Continental Shelf Research最新文献

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Dynamics of small metazooplankton in relation with environmental factors: A 12-year study in the coastal zone of the Southwestern Crimea (the Black Sea) 小型浮游动物的动态与环境因素的关系:对克里米亚西南部沿海地区(黑海)为期 12 年的研究
IF 2.1 3区 地球科学
Continental Shelf Research Pub Date : 2024-09-26 DOI: 10.1016/j.csr.2024.105336
{"title":"Dynamics of small metazooplankton in relation with environmental factors: A 12-year study in the coastal zone of the Southwestern Crimea (the Black Sea)","authors":"","doi":"10.1016/j.csr.2024.105336","DOIUrl":"10.1016/j.csr.2024.105336","url":null,"abstract":"<div><div>Based on continuous 12-year (2010–2021) monitoring of the average summer abundance of small metazooplankton (SMZ) in the coastal zone of the Southwestern Crimea, the patterns of its interannual fluctuations were investigated. The total SMZ abundance during the study period varied from 37.8 to 176.0 thousand·m<sup>−3</sup> in the open coastal area (on average, 104.0 ± 49.2 thousand·m<sup>−3</sup>) and from 90.3 to 556.8 thousand·m<sup>−3</sup> at the bay mouth (on average, 264.5 ± 121.0 thousand·m<sup>−3</sup>). The crustacean fraction accounted for 85–91% of the total SMZ abundance. Principal component analysis (PCA) showed a noticeable contribution of 48 % of total temperatures and wind speed and different direction repeatability to the SMZ abundance variability. For native data, significant relationships were revealed between the abundance of individual SMZ fractions and hydrometeorological parameters: total temperatures of the warm period of the year (May–October), periodicity of the southern and southwestern, northern winds, calm conditions (events of the absence of wind), and the summer index of the North Atlantic Oscillation (NAO) with a 1-year lag. The application of fast Fourier transform (FFT) with a Hamming filter to the original series and periodograms analysis allowed revealing typical periods of variability in SMZ abundance and hydrometeorological parameters of the environment: 2–4-year and 5–6-year ones. At these scales, a higher number of significant relationships was established with the indicated hydrometeorological parameters, <em>inter alia</em> winter and summer NAO indices, than during the analysis of the original series. The total contribution of hydrometeorological and climatic factors to the variation in the abundance of SMZ increased to 78–79 %. This confirms the assumption that the relationship between SMZ and environmental parameters is characterized by its own features at different scales. Analysis of long-term SMZ different fractions tendencies for Summer 2010–2021, according to the Mann-Kendall criterion, did not show significant results.</div></div>","PeriodicalId":50618,"journal":{"name":"Continental Shelf Research","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2024-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142418766","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Clay mineral composition and transport pattern of surface sediments in the Ganges Submarine Delta 恒河海底三角洲表层沉积物的粘土矿物成分和迁移模式
IF 2.1 3区 地球科学
Continental Shelf Research Pub Date : 2024-09-19 DOI: 10.1016/j.csr.2024.105333
{"title":"Clay mineral composition and transport pattern of surface sediments in the Ganges Submarine Delta","authors":"","doi":"10.1016/j.csr.2024.105333","DOIUrl":"10.1016/j.csr.2024.105333","url":null,"abstract":"<div><div>The Ganges Submarine Delta is a key land-sea transitional area in the northeastern Indian Ocean. An understanding of sediment distribution, provenance, and transportation in this area is of great importance for understanding its sedimentary environment and the sediment “source-sink” system of the northeastern Indian Ocean. This study aimed to identify the provenances and transport patterns of fine-grained sediments in the Ganges Submarine Delta through analysis of the grain size and clay mineral content of 84 surface sediment samples. Sediment illite, chlorite, kaolinite, and smectite contents were ∼66%, 18%, 11%, and 5%, respectively. Sediment illite content decreased from north to south; smectite and chlorite decreased and increased from northwest to southeast, respectively; kaolinite content was highest in the south. Spatial cluster analysis of the four clay minerals grouped the study area into two provinces: province I in the north is characterized by a clay mineral assemblage similar to that of the Ganges-Brahmaputra rivers; province II in the south is characterized by deep water and changes to clay mineral characteristics due to the mixing of material originating from the Indian Peninsula. This study used the illite/(smectite + chlorite + kaolinite) and kaolinite/illite ratios to discuss sediment transport paths in the two provinces. Himalayan material is widely distributed throughout the study area, and mainly transported from the estuary to the southwestern area by the tides, plume, and monsoons; sediments of the Mahanadi river are transported from southwest to northeast by the southwest monsoon, thereby affecting the sediment composition of province II.