Coastal Mud Research Articles

Cohesiveness of the Nigerian Mahin mud coast sediment: Implications for erodibility and morphodynamic modelling

Cohesive sediments in coastal zones and estuarine mudflats have transport mechanisms that are not well understood due to the complex sediment properties that influence their erodibility. However, understanding coastal sediment composition and behaviour is important to determine its resistance to hydrodynamic forcing. This study investigates the properties of mudflats along the Mahin coast of southwestern Nigeria to identify the dominant factors controlling their resistive forces and erodibility potentials. Sediment samples obtained from 6 stations along this muddy coast were subjected to physical, mechanical, electrochemical and mineralogical analyses. Our results show that the sediments are inorganic silt of high plasticity, containing inactive clay minerals. With cohesion and frictional angles (φ) that ranged from 42.4 to 46.9 kN/m2 and 10.2–11.7°, respectively, the sediments can be described as highly cohesive and overconsolidated. Organic contents in the muds are <20% of the entire sediment mass, reflecting the impact of vegetation removal along the coast. Whereas fairly neutral to alkaline pH shows the role of seawater in maintaining the chemical balance in the mud. Sediments with proximity to the western and eastern estuaries in the study area show similar characteristics compared to those farther from the estuaries. In addition, sediments closer to the estuaries are dominated by an active illite-montmorillonite mixed clay layer, which makes up <20% of their bulk composition, while those farther are dominated by illite and kaolinite. The correlation analysis revealed that the physical and mechanical properties of the mudflat sediments along the Mahin coast, southwestern Nigeria are influenced by their chemistry and mineralogical composition. Estuarine dynamics also play a key role in recent sediment transport along the mudflat. This study thus provides baseline data on sediment properties for modelling morphological changes of the Nigerian Mahin mud coast. In-situ erodibility experiments are recommended to ascertain the erosion parameters of the area.

Polycyclic aromatic hydrocarbons in sediment–porewater system from the East China Sea: Occurrence, partitioning, and diffusion

The distribution, partitioning behavior, and diffusion of polycyclic aromatic hydrocarbons (PAHs) within sediment–porewater system were determined in two cores obtained from the Min-Zhe coastal mud of the East China Sea (ECS). Depth profiles of apparently dissolved PAH levels exhibited greater variabilities, with their elevated levels at depth and a high abundance of two-to three-ring PAHs observed. These distribution and composition patterns were inconsistent with the corresponding sediment PAHs, indicating differences in controlling factors for PAHs present in the system. In addition to compound's hydrophobicity, low detection of heavier PAHs in porewater was possibly correlated with the sediment transport process, as indicated by a relatively high weathering ratio in southern Min-Zhe coastal mud. PAH sorption affinity to the collected core sediments exhibited a generally decreasing trend downcore, as expressed by sediment–porewater partition coefficients. This was consistent with the higher content of porewater PAHs in deep core sediment. The established sediment total organic carbon (TOC)–porewater partitioning profiles in cores were predicted with amorphous organic carbon (AOC)-, coal tar-, and TOC-based distribution models, suggesting a dominant nonlinear sorption of PAHs to AOC. Through activity determinations, PAH diffusion within porewater was elucidated, with significant upward and downward mass transfer for PAHs occurring in both cores. The upward diffusion in the core collected from northern Min-Zhe coastal mud was in significant association with sediment TOC. This suggests that sediment TOC (especially AOC)-desorption of lighter PAHs into porewater, and therefore the possibility of their participation in environmental cycling. Baseline toxicity potential and toxic unit calculations indicated a relatively low exposure risk for benthic organisms to porewater PAHs.

