Nearshore Marine Sediments Research Articles

Distribution of terrestrial organic material in intertidal and nearshore marine sediment due to debris flow response efforts

We examined the distribution and processing of terrestrial organic material, derived from the disposal of material from a massive debris flow event following a major wildfire in a coastal California (USA) catchment in intertidal and nearshore subtidal marine sediments. Organic matter biomarkers, pyrogenic carbon and lignin phenols, were used to trace the distribution of terrestrial debris material in marine environments. In intertidal sediments located <1 km east of the debris deposition site, pyrogenic carbon values did not significantly change and lambda values, a lignin measure, decreased over time, indicating little lateral transport of the disposed material. In subtidal sediment, pyrogenic carbon and lambda values were greatest in 20 m water depths indicating transport and deposition of this material nearshore. An additional lignin measure indicative of degradation suggested terrestrial organic material degradation in subtidal sediment decreased with distance from shore. Terrestrial biomarkers demonstrated that the disposed material was not detected in the top 20 cm of intertidal sediment but was retained in subtidal sediment offshore of the disposal site. Results suggest coastal management should incorporate consideration of the effects of debris disposal activities on nearshore benthic communities and biogeochemical cycling.

Spatial Distribution of Heavy Metals in Near-Shore Marine Sediments of the Jeddah, Saudi Arabia Region: Enrichment and Associated Risk Indices

Red Sea coastal development has rapidly accelerated in recent decades that has led to a rise in the anthropogenic heavy metal levels in sediments. A total of 80 surficial sediment samples were collected from the shallow waters along the eastern Red Sea coast near Jeddah, Saudi Arabia. These samples were collected from three locations, designated as North, Middle and South of Jeddah, to assess the concentrations of six heavy metals: chromium (Cr), manganese (Mn), nickel (Ni), copper (Cu), zinc (Zn), and lead (Pb). The results showed that the concentrations (mg/kg) of these metals in the studied sediments follow this order: Pb (77.34 ± 150.59) &gt; Mn (36.52 ± 37.72) &gt; Zn (18.02 ± 23.94) &gt; Cr (9.56 ± 5.81) &gt; Cu (9.18 ± 13.67) &gt; Ni (3.68 ± 4.54). The majority of the polluted sediments were recorded in the Middle and South locations. Pollution and enrichment indices such as Geo-accumulation indices (Igeo), Enrichment Factors (Ef), Contamination Factors (Cf), Pollution Load Indices (PLI), Potential Ecological Risk Indices (PERI) and Potential Toxicity Response Indices (RI) were calculated from the measured metals to establish baselines for the region and assess specific metal enrichments by location along the Jeddah coastline. The Igeo values showed that 30% of the Southern location stations are considered moderately to highly polluted. The Ef for all the studied sediments followed this order: Pb (extremely severe enrichment) &gt; Zn &gt; Cu &gt; Cd &gt; Cr (severe enrichment) &gt; Ni (moderate enrichment).

Sources of Low Level Human Fecal Markers in Recreational Waters of Two Santa Barbara, CA Beaches: Roles of WWTP Outfalls and Swimmers

Worldwide, fecal indicator bacteria (FIB) evidence coastal water contamination for which sources are unknown. Here, for two FIB-impacted Santa Barbara recreational beaches, hypothesized fecal sources were investigated over three dry seasons (summers) using nearly 2000 field samples of water (ocean, creek, groundwater), sand, sediments, effluent and fecal sources. In years 1 and 2, gull and dog feces were identified as the probable main FIB sources to surf zone waters, yet HF183 human fecal markers were consistently detected. Determining HF183 sources was therefore prioritized, via year 3 sub-studies. In lower watersheds, human and dog wastes were mobilized by small storms into creeks, but no storm drain outfalls or creeks discharged into surf zones. Beach area bathrooms, sewers, and a septic system were not sources: dye tracing discounted hydraulic connections, and shallow groundwater was uncontaminated. Sediments from coastal creeks and downstream scour ponds, nearshore marine sediments, and sands from inter- and supratidal zones contained neither HF183 nor pathogens. Two nearby wastewater treatment plant (WWTP) outfalls discharged HF183 into plumes that were either deep or distant with uncertain onshore transport. Regardless, local sources were evidenced, as surf zone HF183 detection rates mostly exceeded those offshore and nearshore (around boat anchorages). The presence of swimmers was associated with surf zone HF183, as swimmer counts (on weekdays, holidays, weekends, and during races) significantly correlated (p<0.05, n = 196) to HF183 detections. Besides comprehensively assessing all possible fecal sources, this study provides new explanations of chronic low-level human markers in recreational beach surf zones, suggesting likely lowest achievable HF183 thresholds.

