Showing papers on "Water column published in 2022"
TL;DR: In this paper, the authors assessed the environmental quality of the marine coastal area impacted by a mining disaster (Fundao Mine dam collapse on 05 November 2015, Southeast Brazil) by applying a geochemical multi-index and physical approach over 18 months.
32 citations
TL;DR: The prevalence of plastics in the entire water column is unveiled, highlighting the urgency for more quantification of the deep-ocean MP, particularly the smaller size fraction, to better understand ecosystem exposure and to predict MP fate and impacts.
Abstract: Hundreds of studies have surveyed plastic debris in surface ocean gyre and convergence zones, however, comprehensive microplastics (MPs, ≤5 mm) assessments beneath these surface accumulation areas are lacking. Using in situ high‐volume filtration, Manta net and MultiNet sampling, combined with micro‐Fourier‐transform‐infrared imaging, we discovered a high abundance (up to 244.3 pieces per cubic meter [n m−3]) of small microplastics (SMPs, characteristically <100 μm) from the surface to near‐sea floor waters of the remote South Atlantic Subtropical Gyre. Large horizontal and vertical variations in the abundances of SMP were observed, displaying inverse vertical trends in some cases. SMP abundances in pump samples were more than two orders of magnitude higher than large microplastics (LMPs, >300 μm) concurrently collected in MultiNet samples. Higher‐density polymers (e.g., alkyd resins and polyamide) comprised >65% of the total pump sample count, highlighting a discrepancy between polymer compositions from previous ocean surface‐based surveys, typically dominated by buoyant polymers such as polyethylene and polypropylene. Contrary to previous reports stating LMP preferentially accumulated at density gradients, SMP with presumably slower sinking rates are much less influenced by density gradients, thus resulting in a more even vertical distribution in the water column, and potentially longer residence times. Overall, our findings suggest that SMP is a critical and largely underexplored constituent of the oceanic plastic inventory. Additionally, our data support that weak current systems contribute to the formation of SMP hotspots at depth, implying a higher encounter rate for subsurface particle feeders. Our study unveils the prevalence of plastics in the entire water column, highlighting the urgency for more quantification of the deep‐ocean MP, particularly the smaller size fraction, to better understand ecosystem exposure and to predict MP fate and impacts.
30 citations
TL;DR: In this paper , the authors focus on eukaryotic extraorganismal eDNA, outline how water chemistry and suspended mineral particles likely affect conversion among each eDNA state, and indicate how environmental parameters affect persistence of states in the water column.
Abstract: Increased use of environmental DNA (eDNA) analysis for indirect species detection has spurred the need to understand eDNA persistence in the environment. Understanding the persistence of eDNA is complex because it exists in a mixture of different states (e.g., dissolved, particle adsorbed, intracellular, and intraorganellar), and each state is expected to have a specific decay rate that depends on environmental parameters. Thus, improving knowledge about eDNA conversion rates between states and the reactions that degrade eDNA in different states is needed. Here, we focus on eukaryotic extraorganismal eDNA, outline how water chemistry and suspended mineral particles likely affect conversion among each eDNA state, and indicate how environmental parameters affect persistence of states in the water column. On the basis of deducing these controlling parameters, we synthesized the eDNA literature to assess whether we could already derive a general understanding of eDNA states persisting in the environment. However, we found that these parameters are often not being measured or reported when measured, and in many cases very few experimental data exist from which to draw conclusions. Therefore, further study of how environmental parameters affect eDNA state conversion and eDNA decay in aquatic environments is needed. We recommend analytic controls that can be used during the processing of water to assess potential losses of different eDNA states if all were present in a water sample, and we outline future experimental work that would help determine the dominant eDNA states in water.
28 citations
TL;DR: In this article , the seasonal occurrence and distribution of microplastics in the surface water samples of Lake Manipal in southwest India was investigated, and the concentration of small-sized (0.3-1 mm) microplastic were greater in both seasons.
22 citations
TL;DR: In this paper , the Vollenweider's complete-mix phosphorus budget model was adapted to account for high water level variations, which are a common feature in tropical reservoirs, and for internal phosphorus loads.
22 citations
TL;DR: In this paper, the ingestion and egestion of microplastics by copepods in the Black Sea was assessed for the first time, and the most common types of ingested microplastic were fibres, followed by films and fragments.
19 citations
TL;DR: In this paper , the ingestion and egestion of microplastics by copepods in the Black Sea was assessed for the first time, and the most common types of ingested microplastic were fibres, followed by films and fragments.
