Coastal Lakes Research Articles

The use of nutrient budget approach for informing eutrophication management in urbanised shallow coastal lakes: A case study from Lake Nokoué in Benin

Lake Nokoué in Benin supports the livelihoods of more than 500.000 people through fish production and sand mining. However, its health is jeopardised by eutrophication and excessive growth of the invasive water hyacinth, which dies off and sink to sediment during dry seasons when the lake's salinity increases due to tidal intrusion. Water-hyacinth constitutes then a potential source of internal nutrient loading through the decomposition of detritus and therefore can exacerbate eutrophication problems. An important management question is whether the removal of water hyacinth before it dies would significantly reduce eutrophication problems through the removal of nutrients. To compare the amount of nutrients removed by water-hyacinth biomass to the amount of nutrients transported into the Lake, mass-balance approach has been taken. Nutrient concentrations, water hyacinth cover, and hydrological inflows were measured over a 12 month period from November 2016 to October 2017. Water-hyacinth biomass estimation was based on a calibrated NDVI and field measurement relationship. In total the hyacinth covered up to 18 km2 (10%) of the lake, corresponding to 80,000 tonnes of dry weight which sink to the bottom each year when salinity rise. The potential internal nutrient loaded from hyacinth to the system was estimated to 1021 tonnes of nitrogen (8% of external input) and 231 tonnes of phosphorus (40% of external input). Considering that the tidal nutrient output compensates almost all the external nutrient inputs (about 70%), part of the nutrient available for eutrophication must come from internal sources, likely through the decomposition of sediment detritus.

Assessment of the metal pollution in surface sediments of coastal Tasaul Lake (Romania)

Forty-three surface sediment samples were collected in September 2019 from Tasaul Lake (Black Sea coast, Romania) to examine the metal distribution patterns, assess the level of metal contamination, and identify the pollutant sources. The determined mean metal concentrations were as follows: Al 49,772 mg/kg, Zn 84.40 mg/kg, Cr 83.70 mg/kg, V 76.45 mg/kg, Ni 42.53 mg/kg, Cu 34.27 mg/kg, Pb 26.30 mg/kg, As 12.49 mg/kg, and Hg 0.06 mg/kg. The metals in the surface sediments of Tasaul Lake displayed moderate spatial variation, with higher metal concentrations mainly occurring in the south and southeast (As, Pb, and Hg), southwest (Cu and Zn), and west of the lake (Cr, Ni, and V). Heavy metal contamination in sediments is assessed using pollution indices such as enrichment factor, contamination factor, and pollution load index. The highest CFs and EFs were determined for As (moderate to high pollution), followed by Pb (low to moderate pollution). The Cu, Zn, and Hg pollution indices showed values corresponding to low pollution levels, while Ni, Cr, and V presented the lowest indices, suggesting unpolluted sediments. Multivariate statistical analyses were performed to identify the origin of the analyzed heavy metals. Cr was predominantly sourced from lithogenic components, Ni and V originated from both natural and anthropogenic sources, and As, Cu, Zn, Pb, and Hg showed mainly anthropogenic sources such as agricultural runoff, domestic and industrial wastewater discharges, and quarrying activities.

Characterizing the Great Lakes Coastal Wetlands with InSAR Observations from X-, C-, and L-Band Sensors

We investigated the potential of using Synthetic Aperture Radar (SAR) imagery from three different frequencies: X-, C-, and L-band, to characterize coastal wetlands in the Great Lakes. Three sets of SAR data acquired over the Bay of Quinte, Ontario, Canada between 2016 and 2018 from Radarsat-2, 2016 from TerraSAR-X, and 2018 from ALOS-2 satellites were processed using small baseline subset (SBAS) Interferometric SAR (InSAR) techniques to provide maps of surface changes in marshes and swamps. Results showed that SAR backscatter and coherence were sensitive to sensor characteristics (frequency, polarization, incidence angle, acquisition interval), changes in water level, and phenology. InSAR time series observations were evaluated using measurements from water level loggers based on correlation and root mean square error (RMSE) from a linear regression model. Correlation between InSAR measurements and water level changes in the field varied from −1 to 1 depending on the site, type of wetland vegetation, and incidence angle. Although results from some sensor modes provided good correlation (0.77–1) at a few locations, the low fringe rate and large RMSE between 4 and 64 cm indicated that InSAR observations of water level changes in the dynamic wetland environment were generally underestimated.