Terrestrial Organic Matter Inputs to Nearshore Marine Sediment Under Prolonged Drought Followed by Significant Rainfall as Indicated by Lignin

Terrestrial organic matter (TOM) exported to nearshore marine regions may be altered by drought or large amounts of precipitation. We examined how significant precipitation in southern California during the winter seasons of 2015 and 2016, following a prolonged drought from 2011 to 2015, impacted the quantity and quality of TOM transported to nearshore kelp forests of the Santa Barbara Channel. Based on organic matter content, lignin oxidation by-products, and carbon isotopic signatures, biomarkers of TOM were detected in stream, estuarine, and marine sediments. Quantitative measures of lignin differentiated between the three environments. Qualitative lignin signatures revealed temporal patterns that appeared in stream, estuarine, and marine sediment. These patterns indicated that TOM delivered into nearshore coastal regions from mountain watersheds was less degraded over time and its source material changed through time. Our findings suggest lignin oxidation compounds can be used as biomarkers of TOM transported during storm events from coastal watersheds into nearshore marine sediment.

Geochemical changes across a marginal marine Permo-Triassic boundary section on the Adria carbonate platform at Brsnina, Slovenia

The Brsnina Permian–Triassic nearshore marine sediments were deposited on the Adria carbonate platform in tropical latitudes at the western end of the Neotethys Ocean. Continuous channel samples across the boundary show no consistent change in element or element/Al ratios, except that most element/Al ratios increase in the top 0.5 m of the Permian strata. Though there are sporadic higher values of some element/element ratios, such as Ti/Zr, Th/Sc, Zr/Sc, Cr/Ni, Y/Ni, Co/Th, Cu/Zn, and Nb/Ta, La/Sc, the overall geochemistry indicates that the sediments were derived from dominantly silica-rich continental rather than silica-poor sources though with some more silica-poor inputs at times. Sporadic high Ti/Zr ratios indicate periods of increased aridity, but no overall increase across the boundary. Various geochemical redox proxies suggest mainly oxic depositional conditions, with episodes of anoxia, but with little systematic variation across the boundary. Geochemical proxies for productivity indicate little change up the section with values two orders of magnitude less than elsewhere. The lack of consistent element geochemical changes across the boundary accompanied by significant C, S, and other isotopic changes suggests that atmospheric and oceanic chemical variations drove the Permian–Triassic boundary environmental changes at least on the sabkha environments of the tropical Adria platform.

Sediment oxygen demand and benthic foraminiferal faunas in the Arabian Gulf: A test of the method on a siliciclastic substrate.

In this study, we investigated the relationship between environmental parameters (water and sediment) and benthic foraminiferal assemblages found in nearshore siliciclastic sediment in the Arabian Gulf. Nearshore marine water and sediment samples were collected from a beach on the Gulf of Bahrain located south of Al Khobar, Saudi Arabia. The water samples were analyzed for biochemical oxygen demand (BOD5) and other chemical analyses. The sediment samples were tested for sediment oxygen demand (SOD) and heavy metal analysis. Results showed the BOD5 levels were below the detection limit (<1 ppm), while the mean SOD value was 0.97 ± 0.08 g/m2·day. The water and sediments were unpolluted and free of eutrophic enrichment, while the sediment was anoxic. The two most common genera in the benthic foraminiferal assemblage, Ammonia and Elphidium, are typical of shallow water sandy substrates. This is the first reported comparison between SOD and benthic foraminiferal assemblages.

Inference of Organophosphate Ester Emission History from Marine Sediment Cores Impacted by Wastewater Effluents.