Numerical modelling of sediment transport in southwest coast of Nigeria: Implications for sustainable management of coastal erosion in the Bight of Benin

Coastal erosion is widespread across the Bight of Benin owing to the perturbation of the sediment transport by the installation of the major ports of Lomé (Togo), Cotonou (Benin), and Lagos (Nigeria), among other factors. While different coastal management measures have been put in place to mitigate the effects of this hazard, they have seldom lessened the damage caused by it. To this end, this study examined the coastal processes in Southwest Nigeria (Barrier-Lagoon and Mud coast sections) through the numerical modelling of the hydrodynamic, spectral-wave, and sediment transport for three months to apprehend the poor performance of the management measures. Model results reveal that the nearshore current is mainly directed eastward with the persistent exposure of the area to wave-action. Two major sediment transports; the eastward/south-eastward and westward/north-westward sediment transports, were also identified. The predominance of these sediment transport patterns implies that the continuous adoption of reactive, site-specific hard-engineering coastal management approaches will give counter-productive results. Thus, to sustainably manage the coastal erosion problem across the Bight of Benin, there is the need to adopt a long-term, regional perspective with a cascade of coastal management measures covering all areas under the influence of the predominant sediment transports.

Coastal evolution assessment and prediction using remotely sensed front vegetation line along the Nigerian Transgressive Mahin mud coast

Over the past decades, the Transgressive Mahin mud coastline has drastically receded due to the continuous impacts of waves and the intensifying frequency of floods. Consequently, changes in the coastline positions for the past 20 years were investigated using multispectral satellite images within the Geographic Information System environment. The study area was divided into three sectors, and the sectors were further divided into several transects at uniform intervals. Statistical Linear Regression Rate (LRR), Endpoint Rate (EPR) and Root Mean Square Error (RMSE) methods were used to assess the rates of changes in coastline positions. Also, future coastline positions for 2022 and 2029 were predicted and estimated. The study revealed that more land area was lost in the eastern sector than any other sector after about 95% of the coastline along the entire region eroded from 2015 to 2019. This confirms a shift of erosion dominance from the central sector, which has been the most vulnerable to coastal hazards over the past decades. In the same period, it was revealed from the transect rates that about 51% of the western sector’s coastline experienced accretion attributable to sand deposition from the adjacent Barrier-lagoon coast, though, approximately 65% of the coastline along the same sector had previously eroded from 1999 to 2015. Based on these findings, and without immediate response to the coastal challenges, about 3.6 km 2 and over 11.3 km 2 could be lost by 2022 and 2029, respectively. To develop a practical solution, recent changes and future projections would need to be factored in. Therefore, the relevance of this study cannot be overemphasised, as it (i) identified areas of erosion, (ii) predicted future changes of the coastline, (iii) aims to start a new trend of future projections to enhance decision making and (iv) proposed a management plan for the area.

Neglected role of continental circulation in cross-shelf sediment transport: Implications for paleoclimate reconstructions

Coastal currents play a key role in regulating alongshore sediment transport, and their relationships with winter storms (burst of the East Asian winter monsoon) and formation of the coastal mud deposits on the eastern China shelf have been established, based on which the evolution of the East Asian winter monsoon has been widely explored. Unlike that of coastal deposits, the formation of offshore deposits on the eastern China shelf is very complex and highly debated, leading to enormous challenges on paleoclimate reconstructions based on these deposits. In this study, cross-front sediment transport under a variable Yellow Sea Warm Current (YSWC) was explored using remote sensing imagery and sedimentary records (seismic profile and sediment grain size) from the North Yellow Sea (NYS). The results indicate that, although the offshore mud deposit in the western NYS is formed by winter storms through triggering cross-front transport of coastal sediment around the Shandong Peninsula, the winter storm signal was completely obscured by that of the YSWC, which might determine the flux of cross-front sediment transport on a millennial scale. The 1500 y sub-orbital climate variability cycle could also be observed in distal muds after 2.8 ka. By comparing the sediment composition within the same mud deposit or between adjacent mud deposits in the NYS, we found that the response of cross-front sediment transport to the YSWC varied spatially, which may be a reason for discrepancies observed in previous winter monsoon reconstructions on the eastern China shelf. Therefore, as indicated by this study, offshore deposits on the eastern China shelf are not suitable for inversions of the winter monsoon. In addition, mud deposits on the eastern China shelf are also dramatically affected by other dynamic factors, including typhoons and river flooding; thus, deeply exploring the dynamic characteristics and formation mechanism of these deposits are prerequisites for paleoclimate reconstruction.

