Surface Sediment Distribution Research Articles

Spatial distribution and ecological risk assessment of the coastal surface sediments from the Red Sea, northwest Saudi Arabia

To assess the spatial distribution and ecological risk assessment along the Red Sea coast, Saudi Arabia, 30 samples were collected for aluminum, chromium, copper, zinc, cadmium, lead, mercury, iron, cobalt, nickel and organic matter analysis. The descending order of metal concentrations was Al > Fe > Cr > Cu > Zn > Ni > Co > Pb > Hg > Cd. Average values of enrichment factor of Hg, Cd, Cu, Co, Cr, Ni, Pb and Zn were higher than 2 (209.50, 25.52, 20.36, 9.62, 7.28, 6.52, 6.21 and 6.07 respectively), which means anthropogenic sources of these metals. The average levels most of the studied metals were lower than those of the background shale and the earth crust and those recorded along most worldwide coasts, while the average values of zinc, copper, cobalt and nickel were higher than the values recorded from the Red Sea coast, the Gulf of Aqaba and some Caspian Sea coasts. The Duba bulk plant-Saudi Aramco, Duba refinery station and the tourist resort were the possible anthropogenic sources of pollutants in the southern part of the study area; and the landfilling, cement factory and Duba port and shipment operations in the central part, while the landfilling resulting from construction of the green Duba power plant and crowded fish boats were the possible sources in the northern part.

Mineralogy, composition and heavy metals’ concentration, distribution and source identification of surface sediments from the saline Maharlou Lake (Fars Province, Iran)

This study concerns the mineralogy, spatial distribution and sources of nine heavy metals in surface sediments of the Maharlou saline lake, close to the Shiraz metropolis in southern Iran. The sources for these sediments were studied by comparing the mineralogy and the distribution of heavy metals, using multivariate statistical analysis (correlation analysis and principal component analysis). The geochemical indices, including geo-accumulation index (Igeo), contamination factor (CF) and pollution load index (PLI), were used to assess the degree of heavy metal contamination in surface sediments. Sediment quality guidelines (SQGs) have also been applied to assess its toxicity. The XRD analysis shows that the main minerals of the surface sediments are aragonite, calcite, halite and quartz, with small amounts of montmorillonite, dolomite and sepiolite. The total heavy metal contents in surface sediments decrease in order of Sr > Ni > Cr > Zn > Cu > Co > Pb > As > Cd and the average concentrations of Sr, Ni and As exceeded more than 10, 5 and 3 times, respectively, by comparing with the normalized upper continental crust (UCC) values. The results of pollution indices (Igeo, CF and PLI) revealed that strontium (Sr), nickel (Ni) and arsenic (As) were significantly enriched in those sediments. Based on the sediment quality guidelines (SQGs), Ni would infrequently cause toxicity. Multivariate statistical analysis indicated that the Ni, Co and Cr came mainly from natural geological background sources, while Cd, Cu, Pb, and Zn were derived from urban effluents (especially traffic emissions) and As originated from agriculture activities. Significant relationships of Sr with S, CaO and MgO in sediments suggest that Sr was derived from carbonate- and gypsum-bearing catchment source host rocks.

Geochemistry and grain size distribution of surface sediments of a large semi-enclosed lagoon connected to the western Bay of Bengal

Batticaloa is a large (135.5 km2), semi-enclosed, micro-tidal lagoon that formed by barrier deposits in eastern Sri Lanka and has a unique geographic position due to its tropical monsoonal climate and absence of tectonics. The recent soft bottom sediments of Batticaloa lagoon were studied on the basis of geochemistry and grain size distribution in order to interpret their characteristics and provenance. Poor to moderately sorted medium sands are the dominant sedimentary deposits for the lagoon; therefore, a medium energy condition is suggested for sediment deposition. The average silt and clay fraction of the lagoon sediments is less than 3%, indicating medium or high energy flows. Coarser deposits are restricted to channel and lagoon mouths. The scatter plots of Nb, Zr, Cr and Sc vs. Th and Cr/V vs. Y/Ni show a felsic provenance for the sediments. The normalized diagrams of major element oxides and trace elements for the regional rocks (Vijayan Complex of Sri Lanka) indicate high country rock influence for the sedimentation for the semi-enclosed setting. The enrichment and distribution of Zr, Th, Nb, Cr and TiO2 suggest the possibility of mineral sands that are fractionated with hydrodynamic setting of the lagoon.