Are virtual journeys around great lakes effective for finding megaclast deposits? Evidence from the Lake Malawi

ABSTRACT Google Earth Engine is used to trace the spatial distribution of the lacustrine coastal megaclast deposits (LCMDs) of the Lake Malawi. Wide distribution of LCMDs is established, and they are especially common on the northeastern and southern coasts. The studied deposits can be subdivided provisionally into lenticular, patchy, and point-scale categories. Apparently, the spatial distribution of these deposits around the Lake Malawi is controlled by the regional geology and topography. This case study proves the efficacy of the virtual journeys for quick finding and mapping LCMDs along lake coasts, although not for their quantitative analysis and in-depth descriptions.

Sources, distribution and biogeochemical cycling of dissolved trace elements in the coastal lakes of Larsemann Hills, East Antarctica

Coastal lakes in Antarctica receive an enormous amount of ions and trace elements (TEs) during the austral summer. Some of these TEs and ions are utilised as essential nutrients in primary productivity. In the present study, selected dissolved TEs (Ba, Mn, Cu, Co, Cd, Mo and U) along with dissolved organic carbon (DOC) and Chlorophyll-a were studied in ten coastal lakes of the Larsemann Hills, East Antarctica to decipher their (TEs) sources, understand geochemical behaviour and assess their role on nutrient dynamics. Dissolved concentrations of these TEs are in sub-nanomolar range; almost an order of magnitude lower than the average seawater and global river concentrations. Sea-salt spray and chemical weathering in the catchments of these lakes are dominant sources for these TEs and ions. Though most of the Antarctic lakes have been reported for their oligotrophic character, however, a significant amount of DOC and Chlorophyll-a, and occurrence of algal mats in some of the LH lakes indicate seasonal (austral summer) productivity with the availability of sunlight and nutrients. Our investigation reveals that phosphate (PO43−) and Mo act as limiting nutrients because of their lower concentrations in the water column. Dissolved Cu plays an important role in bacterial-induced organic matter decompositions and release of organic carbon to lake water. We also found Ba excess (non-terrigenous) in the lake and catchment sediments varying from 26 to 63%. The higher Baexcess in the catchment sediments could be due to significant removal of dissolved Ba during the solute transport and later supplied to these lakes. The geochemical data sets presented in this study were found at a natural background level and therefore, would be useful for comparison with other global aquatic environments. Findings of the present study improve our understanding about the biogeochemical cycling of trace elements and their critical role in oligotrophic lakes of Antarctica.

Relationships between the Baltic Sea ice extent and ice parameters in the sheltered basins of the southern Baltic coast

Abstract In the study, archive data on the maximum annual ice extent in the Baltic Sea (MIB) for the period 1961–2018 were used. They were obtained from the FIMR database. Data on ice parameters for the four largest southern Baltic coastal lakes: Jamno, Bukowo, Gardno and Łebsko, and for Szczecin, Puck, and Vistula Lagoons, come from the Maritime Branch of Institute of Meteorology and Water Management – National Research Institute (in Polish: Instytut Meteorologii i Gospodarki Wodnej – Panstwowy Instytut Badawczy, IMGW-PIB) in Gdynia. The time series for the lakes cover the years from 1960 to 2018, and for the lagoons – from 1946 to 2018. Three ice parameters were selected for this study: the number of days with ice, the duration of the ice season and the maximum ice thickness for a given winter. Relationships between the selected ice parameters for the studied basins and the MIB were examined using correlation and regression methods. Correlations between the MIB and values of the ice parameters for the lakes and the southern Baltic coastal lagoons do not differ significantly. Considerable differences are observed amongst the correlation coefficients for individual ice parameters and the MIB. Larger differences are found in relationships between the values of individual ice parameters in the sheltered basins and the MIB. The strongest correlation with the MIB is observed for the maximum ice thickness and the number of days with ice.

Great Lakes Coastal Wetland Monitoring Program (EPA)

Federal Grants & ContractsVolume 44, Issue 20 p. 5-5 Grants Alerts Great Lakes Coastal Wetland Monitoring Program (EPA) First published: 14 September 2020 https://doi.org/10.1002/fgc.31299Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume44, Issue2017 September 2020Pages 5-5 RelatedInformation

Effects of Heavy Metals in Lake Water and Sediments on Bottom Invertebrates Inhabiting the Brackish Coastal Lake Łebsko on the Southern Baltic Coast.

