Van Veen Grab Research Articles

Differences in distribution and characteristics of microplastics in sediments of the south-eastern part of the Gulf of Trieste

IntroductionThe Gulf of Trieste is prone to the accumulation of various pollutants and microplastics due to its geomorphological and hydrological characteristics. However, the distribution and sources of microplastics in this semi-enclosed area are poorly studied. The aim of our study was to determine the distribution and chemical composition of MP particles in the sediments of the Gulf of Trieste.MethodsIn this study, we collected 24 surface sediment samples using a Van Veen grab. Microplastics were extracted by density separation using NaCl. The size, shape, and color of the extracted microplastics were determined using an optical microscope, and the composition of the polymers was determined by Fourier transform infrared spectroscopy.Results and discussionThe highest concentrations of up to 125 microplastic particles per 100 g dry sediment were found in coastal areas. Concentrations in the open sea were much lower, with an average of 3 particles per 100 g of sediment. Most of the microplastic was fibrous, made of polypropylene, 100–300 µm in size, and blue. This is the first study showing that microplastics are present in the sediments of the south-eastern part of the Gulf of Trieste. The findings suggest that microplastics exhibit a tendency to be retained within the sediment, leading to their accumulation primarily in a narrow coastal area rather than dispersing offshore. Our results will contribute to a better knowledge of the distribution and possible sources of plastics and microplastics in the Gulf of Trieste and even beyond in similar semi-enclosed marine areas.

The Roles of Alpha, Beta, and Functional Diversity Indices in the Ecological Connectivity between Two Sub-Antarctic Macrobenthic Assemblages

The study of ecological connectivity is a global priority due to the important role it plays in the conservation of diversity. However, few studies in this context have focused on marine benthic ecosystems. To address this issue, the present work determines the ecological connectivity between two sub-Antarctic macrobenthic assemblages through assessment of the α-, β-, and functional diversity indices. Samples were collected using a van Veen grab at stations located in Bahia Inútil and Seno Almirantazgo. The ecological analysis was based on a total of 113 invertebrate taxa. The mean abundance values were lower in Bahia Inútil (888.9 ± 26.8 ind m−2) than in Seno Almirantazgo (1358.6 ± 43.4 ind m−2). While the mean α-diversity values showed significant differences between assemblages, β- and functional diversity indices presented no significant differences. These results indicate that, despite the distance (56 km) separating the two basins from each other, there is a high degree of connectivity at the functional level between the assemblages due to the high number of shared species and their functional traits. The species most responsible for this observation were the polychaetes Capitela capitata and Aricidia (Acmira) finitima, as well as the bivalves Nucula pisum and Yoldiella sp. 1. In terms of functional biodiversity, species characterized as omnivorous and with lecithotrophic larval development were mostly responsible for connectivity between assemblages. These results suggest the importance of including β- and functional diversity indices as criteria in the future planning of marine protected areas for the maintenance of marine ecosystem integrity.

Diversity, distribution and knowledge gaps of Polychaeta on the continental shelf of southern Namibia

This study investigated the diversity, composition and distribution patterns of polychaete macrofauna inhabiting unconsolidated sediments on the continental shelf of southern Namibia. During the austral summer of 2021, 910 Van Veen grab samples were collected from 91 sites in water depths ranging between 43 and 146 m. All benthic macrofauna (> 1 mm) were extracted, identified, enumerated and weighed. Polychaetes were the most abundant taxon, equating to 66% of total abundance and 37% of total biomass. A total of 83 712 polychaete specimens comprising 112 species, 80 genera and 33 families were collected. Several taxa identified were listed as putative cosmopolitans (19 taxa) or have known wide local distributions (10 taxa). Voucher specimens were collected for DNA barcoding to improve reference sequence libraries for the region. Hierarchical cluster analyses using both abundance and biomass data were undertaken to determine spatial distribution patterns in polychaete communities. Both datasets yielded similar results with polychaete assemblages divided into inshore and offshore communities, that were further subdivided at a local scale. Investigation of physical and chemical drivers suggested that polychaete communities in southern Namibia are structured to varying degrees by water depth, latitude, sediment composition, redox potential and organic content. Deeper stations comprised the highest diversity of polychaeta fauna. Species adapted to hypoxic conditions (e.g. Sigambra parva, Pararionospio pinnata, Diopatra cf. monroi and Nepthys cf. hombergii) dominated an area known as the mudbelt, where organically enriched silts and clays originating from the Orange River are deposited on the mid-shelf between the 40 and 120 m isobaths.