Organic Matter, Textures, and Pore Attributes of Hypersaline Lacustrine Microbial Deposits (Holocene, Bahamas)

Research Article| July 31, 2018 Organic Matter, Textures, and Pore Attributes of Hypersaline Lacustrine Microbial Deposits (Holocene, Bahamas) Hannah L. Hubert; Hannah L. Hubert Kansas Interdisciplinary Carbonates Consortium, Department of Geology, University of Kansas, Lawrence, Kansas 66045, U.S.A. Search for other works by this author on: GSW Google Scholar Eugene C. Rankey; Eugene C. Rankey Kansas Interdisciplinary Carbonates Consortium, Department of Geology, University of Kansas, Lawrence, Kansas 66045, U.S.A. Search for other works by this author on: GSW Google Scholar Christopher Omelon Christopher Omelon Kansas Interdisciplinary Carbonates Consortium, Department of Geology, University of Kansas, Lawrence, Kansas 66045, U.S.A. Search for other works by this author on: GSW Google Scholar Journal of Sedimentary Research (2018) 88 (7): 827–849. https://doi.org/10.2110/jsr.2018.42 Article history first online: 31 Jul 2018 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Tools Icon Tools Get Permissions Search Site Citation Hannah L. Hubert, Eugene C. Rankey, Christopher Omelon; Organic Matter, Textures, and Pore Attributes of Hypersaline Lacustrine Microbial Deposits (Holocene, Bahamas). Journal of Sedimentary Research 2018;; 88 (7): 827–849. doi: https://doi.org/10.2110/jsr.2018.42 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search nav search search input Search input auto suggest search filter All ContentBy SocietyJournal of Sedimentary Research Search Advanced Search Abstract Discovery of lacustrine microbialite reservoirs in South Atlantic pre-salt has motivated the search for analogs for perspectives on their deposition and initial porosity. Although previous efforts mapped spatial patterns and produced facies models of large microbial lacustrine systems, details of the origins of microbialite fabrics are less well constrained. To address these unknowns, this study evaluates the influence of organic-matter source, abundance, and growth habit on Holocene microbialite fabrics. Integrated multi-scale analyses characterize fabrics of Holocene microbialites in a small (< 1 km2), shallow (< 1 m), hypersaline, alkaline lake on Crooked–Acklins Platform in the southern Bahamas. The results of analyses indicate systematic distribution of surface sediment across the lake, from various types of unlithified microbial mats to calcareous microbialites; bottom type relates to water depth. Spherules with laminae of radial aragonite are common in organic-rich mats, and can have competitive growth boundaries. Calcareous microbialites in the lake center can reach up to 60 cm tall and 2+ m across, and include macrofabrics and microfabrics that vary considerably, across micrometer to meter scales. Porosity varies from 43 to 59%, in pore types ranging from intra-fibrous (IF), breccia (BR), vuggy (VUG), intra- (WL) and inter-laminar (IL), digitate (DG), to branching (BRA). Microfabrics are not unique to individual macrofabrics, and organic-matter source is similar among fabrics. The abundance of organic matter and growth habit of organics on the outer parts of microbialites varies markedly among fabrics, suggesting that these parameters may control rock fabric. The occurrence of Mg silicates in association with these microbialites may favor preservation of the depositional pores. Although ultimate preservation is unknown, understanding the genesis of primary fabrics may provide insights into possible pore evolution in reservoir analogs. You do not currently have access to this article.

Source, processes and productivity from distribution of surface sediments, Prydz Bay, East Antarctica

Source of sediments and depositional processes of surface sediments along the Prydz Bay were investigated through grain size, organic carbon, nitrogen, phosphorus, calcium carbonate and metal concentration. High content of sand and higher values of Al2O3 and TiO2 at shallow water depth indicate their terrigenous source and relatively higher hydrodynamic conditions near the coast. Al2O3/TiO2 ratio ranging from 3.77- 12.73 suggests a mafic source for the sediments. C/N ratio ranging from 5.76 to 9.13 indicates autochthonous (in-situ) source for organic matter, for which phytoplanktons and algae may be the major contributors. However, N/P ratio lower than the Redfield ratio indicated a limitation of either N or P in the study area. Calcium carbonate concentration is low possibly due to increased loads of clay which must have caused the dilution of carbonates. Metals like Fe, Mn and Mg exhibit strong correlation with lithogenic elements while, the trace metals such as Cd, Co, Cu, Ni and Zn show significant correlation with organic elements indicating that lithogenic and biogenic inputs are their main sources. Trace elements namely, Cd and Zn show nutrient like behavior suggest the role of trace metal in addition to nutrients in the regulation of productivity. Thus, the present study provides an understanding of recent sedimentary environments and processes, which are used as a tool to interpret palaeoenvironmental records.