Combining sterols with stable carbon isotope as indicators for assessing the organic matter sources and primary productivity evolution in the coastal areas of the East China Sea

To identify the sedimentary organic matter (OM) sources and reconstruct primary productivity evolution process in the coastal areas of the East China Sea (ECS), carbon, nitrogen and carbon stable isotope (δ13C) combined with sterols were studied in the surface and core sediments. The quantitative calculations of δ13C model and characteristic sterols suggested that the OM is derived from mixed marine and terrestrial inputs. Sinking marine phytoplankton was the dominant marine OM (MOM) source, with the average MOM proportion calculated by two end-member model of δ13C and characteristic sterol analysis of 73% and 62%, respectively. Terrestrial organic matter (TOM) displayed a decreasing trend seaward, attributed to the Changjiang River input as the dominant terrestrial source pathway. The decreased proportion of TOM with age in the core sediment was mainly controlled by the fluctuating changes of freshwater and sediment influxes of the Changjiang River. The sum content of epi-brassicasterol and dinosterol increased with age in recent 30 years, suggesting the increasing phytoplankton productivity. Enhanced anthropogenic nutrient inputs from the Changjiang River as well as the incremental nutrient supplement from the deep waters of the coastal upwelling area aggravated the phytoplankton blooms. Besides, the increasing ratio of epi-brassicasterol to dinosterol contents (B/D ratio) with age revealed the increasing diatom productivity relative to dinoflagellate productivity. This variation was mostly attributed to the natural forcing of the increased nutrient supplement from intensified coastal upwelling in the Zhejiang coastal mud area.

Dolomite genesis in bioturbated marine zones of an early-middle Miocene coastal mud volcano outcrop (Kuwait)

The origin of spheroidal dolomitized burrow from Al-Subiya sabkha in Kuwait was previously described as enigmatic as no evidence of precursor calcium carbonate was found in the siliciclastic sediment. An assumption for the genesis of spheroidal dolomite from the same area was attributed to hydrocarbon seepage but no evidence was provided. Here, we investigated a recently discovered early-middle Miocene coastal mud volcano outcrop in Al-Subiya sabkha where dolomitized burrows and spheroidal dolomite are found in bioturbated marine zones, and associated with traces of salt. Conversely, the continental zone lacks bioturbation features, dolomite and traces of salt, which together contrast with bioturbated rich marine zones. Geochemical signatures of Rare Earth Elements + Yttrium show a true positive Ce anomaly (Ce/Ce* > 1.2) and positive Eu/Eu* anomaly of spheroidal dolomite indicating strictly anoxic conditions, and sulphate reduction to sulphide, respectively. Our results are suggestive of a relationship between dolomite formation and interdependent events of hydrocarbon seepage, flux of hypersaline seawater, bioturbation, and fluid flow in the marine zones of the mud volcano. The bioturbation activity of crustaceans introduced channels/burrows in the sediment–water interface allowing for the mixing of seeped pressurized hydrocarbon-charged fluids, and evaporitic seawater. In the irrigated channels/burrows, the seeped pressurized hydrocarbon-charged fluids were oxidized via microbial consortia of methanotrophic archaea and sulphate-reducing bacteria resulting in elevated alkalinity and saturation index with respect to dolomite, thus providing the preferential geochemical microenvironment for dolomite precipitation in the bioturbated sediment.

Marine Sedimentary Carbon Stocks of the United Kingdom’s Exclusive Economic Zone

Continental shelf sediments are recognized as long-term stores of globally significant quantities of carbon (C) and potentially provide an important, yet largely overlooked climate regulation service via the Earth’s C cycle. Current understanding of the spatial distribution of sedimentary C across continental shelves remains poor, inhibiting the targeted management and potential inclusion of these globally significant C stores into national C budgets. Further understanding of the spatial heterogeneity of continental shelf sediments and associated C provides a foundation to quantify the organic carbon (OC) stock and better understand the role that marine sediments play in regulating the global climate and the potential for CO2to be released through anthropogenic disturbance of these C stores. Utilizing a spectrum of available marine data, we have created bespoke sediment maps that quantify the surficial (top 10 cm) OC stock and highlight significant spatial heterogeneity in the distribution of sediments and their associated C content across the United Kingdom’s Exclusive Economic Zone (EEZ). The surficial sediments within the UK EEZ are estimated to store 524 ± 68 Mt of organic carbon (OC) and 2,582 ± 168 Mt of inorganic carbon (IC). The spatial mapping of this C highlights well-defined OC accumulation hotspots in fjords, estuaries and coastal muds, while large accumulations of IC are found in the tidally swept areas around Orkney, Shetland and the South West of England. Within the well-defined OC hotspots, muddy sediments store the greatest quantity of OC; the muds offer potentially valuable opportunities for targeted future management and protection of sedimentary C stores within the UK EEZ. In the future, if areas of the seafloor were to be managed to include the protection of these valuable sedimentary C resources, we recommend an initial focus on hotspots of high sedimentary OC density.

