposition of allochthonous OM in our study area depends on coastal topography, which influences the local currents and well-ventilated waters, promoting the dispersion and assimilation of OM and thus providing an environment with a high capacity for natural remediation.