Heavy metal pollution and spatial distribution in surface sediments of Mustafakemalpaşa stream located in the world's largest borate basin (Turkey)

Mining activities in addition to the geology of Mustafakemalpaşa catchment have for long been linked to its deteriorating water and sediment quality. This study assessed contamination levels of heavy metals and other major elements (Pb, As, B, Cd, Zn, Cr, Mo, Co, Ni, Cu, and Ag) in surface sediments of the area, and identified possible pollution sources. Sediment quality indicators, such as contamination factor (CF), enrichment factor (EF), geo-accumulation index (Igeo) and sediment quality guidelines were used, in addition to multivariate statistical technics; Pearson Correlation Matrix (PCM), Principal Component Analysis (PCA) and Hierarchical Cluster Analysis (HCA). The highest contamination (annual average > 110 mg kg-1) was revealed by B, Cr, Ni, Zn and As. Moreover, As, Cd and Ni levels exceeded their respective probable effect concentrations (PEC), posing a potential negative impact to biota. The highest Igeo values were recorded for Cr, B, Ni, As and Zn, and occurred near urban settlements and mining sites, particularly of coal and chromium. The present study also suggests use of site rank index (SRI) as an alternative to pollution load index (PLI), since the former is derived from the data of interest and eliminates arbitrary classifications. The sources of heavy metals in the sediments were attributed to fly ashes of coal-powered plants, urban waste leachate and weathering of sulfide ore minerals for Pb, Zn and Cu; urban-industrial wastes and mining wastes for Ni. Although Cr, As, Cd and B were ascribed to natural occurrence, their presences in river sediment is accelerated by mining.

Clay mineral distribution and provenance in surface sediments of Central Yellow Sea Mud

The provenance of the Central Yellow Sea Mud (CYSM) in the Yellow Sea has been attracted a great deal of attention over the last three decades, but a consensus is not yet reached. In this study, 101 surface sediment samples collected from the CYSM were investigated to determine provenance and transport mechanisms in the area using the clay minerals and major element components. The Huanghe sediments are characterized by higher smectite, but the Changjiang sediments are more abundant illite contents. Western Korean rivers contain more kaolinite and chlorite than do Chinese rivers. The Chinese rivers have higher Fe2O3, MgO, and CaO than the Korean rivers at the same Al2O3 concentration. Therefore, the clay minerals and major element concentrations can be useful indicator for the source. Based on our results, we suggest that the surface sediments in CYSM were composed mainly of Changjiang sediments, mixed a partly with sediments from the Huanghe and the western Korean rivers. Although the northwestern part of CYSM is proximate to the Huanghe, the contents of smectite and CaO were extremely low. It could be evidence that the Huanghe materials do not enter directly into the CYSM due to the Shandong Peninsula Front. Considering the oceanic circulation in the Yellow Sea, the Changjiang sediments could be transported eastward with the Changjiang Diluted Water and then mixed in CYSM via the Yellow Sea Warm Current (YSWC). Huanghe sediments could be provided by coastal currents (Shandong Coastal Current and Yellow Sea Coastal Current) and the YSWC. In addition, sediments from western Korean rivers might be supplied into the CYSM deposit via the Korean Coastal Current, Transversal Current, and YSWC.

