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Erosion of permafrost coasts due to climate warming releases large quantities of organic carbon (OC) into the Arctic Ocean. While burial of permafrost OC in marine sediments potentially limits degradation, resuspension of sediments in the nearshore zone potentially enhances degradation and greenhouse gas production, adding to the "permafrost carbon feedback." Recent studies, focusing on bulk sediments, suggest that permafrost OC derived from coastal erosion is predominantly deposited close to shore. However, bulk approaches disregard sorting processes in the coastal zone, which strongly influence the OC distribution and fate. We studied soils and sediments along a transect from the fast‐eroding shoreline of Herschel Island—Qikiqtaruk (Yukon, Canada) to a depositional basin offshore. Sample material was fractionated by density (1.8 g cm−3) and size (63 μm), separating loose OC from mineral‐associated OC. Each fraction was analyzed for element content (TOC, TN), carbon isotopes (δ13C, Δ14C), molecular biomarkers (n‐alkanes, n‐alkanoic acids, lignin phenols, cutin acids), and mineral surface area. The OC partitioning between fractions changes considerably along the transect, highlighting the importance of hydrodynamic sorting in the nearshore zone. Additionally, OC and biomarker loadings decrease along the land‐ocean transect, indicating significant loss of OC during transport. However, molecular proxies for degradation show contrasting trends, suggesting that OC losses are not always well reflected in its degradation state. This study, using fraction partitioning that crosses land‐ocean boundaries in a way not done before, aids to disentangle sorting processes from degradation patterns, and provides quantitative insight into losses of thawed and eroded permafrost OC. Plain Language Summary: The Arctic coastline is vulnerable for erosion, since it mostly consist of permafrost (permanently frozen ground), which undergoes rapid warming due to climate change. Thaw and erosion of permafrost along the coast releases organic carbon (OC), that has been stored for millennia, into the ocean. There, in the ocean, this carbon can be degraded back into CO2, potentially enforcing climate warming, or it can settle to the sediments, and potentially be stored again for millennia. The permafrost and the sediment consist of particles, for example, sand, silt, and clay, and loose fragments of vegetation. In this study, we separated the OC that is associated with fine particles (silt and clay) from the loose fragments of organic matter. We observe that these two fractions of sediment have a very different composition and source, and end up somewhere else in the marine system. This study further shows that a large part of the OC associated with minerals (silt and clay) is lost during transport, but also that indicators for degradation show contrasting results. Overall, we highlight the importance of looking at sediment fractions separately, and also emphasize studying the transitional zone between land to ocean for the permafrost carbon cycle. Key Points: Size and density fractionation of sediment organic carbon (OC) reveals substantial contrasts between different fractions and environmentsOC‐ and biomarker loading shows that a significant amount of terrestrial OC is lost along a land‐ocean transectCombining methods in dynamic environments such as the nearshore zone is key in studying the fate of permafrost OC [ABSTRACT FROM AUTHOR]

In 2020, the COVID-19 pandemic interrupted all aspects of human activity, including environmental research and monitoring. Despite a lack of laboratory access and other restrictive measures, we adapted an existing community science monitoring program to continue through the summer of 2020. We worked with local community groups to recruit 58 volunteers who collected lake water samples from 60 sites on 16 lakes in south-central Ontario from June to September 2020. We organized drop-off depots and had volunteers freeze samples to monitor nearshore nutrients (phosphorus and nitrogen) and chlorophyll-a. A survey was distributed to volunteers to analyze lake-front property owners’ activities during the pandemic. We found spatial patterns in nearshore water quality across the lakes, with sub-watershed development being a significant predictor of nutrients and chlorophyll-a. Additionally, pre-pandemic (2019) and pandemic (2020 and 2021) nutrient concentrations were compared, but there was no clear impact of the pandemic on nearshore nutrient concentrations, despite changes in lake-front property owners activities. Overall, this study demonstrated the ability of community science to provide water quality data on a large spatial scale despite a major societal disruption, providing insight into regional nutrient trends during the first year of the pandemic.

The nearshore zone turns out to be the area with the higher concentration of plastic debris and, for this reason, it is important to know the processes that affect the transport and the fate of this type of litter. This study focuses on investigating the dynamics of various plastic types under several hydrodynamic conditions primarily induced by waves. 2D tests were carried out at the Hydraulic Laboratory of the University of Messina reproducing the main phenomena that occurred during the wave propagation on a planar beach. More than 200 different conditions were tested changing the wave characteristics, the water depth, the plastic debris characteristics (density and shape), and the roughness of the fixed bottom. In general, it can be observed that the reduction in particle displacement occurs due to: i) a decrease in wave steepness; ii) an increase in depth; iii) an increase in particle size; iv) an increase in plastic density. However, the experimental investigation shows that some plastic characteristics and bed roughness, even when hydraulically smooth, can alter these results. The experimental data analysis identified a criterion for predicting the short-term fate of plastic debris under wave action. This criterion to determine equilibrium conditions, based on an empirical relationship, takes into account the wave characteristics, the bed roughness and slope, and the weight of the debris. • Various types of plastics were subject to hydrodynamic forcing to test their motion. • The displacement of the plastic increases as the wave steepness increases. • The bed roughness determines a nonlinear plastic displacement behaviour. • A methodology to understand the short-term fate in wave-driven transport was defined. [ABSTRACT FROM AUTHOR]