Abundance and Distribution of Benthic Macro-Invertebrates of Luhu Dam, Michika, Adamawa State, Nigeria

The study uses benthic macroinvertebrates as indicators to assess water quality in the Luhu Mini Dam, Michika, Adamawa State. The study involves the collection of benthic macroinvertebrate samples over six months, utilizing the Van Veen grab method for sampling and preservation in formalin. Upon transportation to the laboratory, the samples were identified and subjected to statistical analysis, including the Shannon and Weiner Index, Margalef’s Index, Simpson’s diversity Index, and Pielou’s Evenness. The study aims to provide fundamental information on the health of the Luhu Mini Dam and to understand the water quality and pollution status, thereby informing necessary management measures. The distribution and diversity of species across three different stations. A total of 462 individuals representing 20 taxa from 3 phyla were collected. Station 1 yielded 16 taxa and 162 individuals, station 2 had 17 taxa and 201 individuals, and station 3 had 17 taxa and 99 individuals. The diversity indices revealed variation in the number of species across stations, with stations 3 and 2 having the highest number of species, while station 1 had the lowest. The general diversity (H') was highest at station 3, followed by stations 1 and 2, whereas station 3 also exhibited the highest Evenness index (E). Moreover, the taxa richness index, as calculated by Margalef's Index (d), peaked at station 3. Simpson's dominance index showed that Station 2 exhibited the highest dominance, followed by Station 1 and Station 3. These findings provide valuable insights into the distribution and diversity of species across different biotopes.

Macrobenthic community structure and diversity across a bathymetric gradient within and below the oxygen minimum zone in central Peru

Oxygen minimum zones (OMZs) are characteristic of highly productive upwelling ecosystems and create unique conditions for benthic organisms that can adapt to hypoxic conditions and high quantities of organic material. Community structure, macrobenthic organism diversity, and biomass of giant filamentous bacteria (Candidatus Marithioploca) were studied along a bathymetric gradient from 79 to 935 m, including depths within and below the OMZ. Sediment samples were taken in both Huacho (11°S) and Callao (12°S) on the central coast of Peru using a van Veen grab sampler and multi-corers in October and November 2008. In addition to the biomass of Candidatus Marithioploca, the abundance, biomass, species richness, and structure of the macrobenthos were estimated on the surface as well as in the sediment column (i.e., 0–1, 1–2, 2–5, and 5–10 cm). The results indicate that, within the OMZ, there was a lower abundance and biomass of the macrobenthos but higher biomass of Candidatus Marithioploca. Within the OMZ, polychaetes were the dominant group, whereas below the OMZ, a diversity of taxonomic groups was recorded. The community structure reflects the gradient at depth as dissimilarity increases with depth. Diversity and evenness were lower within the OMZ and higher below the OMZ. The consistency of this pattern stands when compared to macrobenthos in the OMZ of other regions. The results of the present study highlight the importance of the OMZ as a modifying factor of benthic composition along depth gradients, particularly in diversity patterns.