</div></div>","PeriodicalId":50618,"journal":{"name":"Continental Shelf Research","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2024-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142312655","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Sources and transport pathways of trace metals to the outer continental shelf off South Carolina and Georgia, USA revealed from the otoliths of moray eels 从海鳗耳石中揭示美国南卡罗来纳州和佐治亚州外大陆架痕量金属的来源和迁移途径
IF 2.1 3区 地球科学
Continental Shelf Research Pub Date : 2024-09-15 DOI: 10.1016/j.csr.2024.105331
{"title":"Sources and transport pathways of trace metals to the outer continental shelf off South Carolina and Georgia, USA revealed from the otoliths of moray eels","authors":"","doi":"10.1016/j.csr.2024.105331","DOIUrl":"10.1016/j.csr.2024.105331","url":null,"abstract":"<div><div>Trace metal concentrations in otoliths of spotted moray eels (Gymnothorax moringa), non-migratory residents of hard bottom reefs at depths of ∼30–70m along the outer shelf adjacent to South Carolina and Georgia, were analyzed to determine if results provide insights into trace metal sources and transport processes in this dynamic region of the shelf. Li and Mg appear to reflect exposure to local sea water circulated through adjacent porous rock outcrops where the eels reside. Concentrations of Mn, V, Cu, and Zn in otoliths appear to be associated with deep water upwelled along the shelf break. Based on 30 years of water temperature data from fishery surveys, Scamp Ridge, located at 32.3<sup>0</sup> N at a depth of ∼50m, has significantly lower summertime bottom temperature than elsewhere along the shelf edge, indicating locally enhanced upwelling at that location. The highest levels of Cu and Zn and the lowest of Mn and V were also found in otoliths of eels collected in the vicinity of Scamp Ridge. These results indicate that otolith chemistry in eels can reveal fine-scale structure of water mass inputs to the outer shelf of the southeastern US coast.</div></div>","PeriodicalId":50618,"journal":{"name":"Continental Shelf Research","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2024-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142528862","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Interplay of natural and anthropogenic factors in sediment dynamics and trace element distribution in Güllük Gulf, western Türkiye: A comprehensive geochemical and hydrodynamic analysis 图尔基耶西部 Güllük 海湾沉积物动力学和微量元素分布中自然和人为因素的相互作用:地球化学和水动力综合分析
IF 2.1 3区 地球科学
Continental Shelf Research Pub Date : 2024-09-14 DOI: 10.1016/j.csr.2024.105332
{"title":"Interplay of natural and anthropogenic factors in sediment dynamics and trace element distribution in Güllük Gulf, western Türkiye: A comprehensive geochemical and hydrodynamic analysis","authors":"","doi":"10.1016/j.csr.2024.105332","DOIUrl":"10.1016/j.csr.2024.105332","url":null,"abstract":"<div><p>Güllük Gulf, located in the southeastern Aegean Sea, is significantly impacted by diverse human activities, including urban development, tourism, and intensive aquaculture. This study aims to assess the spatial distribution of trace metals in the Gulf's sediments, identify their sources, and evaluate their environmental impacts to inform effective management strategies. It also examines sediment transport patterns, which are crucial in influencing the distribution and concentration of pollutants. Establishing background concentration levels for various elements provides a baseline to assess pollution levels and identify deviations due to anthropogenic impact. Sediment samples were collected from 45 stations and analyzed for grain size, organic carbon, carbonate content, and concentrations of 26 elements. Contamination was assessed using indices such as Enrichment Factor (EF), Geoaccumulation Index (I<sub>geo</sub>), Contamination Factor (Cf), Degree of Contamination (C<sub>deg</sub>), Pollution Load Index (PLI), Modified Pollution Index (MPI), and Toxic Risk Index (TRI). Statistical analyses, including Principal Component