In recent years, algal blooms break out frequently and often accumulate in nearshore zones of eutrophic lakes and reservoirs, which seriously threaten regional water supply security. It is of great significance to grasp the status of algal blooms in key nearshore zones timely for the emergency prevention and control of algal blooms. A video surveillance system provides a new method for achieving this goal. The results of algal-bloom monitoring in current research, however, are usually interfered by onshore vegetation for their similar textural features. Accordingly, there are great limitations in current works in terms of decision support for emergency prevention and control of algal blooms. To solve this problem, a binocular video surveillance system based an accurate monitoring method of algal blooms is proposed in this paper. Binocular images of monitoring areas are obtained periodically by exploiting the binocular video surveillance system, which is performed by a stereoscopic 3D reconstruction method to obtain the 3D point cloud data of monitoring areas. Afterward, water regions and non-water regions are intelligently discriminated according to the elevation characteristics of point clouds, and only the image data of the water regions are finally adopted for algal-bloom extraction. Thus, the influence of onshore vegetation on the extraction of algal blooms can be eliminated. The system was implemented and applied, and the experimental results show that the proposed method can eliminate effectively the interference of onshore vegetation on the extraction of algal blooms and improve significantly the accuracy of existing methods for algal-bloom monitoring based on video surveillance system. [ABSTRACT FROM AUTHOR]

A profound understanding of the adsorption and desorption characteristics of arsenic on various media in aqueous solutions is helpful for evaluating the behavior of arsenic in groundwater. In this study, the characteristics of arsenic adsorption and desorption on aqueous media including silty clay, fine sand, medium sand, and coarse sand with gravel from Shenyang Huangjia water source, China were investigated by batch experiments. The results showed that the aqueous media in the study area had a strong fixation ability for arsenic, and both physical and chemical adsorption of arsenic occurred. Among them, silty clay had the strongest adsorption capacity and the largest buffer capacity for arsenic. As the specific surface area (SSA) of the medium decreased, the adsorption capacity decreased, and the desorption capacity increased. There was an obvious positive correlation between the desorption capacity and adsorption capacity of arsenic, and the force of the adsorption process was larger than that of the desorption process. The pH, temperature, carbonate, and ionic strength all affected the arsenic adsorption and desorption, and adsorption of arsenic occurred mainly by obligate adsorption in the study area. [ABSTRACT FROM AUTHOR]

The Arctic is greatly affected by climate change. Increasing air temperatures drive permafrost thaw and an increase in coastal erosion and river discharge. This results in a greater input of sediment and organic matter into nearshore waters, impacting ecosystems by reducing light transmission through the water column and altering biogeochemistry. This potentially results in impacts on the subsistence economy of local people as well as the climate due to the transformation of suspended organic matter into greenhouse gases. Even though the impacts of increased suspended sediment concentrations and turbidity in the Arctic nearshore zone are well-studied, the mechanisms underpinning this increase are largely unknown. Wave energy and tides drive the level of turbidity in the temperate and tropical parts of the world, and this is generally assumed to also be the case in the Arctic. However, the tidal range is considerably lower in the Arctic, and processes related to the occurrence of permafrost have the potential to greatly contribute to nearshore turbidity. In this study, we use high-resolution satellite imagery alongside in situ and ERA5 reanalysis data of ocean and climate variables in order to identify the drivers of nearshore turbidity, along with its seasonality in the nearshore waters of Herschel Island Qikiqtaruk, in the western Canadian Arctic. Nearshore turbidity correlates well to wind direction, wind speed, significant wave height, and wave period. Nearshore turbidity is superiorly correlated to wind speed at the Beaufort Shelf compared to in situ measurements at Herschel Island Qikiqtaruk, showing that nearshore turbidity, albeit being of limited spatial extent, is influenced by large-scale weather and ocean phenomenons. We show that, in contrast to the temperate and tropical ocean, freshly eroded material is the predominant driver of nearshore turbidity in the Arctic, rather than resuspension, which is caused by the vulnerability of permafrost coasts to thermo-erosion. [ABSTRACT FROM AUTHOR]

This article focuses on improving the understanding of the electromagnetic (EM) scattering from water waves modulated by shoaling effect arising from different upslope submarine topography in the nearshore zone. Simulation of EM bistatic scattering from water waves in the nearshore zone where the water depth becomes gradually shallower is presented. The shallow water waves with periodic sinusoidal type are simulated by the model that is based on Boussinesq approximation theory, which can accurately construct the detailed wave structure in the nearshore zone, and the analytical model-the second-order small slope approximation is applied to modeling the EM bistatic scattering from the shallow water waves. Comparisons of the bistatic scattering coefficient (BSC) between water waves corresponding to different submarine plane-upslope topography in the nearshore zone have shown that the angular position of harmonics of BSC will change as upslope varies: higher-order harmonics for plane-upslope cases would be far away from the specular peaks for flat topography case. Moreover, the wave height of the shallow water waves and nonlinear effect will greatly impact changing trend of the BSC. Simulations for TMA spectrum-based water waves also support the fact that the transfer of wave energy from low frequency to higher frequency wave components would be intensified in the shallow water zone with the upslope submarine topography. The results in this article indicate that shallow water waves would reflect some interesting scattering features that traditional deep-sea waves did not show, which will be helpful to the further quantitative investigation of scattering characteristics of nearshore waves.