Organophosphate esters (OPEs) have been in use as flame retardants for many decades, with their actual usage varying over time. Knowledge of the emission history of OPEs is valuable for improving our prediction of their environmental loadings and associated risks. In this study, concentrations and compositions of 10 OPEs were measured in three dated sediment cores from the Palos Verdes Shelf (PVS) off the coast of Los Angeles, which has been impacted by wastewater treatment plant (WWTP) effluents for over a century. The total OPE concentrations varied from 0.68 to 1064 ng/g along the sediment profile, with two apparent peaks. The first peak occurred in the 1970s, coinciding with peak emissions from WWTPs. The second peak appeared in the 2000s and was possibly attributed to increased consumption of OPEs as replacement flame retardants. Since downward movement of OPEs in the PVS sediment bed was retarded by their slow desorption, the reconstructed history likely provided an accurate picture of OPE emissions in Southern California and North America. These findings suggest that the near-shore marine sediments affected by WWTP effluents could serve as an environmental proxy documenting history in OPE use and emissions.

Concentrations of some metals in the nearshore marine sediments of Western Australia's Pilbara Region.

Concentrations of arsenic, nickel and chromium in sediments of the nearshore Pilbara Region of Western Australia's mid -north coast have caused concerns to regulators issuing ocean disposal permits for many years. A meta-analysis of data from a large number of surveys, conducted in support of permit applications over many years and across hundreds of kilometres of coastline, shows that, when assessed as total metal concentrations, chromium and nickel occur routinely at concentrations above those recommended as screening triggers by national guidelines and arsenic more rarely. Arsenic was concentrated in surface sediments, consistent with an organic origin. Concentrations of nickel and chromium were higher in deeper sediment layers, consistent with a natural geological origin. However, sediment particle sizing was a major determinant of total metal concentrations of all three metals, and bioavailability was always much lower and within recommended guidelines. Past dredging activity for channels and berths in the large ports of the Pilbara has most likely led to an elevation of fine fractions of surface sediments within operating port areas, when compared to the undisturbed surrounding areas, and may also have increased the proportion of sediment from deeper substrates at the surface. Whilst total concentrations of chromium and nickel commonly exceed screening guidelines throughout the nearshore Pilbara Region, their bioavailability was low and these metals present a little threat to biota.

Reprint of 'Elemental and mineralogical analysis of marine and coastal sediments from Phra Thong Island, Thailand: Insights into the provenance of coastal hazard deposits'

Sediment records left by coastal hazards (e.g. tsunami and/or storms) may shed light on the sedimentary and hydrodynamic processes happening during such events. Modern onshore and offshore sediment samples were compared with the 2004 Indian Ocean Tsunami, three palaeotsunami and a 2007 storm deposit from Phra Thong Island, Thailand, to determine provenance relationships between these coastal overwash deposits. Sedimentological and stratigraphic characteristics are generally inadequate to discriminate tsunami and storm deposits so a statistical approach (including cluster analysis, principal component analysis and discriminant function analysis) was used based on grain size, mineralogy and trace element geochemistry. The mineral content and trace element geochemistry are statistically inadequate to distinguish the provenance of the modern storm and tsunami deposits at this site, but the mean grain size can potentially discriminate these overwash deposits. The 2007 storm surge deposits were most likely sourced from the onshore sediment environment whereas all four tsunami units statistically differ from each other indicating diverse sediment sources. Our statistical analyses suggest that the 2004 tsunami deposit was mainly derived from nearshore marine sediments. The uppermost palaeotsunami deposit was possibly derived from both onshore and nearshore materials while the lower palaeotsunami deposits showed no clear evidence of their sediment sources. Such complexity raises questions about the origin of the sediments in the tsunami and storm deposits and strongly suggests that local context and palaeogeography are important aspects that cannot be ignored in tsunami provenance studies.

A Review of the Fossil Record of Turtles of the CladeThalassochelydia

The Late Jurassic (Oxfordian to Tithonian) fossil record of Europe and South America has yielded a particularly rich assemblage of aquatic pan-cryptodiran turtles that are herein tentatively hypothesized to form a monophyletic group named Thalassochelydia. Thalassochelydians were traditionally referred to three families, Eurysternidae, Plesiochelyidae, and Thalassemydidae, but the current understanding of phylogenetic relationships is insufficient to support the monophyly of either group. Given their pervasive usage in the literature, however, these three names are herein retained informally. Relationships with marine turtles from the Cretaceous have been suggested in the past, but these hypotheses still lack strong character support. Thalassochelydians are universally found in near-shore marine sediments and show adaptations to aquatic habitats, but isotopic evidence hints at a broad spectrum of specializations ranging from freshwater aquatic to fully marine. A taxonomic review of the group concludes that of 68 named taxa, 27 are nomina valida, 18 are nomina invalida, 18 are nomina dubia, and 5 nomina oblita.