18 citations
TL;DR: Wang et al. as mentioned in this paper combined intact sediment core incubation, high-resolution peeper (HR-Peeper) sampling, and analysis of internal nitrogen (N) and phosphorus (P) forms and other environmental factors in the water column and sediments to evaluate the contributions of internal N and P loading to water eutrophication.
16 citations
TL;DR: Wang et al. as discussed by the authors monitored the microplastic pollution characteristics in the fish digestive tract and surface water of the Nandu River, the largest river in Hainan, China.
16 citations
TL;DR: In this article , the elemental ratio of silicon to nitrogen (N) of sinking biogenic matter was found to increase by 17 ± 6 per cent under the year 2100, when ocean acidification was predicted.
Abstract: Abstract Diatoms account for up to 40% of marine primary production 1,2 and require silicic acid to grow and build their opal shell 3 . On the physiological and ecological level, diatoms are thought to be resistant to, or even benefit from, ocean acidification 4–6 . Yet, global-scale responses and implications for biogeochemical cycles in the future ocean remain largely unknown. Here we conducted five in situ mesocosm experiments with natural plankton communities in different biomes and find that ocean acidification increases the elemental ratio of silicon (Si) to nitrogen (N) of sinking biogenic matter by 17 ± 6 per cent under $${{p}}_{{{\rm{CO}}}_{2}}$$ p CO 2 conditions projected for the year 2100. This shift in Si:N seems to be caused by slower chemical dissolution of silica at decreasing seawater pH. We test this finding with global sediment trap data, which confirm a widespread influence of pH on Si:N in the oceanic water column. Earth system model simulations show that a future pH-driven decrease in silica dissolution of sinking material reduces the availability of silicic acid in the surface ocean, triggering a global decline of diatoms by 13–26 per cent due to ocean acidification by the year 2200. This outcome contrasts sharply with the conclusions of previous experimental studies, thereby illustrating how our current understanding of biological impacts of ocean change can be considerably altered at the global scale through unexpected feedback mechanisms in the Earth system.
16 citations
TL;DR: In this paper , the vertical distribution of microplastics in the water column and surface sediments and explored the effect of tidal variation on the transport of micro-plastic in Jiulong Estuary and Xiamen Bay, China.
01 Mar 2022
TL;DR: The vertical distribution of microplastic abundances throughout the water column in two Marine Strategy Framework Directive (MSFD) demarcations from the western Mediterranean Sea during July 2019 was reported in this article .
Abstract: The abundance of microplastics (plastic particles of less than 5 mm) along the sea surface and in seafloor sediments have been extensively documented worldwide; however, little is known in terms of the vertical distribution of microplastics in the water column, especially in the epipelagic zone. Considering the biological importance of this area, the quantification of microplastics available here is essential to identify potential impacts for marine organisms. This study reports the vertical distribution of microplastic abundances throughout the water column in two Marine Strategy Framework Directive (MSFD) demarcations from the western Mediterranean Sea during July 2019. Three concatenated 5-L Niskin bottles were used for sampling at 5, 15 and 25 m from the sea surface in stations with a total depth smaller than 50 m and at 5, 25 and 50 m from the sea surface in stations with a total depth greater than 50 m. This study demonstrates the ubiquitous abundance of microfibers, 96% of the microplastic items identified in the upper epipelagic layer of the western Mediterranean Sea. Microplastics exhibit a heterogeneous vertical and horizontal spatial distribution. Fragments had a very low representation (4% of the items) but showed a similar frequency of occurrence along all sampling depths. In terms of size, 68% of the microplastics were less than 2 mm in length. Microplastics quantified within the study area were mainly composed of low-density polyethylene (LDPE) and polypropylene (PP) (20% each) followed by cellulose acetate (CA) (16%) and polyestyrene (PS) (14%). Regarding the spatial distribution of microplastics, higher abundances were found at intermediate distances (5–10 km from the coast) with mean values of 2.41 ± 1.90 items L−1 and further away (>20 km) from the coast, with mean values of 2.11 ± 1.80 items L−1. A slight decreasing trend in the abundances of microplastics from the sub-surface to deeper waters was also observed. Stations within MPAs waters showed no significant differences in microplastic abundances when compared to non-MPAs stations. Overall, the results of this study highlight the ubiquitous presence of microplastics, primarily microfibers, along the epipelagic layer of the Spanish Mediterranean continental shelf.
TL;DR: In this article , the authors studied the distribution of isoGDGTs and their hydroxy derivatives in the water column of the deep (288 m), meromictic northern basin of Lake Lugano (Switzerland) using quantitative analysis.