The Arctic is greatly impacted by climate change. The increase in air temperature drives the thawing of permafrost and an increase in coastal erosion and river discharge. This leads to a greater input of sediment and organic matter into coastal waters, which substantially impacts the ecosystems by reducing light transmission through the water column and altering the biogeochemistry, but also the subsistence economy of local people, and changes in climate because of the transformation of organic matter into greenhouse gases. Yet, the quantification of suspended sediment in Arctic coastal and nearshore waters remains unsatisfactory due to the absence of dedicated algorithms to resolve the high loads occurring in the close vicinity of the shoreline. In this study we present the Arctic Nearshore Turbidity Algorithm (ANTA), the first reflectance-turbidity relationship specifically targeted towards Arctic nearshore waters that is tuned with in-situ measurements from the nearshore waters of Herschel Island Qikiqtaruk in the western Canadian Arctic. A semi-empirical model was calibrated for several relevant sensors in ocean color remote sensing, including MODIS, Sentinel 3 (OLCI), Landsat 8 (OLI), and Sentinel 2 (MSI), as well as the older Landsat sensors TM and ETM+. The ANTA performed better with Landsat 8 than with Sentinel 2 and Sentinel 3. The application of the ANTA to Sentinel 2 imagery that matches in-situ turbidity samples taken in Adventfjorden, Svalbard, shows transferability to nearshore areas beyond Herschel Island Qikiqtaruk.

In recent years, algal blooms break out frequently and often accumulate in nearshore zones of eutrophic lakes and reservoirs, which seriously threaten regional water supply security. It is of great significance to grasp the status of algal blooms in key nearshore zones timely for the emergency prevention and control of algal blooms. A video surveillance system provides a new method for achieving this goal. The results of algal-bloom monitoring in current research, however, are usually interfered by onshore vegetation for their similar textural features. Accordingly, there are great limitations in current works in terms of decision support for emergency prevention and control of algal blooms. To solve this problem, a binocular video surveillance system based an accurate monitoring method of algal blooms is proposed in this paper. Binocular images of monitoring areas are obtained periodically by exploiting the binocular video surveillance system, which is performed by a stereoscopic 3D reconstruction method to obtain the 3D point cloud data of monitoring areas. Afterward, water regions and non-water regions are intelligently discriminated according to the elevation characteristics of point clouds, and only the image data of the water regions are finally adopted for algal-bloom extraction. Thus, the influence of onshore vegetation on the extraction of algal blooms can be eliminated. The system was implemented and applied, and the experimental results show that the proposed method can eliminate effectively the interference of onshore vegetation on the extraction of algal blooms and improve significantly the accuracy of existing methods for algal-bloom monitoring based on video surveillance system.

In this study, the wave-induced distribution of 13 microplastic (MP) samples of different size, shape, and density was investigated in a wave flume with a sandy mobile beach bed profile. The particle parameter were chosen based on an occurrence probability investigated from the field. MP abundances were analyzed in cross-shore and vertical direction of the test area after over 40,000 regular waves. It was found, that MP particles accumulated in more shallow waters with increasing size and density. Particles with high density (ρs>1.25 g/cm3) have been partly confined into deeper layers of the sloping beach during the formation of the bed profile. Particles with a density lower than that of water used in the experiments floated constantly in the surf zone or deposited on the beach caused by wave run-up. A correlation was found between the settling velocity of the MP particles and the flow velocity at the accumulation point and a power function equation developed. The obtained results were critically discussed with findings from the field and further laboratory studies.

Collapse of permafrost coasts delivers large quantities of particulate organic carbon (POC) to Arctic coastal areas. With rapidly changing environmental conditions, sediment and organic carbon (OC) mobilization and transport pathways are also changing. Here, we assess the sources and sinks of POC in the highly dynamic nearshore zone of Herschel Island‐Qikiqtaruk (Yukon, Canada). Our results show that POC concentrations sharply decrease, from 15.9 to 0.3 mg L−1, within the first 100–300 m offshore. Simultaneously, radiocarbon ages of POC drop from 16,400 to 3,600 14C years, indicating rapid settling of old permafrost POC to underlying sediments. This suggests that permafrost OC is, apart from a very narrow resuspension zone (<5 m water depth), predominantly deposited in nearshore sediments. While long‐term storage of permafrost OC in marine sediments potentially limits biodegradation and its subsequent release as greenhouse gas, resuspension of fine‐grained, OC‐rich sediments in the nearshore zone potentially enhances OC turnover. Plain Language Summary: The coast around the Arctic Ocean consists mostly of permafrost, permanently frozen ground, which contains large amounts of millennia‐old organic carbon. Due to rising temperatures, this several thousand years old organic carbon is released to the Arctic Ocean at an increased rate by permafrost thaw and coastal erosion. Once released, organic carbon can be degraded and emitted as greenhouse gas to the atmosphere, or it can be stored away in marine sediments. In this study, we find that this old organic carbon quickly settles after release into the ocean and is buried in sediments close to shore, whereas the overlying sea water is dominated by young organic carbon from other sources than permafrost. However, sediments close to shore can be reworked by waves and currents, releasing the organic carbon again. This makes the zone closest to shore an important research area to assess the impact of thawing permafrost on climate. Key Points: Suspended particulate organic carbon (POC) sharply decreases in age and concentration within the nearshore zoneBeyond a narrow resuspension zone, permafrost‐derived OC dominates surface sediments, whereas much younger OC is found in the water columnPermafrost‐derived POC is rapidly removed from the water column, showing the critical role of nearshore dynamics for OC transport [ABSTRACT FROM AUTHOR]