Not to be Sneezed at: Does Pollen from Forests of Exotic Pine Affect Deep Oceanic Trench Ecosystems?

Pollen is ubiquitous in nearshore marine sediments; however, its potential importance for food-limited deep-seabed communities remains unknown. Here we report on the distribution of pollen to depths of 10,800 m in two Southwest Pacific trenches, as well as relationships between pollen concentrations and the sediment fauna. Pine (Pinus radiata) pollen, most likely originating from extensive plantations in New Zealand, was common in all sediment samples. These pine plantations may have altered the flux of terrestrially derived organic matter to vast stretches of the deep sea, with potential consequences for carbon sequestration and food availability. There was a significant, positive correlation between pine pollen and the abundance of infauna, which were greatest at the 7000-m-deep site in the Kermadec Trench and 10,800-m site in the Tonga Trench. This finding, together with the occurrence of pine pollen in unicellular organisms (gromiids), shows for the first time that pollen may represent food source for deep-sea benthic organisms.

Selenium deficiency in subtropical littoral pampas: environmental and dietary aspects.

Se deficiency has a critical effect on human health. The littoral near Patos Lagoon in the south of Brazil is composed of Quaternary sandy deposits and nutrient-deficient soils, which contribute to Se deficiency in the surrounding environment. The average concentration of Se in littoral soils is six times lower than the metalloid deficiency threshold of 0.5mgkg-1 and is close to that in countries where Keshan disease is registered. The sediments in the Patos Estuary are also notably lower in Se than near-shore marine sediments. Foodstuffs produced in the littoral pampas are characterised by extremely low Se concentrations compared with the same alimentary products reported worldwide. The total daily dietary intake of Se in the region is 24μgday-1, which is half the Estimated Average Requirement for adults. Black beans in the local diet provide over 40% of daily Se intake. Prescriptive addition of Se to prevalent products seems the most effective solution to the problem of metalloid dietary deficiency in the region. Similar environmental conditions and significant concentration of the population in the littoral zone suggest that the problem of Se deficiency probably affects a large proportion of the population along the Atlantic coast of Brazil.

Elemental and mineralogical analysis of marine and coastal sediments from Phra Thong Island, Thailand: Insights into the provenance of coastal hazard deposits

Sediment records left by coastal hazards (e.g. tsunami and/or storms) may shed light on the sedimentary and hydrodynamic processes happening during such events. Modern onshore and offshore sediment samples were compared with the 2004 Indian Ocean Tsunami, three palaeotsunami and a 2007 storm deposit from Phra Thong Island, Thailand, to determine provenance relationships between these coastal overwash deposits. Sedimentological and stratigraphic characteristics are generally inadequate to discriminate tsunami and storm deposits so a statistical approach (including cluster analysis, principal component analysis and discriminant function analysis) was used based on grain size, mineralogy and trace element geochemistry. The mineral content and trace element geochemistry are statistically inadequate to distinguish the provenance of the modern storm and tsunami deposits at this site, but the mean grain size can potentially discriminate these overwash deposits. The 2007 storm surge deposits were most likely sourced from the onshore sediment environment whereas all four tsunami units statistically differ from each other indicating diverse sediment sources. Our statistical analyses suggest that the 2004 tsunami deposit was mainly derived from nearshore marine sediments. The uppermost palaeotsunami deposit was possibly derived from both onshore and nearshore materials while the lower palaeotsunami deposits showed no clear evidence of their sediment sources. Such complexity raises questions about the origin of the sediments in the tsunami and storm deposits and strongly suggests that local context and palaeogeography are important aspects that cannot be ignored in tsunami provenance studies.