TL;DR: In this paper , the authors assess progress toward creating a global accounting of carbon export and sequestration via the biological pump and suggest a potential path toward achieving this goal, which is the goal of this paper.
Abstract: The biological pump transports organic matter, created by phytoplankton productivity in the well-lit surface ocean, to the ocean's dark interior, where it is consumed by animals and heterotrophic microbes and remineralized back to inorganic forms. This downward transport of organic matter sequesters carbon dioxide from exchange with the atmosphere on timescales of months to millennia, depending on where in the water column the respiration occurs. There are three primary export pathways that link the upper ocean to the interior: the gravitational, migrant, and mixing pumps. These pathways are regulated by vastly different mechanisms, making it challenging to quantify the impacts of the biological pump on the global carbon cycle. In this review, we assess progress toward creating a global accounting of carbon export and sequestration via the biological pump and suggest a potential path toward achieving this goal. Expected final online publication date for the Annual Review of Marine Science, Volume 15 is January 2023. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
TL;DR: In this paper , the elemental ratio of silicon to nitrogen (N) of sinking biogenic matter was found to increase by 17 ± 6 per cent under the year 2100, when ocean acidification was predicted.
Abstract: Abstract Diatoms account for up to 40% of marine primary production 1,2 and require silicic acid to grow and build their opal shell 3 . On the physiological and ecological level, diatoms are thought to be resistant to, or even benefit from, ocean acidification 4–6 . Yet, global-scale responses and implications for biogeochemical cycles in the future ocean remain largely unknown. Here we conducted five in situ mesocosm experiments with natural plankton communities in different biomes and find that ocean acidification increases the elemental ratio of silicon (Si) to nitrogen (N) of sinking biogenic matter by 17 ± 6 per cent under $${{p}}_{{{\rm{CO}}}_{2}}$$ p CO 2 conditions projected for the year 2100. This shift in Si:N seems to be caused by slower chemical dissolution of silica at decreasing seawater pH. We test this finding with global sediment trap data, which confirm a widespread influence of pH on Si:N in the oceanic water column. Earth system model simulations show that a future pH-driven decrease in silica dissolution of sinking material reduces the availability of silicic acid in the surface ocean, triggering a global decline of diatoms by 13–26 per cent due to ocean acidification by the year 2200. This outcome contrasts sharply with the conclusions of previous experimental studies, thereby illustrating how our current understanding of biological impacts of ocean change can be considerably altered at the global scale through unexpected feedback mechanisms in the Earth system.
TL;DR: In this article, the authors conducted an intensive sampling campaign in the marginal sea water column off southeast China, which is an area that is greatly influenced by high MP emissions and found that hydrological effects largely regulated the spatial variations of MP fiber distribution and that MP fibers likely were not entering the South China Sea through terrestrial input from southeast China during the summer monsoon.
TL;DR: This paper used data science techniques to identify two distinct patterns of archaeal lipid distribution from globally distributed seawater and surface sediments, indicative of shallow and deep ecotypes in the modern oceans.
Abstract: Significance Archaeal lipids are ubiquitous in marine sediments and are commonly used to infer past marine sea surface temperatures. However, these molecules can also be used to investigate the ecological and evolutionary history of marine archaea. Here we utilized data science techniques to identify two distinct patterns of archaeal lipid distribution from globally distributed seawater and surface sediments, indicative of shallow and deep ecotypes in the modern oceans. Further investigation of ancient marine sediments across the Mesozoic–Cenozoic suggests that deep water AOAs were suppressed in global oceans during greenhouse climates, which has not been observed by traditional molecular evolutionary models. This perspective carries important implications for marine nitrogen and carbon cycling and the reconstruction of past ocean temperatures.
TL;DR: In this paper , the authors conducted an intensive sampling campaign in the marginal sea water column off southeast China, which is an area that is greatly influenced by high MP emissions and found that hydrological effects largely regulated the spatial variations of MP fiber distribution and that MP fibers likely were not entering the South China Sea through terrestrial input from southeast China during the summer monsoon.
TL;DR: In this paper , the authors investigated the microplastics distribution in the sediments of such a lake in Tianjin, China receiving reclaimed water and determined the factors affecting the settlement of micro-plastics in the sediment column.
TL;DR: In the Gulf of Mexico (GoM), the upper 300m of the water column contains a mixture of water types derived from water masses from the North Atlantic and the Caribbean Sea, namely Caribbean Surface Water (CSW), Subtropical Underwater (SUW), Gulf Common Water (GCW), and Tropical Atlantic Central Water (TACW), which are mainly altered by mesoscale processes and local evaporation as mentioned in this paper.