Kum, B.-C.; Shin, D.-H.; Jang, S.; Lee, S.Y.; Lee, J.H.; Moh, T.J.; Lim, D.G.; Do, J.-D., and Cho, J.H., 2020. Application of unmanned surface vehicles in coastal environments: Bathymetric survey using a multibeam echosounder. In: Malvárez, G. and Navas, F. (eds.), Global Coastal Issues of 2020. Journal of Coastal Research, Special Issue No. 95, pp. 1152-1156. Coconut Creek (Florida), ISSN 0749-0208. This paper presents the practical application and results of a bathymetric survey carried out in a shallow marine coastal zone (Hujeong beach, located in the East Sea, South Korea) using a multi-functional unmanned surface vehicle (USV) equipped with a multibeam echosounder. Operation of the USV was conducted along the coast in very shallow water [depth ≤ 1.5 m (0.3 m below the transducer)], which is inaccessible to manned research vessels. High-resolution bathymetric data is expected to help with assessment and prediction of rapid changes in the shallow coastal zone. This work supports the applicability of USVs to scientific research and environmental monitoring in very shallow coastal areas. The USV will be the most extensively used technique for observing marine coastal environment. [ABSTRACT FROM AUTHOR]

Abstract In order to investigate the effect of wave processes on the geotechnical characteristics of topmost sediments, a Portable Free Fall Penetrometer (PFFP) was deployed in the energetic nearshore zone of the U.S. Army Corps of Engineers' Field Research Facility (FRF) in Duck, NC. A total of 335 deployments were conducted from the FRF's 560 m long pier over six non-consecutive days in September and October of 2016. During the surveying period, significant wave heights varied between H s = 0.8–2.4 m measured at a water depth of 17.4 m. The results showed that the sediment strength is affected by the wave climate. The derived average maximum quasi-static bearing capacities (qsbc), which reflects sediment strength, during low energy wave periods (September 22–24 and 26; H s = 0.8–1.3 m) ranged between 67 and 73 kPa with maximum qsbc values of 120–136 kPa, while the average values were 47–59 kPa with a maximum qsbc of 82–98 kPa during the high energy wave periods (October 5–6; H s = 2.4 m). Results also showed that the sediment strength decreased in the shallow water depth regions in spite of the increase in the particle size distribution, due to the increasing wave impact on the seabed within the shallow water region. The area where seabed strength variations were affected by the wave action became wider in the cross-shore direction as the wave height increased. Results further showed that the strength of the topmost sediment layers varied spatially along the profile and temporarily with variations in significant wave height. This likely reflects the impact of waves on sediment strength. Highlights • Sediments strength variations were investigated in an energetic nearshore zone. • Special attention was given to effects of wave breaking and storm conditions. • The lowest sediment strength along the profile was found in the breaking zone. • Mobilization processes on the first day of storm resulted in low measured strength. • Significant erosion resulted in a higher strength on the second day of the storm. [ABSTRACT FROM AUTHOR]

Abstract Three field observations were conducted in three consecutive years on a sandy beach on the east coast of Japan. Sediment cores were collected from the shoreline to the end of the offshore bar region. Each core was subdivided into layers and the sorting and skewness were analyzed using predefined Trask coefficients. The correlations between sediment properties, that is, median diameter, sorting, and skewness, with respect to the change in the bed profile are discussed in this paper. The weekly bed profiles, offshore wave conditions, and wave energy along the bed profile during the observation periods are discussed. Two significant sediment types were observed: finer well-sorted sediment and coarser poorly sorted sediment, both coarser skewed. The latter sediment properties were observed near the shoreline and at deeper elevations of the cross-shore bed profile. Finer well-sorted sand was transported away from and toward the coast depending on the wave intensity, which causes in-depth materials of coarser poorly sorted sediments to reappear with time. The offshore bar and trough region has a limited erosional depth due to the existence of poorly sorted coarser materials, which has been confirmed using weekly bed profile measurements. The sediment properties have a direct influence on the change of the bed profile. Highlights • Mapping cross-shore and in-depth sediment characteristics for a dissipative beach using core samples • Sediment layering in depth and cross-shore, stratified by the wave conditions and sediment characteristics • Limitation of bed profile change due to the grain size and sorting parameters [ABSTRACT FROM AUTHOR]

Abstract River plumes form in coastal areas where tributaries mix with their receiving waters. Plume waters are enriched with terrestrial-derived nutrients from their watersheds creating hotspots of biological productivity. The biological importance of plumes scales with the size and persistence of the plume; therefore, large, persistent plumes are more important than small, transient plumes. To date, most studies of plumes have focused on assimilation of terrestrial-derived energy by aquatic species or lower-level food web effects, primarily in marine systems. Few studies have described fish communities near plume habitats and compared them to non-plume areas, especially for the numerous small plumes in the Laurentian Great Lakes. Here we demonstrate that small plumes in the main basin of Lake Michigan enhance local primary productivity and influence distribution and abundance of nearshore Great Lakes fishes. We found that plume fish communities were relatively depauperate and did not support higher biological diversity of fishes compared to non-plume areas. However, individual species including rainbow smelt Osmerus mordax , spottail shiner Notropis hudsonius , and white sucker Catostomus commersonii were more abundant around plumes. Our results demonstrate that small plumes in the main basin of Lake Michigan support highly localized hotspots of biological productivity and fish abundance, primarily within 2 km of river mouths. [ABSTRACT FROM AUTHOR]