Lake Łebsko is the largest and most productive coastal lake of the southern Baltic Sea to which it is permanently connected. The shoreline is well-developed, and the lake is divided into three parts: eastern, central, and western. Seawater intrusion affects most strongly the eastern part, where the Łeba River connects it with the sea. Samples of water and sediments were collected in 2014–2015. In the same places and time interval, bottom fauna was collected to determine the influence of environmental predictors on its qualitative-quantitative structure. Metals Cr (chromium), Pb (lead), Ni (nickel), Cu (copper), and Al (aluminium) in the samples were analyzed using inductively coupled plasma optical emission spectrometry. Most of the analyzed physicochemical variables of water were significantly higher in the eastern part: conductivity, salinity, sulfates (p < 0.0001) and chlorides (p = 0.01). Metal concentrations in water did not differ significantly between the lake parts, but in sediments they were generally higher in the western part. During the study, we detected significant changes in descriptors and abundance of the major groups of benthic fauna (Oligochaeta and Diptera), mostly between the eastern and western parts. BIO-ENV analysis showed that the benthic community of Lake Łebsko is shaped primarily by physicochemical variables of water (42% of the variance), linked with intrusion of seawater. Secondarily, the structure of the benthic community is affected by the amounts of heavy metals in sediments (31%) and water (12%). The findings can help us improve the principles of management of coastal lakes, including modification of hydrological conditions.

A Study on the Formation Environment of the La Cumbre Amber Deposit, from Santiago Province, the Northwestern Part of the Dominican Republic

The amber-bearing coaly shale from the La Cumbre deposit (Cordillera Septentrional, Dominican Republic) contains a large quantity of altered, coalified plant detritus. The coals in these shales are in the transition stage from meta-lignite to subbituminous coals. They are composed mainly of inertinite macerals such as fusinite, semifusinite, macrinite and secretinite. Fossil resin found in the deposit occurs in two forms: detrital grains up to several centimetres in size (type I) and very fine authigenic grains, of a few micrometers in size, inside the humic laminae (type II, resinite). The detrital fossil resins are transparent, with few mineral and organic inclusions. In their composition they contain sulfides, which may come from sulfate reduction, inclusions of plants and/or insects or be caused by volcanic activity developed in surrounding coal series. The resinites are strongly saturated with various inclusions and spatially associated with framboidal pyrite aggregates. Both fossil resin types were probably deposited in a shallow coastal lake environment in the zone bordering the floodplain of the river, with periodic floods. The marine environment conditions, which were progressively changing from oxidizing to reducing, are likely associated with the formation of the fossil resin.

Human-environment interaction in the hinterland of Ephesos – As deduced from an in-depth study of Lake Belevi, west Anatolia

Lacustrine sediments are important archives for high resolution palaeoenvironmental reconstructions of the Holocene. Despite the density of ancient cities and settlements along the western coast of Turkey, the archives from coastal lakes in this area have until now not been recognized to their fullest potential and are, therefore, only poorly studied.The exceptional geo-bio-archive of Lake Belevi is located close to the ancient city of Ephesos in western Turkey. Two sediment cores have been analysed using geochemical, sedimentological, microfaunal, palynological, and archaeoparasitological methods. The in-depth study of these Holocene deposits is supported by a robust age-depth model that used 33 radiocarbon dates and tephrochronology.The results reveal the existence of a freshwater lake in the Early Holocene which turned brackish when the rising sea level connected it with the sea. The delta evolution of the Küçük Menderes led to the re-establishment of a freshwater lake. The natural vegetation was represented by open oak woodlands. There are hints for first agricultural activities in the environs of Belevi as early as 8000 cal yr BP. Intensive cultivation of Olea is proven since 3000 cal yr BP. Starting during the 3rd millennium BP, the human impact with enhanced deforestation activities and correlative high sedimentation rates is attested for sites such as Belevi (Ephesos), Elaia (Pergamon) and Miletos. For the first time, tephra from the eruption of Minoan Santorini has been identified in the environs of Ephesos. This ash covered the vegetation by a thick layer, wherefore low-growing plants were strongly affected. The comparison between the results from the quasi natural area of Lake Belevi and the area around the city of Ephesos gives insights into the development and use of the landscapes, the environmental changes as well as the duration and intensity of the human impact.