TL;DR: In this paper , the settling velocities of various biodegradable and nonbiodegradability polymers of various shapes, sizes, and biofilm colonization were measured in a settling column.
Abstract: Microplastics residence times in lakes are currently poorly understood. In this work, settling experiments with pristine and biofilm‐colonized microplastic particles were combined with model calculations to evaluate settling velocities, particle distributions, and residence times in the epilimnion, metalimnion, and hypolimnion of a hypothetical stratified lake broadly based on Upper Lake Constance. Settling velocities of various biodegradable and nonbiodegradable polymers of various shapes, sizes, and biofilm colonization were measured in a settling column. The settling velocities ranged between ~ 0.30 and ~ 50 mm s−1. Particle sizes and polymer densities were identified as primary controls on settling rates. Microplastic particles that had been exposed to a lake environment for up to 30 weeks were colonized by a range of biofilms and associated extracellular polymeric substances; surprisingly, however, the settling velocity did not vary significantly between pristine and colonized microplastic particles. Simulated microplastic residence times in the model lake varied over a wide range of time scales (10−1 to 105 d) and depended mainly on the size of the particles and depth of the lake layer. Long residence times on the order of 105 d (for 1‐μm microplastic particles) imply that for small microplastic particles there is a high probability that they will be taken up at some stage by lake organisms. As the lake retention time (~ 4.5 years) is considerably shorter than the residence time of small microplastics, negligible quantities of these microplastic particles should be found in the lake sediment unless some other process increases their settling velocity.
TL;DR: In this article , the authors constrain global lake water CH4 emissions by using new information on lake area and distribution and CH4 fluxes distinguished by major emission pathways; ecoclimatic lake type; satellite-derived ice-free emission period length; and diel and temperature-related seasonal flux corrections.
Abstract: Lakes have been highlighted as one of the largest natural sources of the greenhouse gas methane (CH4) to the atmosphere. However, global estimates of lake CH4 fluxes over the last 20 years exhibit widely different results ranging from 6 to 185 Tg CH4 yr-1, which is to a large extent driven by differences in lake areas and thaw season lengths used. This has generated uncertainty regarding both lake fluxes and the global CH4 budget. This study constrains global lake water CH4 emissions by using new information on lake area and distribution and CH4 fluxes distinguished by major emission pathways; ecoclimatic lake type; satellite-derived ice-free emission period length; and diel- and temperature-related seasonal flux corrections. We produced gridded data sets at 0.25° latitude × 0.25° longitude spatial resolution, representing daily emission estimates over a full annual climatological cycle, appropriate for use in global CH4 budget estimates, climate and Earth System Models, bottom-up biogeochemical models, and top-down inverse model simulations. Global lake CH4 fluxes are 41.6 ± 18.3 Tg CH4 yr-1 with approximately 50% of the flux contributed by tropical/subtropical lakes. Strong temperature-dependent flux seasonality and satellite-derived freeze/thaw dynamics limit emissions at high latitudes. The primary emission pathway for global annual lake fluxes is ebullition (23.4 Tg) followed by diffusion (14.1 Tg), ice-out and spring water-column turnover (3.1 Tg), and fall water-column turnover (1.0 Tg). These results represent a major contribution to reconciling differences between bottom-up and top-town estimates of inland aquatic system emissions in the global CH4 budget.
TL;DR: Li et al. as mentioned in this paper examined the spatial-temporal characteristics of nitrate concentrations, δ15N-NO3-, δ18O-NO-3-, and related environmental factors in a subtropical eutrophic reservoir (Hongfeng Reservoir, HFR).
Abstract: Reservoirs are regarded as hotspots of nitrogen transformation and potential sources of nitrous oxide (N2O). However, it remains unclear how the hydrological conditions due to dam construction control the processes of nitrogen transformation in reservoir waters. To address this issue, we examined the spatial-temporal characteristics of nitrate concentrations, δ15N-NO3-, δ18O-NO3-, δ18O-H2O, relative water column stability (RWCS), and related environmental factors in a subtropical eutrophic reservoir (Hongfeng Reservoir, HFR), Southwest China. We found that denitrification was the most important nitrogen transformation process in the HFR and that higher denitrification intensity was associated with increased RWCS in summer, which suggested hydrological control of the denitrification process. In contrast, low RWCS conditions favored the nitrification process in the HFR in winter. Additionally, dissolved oxygen (DO; p
TL;DR: In this article , the effects of microplastic microplastics in aquatic ecosystems can affect organisms and communities in multiple ways, and the authors conducted the first in situ community-level mesocosm experiment to examine the impact of MP on freshwater lake ecosystems, and provided the first observation of MP transfer to terrestrial ecosystems by emerging chironomids.