ABSTRACT Kum, B.-C.; Shin, D.-H.; Lee, J.H.; Moh, T.J.; Jang, S.; Lee, S.Y., and Cho, J.H., 2018. Monitoring Applications for Multifunctional Unmanned Surface Vehicles in Marine Coastal Environments. In: Shim, J.-S.; Chun, I., and Lim, H.S. (eds.), Proceedings from the International Coastal Symposium (ICS) 2018 (Busan, Republic of Korea). Journal of Coastal Research, Special Issue No. 85, pp. 1381–1385. Coconut Creek (Florida), ISSN 0749-0208. This work investigates the application of unmanned surface vehicles (USVs) for the management of coastal environment. USVs are an important and highly accessible tool for operating in shallow and nearshore waters. Sea trials are used to test the maneuverability and bathymetric survey capabilities of USVs. The results show that USVs have the potential to be an integrative platform for surveying shallow water zones (rivers, estuaries, and coasts), which can be enhanced by installing various transducers and sensor modules. The advances in sensing technologies and microelectronics will lead to the miniaturization of sensors and devices resulting in the proliferation of USVs in the field of coastal management. [ABSTRACT FROM AUTHOR]

The feasibility of a small scale Pressure Retarded Osmosis (PRO) plant located along the eastern coast of Sicily (Italy) is assessed by considering fresh water intake from a river and salt water intake from the sea. Firstly, PRO design methods are applied in order to estimate potential power production in terms of both the availability of water resources and of local salinity gradients. Secondly, the discharge dynamics of the brackish plant effluent in the coastal waters is investigated using an hydrodynamic model, taking into account wave - current interaction close to the river mouth. The results of the numerical simulations allow to identify the area affected by the brackish discharge, as a function of the nearshore wave climate conditions. Results show that the plume propagation is mainly controlled by the wave direction, whereas significant wave height and peak wave period have a minor influence. Plume hydrodynamics analysis is useful in optimizing the layout of the PRO plant in terms of the placement of the sea water intake and the effluent discharge, both of which should be properly located outside the surf-zone. Plume hydrodynamics analysis is also important for the evaluation of PRO plant impacts on the coastal saline concentration which may affect the local ecosystems. [ABSTRACT FROM AUTHOR]

Plastic debris is a significant threat to marine and coastal ecosystems. Previous research found that waves, wind, as well as density, size, and shape of microplastics, drive their transport and dispersion. In this paper, a set of laboratory experiments on the effect of waves and wave-induced currents on the input rate and cross-shore transport and dispersion of different types of plastic debris, including the macro and mesosizes, in addition to microplastics is presented. 15 plastic-debris types characterized by different sizes, shapes, and densities, including facemasks, were analyzed under regular and irregular wave conditions. The results show that input and transport rates of plastics depend on their terminal velocities and wave steepness. Plastics with higher settling velocities under less-steep wave conditions are likely to escape coastal entrapment and end up in the breaking zone. However, plastics with greater buoyancy rates under steeper waves show a predominant accumulation closer to the shoreline. • New laboratory experiments on cross-shore transport/distribution of plastic debris • Micro, meso, and macro plastic debris tested under regular and irregular waves. • Land-sea plastic input and transport depend on terminal velocity and wave steepness. • Heavier plastics accumulate in the breaking zone. • Buoyant items accumulate predominantly closer to the shoreline. [ABSTRACT FROM AUTHOR]

This study applies the numerical model GPUSPH, an implementation of the weakly compressible smoothed particle hydrodynamics (SPH) method on graphics processing units, to simulate nearshore tsunami processes. Two sets of laboratory experiments that involve violent wave breaking are simulated by the three-dimensional numerical model. The first set of experiments addresses tsunamilike solitary wave breaking on and overtopping an impermeable seawall. Comparison with free-surface profiles and laboratory images shows that GPUSPH satisfactorily reproduces the complicated wave processes involving wave plunging, collapsing, splash-up, and overtopping. The other set of experiments investigates tsunamilike solitary wave breaking and inundation over shallow water reefs. The performance of GPUSPH is evaluated by comparing its results with (1) experimental data including free-surface measurements and cross-shore velocity profiles, and (2) published numerical results obtained in two mesh-based wave models: the nonhydrostatic wave model CCHE2D and the Boussinesq-type wave model FUNWAVE. The capability of GPUSPH to simulate nonlinear wave phenomena, such as wave shoaling, reflection, and refraction, is confirmed by comparing the wave field predicted by CCHE2D. Although all three models correctly simulate the solitary wave propagation offshore and the bore due to the broken wave run-up nearshore, GPUSPH outperforms CCHE2D and FUNWAVE in terms of resolving wave plunging and collapsing. The conducted two case studies show that the meshless SPH method is reliable for predicting tsunami breaking in the nearshore zone. [ABSTRACT FROM AUTHOR]