Multidisciplinary characterisation of the biodiversity, geomorphology, oceanography and glacial history of Bowditch Seamount in the Sargasso Sea

The first multidisciplinary characterisation of Bowditch Seamount in the Sargasso Sea was conducted to provide new baseline knowledge of the biodiversity, geomorphology, oceanography and glacial history of this seamount. A dropframe camera transect 1483–1562 m deep on the seamount documented 77 megafaunal taxa including Vulnerable Marine Ecosystem indicator taxa such as sponges, cold-water corals, and stalked crinoids. Seabed terrain analysis of multibeam echosounder data showed species varied significantly along this transect in response to local geomorphological variability (R2adj = 31%, p < 0.0001), with changes in seafloor relief and substrata driving species composition over the seamount. 14C-calibrated and 230Th-ages of fossil corals (Desmophyllum dianthus) collected by Van Veen grabs 1517 m deep showed corals thrived on the seamount ∼24 ka BP and ∼17 ka BP. Abrupt excursions between higher and lower radiogenic εNd-composition values of the skeletons suggested that D. dianthus persisted on the seamount over times of southern source water input and detrital sediments from the melting Laurentide Ice Sheet, respectively. In agreement with other studies from the western North Atlantic, living D. dianthus were absent in the contemporary setting at these depths, and suggest a significant re-organisation of the seamount community since the deglacial when ice-rafted debris of carbonates likely resulted in a lower aragonite compensation depth allowing D. dianthus to proliferate at deeper depths. New conductivity-depth-temperature profiling revealed the seamount at these depths is now bathed by highly oxygenated Labrador Sea Water (LSW) formed at high latitudes. Co-analysis of a newly constructed 70-year long time series of temperature and salinity for the Labrador Sea and Bermuda regions revealed a 10-year transit time from high latitudes to Bowditch Seamount. This multidisciplinary approach shows how geomorphology drives local biodiversity patterns, but also how upstream climatic forcing in subpolar regions may influence Bermuda's subtropical seamount ecosystem.

Light traps as an exploratory tool in light pollution studies: Assessment of vulnerable species and their migratory patterns

Artificial Light at Night (ALAN) is one of the most widespread stressors on coastal marine habitats. Despite their sparse use in light pollution studies, light traps are a useful methodology to explore which species are attracted by ALAN. For that purpose, we placed light traps during the day and at night in the shallow subtidal adjacent to three natural sandy shores. Additionally, to determine the origin of the catches, the sediment and the water column were also sampled in both periods by a Van Veen grab and a plankton net, respectively. Our results showed that light traps catches at night were dominated by migrant fauna, mostly amphipod crustaceans emerging from the sediment. Other species that perform diel vertical migrations, such as calanoid copepods, were also attracted. This approach may help to understand which taxa are more susceptible to ALAN in these shallow habitats.

ASSESSMENT OF PHYSICOCHEMICAL PARAMETERS AND METAL CONTAMINATION IN SEDIMENTS OF THE PERI-URBAN AMAGBA-OKOROMA RIVER, BENIN CITY, NIGERIA.

The key role of sediments in aquatic systems is widely known, sediments are frequently neglected as a factor in the evaluation of water quality assessment. This study assessed the sediment quality of the Peri-urban Amagba-Okoroma River, Benin City, Nigeria, emphasizing physicochemical parameters and heavy metal contamination. Three sites (Upstream site 1, Midstream site 2 and Downstream site 3) were studied and river sediments were collected from each of these sites using Van veen grab. The sediments were collected three times each in the month of March and July, 2023. The results revealed temperature (25.67°C-26°C), slightly alkaline pH (7.55-7.68), and low electrical conductivity (49.33µS/cm-54.67µS/cm). Heavy metals evaluated were all within threshold/probable effect level guideline: Cd (0.09-0.10 mg/kg), Cr (5.61-6.10mg/kg), Cu (18.62-19.90mg/kg), Pb (0.33t-0.37mg/kg), and Zn (32.47-35.01mg/kg). However, Cu slightly exceeded thresholds-effect level limits at midstream site 2 and downstream site 3, indicating localized pollution sources. Principal component analysis and cluster analysis identified significant correlations between Cd-Cr and Cu-Zn, suggesting shared pollution sources likely from industrial or agricultural runoff. Cluster analysis reveal that sites 2 and 3 are more similar compare to site 1 (upstream). The heavy metal pollution indices collectively indicated no sediment contamination across the sites. Geo-accumulation index values for Cd, Cr, Cu, Pb, and Zn suggested unpolluted conditions across all sampling sites. Contamination factor values corroborated these findings, indicating low contamination levels for all metals. Contamination degree values further confirmed the sediment's low degree of contamination, aligning with Pollution load index values, indicating non-pollution. This study underscores the significance of regular monitoring and targeted mitigation efforts to sustain the ecological health of the river ecosystem amidst potential anthropogenic pressures.