Impact of coastal environmental factors on quinolone distribution in intertidal surface sediments of the Bohai Sea and Yellow Sea, China

Abstract Freshwater contaminants tend to precipitate into intertidal surface sediments, particularly in the estuary and intertidal zones during freshwater–seawater mixing. Quinolone-type antibiotics are such contaminants, and their concentrations in the intertidal sediments are important indicators for the whole spectrum of antibiotics used in the estuary and adjacent areas. The impacts of sediment types and environmental factors on the distribution of 16 quinolones were probed based on nine Bohai and 42 Yellow Sea intertidal sediment samples. The samples were collected from locations along the coastal areas in China. Quinolones were detected in all samples, while moxifloxacin, ciprofloxacin, and ofloxacin were detected at a frequency &amp;gt;50%. Sediment types, pH, organic carbon content, K, Na and Fe concentrations had little correlation with quinolone distributions in intertidal sediments. However, combined concentrations of Ca + Mg (46.7 g/kg in Bohai and 13.7 g/kg in Yellow Sea samples) appeared to correlate with oxolinic acid detecting frequencies (88.9% and 4.8%, respectively) and concentrations (2.0–10.1 μg/g and up to 3.09 μg/g, respectively). Different detection frequencies of the quinolones could be attributed to the formation of cation bridges between oxolinic acid and Ca + Mg, which results in dominant sorption of oxolinic acid at different locations and sediment matrices.

Trace metal contamination by phosphogypsum discharge in surface and core sediments of the Gabes coast area (SE of Tunisia)

The purpose of the present study is to ascertain the extent of the effect that phosphate fertilizer industrial waste has on the surface and bottom sediments of the Ghannouch-Gabes coast, off the Tunisian Mediterranean Sea. To achieve this, 44 surface sediments and 3 core sediments were studied for mineralogy, trace metals (Cd, Cu, Pb, and Zn), F, CaO, and SO3. For all the analyzed elements, the spatial distribution in surface sediments showed that the area located between the commercial and the fishing port of Gabes is the most polluted zone. The ranking of metal contents was found to be Zn > Cd > Cu > Pb. The vertical distribution of trace metals indicated that the highest levels were found in the uppermost segment of the sediment cores compared to the lower depth subsurface due to a continuous input of phosphogypsum (PG) release and confirmed that the area between the two harbors suffered from several types of pollutants compared to reference core C1, collected from other non-industrialized areas. This spatial and vertical distribution is probably due to the harbor piers which acted as barriers and limited the dispersion of PG discharge. The contamination factor, the geoaccumulation index, and the pollution load index were determined. The results obtained confirm the anthropogenic impact on the levels of metal, on the fluorine, calcium, and sulfate concentrations in the area, located between the commercial harbor of Ghannouch and the fishing harbor of Gabes, whereas the concentrations of elements analyzed tends to decrease on both sides of this sector. Statistical analyses (principal component analysis) showed trace metals, fluoride, sulfate, and a large amount of calcium resulting from the same anthropogenic source.

Spatial distribution, fractionation, toxicity and risk assessment of surface sediments from the Baiyangdian Lake in northern China

The pollution of Baiyangdian Lake (BYDL) has been of concern since the Xiongan New Area was established. To conduct ecological restoration of BYDL, the heavy metals (HMs) levels in sediments were assessed. Specifically, Surface sediments (0–10 cm) samples in BYDL were analyzed for Cd, Cr, Cu, Ni, Pb and Zn in October 2016 to evaluate the risk posed by trace metals, as well as their bioavailability and toxicity. The results demonstrated that HMs showed high pollution and risk levels in most sample sites as a result of Cd and Pb. Metals speciation analysis demonstrated that Cd, Cu, Pb and Zn were dominated by non-residual fractions that originated from anthropogenic sources and presented higher bioavailability. The risk assessment code indicated that Cd poses a medium level biological risk in BYDL, which reached 10.25% and 29.38%. The bioavailable metals index showed a strong correlation with acute toxicity (R2 = 0.704), indicating bioavailable metals are an important reason for sediment acute toxicity. Canonical correspondence analysis demonstrated that HMs have a coercive effect on the distribution of benthic invertebrates. Overall, the results indicate that HMs pollution should be considered during the development of strategies for ecological restoration in BYDL.

An optimized method for the analysis of cyclic and linear siloxanes and their distribution in surface and core sediments from industrialized bays in Korea.