Analysis (PCA) and Cluster Analysis (CA), were used to identify pollution sources. Results indicated that Güllük Gulf's sediments are predominantly sandy, with significant silt and clay fractions in sheltered bays. Organic carbon content averaged 1.68%, with higher values near urban and aquaculture areas. Trace metal concentrations exhibited notable spatial variability, with elevated levels of Pb, Cu and Zn in specific areas, indicating both natural and anthropogenic sources. PCA identified five significant factors contributing to metal presence, linking them to lithogenic origins, aquaculture activities, and industrial inputs. TRI results showed moderate toxic risk in Asin Bay, primarily due to Ni, As and Cr. The sediment transport model of Güllük Gulf, crucial in understanding regional pollution dynamics, revealed a complex interplay of hydrodynamic forces. The study underscores the significant environmental impact of human activities on sediment quality in Güllük Gulf. Elevated trace metal levels near aquaculture sites emphasize the need for stringent environmental management practices. Effective strategies should include regular monitoring, sustainable aquaculture practices, and stakeholder engagement to mitigate environmental impacts and preserve the Gulf's ecological integrity. This comprehensive approach provides crucial insights for future research and environmental management policies aimed at addressing the complex challenges facing Güllük Gulf.</p></div>","PeriodicalId":50618,"journal":{"name":"Continental Shelf Research","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2024-09-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142244179","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Impact of seasonal variations in fronts on suspended sediments transport off the coastal area of Fujian Province 锋面季节变化对福建沿海悬浮泥沙输移的影响
IF 2.1 3区 地球科学
Continental Shelf Research Pub Date : 2024-09-07 DOI: 10.1016/j.csr.2024.105330
{"title":"Impact of seasonal variations in fronts on suspended sediments transport off the coastal area of Fujian Province","authors":"","doi":"10.1016/j.csr.2024.105330","DOIUrl":"10.1016/j.csr.2024.105330","url":null,"abstract":"<div><p>The Zhejiang-Fujian (Zhe-Min) coastal muddy area plays a crucial role in facilitating sediment exchange through a cross-front. The mud depocenter off the Zhe-Min coastal area is a source of suspended sediment that can be transported to the continental shelf of the East China Sea (ECS). Although the front of the inner shelf of the ECS has been extensively reported, the cross-front material transport off the coastal area of Zhe-Min in summer has not been well studied, especially using measured data. To reveal how the front controls the transport of suspended sediment, this study focuses on the impact of fronts on the dispersion of suspended sediment off the coastal area of Fujian Province in different seasons. The results indicate that the front acts as a barrier, inhibiting the dispersion of suspended sediment into the sea. The high-concentration suspended sediment is mainly found to the northwest of the front, with an average SSC of 8.5 mg/L in winter and 3.1 mg/L in summer. The suspended sediment concentration (SSC) follows a V-shaped distribution along the cross-isobath transects, with lower SSC observed at the 50-m isobath compared with the shallow water area and the deep water area. The SSC at the front was the lowest, with an average concentration of 2.3 mg/L in winter and 1.9 mg/L in summer. The front is crucial for the development of the Zhe-Min coastal muddy area. The winter monsoon is strong, resulting in a sufficient supply of suspended sediments in the muddy area and a high transport flux of suspended sediments in the nearshore. The front hinders the dispersion of high-concentrated sediment from the nearshore to the offshore, resulting in the deposition of fine-grained sediments in the nearshore and the formation of an inner shelf muddy sedimentary zone. The findings of this study will help improve our understanding of the sediment source-to-sink processes in the ECS and land–sea interactions.</p></div>","PeriodicalId":50618,"journal":{"name":"Continental Shelf Research","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2024-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142167875","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Environmental factors affecting the distribution of deep-water rose shrimp (Parapenaeus longirostris, Lucas, 1846) abundance in the Strait of Sicily (Mediterranean Sea) 影响西西里海峡(地中海)深水玫瑰虾(Parapenaeus longirostris, Lucas, 1846)数量分布的环境因素