Microplastic analysis in sediments of the Elbe River by electrostatic separation and differential scanning calorimetry

This study presents the most extensive investigation of microplastic (MP) contents in sediment from the Elbe River. We employed electrostatic separation (ES) and differential scanning calorimetry (DSC) to overcome limitations of sample throughput and time-consuming analysis. In total 43 sediment samples were collected using a Van-Veen grab. Subsequently, coarse materials (d10 > 100 μm) and fine materials (d10 ≤ 100 μm) were enriched using ES and density separation. DSC was utilized for MP identification and quantification, based on the phase-transition signals of eight different polymers. MP presence was detected in 25 samples, with successful quantification in 12 samples. The MP content in coarse material samples from shoreline areas ranged from 0.52 to 1.30 mg/kg, while in fine material samples from harbor basins, it ranged from 5.0 to 44.6 mg/kg. The most prevalent polymers identified were LD-PE, HD-PE, PP, and PCL. These findings confirmed the suitability of DSC for analyzing MP in complex environmental samples. MP hotspots were identified in harbor basins, where natural sedimentation processes and increased anthropogenic activities contribute to MP accumulation. Additionally, industrial sewage potentially contributed to MP content in sediment samples. The highest pollution levels were observed in the middle Elbe, between the confluences of Mulde and Havel. Lowest MP contents were found in the lower Elbe, potentially influenced by tides. Future studies should focus on holistic investigations of selected river sections, encompassing sediment, water, and biota samples, rather than the entire catchment area. This approach would facilitate the generation of spatiotemporal data on MP distribution in freshwater streams. In addition, more research is needed to explore potential interactions between different MP and sediment types during DSC measurements.

Gamma Ray Spectroscopy Analysis of Sediments of Coastal Areas in Ennore, Tamil Nadu

Objectives: This research focuses on the determination of the natural radionuclides radium, thorium, and potassium in the twenty-six sediment samples collected at the sea, beach, and creek regions of Ennore Port. Methods: The activity concentrations of 226Ra, 232Th, and 40K were determined using gamma ray spectrometry with a high-purity germanium (HPGe) detector. Findings: The average activity concentrations of 226Ra, 232Th, and 40K were in the descending order of 40K (397.58 Bq kg-1) &gt; 232Th (65.83 Bq kg-1) &gt; 226Ra (18.28 Bq kg-1). The estimated average values of radiological parameters such as radium equivalent activity (143.04 Bq kg-1), absorbed dose rate (64.91 nGy h-1), annual effective dose equivalent (0.32 mSv y-1), and external hazard index (0.39) were lower than the respective world average values, reported by United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR, 2000). Moreover, the representative level index and annual gonadal dose equivalent were slightly higher than the world average value. Hence, this research proved that the study area is radiologically safe for humans and the environment. Novelty: A location and sample collection-based novelty is approached to carried out the work. Sea sediments were also collected along with samples from creek and beach regions in order to examine the dispersion of natural radionuclides from land to marine environments. The samples from the beach and creek regions were collected using a Peterson grab sampler. Especially in the sea region, the samples were collected using a Van Veen grab sampler at a depth of 4 m and a distance of 10 m parallel to the shoreline. Keywords: Natural radioactivity, Sediment, Ennore, Gamma ray spectrometry, HPGe detector, Radiological parameters