REE fractionation and quantification of sediment source in the Yellow Sea mud deposits, Εast Αsian marginal sea

Discriminating sediment sources quantitatively of several unique shelf-mud deposits in the Yellow Sea has received considerable attention, because they are active sedimentary depocenters that can elucidate the river sediment dispersal patterns and the depositional systems of the sea. Here, we propose a new sediment source proxy model of rare earth elements (REEs) that reflects innate characteristics of their fractionation distribution patterns and provides a reasonable and practical estimation for quantifying sediment source apportionments in the Yellow Sea. REEs of riverine and shelf-mud sediments were granulometrically and chemically partitioned, and the unique characteristics of their fractionation patterns were recorded and numerically indexed. We found distinct differences in the REE fractionation pattern index of riverine sediments, possibly due to the different source rock compositions. Notably, the acid-leached phase of the clay fraction may be a better material for quantitative evaluation of river contributions in the Yellow Sea. Using the REE-source index model presented here, proportional contributions of Chinese river sediments to the central and southeastern Yellow Sea mud deposits were estimated to be 55–80% and 10–40%, respectively, with higher percentage in the leached fraction. Our results elucidate the disagreement between mud budget and river discharge, particularly in Korean coastal mud deposits, as well as the source interpretation of the Yellow Sea shelf-mud deposits, which have been debated since the 1980s.

Novel Comprehensive Molecular and Ecological Study Introducing Coastal Mud Shrimp (Solenocera Crassicornis) Recorded at the Gulf of Suez, Egypt

Solenocera crassicornis is a commercially important shrimp of the Solenoceridae family. The current study investigated the morphology, molecular identification, phylogenetic relationships, and population dynamics of S. crassicornis in Egypt. Samples were collected monthly (total, 1722; male = 40.19%, wet weight, 0.89–10.77 g; female = 59.81%, wet weight, 1.55–19.24 g) from Al-Attaka commercial catch in the Gulf of Suez in the Red Sea. Two barcode markers, 18S rRNA and cytochrome c oxidase subunit I (COI), were used for molecular identification. COI partial sequences were used to construct the phylogenetic relationships among different species of genus Solenocera and to infer the origin of the studied Solenocera crassicornis. The applied molecular markers successfully identified the studied species to the species level. The genetic distances among S. crassicornis sequences from different countries revealed the Indo-West Pacific origin of S. crassicornis. The relationship between total length (TL) and total weight (TW) was TW = 0.035TL2.275 and r2 = 0.805 for males and TW = 0.007TL3.036 and r2 = 0.883 for females, indicating that females were heavier than males. Despite its social and economic relevance in the area, information on the hatching, larval rearing, and farming of S. crassicornis is scarce and requires future studies under Egyptian conditions.

Multiple lipid biomarkers record organic matter sources and paleoenvironmental changes in the East China Sea coast over the past 160 years