Abstract: A long-term, 7-year lake-wide study was paired with a short-term intensive nearshore study to characterize water quality conditions of coastal Lake Ontario in New York. Mean total phosphorus (TP) concentrations in rivers (84.3±7μg P/L), embayments (129.7±9.6μg P/L), and shoreside sites (61.9±7.4μg P/L) exceeded the IJC goal of 10μg P/L for Lake Ontario waters and were significantly higher than in offshore waters (L0-100m, 9.5±0.7μg P/L; LO-30m, 10.4±0.08μg P/L). In three 5×20-km regions of the nearshore located at Oak Orchard, Rochester, and Mexico Bay, TP levels exceeded the 10μg P/L goal for Lake Ontario in 48% and 32% of the samples in June and August, respectively. Also, shoreside and embayment chlorophyll a were significantly higher than in offshore waters. Elevated sodium levels observed at shoreside sites of Lake Ontario are likely due to the heavy use of salt during the winter to deice roads. The elevated phosphorus concentrations observed at the shoreside sites extended into Lake Ontario. For example, at the Rochester nearshore sites in June, both TP and turbidity were elevated out to at least 4km from the shoreline, whereas temperature and specific conductance were elevated out to 3km from the shoreline. Shoreside sites had some chemical characteristics distinct from both the offshore (LO-30m and LO-100m) and river sites within the sampling polygon. A thin band of water with a unique water chemistry compared to both the offshore waters and tributaries extends up to 4km into the open waters along the southern coast of Lake Ontario during the late spring and summer. [Copyright &y& Elsevier]

Abstract: A thermal front was evident within the nearshore zone of the south shore of Lake Ontario near Oak Orchard Creek on 28 May 2008. Here, we characterize nutrient concentrations during thermal bar formation on the shoreside and lakeside of the thermal front within a 5×20-km polygon. We observed that total phosphorus levels and turbidity were elevated while silica and nitrate were reduced on the shoreside relative to the offshore of the thermal front. Phosphorus and suspended solid flux from Oak Orchard Creek contributed to elevated turbidity and phosphorus concentrations on the shoreside of the thermal front and were not transported to the lakeside of the thermal front. Two hypotheses, not mutually exclusive, are offered as potential explanations for the observed reduction in silica and nitrate: biological uptake by phytoplankton and benthic algae and long-shore transport of nutrient poor Niagara River water. This work not only demonstrates that nutrient entrapment may occur but also that biological mechanisms function to reduce nutrient levels within the shoreside of the thermal front. [Copyright &y& Elsevier]

Abstract: Large lakes have characteristics, such as a spring thermal bar; nearshore offshore gradients of nutrients, sediment, and biota; and the development of a nearshore zone often chemically, biologically, and physically different from the offshore region, that are not commonly observed in smaller lakes. The research presented here focuses on the role of rivers affecting the cross margin transport of terrigenous materials delivered during the summer on nearshore waters of Lake Ontario. On the south shore of Lake Ontario, levels of chlorophyll, total phosphorus (TP), and total coliform were higher in the Oak Orchard Creek river plume than out of it. Similarly at the Genesee River polygon, turbidity, specific conductance, temperature, TP, and chlorophyll were substantially higher in the plumes than outside of the plumes. Graphic depictions and the strong correlations (r>=0.70) between specific conductance and TP, soluble reactive phosphorus , temperature, chlorophyll, total Kjeldahl nitrogen, and turbidity indicate the plumes of water are from the Genesee River and Oak Orchard Creek. The load from all creeks on the New York shore of Lake Ontario ranged from ~18 to 25% of the annual phosphorus load of the Niagara River. The cumulative impact of these small streams entering the nearshore and embayments of Lake Ontario is potentially great, as the mixing of plume and lake water appears to be limited to the nearshore areas. Terrigenous inputs likely provide the nutrient, phosphorus, which contributes to the periodic development of benthic algae blooms observed along the south shore of Lake Ontario. The conclusion that river plumes impact and sustain the nearshore of large lakes is suggested by the data. [Copyright &y& Elsevier]

Abstract: Intensive sampling of seven 100-km2 nearshore sites and a lake circumnavigation using geo-spatially linked, continuous-measuring sensors allowed unprecedented detail on the structure of the nearshore of Lake Ontario in the post-dreissenid era. The 23 manuscripts describe the wide variability in nearshore nutrients, suspended solids, and organic wastewater correlated with proximity to the shoreline and among geographic areas. Although 7.71×105 mT of dreissenids exist in the nearshore, phosphorus regenerated was not enough to sustain populations of Cladophora. The phosphorus load of tributaries to Lake Ontario was 234% higher than of wastewater treatment plants and 67.5% of the 1982 Niagara phosphorus load. Phosphorus loading from local watersheds appeared to be the underlying driver for the spatial nearshore variability in Cladophora biomass. Such research has implications for the nearshore of other large lakes and is a necessary prerequisite to more fully understand how the nearshore functions in the post-dreissenid era. Consistent monitoring should be conducted on the major tributaries and representative smaller water courses in Ontario and New York to obtain ongoing information on the spectrum of influences that shoreline runoff has on the nearshore and the lake as a whole. We believe, however, that this falls short of what is needed to effectively manage nearshore water resources. We suggest that nearshore management might be advanced by a more purposeful coupling of the knowledge that exists in the field of watershed science with that of the limnology of large lakes to predict explicit nearshore conditions in the face of potential future environmental management regimes. [Copyright &y& Elsevier]

Abstract: A two-dimensional two-phase flow framework for fluid–sediment flow simulation in the surf and swash zones was described. Propagation, breaking, uprush and backwash of waves on sloping beaches were studied numerically with an emphasis on fluid hydrodynamics and sediment transport characteristics. The model includes interactive fluid–solid forces and intergranular stresses in the moving sediment layer. In the Euler–Euler approach adopted, two phases were defined using the Navier–Stokes equations with interphase coupling for momentum conservation. The closure model and volume of fluid approach were used to describe the turbulence and tracking of the free surface, respectively. Numerical simulations explored incident wave conditions, specifically spilling and plunging breakers, on both dissipative and intermediate beaches. It was found that the spatial variation of sediment concentration in the swash zone is asymmetric, while the temporal behavior is characterized by maximum sediment concentrations at the start and end of the swash cycle. The numerical results also indicated that the maximum turbulent kinetic energy and sediment flux occurs near the wave-breaking point. These predictions are in general agreement with previous observations, while the model describes the fluid and sediment phase characteristics in much more detail than existing measurements. With direct quantifications of velocity, turbulent kinetic energy, sediment concentration and flux, the model provides a useful approach to improve mechanistic understanding of hydrodynamic and sediment transport in the nearshore zone. [Copyright &y& Elsevier]