Microplastic Abundance and Distribution in the Sediment of Cagayan de Oro River, Philippines

ABSTRACT Microplastics (MPs), or plastic particles smaller than 5 mm, are emerging contaminants that potentially affect aquatic species and humans. More research has been undertaken in the marine environment; however, rivers that serve as a sink and pathways for plastic entering the ocean have received less attention. The current study investigated the presence of MPs in the sediments of the Cagayan de Oro River, one of the top plastic-emitting rivers listed in the Philippines. Sediment samples were collected from the six sampling stations from upstream to downstream using a Van Veen grab sampler. Through stereomicroscope and Fourier-transform infrared spectroscopy (FTIR), MPs were analyzed and categorized according to color, shape, size, and polymer type. All the sampling stations were contaminated with MPs ranging from 4.4 ± 2.57 to 33.3 ± 4.44 items/kg. The highest density of MPs was found close to the river mouth that drains into Macajalar Bay which suggests that riverine contributions are substantial contributory to MPs contamination in the marine environments. Prevalent types of MPs are blue-colored (41%), fiber-shaped (41%), 0.5–1.0 mm (43%), and polyethylene (43%) particles. Microplastic accumulation is generally higher downstream than upstream.

Occurrence, Distribution, and Sources of Aliphatic and Cyclic Hydrocarbons in Sediments from Two Different Lagoons along the Red Sea Coast of Saudi Arabia

Surface sediment samples from Al-Qahma lagoon in the southern part and Al-Wajh lagoon in the northern part of the Red Sea coast of Saudi Arabia were collected by a Van Veen grab sampler to determine the characteristics, distribution, and sources of aliphatic and cyclic hydrocarbons. The total extractable organic matter (TEOM) was extracted with a dichloromethane/methanol mixture after drying and sieving the sediments and identified by gas chromatography–mass spectrometry. The TEOM comprised n-alkanes (302.6 ± 446.7 ng·g−1 and 64 ± 50 ng·g−1), hopanes (29.8 ± 132.3 ng·g−1 and 1.0 ± 2.5 ng·g−1), steranes (0.0 and traces), n-alkanoic acids (745.8 ± 799.6 ng·g−1 and 120.7 ± 92.0 ng·g−1), n-alkanols (457.4 ± 1085.6 ng·g−1 and 49.7 ± 32.3 ng·g−1), polycyclic aromatic hydrocarbons (PAHs) (54.5 ± 96.8 ng·g−1 and 7.8 ± 8.5 ng·g−1), and phthalates (185.3 ± 169.9 ng·g−1 and 67.4 ± 70.4 ng·g−1) in the Al-Qahma and Al-Wajh lagoon sediments, respectively. The percentages of the various sources relative to total aliphatic and cyclic hydrocarbon concentrations were 6.9 ± 6% for terrestrial plants, 53.7 ± 19% for algae, 10 ± 2% for microbial, 16 ± 12% for petroleum, and 13.4 ± 7 for plasticizer inputs in Al-Qahma lagoon. In Al-Wajh lagoon, they were 9.7 ± 4% for terrestrial plants, 30.8 ± 14% for algae, 25.2 ± 5% for bacteria, 11.2 ± 3% for petroleum, and 23.1 ± 11% for plasticizers.