The release of legacy phosphorus from deforestation-derived sediments in shallow, coastal lake Forsyth/Te Roto o Wairewa

ABSTRACT Phosphorus (P) release from sediments accumulating since catchment deforestation, has been linked to algal blooms which have occurred in Lake Wairewa (Canterbury, NZ) for over a century. However, the mechanisms controlling this internal P loading are poorly understood. To address this issue, we investigated sediment P fractions, P release, dissolved oxygen (DO) and pH at the sediment–water interface, and undertook targeted water sampling. Sediment depth profiles of P fractions indicated surface enrichment (1600 mg P kg−1), which was due to an upward flux of P from legacy sediments deposited over at least the last 100 years. Phosphorus release under reducing conditions (0.75–64 mg P m−2 d−1) and pH >9.00 (3.27–11.07 mg P m−2 d−1) indicated the potential for internal loading. Low DO events (<2 mg L−1) in bottom waters were short-lived, and spatially discrete, although longer events (13 days) were observed. pH was variable (6.20–10.80), and prolonged periods of pH >9 (5–6 days) were recorded. Macrophyte beds were key drivers of low DO, elevated pH, and sedimentary P release. The results challenge the paradigm of well mixed shallow lakes and contribute to the knowledge required to understand shallow lake systems impacted by land-use change.

Land cover is the main correlate of phytoplankton beta diversity in subtropical coastal shallow lakes

Environmental heterogeneity and productivity are factors driving beta diversity of freshwater communities. Further, characteristics as spatial extent and connectivity, as well as land use and cover, can determine local biodiversity patterns. We evaluated the correlates of within-lake beta diversity of phytoplankton communities in 25 coastal shallow lakes in southern Brazil. We hypothesize that within-lake beta diversity is positively related to environmental heterogeneity, productivity, spatial extent and connectivity. We also searched for correlates between beta diversity and land cover, once the studied lakes are mostly surrounded by natural landscapes. We measured beta diversity using four dissimilarity coefficients that provide a gradient of emphasis on compositional and abundance changes. We found that beta diversity differed among lakes, indicating changes in both species’ composition and abundance, but how it correlated with predictors differed depending on how beta diversity was measured. Beta diversity based on changes in species incidence and in two measures of abundance (modified Gower based on log10 and log2) was positively related to percentage of wetland cover and negatively related to percentage of grassland. Further, environmental heterogeneity was related to abundance-based (modified Gower log2) beta diversity. Our hypotheses were partly corroborated, indicating that factors modulating beta diversity patterns are complex and not easy to detect. We show that phytoplankton beta diversity in shallow coastal lakes is promoted by factors acting at both local and landscape scales. Finally, we emphasize that investigating beta diversity patterns should thoughtfully consider the use of dissimilarity coefficients measuring both changes in species composition and abundance.

δ18O and δ13C of Cyprideis torosa from coastal lakes: Modern systematics and down-core interpretation

Stable isotope analyses of ostracod shells are a commonly-used proxy for palaeoenvironmental reconstruction. Although the fundamental controls on isotope composition of ostracod shells are well understood and, in some instances, quantifiable, the paleoclimatic and palaeoenvironmental interpretation of records from lake sediments depends strongly on the characteristics of individual lakes including the climatic setting, depth, volume, hydrology, aquatic vegetation and catchment properties. This is particularly important for coastal lakes where physio-chemical variations may occur on diurnal timescales. Here, we combine variations in δ 18 O water , δ 18 O ostracod and δ 13 C ostracod , hourly water temperature, and Mg/Ca ostracod inferred water temperatures (constraining calcification temperature) to improve palaeoenvironmental interpretation and provide insights into lake carbon cycle. The dataset improves understanding of complex coastal lake site systematics and downcore interpretation of stable isotopes from C. torosa , a geographically widespread brackish water ostracod. The δ 18 O ostracod values show a complex relationship with temperature and suggest, in most circumstances, that δ 18 O water is the dominant control on δ 18 O ostracod . During times of fresher water, δ 13 C ostracod increases, suggesting increasing aquatic productivity. Above a certain δ 18 O water threshold however, aquatic productivity begins to decline. The interpretation of δ 13 C ostracod in some coastal lakes, may therefore be dependent on understanding of the range of expected δ 18 O water . Due to short-term (diurnal to seasonal) variations that cause large ranges in δ 18 O water and δ 18 O ostracod , stable isotope analyses of C. torosa should be: (1) undertaken on multiple single shells (2) where carapaces are preserved, paired with trace-element/Ca analyses on the same individual; and (3) undertaken alongside a study of the modern lake system. • In most circumstances, δ 18 O water is the dominant control on δ 18 O ostracod . • δ 13 C ostracod is likely controlled by productivity and the oxidation of terrestrial organic matter. • Samples that show a relationship with temperature have higher δ 18 O and a decreasing trend with δ 13 C. • Only some valves in a palaeo-dataset with mixed seasonal signals may relate to palaeo-temperature.