Environmental contamination by siloxanes is a matter of concern due to their widespread consumption in personal care as well as industrial products and potential toxicity. Nevertheless, methods for simultaneous determination of cyclic and linear siloxanes in sediment are lacking. In this study, we developed an optimized analytical method to determine cyclic and linear siloxanes based on gas chromatography coupled to tandem mass spectrometry (GC-MS/MS). This method was applied to determine concentrations of 19 siloxane compounds in surface and core sediments from industrialized bays in Korea to assess contamination status, spatial distribution, and historical trends. Total concentrations of siloxanes ranged from 15.0 to 11730 (mean: 712) ng/g dry weight, which were similar to or higher than those reported in other countries. The highest concentrations of siloxanes were found in rivers/streams that discharge into coastal waters and bays close to industrial complexes, indicating that industrial activities are major sources of siloxane contamination. Cyclic siloxanes such as D5 and D6 were predominant in surface and core sediments. A significant correlation existed between the concentrations of cyclic and linear siloxanes, suggesting similar sources in the marine coastal environment. The historical record of cyclic siloxanes in core sediments revealed a clear increasing trend since the 1970s. This finding is consistent with the history of local industrialization and global production of siloxanes. This is the first study of historical trends in siloxanes in the coastal environment.

Steady as a rock: Biogeomorphic influence of nurse rocks and slope processes on kūpaoa (Dubautia menziesii) shrubs in Haleakalā Crater (Maui, Hawai'i)

This study examines biogeomorphic interactions between nurse rocks, slope processes, and 300 kūpaoa (Dubautia menziesii) shrubs in Haleakalā Crater (Maui, Hawai'i). Research objectives were to: assess the association of kūpaoa with substrates upslope and downslope of plants, and proximity to the closest rock uphill; contrast shrub/substrate relationships with site frequency of sediment types; measure surface soil shear-strength and compressibility on 50 paired locations near boulders; and investigate the aggregation characteristics and spatial patterns of kūpaoa in relation to rock and substrate variation. Data analyzed came from three 100-plant surveys at 3 sites: a plant census at 2720–2975m altitude, and wandering-quarter transects (WQTs) across two areas (2610–2710m); ground sediment cover was estimated along four phototransects on these sites. Data for the three 100-plant surveys included substrate type—outcrops, blocks, cobbles, pebbles, exposed soil, organic litter—upslope from each plant, and distance to the largest rock upslope. The two surveys examined along WQTs included substrate type found downslope from kūpaoa, plant height, plant diameters across and along the slope, and distance between successively censused plants. Most plants grew downslope of nurse rocks; >74% were adjacent to blocks or outcrops, and >17% near cobbles. Plants showed avoidance for finer substrates; only ~5.3% and 2.7% grew on/near bare soils and pebbles, respectively. About 92% of kūpaoa were ≤10cm downslope of rocks; >89% grew ≤2cm away, and ~83% in direct contact with a rock. Some seedlings also grew on pukiawe (Leptecophylla tameiameiae) nurse plants. Several stable rock microsites protected plants from disturbance by slope processes causing debris shift. Site sediments were significantly finer than substrates near plants; shrubs grew preferentially adjacent to boulders >20cm wide, which were more common near plants than across sites. Soils downslope of 50 boulders—mean 41.3cm—showed higher shear strength and compressibility than soils along rock sides. These boulder dams stop descending debris, steadily deflecting them toward rock sides, whereas protected soils downslope of blocks are infrequently disturbed and develop into downslope elongated, clast-free fine-earth flags. Kūpaoa were uniformly dispersed across slopes, showing a single-phase mosaic arrangement, without apparent aggregation. Slopes where kūpaoa grows had a relatively uniform distribution of surface sediments; observed kūpaoa patterns may have resulted from the array of microsites generated by surface rocks and sediments, as shrubs simply responded to such spatial structure.

Pollen distribution in surface sediments of the northern Lower Medjerda valley (northeastern Tunisia)

Past Mediterranean vegetation dynamics are commonly reconstructed using fossil pollen records. However, the interpretation of pollen records in terms of vegetation, climate and land-use changes is often limited due to complex pollen–vegetation relationships. So far, such relationships have been poorly examined in the semi-arid regions of Northern Africa. This work aims to document the modern pollen assemblages that reflect the main vegetation types associated to different land-uses in the northeastern Tunisia. For that, we collected 29 modern terrestrial surface samples in the Lower Medjerda valley and compared the pollen spectra to remotely sensed vegetation data. This original approach, coupling pollen and remotely sensed land cover data, presents some limitations and errors affecting both datasets although it gives promising results. Multivariate analyses show that the composition of pollen samples collected within the Mediterranean maquis may be strongly influenced by adjacent land covers such as conifer woodland or open vegetation. In contrast, pollen spectra associated with land-uses corresponding to heterogeneous agricultural areas and open landscape, mainly irrigated lands, have a distinct signature. However, close to water bodies, pollen spectra reflect predominantly the characteristic halophytic vegetation whatever the surrounding land cover types. We also examined the pollen composition of sediment core-tops from the lagoon Sidi Ali Mekki, to evaluate the ability of pollen sequences to record past vegetation and land-use histories in the Ghar el Melh region. We found that core pollen signal is mainly imprinted by the predominant local vegetation of Sidi Ali Mekki shore although regional and extra-regional pollen inputs appear stronger than in modern surface samples.