Geochemical partitioning of Cu and Zn in Pelabuhanratu Bay sediment

Activities such as fishing ports and power plants on the coast of Pelabuhanratu Bay have recently developed and hence, their input of metal-containing waste may influence the seawater quality of the bay as the fishing grounds. This study aimed to determine the potential sources (i.e., anthropogenic and natural) and pollution status in sediments. Sediment samples were collected once at 10 stations in the bay using a Van Veen grab. The geochemical partitioning of non-residual and residual phases of metals was used to assess the anthropogenic and natural sources, respectively. The status of metal contamination was evaluated by determining the geo-accumulation index (Igeo), contamination factor (CF), and pollution load index (PLI). Generally, Cu was dominant in residual fractions ranging 62.79-81.24%, while Zn ranged 39.56-66.02%. This suggests that Cu and Zn in Pelabuhanratu Bay are naturally sourced. Furthermore, the average geo-accumulation index of Cu was categorized as unpolluted (-0.86), and Zn was lightly polluted (0.87). The CF of Cu indicates the uncontaminated category (0.85), whereas Zn indicates a moderate contamination category (CF = 1.54). The pollution level (PLI) in Pelabuhanratu Bay is generally lightly polluted (PLI 1,135).

Decapod Crustacean Records from A Collection of Marine Soft-Bottom Macrofauna of the Italian Waters Supporting the Update of Checklists and Registers of the Mediterranean Basin

Decapod crustaceans are important components of the fauna of soft-bottom habitats. In this work, the records of decapod crustaceans are provided through the analysis of a large soft-bottom benthic macroinvertebrates dataset of the Central Mediterranean Sea. Decapod crustacean assemblages were collected in the last twenty years by a Van Veen grab in 42 study sites located along the Italian coasts at depths ranging from 1 up to 120 m. The spatial distribution of the crustaceans examined, which include 120 species belonging to 40 families, was investigated according to the biogeographical zones identified in the Italian seas. The spatial distribution of 36 species was updated, comparing the ISPRA decapod crustacean dataset with the most recent Italian checklists. For the species updated, the number of specimens, the year and season of sampling, and environmental data, such as the bathymetric range and habitat details, are provided for each site investigated. Data are discussed and compared with the existing literature, also referring to what is reported in the World Register of Marine Species (WoRMS), with the aim of contributing to the knowledge of the biodiversity of the marine species and supporting the updating of checklists and registers in the Mediterranean Basin.

Leuconidae Sars, 1878 (Crustacea: Cumacea) from the southwestern Atlantic, filling the distribution gap along the Brazilian coast.

The family Leuconidae Sars, 1878 is one of the eight widely recognized families of Cumacea and can be found in all oceans, but often in deeper waters (> 200 m). Despite its worldwide distribution, Southwestern Atlantic records were restricted to Argentina and Uruguay, indicating a gap in the knowledge of the group along the Brazilian coast. Samples were collected in the Campos, Esprito Santo and Santos Basins with box core and/or van Veen grabs between 163000 m in depth. A total of five new species and a new genus are described herein. Leucon (Alytoleucon) rhuanae sp. nov., Leucon (Crymoleucon) pseudograndidentatus sp. nov., Leucon (Macrauloleucon) watlingi sp. nov., Eudorella helenae sp. nov. and Gyneleucon tripedium gen. et sp. nov. The lack of knowledge on cumacean leuconids along the Brazilian coast is clearly a result of taxonomic impediment. The present study is an effort towards understanding and revealing the Cumacea fauna from the Brazilian margin, bringing new data on the family Leuconidae found in the continental shelf and slope of the Esprito Santo, Campos and Santos Basins, areas with high oil and gas exploration. Promoting the characterization of these areas is essential to a wide understanding of the local species richness and consequently provides tools for preservation and monitoring activities.

Low abundance and high patchiness of decapod fauna sampled with van Veen grab on the West African continental margin (Gulf of Guinea, Ghana)