Anaerobic Carbon Mineralisation Through Sulphate Reduction in the Inner Shelf Sediments of Eastern Arabian Sea

Monsoon-induced coastal upwelling, land run-off, benthic and atmospheric inputs make the western Indian shelf waters biologically productive that is expected to lead to high rates of mineralisation of organic matter (OM) in the sediments. Dissimilatory sulphate reduction (SR) is a major pathway of OM mineralisation in near-shore marine sediments owing to depletion of other energetically more profitable electron acceptors (O2, NO3−, Mn and Fe oxides) within few millimetres of the sediment-water interface. We carried out first ever study to quantify SR rates in the inner shelf sediments off Goa (central west coast of India) using the 35S radiotracer technique. The highest rates were recorded in the upper 10 cm of the sediment cores and decreased gradually thereafter below detection. Despite significant SR activity in the upper ∼12 to 21 cm at most of the sites, pore water sulphate concentrations generally did not show much variation with depth. The depth integrated SR rate (0.066–0.46 mol m−2 year−1) decreased with increasing water depth. Free sulphide was present in low concentrations (0–3 μM) in pore waters at shallow stations (depth <30 m). However, high build-up of sulphide (100–600 μM) in pore waters was observed at two deeper stations (depths 39 and 48 m), 7–11 cm below the sediment-water interface. The total iron content of the sediment decreased from ∼7 to 5 % from the shallowest to the deepest station. The high pyrite content indicates that the shelf sediments act as a sink for sulphide accounting for the low free sulphide levels in pore water. In the moderately organic rich (2–3.5 %) sediments off Goa, the measured SR rates are much lower than those reported from other upwelling areas, especially off Namibia and Peru. The amount of organic carbon remineralised via sulphate reduction was ∼0.52 mol m−2 year−1. With an estimated average organic carbon accumulation rate of ∼5.6 (±0.5) mol m−2 year−1, it appears that the bulk of organic matter gets preserved in sediments in the study region.

Correlation of bulk sedimentary and compound-specific δ13C values indicates minimal pre-aging of n-alkanes in a small tropical watershed

Abstract Inherent to sedimentary compound-specific isotopic proxies of paleoecological and paleoclimate change is the assumption that biomarkers are coeval with the surrounding sedimentary matrix. Compound-specific radiocarbon analyses of lake and nearshore marine sediments have indicated a potential offset between the ages of terrestrial biomarkers and their surrounding sediments that could confound efforts to establish strong chronological control for compound-specific isotopic data. We conducted high-resolution compound-specific δ13C analyses of n-alkanes (δ13Calkane) in a well-studied sediment core from Laguna Castilla, Dominican Republic, and compared the results to bulk sedimentary δ13C (δ13Cbulk), fossil pollen, and sediment geochemistry to assess potential ‘pre-aging’ of alkanes in the terrestrial environment prior to deposition. We found significant positive correlations between δ13Cbulk values and δ13Calkane values, indicating little or no temporal lag in the response of δ13Calkane values to vegetation change and thus little or no offset in the age of terrestrially-derived compounds and the organic fraction of the sedimentary matrix. While this study highlights the need for further research into the variables affecting age offsets between proxy data, we propose the comparison of δ13Cbulk and δ13Calkane values as a method to assess potential age offsets between compound-specific and other proxy datasets, particularly in small watersheds with sediment records containing a high proportion of allochthonous organic matter. This method is more available to researchers than obtaining numerous compound-specific radiocarbon analyses, which are costly and not a routine service offered by radiocarbon facilities.

Distribution and provenance of modern pollen and spores in the surface sediments of Liaodong Bay, China

To elucidate modern pollen and spore distribution and provenance based on their dispersal patterns, we analyzed 72 surface sediment samples from Liaodong Bay, China and 39 analogous samples from its five inflowing rivers. Our results reveal that most of the pollen and spores in the nearshore marine sediments (water depth <8m) originated from riverine input and that their assemblages corresponded well to the watershed vegetation. Variation in the pollen assemblages in different parts of the marine area could reflect differences in local vegetation. The content of herbaceous pollen decreased with increasing distance offshore, while arboreal pollen and spores increased. Due to the differences in the sedimentary environments and the source areas of pollen and spores, pollen concentrations in the marine area were higher than those in analog sediments in the modern alluvium of the inflowing rivers. The highest pollen concentrations occurred in the northwestern area of Liaodong Bay, where pollen was derived from multiple inflowing rivers. According to the distribution characteristics of pollen and spores from alluvium to marine sediments, it can be inferred that most pollen grains such as Artemisia, Chenopodiaceae, Gramineae, Cyperaceae, Typha, deciduous Quercus, Betula, and Corylus pollen were primarily transported through the inflowing rivers, whereas Pinus and Carpinus pollen were likely to have been transported by wind. The results of DCA [detrended correspondence analysis] analysis and analog dissimilarity analysis suggested that the pollen-spore distribution in the nearshore area of Liaodong Bay mainly reflects fluvial and marine hydrodynamics or water sorting effects, as well as the vegetation distribution onshore. These findings are of critical importance to the interpretation of Quaternary marine pollen data from Liaodong Bay, China.