Effects of seawater exchange on water chemistry among coastal lakes with intermittent connections to the sea

Intermittently closed and open lakes and lagoons (ICOLLs) are a dynamic class of coastal waterbodies with the unique feature of intermittently connecting to the sea. Understanding the functioning and potential threats of these globally rare systems is important to their preservation and protection. Coastal dune lakes of northwest Florida are one example of an understudied group of ICOLLs which connect with the Gulf of Mexico for brief periods of time. Using a 17-year, monthly water chemistry dataset, we analyzed long-term patterns in water chemistry among 16 coastal dune lakes. Using salinity as a proxy for frequency of seawater inflows, principal component analysis and linear mixed-effects models indicated significant relationships between salinity and nitrogen, phosphorous, and pH. Salinity was positively associated with pH and phosphorus, and negatively associated with nitrogen, although relationships within individual lakes varied. Nonparametric trend analysis indicated lake-specific significant shifts in water chemistry in several systems, although a majority of systems did not exhibit notable long-term trends. Results indicate the significance of water exchange with the Gulf of Mexico on water chemistry of coastal dune lakes and have implications for management of ICOLLs globally.

AEOLIAN SANDS IN NORTH AFRICA AND THE SOUTHWEST OF THE ARABIAN PENINSULA

Background. The majority of the world’s deserts were formed within the valleys and coasts of ancient alluvial rivers and lakes. The material carried across many hundreds and thousands of kilometres by the wind was mixing with sediments of various genetic types. In addition, due to the similar physical nature of the wind and water transport of sediments, the recognition of the aeolian environment can be problematic. Aim. Using innovative research approaches, to provide a qualitative structural description of sands; to identify and characterize factors contributing to the formation and preservation of a ferruginous film on grains; to establish the genesis of the transferred sediments, as well as the relationship with the parent rocks. Materials and methods. Samples for analysis were collected from aeolian deposits in three deserts: Rub al Khali (United Arab Emirates), Nubian desert (Egypt) and Grand Erg Oriental (Algeria). Particle size analysis was used to characterize samples in terms of three parameters (length, width, thickness). X-ray diffraction analysis was carried out using an ARL X’tra diffractometer (Switzerland). The collected samples were also studied using a binocular microscope in reflected light and a scanning electron microscope. Results. The mineral composition of the sands under study was examined. The graphs (histograms) of the size distribution of quartz grains (being the most common sand mineral in terms of size and frequency of occurrence) were plotted. The shape and nature of the grain surface were analysed. Conclusion. The frosting on aeolian sand grains can result not only from micro-cracking as the most common sign of wind transfer, but also from the presence of a calcite film on grains. Factors contributing to the formation and preservation of a ferruginous film (desert varnish) were identified. The conditions for the formation of aeolian sands, as well as the genesis of such sand sediments, were established.

Recurrence of extreme floods in southern Sakhalin Island as evidence of paleo-typhoon variability in the northwestern Pacific since 6.6 ka