Sixty morphospecies of Decapoda (Malacostraca: Crustacea) representing 34 families were recorded in the material collected in 2012 from 265 van Veen grab (0.1 m2) samples, from the nine transects distributed along the coast of Ghana in the 25–1000 m depth range. The examined material was dominated by the Diogenidae, Panopeidae, Leucosiidae, Pilumnidae and Xanthidae families. Species accumulation curves showed undersampling of the studied area and a large number of the morphospecies comprised singletons and doubletons. Panopeus africanus was the most frequent morphospecies in the analysed material (9.1% of all samples). We observed a substantial decrease of diversity (Shannon Index) and abundance along a depth gradient. Species richness also decreased with depth, starting from the highest number of morphospecies ‒ 38 at 25 m depth, then 33 at 50 m, 17 at 100 m, 11 at 250 m, 8 at 500 m and ending with 1 morphospecies at 1000 m bottom depth. Higher diversity was observed on the continental shelf (25–250 m – 57 morphospecies), while on the slope (500–1000 m) only eight morphospecies were recorded. Numerous factors of natural and anthropogenic origin may affect decapod communities on the coast of Ghana. Since our material was collected using a sampler collecting material at a very small scale, the observed patterns might be affected by the sampling method.

Bryozoan communities off Franz Josef Land (northern Barents Sea, Russia): Distribution patterns and environmental control

Franz Josef Land is located in the northern region of the Barents Sea and is subjected to the constant influx of cold Arctic water. Although this area is difficult to access, several benthic surveys have been conducted to evaluate the spatial patterns and community structure of the local fauna. However, there is a lack of information regarding the structure of bryozoan communities in this region during the ongoing climate change period. Therefore, we studied the species composition and spatial distribution of bryozoan diversity and biomass at 17 stations sampled by a 0.1 m2 Van Veen grab in the southern region of the archipelago between 2006 and 2008. We found 151 bryozoan species, with Turbicellepora incrassata, Celleporina ventricosa, Leieschara subgracilis, Porella compressa, and Escharopsis lobata being the most prevalent. The proportions of Boreo-Arctic, Arctic, and boreal taxa were 55.6%, 35.8%, and 8.6%, respectively. Twenty-two species were recorded for the first time in this region, including seven boreal species (31.7% of their total number) probably as a result of climate change in the Arctic. Alpha-diversity ranged from 3 to 76, with a mean value of 26 species. Bryozoan biomass ranged from 0.1 to 742 g m−2, averaging 139.4 g m−2. Cluster analysis revealed three groups of stations following the depth gradient and sediment composition in shallow and deep waters. The primary environmental drivers of bryozoan communities were depth and temperature (negative association) and contents of stones and shells (positive link). Our research addresses crucial knowledge gaps, such as benthic diversity shifts during the climate change period and the impact of ecological factors on community structure.

Assessing the impact of anthropogenic influences on the sediment quality of Owalla Reservoir, Southwest, Nigeria

The study aims to investigate the impact of anthropogenic influences within the catchment areas on the sediment physico-chemical quality of Owalla Reservoir in Osun State, Nigeria with the primary aim of creating baseline information on the aspect of limnology. Twenty sampling stations were established along the reservoir representing, its three different sections and two zones. The sampling was conducted for a period of two years to cover both seasons of the year in the area. The sediment samples were collected using a Van-Veen grab of 0.04 m2 area (0.2m × 0.2m) from the waterbed at each sampling locations; labelled, kept in cooler at 4°C and transported to the laboratory for the analysis. The reservoir sediment was mainly clayey-sand in texture, while the particle size distribution was in this order: sand (73.1%) &gt; clay (17.4%) &gt; silt (9.4%). The exchangeable cations order of dominance was in this order: Mg2+ &gt; Ca2+ &gt; H+ &gt; Al3+ &gt; K+ &gt;Na+ and anions in this order: PO34- &gt; SO42- &gt; NO3-&gt; Cl-. The highest mean values for water depth, transparency, air temperature, water temperature and sediment temperature (5.28 ± 0.40 m, 1.60 ± 0.05 m, 31.90 ± 0.29°C, 30.6 ± 0.18°C and 27.6 ± 0.23°C) were recorded during the dry season compared with the rainy season. The results obtained from this study, shows that Owalla Reservoir is fairly clean and not contaminated with toxic pollutants. The sediment pH is within acidic range, and enriched with nutrients due to the anthropogenic activities around this reservoir catchment areas. However, if the organic enrichments and siltation in this reservoir is not controlled, it could lead to the future eutrophication of this waterbody, which can cause water quality degradation, alter the aquatic biota and natural ageing process of this reservoir making it unsuitable for its purposes.