Metal distribution and fractionation in surface sediments of coastal Tema Harbour (Ghana) and its ecological implications

This study investigated the distribution and fractionation of metals (Mn, Ni, Pb, Cr, Cu, Zn, As, Cd, Hg and Sn) in surface sediments of Tema Harbour (Greater Accra, Ghana) as well as its ecological implications. Significant differences in sediment concentrations of Mn, Ni, Cr, Cu, Zn, As and Sn were observed across the Tema Harbour. Geochemical indices indicate that Cd, Hg, Pb, Cu, Zn, As and Sn in the Tema Harbour sediments derived mainly from anthropogenic sources, while Mn, Ni and Cr were mainly of lithogenic origin. Metal fractionation revealed a predominance of Al, Mn, Ni, Pb, Cr, Cu, As and Sn in the residual phase. In contrast, Cd and Hg were mainly present in the exchangeable phase, while Zn was mainly associated with the reducible phase. Based on the metal fractionation in the Tema Harbour sediments, the potential risks of metal bioavailability were high for Cd and Hg, low–medium for Mn, Ni, Zn, As and Sn and low for Pb, Cr and Cu. A screening-level ecotoxicological assessment revealed high potential toxicity of Hg and moderate potential toxicities of Pb, Cu, Zn, As and Cd in the Tema Harbour sediments. The potential influence of the buffer intensity, silt–clay, total organic carbon and carbonate content on the metal distribution in the Tema Harbour sediments was also inferred from their correlations. Comparison with previous studies did not reveal a progressive increase in metal contamination at the Tema Harbour since the year 2000.

GEOMORPHOLOGY, SEDIMENTOLOGY AND GEOCHEMISTRY IN THE MARINE AREA BETWEEN SIFNOS AND KIMOLOS ISLANDS, GREECE

An extensive oceanographic survey was conducted in the marine area between Kimolos and Sifnos Islands, a rather poorly-studied sector of the Aegean Sea, in order to gain better understanding of submarine geomorphological features and associated sediment provenance. Multi-beam bathymetry and surface sediment sampling with a box corer were carried out on board R/V Aegaeo, followed by grain-size analysis, XRD and XRF measurements. A large circular depression was identified north of Kimolos reaching a water depth of 743 m, filled with fine grained sediments. Surface sediment distribution is characterized by gradual decrease in grain-size from silty sand to silt in a S-N direction. The mineralogical composition comprises calcite, Mgcalcite, aragonite, dolomite, quartz, K feldspars, plagioclase, amphiboles and clay minerals. Major sediment provinces identified were: (i) the shallow sector proximal to Kimolos, characterized by higher contents in Si, Al, K, Rb and Ba; (ii) the deep area west of Sifnos, including the large depression, characterized by higher contents in Fe, Ti, Na, Mg, S, Cr, Cu, Ni, V, Zn; and (iii) the south passage between Kimolos and Sifnos, which exhibits higher Ca, S, and Sr contents. Manganese enrichment was observed in and around the bathymetric depression, where Mn oxides act efficiently as scavengers of a suite of metals.

The occurrence of microplastic contamination in littoral sediments of the Persian Gulf, Iran.

Microplastics (MPs; <5mm) in aquatic environments are an emerging contaminant of concern due to their possible ecological and biological consequences. This study addresses that MP quantification and morphology to assess the abundance, distribution, and polymer types in littoral surface sediments of the Persian Gulf were performed. A two-step method, with precautions taken to avoid possible airborne contamination, was applied to extract MPs from sediments collected at five sites during low tide. MPs were found in 80% of the samples. Across all sites, fiber particles were the most dominate shape (88%), followed by films (11.2%) and fragments (0.8%). There were significant differences in MP particle concentration between sampling sites (p value <0.05). The sediments with the highest numbers of MPs were from sites in the vicinity of highly populated centers and municipal effluent discharges. FTIR analysis showed that polyethylene (PE), nylon, and polyethylene terephthalate (PET) were the most abundant polymer types. More than half of the observed MPs (56%) were in the size category of 1-4.7mm length, with the remaining particles (44%) being in the size range of 10μm to <1mm. Compared to literature data from other regions, intertidal sediments in the Persian Gulf cannot be characterized as a hot spot for MP pollution. The present study could, however, provide useful background information for further investigations and management policies to understand the sources, transport, and potential effects on marine life in the Persian Gulf.