The coastal zone of the Eastern Gulf of Finland is actively changed under the influence of complicated natural and anthropogenic factors. The easternmost part of the gulf, a valuable area for recreation, is characterized by very intense coastal processes and is dominated by erosion. Analysis of historical materials, archive aerial photographs and modern high-resolution satellite images together with on-land investigations have shown that the majority of the coast of the easternmost part of the gulf is being eroded and is retreating. A study in the nearshore (side-scan sonar profiling, accompanied by echo-sounding and sediment sampling) enabled the main geological reasons for the coastal erosion to be established. [ABSTRACT FROM AUTHOR]

Abstract: A two-dimensional numerical model was presented for the simulation of wave breaking, runup and turbulence in the surf and swash zones. The main components of the model are the Reynolds-Averaged Navier–Stokes equations describing the average motion of a turbulent flow, a k–ε turbulence closure model describing the transformation and dissipation processes of turbulence and a volume of fluid technique for tracking the free surface motion. Nearshore wave evolution on a sloping bed, the velocity field and other wave characteristics were investigated. First, the results of the model were compared with experimental results for different surf zone hydrodynamic conditions. Spilling and plunging breakers were simulated and the numerical model investigated for different wave parameters. The turbulence field was also considered and the spatial and time-dependent variations of turbulence parameters were discussed. In the next stage of the study, numerical results were compared with two sets of experimental data in the swash zone. Generally, there is good agreement except for turbulence predictions near the breaking point where the model does not represent well the physical processes. On the other hand, turbulence predictions were found to be excellent for the swash zone. The model provides a precise and efficient tool for the simulation of the flow field and wave transformations in the nearshore, especially in the swash zone. The numerical model can simulate the surface elevation of the vertical shoreline excursion on sloping beaches, while swash–swash interactions within the swash zone are accounted for. [Copyright &y& Elsevier]

Abstract: The cross-shore variation of long-term average longshore current velocity was investigated on the basis of a 15-year data set of longshore current, wave and wind. The longshore current velocities were measured once a day along a 427-m-long pier. The results show that the direction of the long-term average longshore current velocity away (>200m) from the shore was the opposite to that near the shore. The southward current was dominant offshore, whereas the northward current was dominant near the shore. The cross-shore variation of the long-term average longshore current velocity was formed owing to a difference between the wave and wind conditions when the northward and southward currents developed. When the northward current developed, the offshore wave height was relatively small and the frequency of the southward wind velocity was almost equal to that of the northward one. As a result, the northward current developed only near the shore and decayed outside the narrow surf zone. On the other hand, when the southward current developed, the offshore wave height was relatively large and the southward wind velocity was predominant, which resulted in the southward current developing not only in the wide surf zone but also outside the surf zone. The superposition of the two cross-shore variations produced a cross-shore variation of the long-term average longshore current velocity with a northward velocity near the shore and a southward velocity away from the shore. [Copyright &y& Elsevier]

Within the two major theories of the generation of rhythmic shoreline features, the earlier one relates to edge waves, whereas the one developed later perceives shoreline rhythmic forms as effects of self-organized shoreline behavior. This study focused on identification of infragravity waves (edge waves) and periodic components of shoreline configuration and searched for their potential relationships in the mildly sloping, sandy south Baltic coast. The objective was not to suggest which theory better describes shoreline rhythmic features but was chosen for an empirical assessment of possible links between the generation of rhythmic morphological beach forms and specific infragravity waves motion at a dissipative shore. The investigated area features a gently sloping seabed with several bars inducing multiple breakers, which can be classified as a dissipative beach. Field measurements were taken during two periods lasting several months each. Long records of water table oscillations, nearshore currents, and measurements of shoreline configurations were analyzed using various signal processing techniques, incorporating traditional spectral analysis and the modern statistical techniques of singular spectrum analysis and discrete wavelet transform. The measurements revealed two clearly visible infragravity components with periods Tk = 30-40 seconds and Tk = 100-120 seconds at a dissipative south Baltic beach with multiple bars. They were detected by all three methods employed in the study. Additionally, less pronounced components were identified with periods Tk = 180 seconds and Tk = 10-12 seconds. The analysis of variability of the shoreline shape found periodic components with wavelengths ranging between several and several hundred meters and more. Results of this study also suggest that there are links between infragravity waves and rhythmic shoreline forms in a dissipative shore with multiple bars. [ABSTRACT FROM AUTHOR]

Abstract: A non-linear wave propagation model, based on the higher order depth-integrated Boussinesq-type equations for breaking and non-breaking waves, was applied to predict irregular wave transformation in two horizontal dimensions. A new source function, adapted for the proposed equations, is introduced inside the computational domain, to generate the desired short-crested waves. The dissipation due to the roller is introduced in the momentum equation in order to simulate wave breaking. Bottom friction and sub-grid turbulent processes are also introduced in the model. At the open boundaries a damping layer is applied together with a radiation boundary condition. Model results are compared with experimental measurements, containing tests with normal or oblique to the shore long- and short-crested irregular waves. The comparisons show that the model is able to simulate successfully the non-linear evolution of a unidirectional or a multidirectional wave filed in the nearshore zone, under the effects of refraction, shoaling, and breaking. [Copyright &y& Elsevier]