Magnetic properties in nearshore marine sediments off southern Chile

Magnetic properties in nearshore marine sediments off southern Chile

Distribution and Pollution Assessment of Heavy Metals in Beidaihe Near-Shore Marine Sediments

The concentrations of heavy metals, Cd, Hg, Pb, Cu and As in marine sediments from 138 sites located in the Beidaihe near-shore area of Bohai bay, were analyzed to find out the distribution characteristics of these heavy metals. Potential Ecological Risk index were adopted to assess the heavy metals contamination, and the assessment results indicated that the content of heavy metals in this area is in a low to moderate level, while high values were found in the southwest and northeast region, and the value in the middle region is comparatively low. The high pollution hazard sites were close to the Renzaohe estuary and Shihe estuary and the high risk is mainly led by Hg.

Novel use of faecal sterols to assess human faecal contamination in Antarctica: a likelihood assessment matrix for environmental monitoring

AbstractWastewater containing human sewage is often discharged with little or no treatment into the Antarctic marine environment. Faecal sterols (primarily coprostanol) in sediments have been used for assessment of human sewage contamination in this environment, butin situproduction and indigenous faunal inputs can confound such determinations. Using gas chromatography with mass spectral detection profiles of both C27and C29sterols, potential sources of faecal sterols were examined in nearshore marine sediments, encompassing sites proximal and distal to the wastewater outfall at Davis Station. Faeces from indigenous seals and penguins were also examined. Faeces from several indigenous species contained significant quantities of coprostanol but not 24-ethylcoprostanol, which is present in human faeces.In situcoprostanol and 24-ethylcoprostanol production was identified by co-production of their respectiveepi-isomers at sites remote from the wastewater source and in high total organic matter sediments. A C29sterols-based polyphasic likelihood assessment matrix for human sewage contamination is presented, which distinguishes human from local fauna faecal inputs andin situproduction in the Antarctic environment. Sewage contamination was detected up to 1.5 km from Davis Station.

ChemInform Abstract: Anthracimycin, a Potent Anthrax Antibiotic from a Marine‐Derived Actinomycete.

The human infectious disease anthrax is caused by the sporeforming, Gram-positive bacterium Bacillus anthracis. The disease, which is most common in those that handle infected farm animals, has also been used as a bioterrorism weapon. In 2001, just a week after the World Trade Center attacks, anthrax was deliberately spread through the US postal system by sending letters with powdered B. anthracis spores. This caused 22 cases of anthrax infection and ultimately claimed five lives. [1] Depending upon the method of exposure (inhalation of spores and direct bacterial contact, among others) B. anthracis infections can require prolonged treatment often for six months with a variety of antibiotics. The pulmonary form of anthrax is considered a medical emergency that may require continuous intravenous therapy with potent antibiotics. In the event of a bioterrorism attack, individuals exposed to B. anthracis will be given antibiotics prior to the onset of the illness. A vaccine has been developed but is not yet available to the general public. [2] Given the severity of this disease, and the fact that it can be spread by aerosol dispersal, the development of effective new antibiotics remains a high priority. As a resource for developing microbial antibiotics, we have focused our efforts on marine microorganisms, particularly those that are in the deep oceans. Examination of a Streptomyces species (our strain CNH365), isolated from near-shore marine sediments found near Santa Barbara, CA, showed that culture extracts possessed significant activity against B. anthracis and methicillin-resistant Staphylococcus aureus in broth dilution assays. Subsequent fractionation of the extract following antibacterial activities yielded a pure