The use of lipid biomarkers as paleoenvironmental proxies relies on an accurate assessment of their organic matter (OM) sources. In this study, we analyzed multiple lipids in core sediments recovered from the Zhejiang–Fujian coastal mud area to provide a 160-year record of OM input to the East China Sea (ECS) coastal sediments and to reconstruct paleoenvironmental conditions over this interval. The molecular composition of the samples was characterized by a mixture of natural lipids, particularly those derived from terrestrial vascular plants, marine/riverine plankton and macrophytes, and bacteria. The sources of some lipid components were ambiguous/mixed as they were potentially derived from multiple precursor organisms and because of limitations associated with modern survey techniques. There is evidence that early diagenesis caused the preferential degradation of labile aquatic lipids and that the degradation of terrestrial lipids was more severe when subjected to complex horizontal–vertical transportation processes associated with deposition, resuspension, and redeposition. These processes may have led to an enhanced terrestrial OM signal in the normal ( n)-alkane and n-alkanol records, which is at odds with, for example, those of the n-fatty acids, hopanoids, steranes, and sterols, which suggest a dominant marine OM source. Furthermore, we conclude that the occurrence of multiple sources, selective diagenesis, and test error has led to the distortion of redox and maturity indicators based on evidence from pristane-to-phytane (Pr/Ph) ratios and sterane/hopane indices in century scale. Overall, the phytol record suggests an increase in productivity after the early 20th century. Correspondingly, the diatom lipid biomarker records (based on C25 highly branched isoprenoid alkenes and C18:1ω9 fatty acids) reveal a fluctuating but overall increasing diatom productivity after the early 20th century, which coincides with a decreased proportion of the contribution from diatoms relative to that of total phytoplankton. This is believed to correspond to natural environmental changes, as well as anthropogenic impact.

Circulation patterns and implication for fine sediment transport in a preserved tropical estuary: The case of the Maroni (French Guiana)

Compared to temperate estuaries, tropical ones are less documented. Among them, the numerous estuaries along the Guiana shoreline present at least two original features: they are still preserved from anthropogenic modifications, and their hydro-morphodynamics are influenced by longshore migration of outer coastal mud banks. This study deals with the Maroni estuary, a mesotidal preserved tropical estuary, currently spotting more attention to better anticipate changes related to the development of harbour activities. Field data collected over semi-diurnal tidal cycles in the lower estuary revealed the presence of a turbidity maximum and seasonally contrasted hydro-sedimentary features. A one-year 3D hydrodynamic simulation covering a wide-range of tidal and fluvial conditions was performed to further analyse the seasonal variability of stratification and residual circulation patterns. The estuary is well-mixed for a very low river discharge (lower than 200 m3/s). It becomes partly mixed in both spring and neap tide in case of a moderate river discharge of 700 m3/s. The strongest stratification, which could be associated to a salt wedge near the mouth, appears during neap tides combined with higher discharge. Residual currents along the navigation channel are usually seaward except during neap tides when the discharge is large enough (∼700 m3/s) to generate stratification and landward residual current near the bottom to mid depth until the first km 15 from the mouth. Residual inflow starts from the location of the mud bank and extends along the navigation channel near the eastern bank. The inflow extension matches with observed highly turbid areas and fresh mud deposits, suggesting an outer supply of mud. In summary, this exploratory work allows a first description of current dynamics of the Maroni, and is a first step before a comprehensive study of changes in estuarine circulation and fine sediment transport under different configurations of coastal mud banks.

Mud on the move.

Humans are reshaping the world9s mud supply, altering where—and how fast—it piles up. Thousands of years ago, our ancestors caused erosion rates to surge by starting to clear forests and plant crops, muddying lakes and rivers. Today, deforestation and urbanization are causing some rivers to carry more sediment, even as dams and efforts to curb erosion choke off sediment supplies to other waterways. Such changes, together with precipitation shifts driven by climate change, are leading to sometimes dramatic transformations in river deltas, coastal mud flats, and the amount of mud that ultimately collects at the bottom of the sea. Graphs, charts, and maps help tell this story.

Diversity of halophilic and halotolerant bacteria in the largest seasonal hypersaline lake (Aran-Bidgol-Iran).