IF 2.1 3区 地球科学
Continental Shelf Research Pub Date : 2024-09-07 DOI: 10.1016/j.csr.2024.105323
{"title":"Environmental factors affecting the distribution of deep-water rose shrimp (Parapenaeus longirostris, Lucas, 1846) abundance in the Strait of Sicily (Mediterranean Sea)","authors":"","doi":"10.1016/j.csr.2024.105323","DOIUrl":"10.1016/j.csr.2024.105323","url":null,"abstract":"<div><p>The distribution of deep-water rose shrimp (<em>Parapenaeus longirostris</em>, FAO 3 alpha code DPS), the main target species of demersal fisheries in the Strait of Sicily, is investigated in relation to surface parameters and biogeochemical processes. Such processes are known to influence sea bottom habitats and may be particularly relevant to the Strait of Sicily because of its relative shallowness and high surface primary production. Shrimp abundances recorded during multi-annual and seasonal trawl surveys (2004–2008) are analyzed. A GAMM and GAM model analysis is performed comparing juvenile abundances to monthly mean spatial patterns of remotely-sensed sea surface temperature (SST) and surface chlorophyll (<em>chl</em>), as well as their frontal structures, with a time-lag of one month, given the pelagic behavior of DPS early life stages preceding settlement. Juvenile and total shrimp abundances are also compared to the flux of particulate organic carbon (POC) to the seabed. The POC flux is computed via 1-D and 3-D models simulating sinking, re-mineralization and horizontal advection and diffusion of surface POC. The latter is derived from surface primary production maps obtained from ocean color data. Results show that the abundance of the juvenile fraction of DPS is significantly correlated with depth, distance to SST fronts and the intensity of <em>chl</em> fronts (correlation <em>R</em><sup><em>2</em></sup> = 80%). Furthermore, results strongly suggest the significant role of bottom POC flux in conditioning the distribution of DPS abundance, indicating that ecological processes occurring in surface waters influence food availability near the seabed in the investigated area.</p></div>","PeriodicalId":50618,"journal":{"name":"Continental Shelf Research","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2024-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0278434324001535/pdfft?md5=12e00018023bc2d13b2c4eea2c6de89b&pid=1-s2.0-S0278434324001535-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142228493","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Unveiling near-inertial wave dynamics and storm-driven currents: Insights from moorings in the coastal Mediterranean Sea 揭示近惯性波动力和风暴驱动流:从地中海沿岸的系泊设备中获得的启示
IF 2.1 3区 地球科学
Continental Shelf Research Pub Date : 2024-09-04 DOI: 10.1016/j.csr.2024.105321
{"title":"Unveiling near-inertial wave dynamics and storm-driven currents: Insights from moorings in the coastal Mediterranean Sea","authors":"","doi":"10.1016/j.csr.2024.105321","DOIUrl":"10.1016/j.csr.2024.105321","url":null,"abstract":"<div><p>This study presents comprehensive observations of currents and seawater properties (temperature, salinity and density) made with moored instruments on the continental slope in the eastern Ligurian Sea (Mediterranean) between 18 October and November 6, 2021. During this period, the depth of the surface mixed layer increased from 40 to 70 m. At the same time, near-inertial waves were consistently observed below the mixed layer. In particular, on 28 October, a depression in the mixed layer depth triggered the formation of a pronounced wave packet. This packet radiated downwards between 70 and 200 m and propagated southward. The wave packet had a vertical and horizontal wavelength of about 80 m and 150 km, respectively, an upward vertical phase speed of 100 m/d, a downward vertical group speed of 10–15 m/d, and a downward energy flux of 0.2–0.3 mW/m<sup>2</sup>. The observed frequency appeared subinertial, likely due to the red-shifting of the effective inertial frequency by the background vorticity. From 1 November, a storm with wind speeds of up to 15 m/s prevailed in the region. Near-inertial motion was pronounced throughout the water column and manifested itself as a first baroclinic mode. This mode exhibited a maximum isopycnal vertical displacement in the thermocline, accompanied by oscillatory currents that reversed with depth. Mainly superinertial currents were observed. The temperature and velocity data collected from all moorings indicated a southwestward propagation with a horizontal wavelength of about 200 km. While a slab model was partially successful in predicting inertial currents in the surface mixed layer, the storm-induced dynamics presented a challenge that was beyond the scope of the model.</p></div>","PeriodicalId":50618,"journal":{"name":"Continental Shelf Research","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2024-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142136549","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Geochronology of a sedimentary core in the northwest of South China Sea and regional paleoenvironmental changes over the last million years 南海西北部沉积岩芯的地质年代与过去一百万年的区域古环境变化