History of variability of tropical cyclones (TC) in the North-Western Pacific is critical for understanding impacts of future climatic changes. Natural archives of paleo-typhoon variability can be used to assess how changes in the planetary climatic system during the Holocene could influence TC frequency and intensity in this part of Pacific. Extreme typhoon-related rains are the main cause of catastrophic floods on Sakhalin Island and deposits of these floods are evidence of paleo-typhoon. The paleo-typhoons that triggered extreme floods on Southern Sakhalin during the last 6.6 kyr are recorded in the sequence on the interfluvial surface in the northern Susunay Lowland (Naiba River basin). The sequence includes peat bog with numerous loam interlayers deposited during extreme floods inundating the bog. We reconstructed paleo-environmental conditions, including humidity and flood activity, based on analysis of diatoms. We found biological indicators that point to the past floods. The mineral content in the peat being one criteria indicative of the high frequency of floods. The peat bog developed in place of a lagoon that existed at the maximum phase of the Holocene transgression. Peat accumulation began in the freshened lagoon coast ~6010 cal yr B.P. When sea level dropped, the lagoon turned into a coastal lake (~5710–5040 cal yr B.P.). A swamp formed in place of the lake under varying moisture conditions. We identified and dated 25 extreme floods and assessed the paleoclimatic background of the events. A recent catastrophic flood from typhoon Phyllis (1981 CE) is considered as an analogue of the paleo-events. The frequency of extreme typhoons increased both during warm (wet and dry) phases and in cold dry phases of the climate fluctuations. We identified three periods of a high typhoon activity (4640–4360; 4030–3580; 1860–1380 cal yr B.P.), when super-typhoons came onto the island once every 30–90 years. A comparison between the extreme typhoons in the south of Sakhalin and in the Sea of Japan region show both synchronism and metachronism of the periods of typhoon activity. Instrumental measurements during 20th–21st centuries revealed considerable changes in super-typhoon tracks; a similar variability may be safely supposed in typhoon tracks in the past. To predict future tropical cyclone activity and the risk of floods under modern climatic instability it is necessary to understand factors influencing variability in the occurrence of strong typhoons and associated extreme floods events on a paleo-scale. This is especially important for areas with rapidly developing coastal economies and intensive use of gas and oil resources, such as Sakhalin Island.

Towards Monitoring of Nutrient Pollution in Coastal Lake Using Remote Sensing and Regression Analysis

The last few decades have witnessed a tremendous increase in nutrient levels (phosphorus and nitrogen) in coastal water leading to excessive algal growth (Eutrophication). The presence of large amounts of algae turns the water’s color into green or red, in the case of algal blooms. Chlorophyll-a is often used as an indicator of algal biomass. Due to increased human activities surrounding Dubai creek, there have been eutrophication concerns given the levels of nutrients in that creek. This study aims to map chlorophyll-a in Dubai Creek from WorldView-2 imagery and explore the relationship between chlorophyll-a and other eutrophication indicators. A geometrically- and atmospherically-corrected WorldView-2 image and in-situ data have been utilized to map chlorophyll-a in the creek. A spectral model, developed from the WorldView-2 multispectral image to monitor Chlorophyll-a concentration, yielded 0.82 R2 with interpolated in-situ chlorophyll-a data. To address the time lag between the in-situ data and the image, Landsat 7 Enhanced Thematic Mapper Plus (ETM+) images were used to demonstrate the accuracy of the WorldView-2 model. The images, acquired on 20 May and 23 July 2012, were processed to extract chlorophyll-a band ratios (Band 4/Band 3) following the standard approach. Based on the availability, the 20 May image acquisition date is the closest to the middle of Quarter 2 (Q2) of the in-situ data (15 May). The 23 July 2012 image acquisition date is the closest to the WorldView-2 image date (24 July). Another model developed to highlight the relationship between spectral chlorophyll-a levels, and total nitrogen and orthophosphate levels, yielded 0.97 R2, which indicates high agreement. Furthermore, the generated models were found to be useful in mapping chlorophyll-a, total nitrogen, and orthophosphate, without the need for costly in-situ data acquisition efforts.

Deciphering multiple controls on mesopore structural heterogeneity of paralic organic-rich shales: Pennsylvanian–Lower Permian Taiyuan and Shanxi formations, Weibei Coalfield, southwestern North China