In this study, the culturable halophilic and halotolerant bacterial diversity was determined in Aran-Bidgol as a thalassohaline seasonal hypersaline lake in Iran. Thirty water, soil, sediments, coastal mud, multi-color brines and salt crystals samples were extracted and cultured using different media and incubation conditions. Totally 958 isolates were obtained and 87 isolates were selected for further studies, based on morphological, physiological and biochemical tests, representing different morphotypes. Based on 16S rRNA gene sequence analyses, the isolates exhibited 94.6-100% sequence similarity to the closest known species of the genera Bacillus, Halomonas, Oceanobacillus, Salinicoccus, Thalassobacillus, Ornithinibacillus, Halobacillus, Salicola, Virgibacillus, Aerococcus, Arthrobacter, Idiomarina, Paraliobacillus, Staphylococcus, Acinetobacter, Aneurinibacillus, Brevibacillus, Brevundimonas, Chromohalobacter, Gracilibacillus, Jeotgalicoccus, Kocuria, Marinilactibacillus, Marinobacter, Microbacterium, Paenibacillus, Paracoccus, Piscibacillus, Pseudomonas and Sediminibacillus and also, comparison of ARDRA patterns among the sequenced strains, using AluI, Bst UI and Hpa II enzymes showed that these patterns are in accordance with the phylogenetic position of these strains. The PCR-RFLP analyses suggested that ARDRA possess a functional potential for distinguishing halophilic bacteria to be used for further studies in elementary steps of isolation to reduce the tedious duplication of isolates.

Correction: Correction: Occurrence and distribution of anthropogenic persistent organic pollutants in coastal sediments and mud shrimps from the wetland of central Taiwan.

[This corrects the article DOI: 10.1371/journal.pone.0231279.].

Ecological impact of land reclamation on Jiangsu coast (China): A novel ecotope assessment for Tongzhou Bay

China's continuous and rapid economic growth has led to the reclamation of large sections of the intertidal mud coast in combination with port construction, such as that of the proposed Tongzhou Bay port on the Jiangsu coast. These reclamations threaten the local ecosystem services. An ecotope distribution map was created and a hydrodynamic numerical model of Tongzhou Bay was set up to quantify the impacts of reclamation on the ecosystem. Based on the field data and model results, several abiotic features were classified into 11 ecotopes and visualized in an ecotope map of the Tongzhou Bay ecosystem. Validation with spatial distributions of two threatened shorebird species (bar-tailed godwit and great knot) showed confirmation with the mid-range and low-range littoral zones (inundated from 40% to 100% of a tidal cycle), indicating the importance of the areas with these conditions to these populations. Overlaying the ecotope map with recent and proposed land reclamation schemes revealed a loss of ecotopes, composed of the high-range (42%), mid-range (48%), and low-range (38%) littoral habitats, corresponding to a 44%–45% loss of the most important ecotopes for bar-tailed godwit and great knot (mid-range and low-range littoral zones). These results confirm the applicability of the novel ecotope assessment approach in practice.

Shoreline Morphology along Barrier and Mahin Transgressive Mud Coast of Nigeria

Coastline is one of the most import line features on the surface of the earth. Information about the coastlines morphology is required by the coastal management for proper coastal planning. Over 60% of the world population lives within few km to the coast. By the turn of the century two-thirds of the population (3.7 billion) in developing countries have occupied the coast. Consequently, unless careful environmental management and planning are instituted, severe conflicts over coastal space and resource utilization are likely, and the degradation of natural resources will close development options. In addition to the population pressure, the world’s coastal areas and small islands are highly vulnerable to climate change. Low‐lying delta, barrier coasts, low‐elevation reef islands, and coral atolls are especially sensitive to the rising sea level, as well as to changes in rainfall, storm frequency, and intensity. The research examined the shoreline changes over time in barrier lagoon coast and mahin mud coast of Nigeria. Satellite images comprising of Landsat MSS, ETM and OLI of 30m by 30m of 1990, 2000, 2010 and 2020; were used as the sources of data. The satellite images underwent series of geo-processing. The bands (red, blue and green) of each image were combined using Arc Map 10.4. The images were added as layer whereby the shoreline from each image was digitized as polylines. The shoreline of 1990 was overlaid on that of 2000, shoreline of 2000 was overlaid on 2010, 2010 on 2020 and that of 1990 on 2020. Thereafter, overlaid maps were converted to polygons using Features to Polygon module of ArcGIS 104. The polygons were grouped to advanced (land gained) or retreat (land lost) with which spatial query was done. The result revealed that Barrier and -mahin mud coast lost about 56.4622km2 of land while 4.44275km2 was gained between 1990 and 2000 whereas between 2000 and 2010; 6.65259km2 was lost while 14.0042km2 of land was gained. During the period between 2010 and 2020, the analysis showed that 15.4195km2 was gained while 12.2509 km2 was lost. The percentage change was highest between 1990 and 2000 with 85.41% of land loss.