IF 2.1 3区 地球科学
Continental Shelf Research Pub Date : 2024-09-01 DOI: 10.1016/j.csr.2024.105322
{"title":"Geochronology of a sedimentary core in the northwest of South China Sea and regional paleoenvironmental changes over the last million years","authors":"","doi":"10.1016/j.csr.2024.105322","DOIUrl":"10.1016/j.csr.2024.105322","url":null,"abstract":"<div><p>The South China Sea (SCS) is ones of the largest marginal seas on the Earth. Apart from IODP/ODP sites, limited progress has been made in establishing chronostratigraphy for long-term geological sequences spanning millions of years. In this study, we present findings from a sediment core (NH-01) collected from the eastern part of Hainan Island, northwest SCS, in terms of magnetostratigraphy and sedimentary/paleoenvironmental changes in the past 1 Myr. The main findings are as follows: (1) Two magnetic polarity zones in core NH-01 can be preliminarily correlated with the upper part of the intervening Matuyama chron and the Brunhes normal chrons, respectively. (2) By tuning the color indices of core NH-01 to the stacked benthic δ<sup>18</sup>O record, the age-depth model was refined, and the sediment accumulation rates are estimated as 10–30 cm/kyr (3) The sedimentary processes in the study area display a dominant 100-kyr cycle, with contributions from precession and obliquity bands, underscoring the influence of regional sea-level changes and monsoonal evolution. Comparisons between the NH-01 sedimentary record and various global climate proxies indicate a significant shift in regional sedimentary processes around 430 kyr, which can be attributed to the pronounced impact of the</p><p>Mid-Brunhes event, potentially linking it to climatic changes in the Southern Hemisphere. Consequently, sedimentary records from the northwest SCS not only capture regional environmental history but also provide insights into potential connections between different climatic systems.</p></div>","PeriodicalId":50618,"journal":{"name":"Continental Shelf Research","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2024-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142151121","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Distribution of methane in the upper water layer of the northern Black Sea: Seasonal and daily trends and seawater-air emissions 黑海北部上水层甲烷的分布:季节和日常趋势以及海水-空气排放
IF 2.1 3区 地球科学
Continental Shelf Research Pub Date : 2024-08-23 DOI: 10.1016/j.csr.2024.105320
{"title":"Distribution of methane in the upper water layer of the northern Black Sea: Seasonal and daily trends and seawater-air emissions","authors":"","doi":"10.1016/j.csr.2024.105320","DOIUrl":"10.1016/j.csr.2024.105320","url":null,"abstract":"<div><p>We report on methane (CH<sub>4</sub>) concentration measurements in the northern Black Sea area conducted during 6 cruises with R/V <em>Professor Vodyanitsky</em> from 2017 to 2019. Our work is a multi-season study at a uniform station grid covering an area of 88 × 10<sup>3</sup> km<sup>2</sup> and including three latitudinal transects that comprises both surface and vertical profile water-column measurements. The main goal of the work was to assess the seasonal patterns of vertical CH<sub>4</sub> structure in the aerobic water column (upper 100 m) and its emission to the atmosphere.</p><p>In surface waters, the mean dissolved CH<sub>4</sub> concentration ranged from 2.6 nmol L<sup>−1</sup> detected in November 2018 to 11.5 nmol L<sup>−1</sup> measured in June–July 2018, respectively. Calculated CH<sub>4</sub> seawater-air fluxes and saturations were mostly positive (i.e. net flux to atmosphere), and winter fluxes (2.6 μmol m<sup>−2</sup> d<sup>−1</sup>) were higher than summer fluxes (1.6 μmol m<sup>−2</sup> d<sup>−1</sup>) due to the higher wind speed. The integral CH<sub>4</sub> flux from the whole study area (88 × 10<sup>3</sup> km<sup>2</sup>) ranged from 84 to 235 kM day<sup>−1</sup>.