Pesticides distribution in surface waters and sediments of lotic and lentic ecosystems in Agbede wetlands

An investigation on the availability and distribution of Lindane (HCHs) and Total organochlorine phosphate (TOCP) in the surface waters and sediments of selected water bodies in Agbede wetlands was carried out from December, 2012 to May, 2014 in order to cover seasonal trends in both matrixes. A Gas Chromatograph model Hewlett-Packard (HP9) 5890 Series II equipped with 63Ni Electron Capture Detector (ECD) of activity 15 mCi with an auto sampler was employed for the analysis of the water and sediment samples in the laboratory under standard condition. Spatial and temporal variations showed that the concentrations of TOCP closely followed that of Lindane in surface water and was a replica in the sediment matrix. Meanwhile, the values obtained for Lindane and TOCP in the sediment were slightly higher than (about 3 folds) that in the surface waters. The concentrations of pesticides in the surface waters and sediments of lotic and lentic ecosystems in Agbede wetlands were found to be far below the set limit of 0.01μgL-1 by the Federal Ministry of Environment of Nigeria (FMEnv) and World Health Organisation (WHO) respectively. The low values recorded in this study suggested seldom application of pesticides particularly on a subsistence form and therefore not indicative of possibility of any serious health issues.Key Words: Below Detection Limit, Concentrations, Ecological Zone, Lindane

Characterization of the New Status of Nador Lagoon (Morocco) after the Implementation of the Management Plan

The present study was carried out in 2011 with the aims of (1) evaluating the changes in sedimentary distribution that occurred in Nador lagoon seabed (Morocco) after the implementation of the lagoon management plan in 2009; and (2) characterizing its new sedimentary status in 2011. Due to the lack of a baseline, we used the 1992 sedimentary status for comparison. The seabed surface sediment distribution showed a great change between 1992 and 2011. We found the same four sediment facies, which were present in 1992, namely: mud, sandy mud, muddy sand, and fine sand. However, in 2011, mud covered more than 54% of the lagoon seabed surface, mostly located in the middle part of the seabed, whereas in 1992, more than 80% of the lagoon seabed was covered by sandy mud. The sediments’ characteristics showed moderately to poorly sorted facies (S0), ranging between platykurtic and leptokurtic (SK) and with various symmetry indices (SG). The organic matter content in sediment has strongly decreased, from values higher than 20% in most areas in 1992 to a mean value of 3.9% in 2011, ranging from 0.2% to 10.4%, thus confirming that the management actions implemented in 2009 were likely effective in reducing the organic pollution.

Factors Influencing the Distribution and Characteristics of Surface Sediment in the Bay of Cartagena, Colombia

ABSTRACT Restrepo, J.C.; Escobar, J.; Otero, L.; Franco, D.; Pierini, J., and Correa, I., 2017. Factors influencing the distribution and characteristics of surface sediment in the Bay of Cartagena, Colombia. This study evaluated patterns of coastal sediment movement and deposition under different seasonal conditions (warm and cold phases of the El Nino–Southern Oscillation [ENSO] and normal conditions) in Cartagena Bay, Colombia. A calibrated numerical model (MOHID modeling system) was applied to assess the spatial distribution of sediments transported by the Canal del Dique to the bay and studied the spatial distribution and major textural characteristics of 234 surface sediment samples. Currents in the Bay of Cartagena are controlled primarily by the strength and direction of the wind. Model results show major sediment deposition in the southern sector of the bay during the dry season. More homogenous spatial distribution of sediments throughout the Bay of Cartagena occurs with an increase in river inpu...

Phosphorus fractions and their spatial distribution in surface sediments of inflow rivers in the northeastern Lake Tanganyika

Phosphorus fractions and their spatial distribution in surface sediments of inflow rivers in the northeastern Lake Tanganyika