TL;DR: In this article , the authors evaluated the microbial degradation and photodegradation processes of DOM after the input of terrestrial materials into the water column and found that more humic fractions are photodegraded.
Abstract: The input of terrestrial materials is an essential source of dissolved organic matter (DOM) in rivers. The mechanism of the influence of terrestrial materials on the DOM cycle in the water column is still unclear. In this study, microbial degradation and photodegradation processes of DOM were evaluated after the input of terrestrial materials into the water column. The input of terrestrial materials promotes the biodegradation and photodegradation process of DOM. PARAFAC results indicated that terrestrial sources of DOM contained more humic-like fractions. C2 and C3 exhibited higher fluorescence intensity after the input of terrestrial materials. The results indicate that more humic fractions are photodegraded. Based on the 16S rRNA analysis results, the input of terrestrial material shifted the microbial community and altered microbial abundance. The network analysis results showed that the microorganisms exhibited completely different degradation mechanisms under light avoidance and exposure conditions. Terrestrial humic fractions can be photodegraded into bioavailable substrates to stimulate microbial metabolism. After the input of terrestrial material, random forest modeling and structural equation modeling screened and validated the critical environmental variables affecting the DOM cycle. The above discoveries may be beneficial for identifying the fate of terrestrial DOM in the water column and predicting future DOM cycling processes in the water column.
TL;DR: A review of the ecology of the dark ocean's prokaryotes is presented in this paper . But the authors focus on the distribution of the biomass in the oceanic waters below a depth of 200 meters.
Abstract: The oceanic waters below a depth of 200 m represent, in terms of volume, the largest habitat of the biosphere, harboring approximately 70% of the prokaryotic biomass in the oceanic water column. These waters are characterized by low temperature, increasing hydrostatic pressure, and decreasing organic matter supply with depth. Recent methodological advances in microbial oceanography have refined our view of the ecology of prokaryotes in the dark ocean. Here, we review the ecology of prokaryotes of the dark ocean, present data on the biomass distribution and heterotrophic and chemolithoautotrophic prokaryotic production in the major oceanic basins, and highlight the phylogenetic and functional diversity of this part of the ocean. We describe the connectivity of surface and deep-water prokaryotes and the molecular adaptations of piezophilic prokaryotes to high hydrostatic pressure. We also highlight knowledge gaps in the ecology of the dark ocean's prokaryotes and their role in the biogeochemical cycles in the largest habitat of the biosphere. Expected final online publication date for the Annual Review of Marine Science, Volume 15 is January 2023. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
TL;DR: In this article , the authors conducted four cruises at 11 sites in the Pearl River Estuary (PRE) to investigate potential NOx- removal rates, their contributions, and corresponding gene abundances, and controlling factors in surface sediments (0-5 cm).
TL;DR: In this paper , the differences in DOM degradation in summer, autumn, and winter water columns were evaluated, and the results showed that bacteria played an essential role in the degradation of DOM in the summer water column, while photosynthetic bacteria produced organic matter through photosynthesis to replenish the water column.
TL;DR: In this article , the effects of tidal cycles on the transport of microplastic (MP) pollution in porous media combined with various environmental and MPs properties were systemically investigated, and the results indicated that smaller substrate sizes exhibited higher retention percentages compared to those of larger substrate sizes under different tidal cycles.
Abstract: Tidal zones providing habitats are particularly vulnerable to microplastic (MP) pollution. In this study, the effects of tidal cycles on the transport of MPs (4-6 μm polyethylene, PE1; 125 μm polyethylene, PE2; and 5-6 μm polytetrafluoroethylene, PFTE) in porous media combined with various environmental and MPs properties were systemically investigated. The results indicated that smaller substrate sizes exhibited higher retention percentages compared to those of larger substrate sizes under different tidal cycles. In terms of the size of MPs, a larger size (same density) was found to result in enhanced retention of MPs in the column. As the number of tidal cycles increased, although the transport of MPs from the substrate to the water phase was enhanced, PE1 was washed out more with the change in water level, compared to PTFE. Additionally, more MPs were retained in the column with the increase of salinity and the decrease of flow velocity under the same tidal cycles. Ultraviolet and seawater aged PE1 showed enhanced transport, while aged PTFE showed enhanced retention under the same tidal cycles. These results can help understand the MP behaviors in the shoreline environment and provide support for future cleanup and sampling in tidal zones.
TL;DR: In this paper, the authors show that the Fe and Mn shuttle mechanism may not strongly affect Tl and V isotopes, at least in extreme cases of water column redox stratification.