Compost of oil palm empty fruit bunches with coastal mud and rice husk biochar to improve the acid sulphate soil fertility

The research purposes: (1) Producing enriched compost of oil palm Empty Fruit Bunches (EFB) with coastal mud and rice husk biochar that is suitable for application to acid sulphate soils, (2) Getting the best dosage to increase acid sulphate soil fertility. The method used: complete random design (CRD) factorial pattern, the first factor composition of enriched oil palm EFB compost, second factor: doses of compost enriched. Data analysis using analysis of Varian (ANOVA), significant differences continued with Honestly Signiant Difference Test (HSD). The variables observed were: soil pH H2O, Each-Al, Total-N, Bray-P and each-K. The results showed: compost oil palm EFB treatment significantly affected the each-K, whilst did not significantly affect the pH H2O, Total-N, Bray-P and each-Al. Although enriched compost treatment did not significantly, and the finding is the treatment enriched compost trend to increased pH H2O, Total-N and Bray-P.

Recent coastal sea-level variations and flooding events in the Nigerian Transgressive Mud coast of Gulf of Guinea

Significant warming and sea-level rise that will greatly impact the coastal zone is expected to intensify the coastal flooding occurrence on low-lying coasts in the next few decades. This challenge necessitates improving understanding of the possible trends and contributions of different oceanic forcing to the local coastal sea-level change at different time-scales at different locations. The present study seeks to understand different processes responsible for sea-level variations and coastal flooding events along the low-lying Nigerian Transgressive Mahin Mud coast in the Gulf of Guinea. The contributions of astronomical tides, altimetry-derived sea level, meteorologically forced non-tide residuals and wave run-up to coastal sea-level variations were assessed over the period between 1993 and 2016. The results show a distinct seasonal cycle, with more occurrences during summer/wet season and fewer events in winter/dry season, typically connected to the annual cycles of swell-waves. The leading contributor to total sea-level variations along this mud coast, at daily, seasonal and inter-annual time-scales was wave run-up. However, the leading contributor to total sea-level variations at the monthly (sub-annual) time scale was astronomical tides. Results further show that while the altimetry-derived sea level was responsible for the trend in total sea-level variability, the wave run-up was the major forcing responsible for the extreme coastal flooding events. However, the interaction between wave run-up and astronomical tides further contributed to the extreme/coastal flooding events along the mud coast. It is concluded that the increase in the coastal flooding events in the last 12 years of the study may have rendered the study area vulnerable to chronic erosion and flood hazards, which may have triggered the accelerated rate of coastal degradation in the study area.

Study on Preparation of Chemical Grouting and Its Hydraulic Properties and Application for Water Seepage Safety

Jiang, H.-D.; Zhong, R.-C., and Peng, Z.-B., 2019. Study on preparation of chemical grouting and its hydraulic properties and application for water seepage safety. In: Gong, D.; Zhu, H., and Liu, R. (eds.), Selected Topics in Coastal Research: Engineering, Industry, Economy, and Sustainable Development. Journal of Coastal Research, Special Issue No. 94, pp. 291–295. Coconut Creek (Florida), ISSN 0749-0208.In order to study the performance of the new grouting material of silty clay, the material selection and ratio of coastal mud cement slurry were studied by laboratory test and in situ test, and the diffusion mechanism of coastal mud cement slurry was analyzed, and the water pressure test was carried out. Borehole stone body and filling rate to evaluate its performance. The results showed that the maximum per unit permeability of the whole hole was 1.39 Lu. the secondary maximum permeability of all the holes was 2.46 Lu. all of them meet the design requirements (less than 5Lu), and the stone body was in the state of full filling and half filling. Total filling accounts for 68.75%, half filling accounts for 31.25%, diffusion radius was 5-10 m, slurry diffusion filling has better plugging effect, water plugging rate is 95.66%, the water plugging rate after grouting can meet the requirement of 85% or more in mine.