This study investigates the various factors that affect the mesopore structural heterogeneity of paralic organic-rich shales in the Pennsylvanian–Lower Permian Taiyuan and Shanxi formations, in the Weibei Coalfield of southwestern North China. This assessment is based on an integrated analysis of facies, mineralogical, petrographic, geochemical, and low-temperature N2 adsorption data. Facies analysis leads to the recognition of five facies associations that record the following depositional systems: medial epeiric shelf (FA1), proximal epeiric shelf (FA2), open-coast tidal flat (FA3), river-dominated delta (FA4), and coastal lake (FA5). Shales from the different depositional facies are classified into five different lithotypes: fossiliferous calcareous shale (FCS), fossiliferous mixed shale (FMS), argillaceous siliceous shale (ASS), illite-dominated argillaceous shale (IAS), and kaolinite-dominated argillaceous shale (KAS). FCS appears to be confined to the carbonate shelf in the medial epeiric shelf. Its mesopore structure is severely damaged by extensive micritization and local micrite recrystallization, and only a few plate-like large mesopores (4.34–50 nm) between the carbonate grains survived. FMS is typical of seaward flank deposits of the proximal epeiric shelf. Although abundant calcite cements are formed by the calcification of aragonite shells, FMS still has a few inkbottle-shaped mesopores due to the input of terrigenous clastic sediment. IAS is widely developed in the open-coast supratidal marsh due to volcanic ash kaolinization and kaolinite illitization. Illite-smectite group clays determine the presence of fine mesopores (3–4.34 nm), which are the main contributors to the specific surface area. Thus, IAS has the most abundant homogeneous fine mesopores, as well as the largest specific surface area and pore volume. Conversely, KAS is formed in the delta-plain interdistributary swamp and has a dense structure. ASS is mainly composed of terrigenous clasts and can be formed in multiple environments. Silt-sized brittle minerals determine the number of large mesopores, which are conducive to the total pore volume. Therefore, ASS has a bimodal pore size distribution, as well as medium pore structure parameters and fractal dimensions. This study contributes to a better understanding and prediction of the mesopore structure evolution of organic-rich shales that formed in various paralic sub-environments.

Connectivity and complexity of coastal lakes as determinants for their restoration – A case study of the southern Baltic Sea

To understand functional mechanisms and ecological conditions of the Baltic coastal lakes (BCL) for the need of their restoration, the current state of knowledge on environmental, ecological, and evolutionary processes responsible for biological diversity is presented. This has allowed the classification of coastal lakes along the southern Baltic Sea coast as freshwater, transitional, and brackish ones. Principles of their functioning are explained here on the basis of the theory of alternative stable states in shallow lake ecosystems (brackish vs. freshwater) separated by adaptive cycles (transitional lakes).Successful concepts for the design and application of restoration of degraded coastal aquatic ecosystems is conditioned by both marine and terrestrial factors. Thus, the restoration plans of the southern Baltic coastal lakes, contrary to freshwater inland lakes, require some specific criteria to be applied due to (i) various connectivity of lakes with the sea, (ii) intrusion of seawater of low salinity as well as (iii) genetic heterogeneity of lake basins. Awareness of these findings makes it possible to trace and predict the threats posed to coastal lakes, as well. As an example, recommendations on the holistic restoration of Lake Jamno are presented. The presented data is useful for determining the state of preservation and methods of management of coastal aquatic habitats under high human pressure.

Rauk - A Forgotten Witness of Holocene Sea-level Change and Development of Baltic Rocky Coasts: A Pilot Geomorphological Study in Lergrav Raukar Field

Strzelecki, M.C.; Duszyński, F.; Tyszkowski, S.; Zbucki, Ł., and Kasprzak, M., 2020. Rauk - Forgotten witness of Holocene sea-level change and development of Baltic rocky coastal zone: A pilot geomorphological study in Lergrav raukar field. In: Malvárez, G. and Navas, F. (eds.), Global Coastal Issues of 2020. Journal of Coastal Research, Special Issue No. 95, pp. 659–663. Coconut Creek (Florida), ISSN 0749-0208.The Holocene history of Baltic Sea evolution is definitely one of the most interesting and intriguing stories of environmental change in Europe. To date, the key information on changes in sea-level and shifts in the environment associated with climate fluctuations were found in coastal lakes, marshes and wide stripe of barrier-lagoon systems of southern Baltic. Only limited research was conducted along rocky coasts, so characteristic features for Baltic islands from Bornholm, through Oland, Gotland, Fårö, Hiiumaa, Saarema to thousands of isles of Åland Archipelago. Among the most thrilling natural wonders found along Baltic coasts are rauks or raukars, unique limestone stacks—often with humanlike features—that tower above rocky shore platforms in northern Gotland and on Fårö, Gotland's sister island. Raukar coasts are one of the greatest touristic attractions in Sweden and the mythical coastal landscape of northern Gotland and Fårö had inspired many artists, including Ingmar Bergman. Surprisingly, what attracts tourists and artists, have been neglected by geomorphologists and those fascinating landforms still wait for detailed explanation of their origin and preservation. This paper provides insight into pilot geomorphological study of raukar coast in Lergrav, NE Gotland. Schmidt hammer rock tests were applied to characterize the degree of weathering of rock surface of well-preserved notches. The results of notch rock surface resistance and elevation above present sea-level are discussed with recent relative sea-level curves developed in the region.