</p><p>It was shown that, on average, the methane concentration in the upper layer for deep-water stations where the seabed is located at depths &gt;160 m (σt &gt;16.2) was lower compared to stations at shallow water depths (28–140 m, σt &lt;16.2). The most distinct difference was obtained for the summer season (June–July 2018) and a less significant difference – for spring (April–May 2019) and winter season (November–December 2018). During these seasons the water column was also considerably less saturated in CH<sub>4</sub> compared to the entire monitoring period. We observed subsurface maxima, which were generally located at the base of the thermocline and exceeded 100 nmol L<sup>−1</sup> at some stations. Exceptions were observed in October 2019 (cruise 110), when vertical CH<sub>4</sub> distributions were characterized by two-peaks at ∼20 and ∼50 m depth. The strong influence of the thermohaline structure on the water column CH<sub>4</sub> distribution has also been shown in studies of daily dynamics of CH<sub>4</sub> vertical profiles in the shallow water region. Despite the high variability of CH<sub>4</sub> concentrations, significant similarities in vertical distributions of CH<sub>4</sub> and chlorophyll-a for which sub-surface maxima coincided at some stations, are shown. Extremely high concentrations of CH<sub>4</sub> (up to 351 nmol L<sup>−1</sup>) in the near-bottom water layer were revealed during all seasons at the station near the Dnieper paleo-channel at the northwestern edge of the study area. This enrichment is assumed to be caused by methane emissions from gas seeps densely located in this region.</p></div>","PeriodicalId":50618,"journal":{"name":"Continental Shelf Research","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2024-08-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142098443","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Changing source waters on the Northeast US Continental Shelf: Variation in nutrient supply and phytoplankton biomass 美国东北部大陆架不断变化的源水:营养供应和浮游植物生物量的变化
IF 2.1 3区 地球科学
Continental Shelf Research Pub Date : 2024-08-22 DOI: 10.1016/j.csr.2024.105319
{"title":"Changing source waters on the Northeast US Continental Shelf: Variation in nutrient supply and phytoplankton biomass","authors":"","doi":"10.1016/j.csr.2024.105319","DOIUrl":"10.1016/j.csr.2024.105319","url":null,"abstract":"<div><p>The Northeast US Continental Shelf (NES) is a highly productive marine ecosystem that has experienced wide swings in phytoplankton chlorophyll concentration (CHL). To better understand this variability, we examined changes in CHL over the period 1998–2022, while also considering three indicators of the potential supply of nutrient source waters including cross-shelf advection via deep channels, transport from beyond the shelf edge via Gulf Stream warm core rings (WCR), and input from river and estuarine discharge. Traditionally, deep channel advection of water across the NES was assumed to be derived from Labrador Slope Water (LSW) and Warm Slope Water (WSW). These designations do not fully capture the range of water types contributing to cross-shelf advection. The contribution of LSW and WSW was reciprocal over time, with the presence of WSW at an increased level in recent years. There has been an increase in the number of WCRs off the NES represented by indices of ring occupancy. Precipitation increased over the study period as well, generally over the NES region and in particular in the Mid-Atlantic Bight drainage. We see evidence of the effect of increased precipitation on the NES proper through a change in the area of the ocean surface having 555 nm reflectance with sr<sup>−1</sup> &gt; 0.004. Using a canonical analysis, CHL correlated positively with the proportion of LSW and negatively with WSW. These correlations suggest there are aspects of the nutrient content associated with these water masses that are key to phytoplankton growth. WCR frequency negatively correlated with CHL, which was expected since the nutrient loadings of WCRs tends to be low. Finally, CHL negatively correlated with precipitation rate, which suggests terrestrial origin nutrient inputs to the NES are minor. We suggest that in order to understand future CHL dynamics in the NES, careful consideration of advective sources of nutrients in the Northwest Atlantic is necessary.</p></div>","PeriodicalId":50618,"journal":{"name":"Continental Shelf Research","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2024-08-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142076966","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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