A scheme, which can be readily used by fisheries and environmental managers and ecologists, has been developed for quantitatively classifying the different habitats found in nearshore marine waters along the heterogeneous lower west coast of Australia. Initially, 25 beach sites, representing a wide range of nearshore environments, were separated into six a priori habitat types on the basis of characteristics that could readily be observed and were likely to influence the extent to which a particular (fish) species occupies a particular habitat. Focus was thus placed on such features as the degree of exposure to wave activity and whether or not seagrass and/or reefs were present in the nearshore vicinity. Subsequently, quantitative data for 27 environmental variables, considered likely to characterise the six habitat types, were obtained for each of the 25 sites from readily accessible sources. When the latter data were subjected to multidimensional scaling (MDS) ordination, the points for the sites representing only three of those six habitat types formed discrete groups. The bvstep routine in the Primer v5.0 statistical package (Clarke & Gorley, Primer v5.0: User Manual/Tutorial, Primer-E Ltd, Plymouth, 2001) was thus used to select a subset of the 27 environmental variables that would provide a better resolution of the six a priori habitat types. This process involved matching the distance matrix constructed from the quantitative environmental data with a matrix constructed from scored data that reflected the criteria for the initial a priori classification scheme. A subset of seven environmental variables gave the best correlation between the two matrices (ρ=0.823), and thus provided the optimal set of quantitative data for discriminating between the six a priori habitat types. These variables comprised both the direct and north-westerly fetches, the minimum distance from the shoreline to the 2 m depth contour, the distance from the shoreline to the first offshore reef chain along a south-westerly transect, and the relative contributions of bare sand, subtidal reef and seagrass. Data for these characteristics at any nearshore site along the coastline can readily be recorded by managers and ecologists and subjected to the ‘nearest-replicate’ classification procedure developed in this study to ascertain the habitat type to which that site should be assigned. Current work is using MDS ordination, in conjunction with associated statistical tests and the bvstep routine, to elucidate the extent to which the compositions of assemblages of fish, benthic macroinvertebrates, meiofauna and zooplankton in nearshore waters along the lower west coast of Australia are related to habitat type(s). [Copyright &y& Elsevier]

Knowledge about the tradeoffs among turbulent kinetic energy (TKE), waves, and suspended sediment concentrations (SSCs) in the nearshore zone is relevant for understanding beach morphodynamics at different temporal and spatial scales. A field measurement lasting for nearly three tidal cycles was conducted to holistically discern couplings between TKE, waves and SSCs, with further evaluation of the relative significance of TKE and waves on SSCs under various wave conditions over a meso-macro tidal beach, Yintan, to the north of Beibu Gulf, China. The results showed a dramatic increase in wave groupiness intensity from the shoaling wave condition to the breaking wave condition and a clear decrease further into the surf bore condition. The near-bed TKEs under the surf bore condition were an order of magnitude larger than those under the breaking and shoaling wave conditions at the measurement position. The averaged SSCs in the near-bed (approximately 10 cm) under the surf bore condition were 1.5 and 4.5 times larger than those under breaking and shoaling wave conditions, respectively. The variations in relative wave height were a decisive indicator for the differences in TKE intensities among different wave conditions, while the occurrence of peak TKEs at the wave front within the intrawave cycle was associated with flow acceleration regardless of wave conditions. Mean SSCs were well correlated with waves in terms of both incident wave scale and wave group scale, which was limited to the shoaling wave condition, and the occurrence of near-bed intrawave peak SSCs was always related to the offshore wave phase. Further, TKE contributed more effectively to sediment suspension at the wave group scale than at the incident wave scale, especially under broken wave condition. Among the hydrodynamic factors, TKE played the most important role in the variations in SSCs for all wave conditions. Flow acceleration served as the second most important factor under the broken wave condition, while wave group, single wave and advection were equivalent and less important factors for SSCs. Unlabelled Image • Variation in relative wave height was a decisive indicator of TKE intensity. • The occurrence of near-bed peak SSCs was related to offshore wave phase. • Correlated TKE events occupying 12.2% of total time produce 42.9% of SSC events. • TKE played the most important role in variations of SSC time series. [ABSTRACT FROM AUTHOR]

Plastic litter in nearshore waters is an environmental pollutant with increasing impact on coastal environments. At present, knowledge on basic plastic particle dynamics and the interaction with complex hydrodynamics is lacking. The present laboratory study, performed under controlled wave and wind conditions, demonstrates the dispersion of plastics in shallow waters. The study presents a simple case looking solely at cross-shore particle transport. The results show that both wind and waves as well as plastic properties (shape and density) govern the behaviour of plastic litter in the nearshore zone. Heavy particles behave like natural sand with accumulation in the wave breaking zone. Light particles have varying accumulation along the coastal profile depending on the wind, waves and particle shapes. More extensive characterization remains to be done in future studies. • Cross-shore distribution of plastics during wind and wave energy revealed. • Both wind, wave and plastic properties important for nearshore plastic distribution • Heavy particles accumulate in the wave breaking zone. • Light particles have varying accumulation along the coastal profile. [ABSTRACT FROM AUTHOR]