Polychlorinated biphenyls (PCBs) in intertidal sediment and water from Lagos lagoon: Baseline report on occurrence, distribution and ecotoxicological risk assessment

To assess the occurrence and potential ecological risk associated with organic micropollutants in Lagos lagoon, 27 polychlorinated biphenyls (PCBs) were analysed in sediments and surface water. Sediment samples were obtained from 18 designated sites (SD1 – SD18) using a Van Veen grab sampler and extracted following standard procedures. Cleaned extracts were analysed using gas chromatography with electron capture detector (ECD). The concentration of ∑PCBs in sediment samples ranged between 6757.61 and 273.46 µg/kg. The PCB homologues distribution patterns in sediments indicated that the low-chlorinated (∑di-PCB - ∑penta-PCB) PCBs were more dominant with 61.1 % occurrence than the high-chlorinated ((∑hexa-PCB - ∑nona-PCB) PCBs with 38.9 % relative abundance. The following is the decreasing order of the average homologue composition of PCBs in sediment samples: ∑tetra-PCB (24.6%) > ∑octa-PCB (21 %) > ∑hexa-PCB (13.8 %) > ∑penta-PCB (12.8) > ∑tri-PCB (11.4 %) > ∑hepta-PCB (7.8 %) > ∑nona-PCB (4.9 %) > ∑di-PCB (2.9 %). More so, the ∑PCBs in surface water samples ranged from 69.28 to 440.90 ng/L, with the mean ranging between 7.21 and 16.33 ng/L. The class distribution of PCB homologue profiles in water samples indicated that highly-chlorinated (∑hexa-PCB to ∑nona-PCB) PCBs were the dominant homologues, with 94.4 % occurrence, compared to the very low occurrence rate (5.6 %) of the low-chlorinated (∑di-PCB to ∑penta-PCB) PCBs. Hexa-PCBs (PCB-138 and PCB-153) were the dominant congeners in most water samples. The concentrations of ∑PCBs in sediments and surface water were unprecedentedly high at almost all locations. The total toxicity equivalent concentrations (TTECs) of dioxin-like PCBs for the sediment samples ranged from 0.001 to 2.43 µg/kg, with an average of 0.34 µg/kg. These findings suggest that PCB congeners are pervasive from anthropogenic point sources of pollution. Intensive site-specific monitoring and remediation are recommended.

Spatio-temporal distribution of microplastic abundances in Izmir Bay (eastern Aegean Sea).

Microplastics (MPs) and their impacts have been extensively studied in the Mediterranean region. However, more research has yet to be conducted on assessing the extent of microplastic (MP) pollution in the eastern Aegean Sea, specifically in Izmir Bay. This study aims to evaluate the current state of MP pollution in surface water and sediment samples collected from Izmir Bay. Ten sampling stations were specifically selected, including locations near stream discharge points, maritime transportation piers, and port areas. Surface water samples were collected using a manta trawl net, while sediment samples were obtained using a Van Veen grab. The mean MP abundances in surface water ranged from 1,083,882 to 8,091,684 items/km2. Fragment type MPs were dominant. In terms of size category, it was found that MP s of 500µm size were dominant. The dominant color of MPs was white. ATR-FTIR analyses revealed that polyethylene and polypropylene were the dominant polymer types. MP concentrations in sediment ranged from 2,125 to 4,925 items/m2, with fiber-type MPs being the most abundant. Black-colored MPs were found to dominate in sediment samples. Overall, the MP levels in Izmir Bay were higher than previous studies findings. Therefore, it is crucial to conduct long-term monitoring studies to obtain more consistent and reliable data on MP pollution levels in Izmir Bay.