Coastal Locations Research Articles

A shallow-water depositional interpretation for the upper Miocene Chagres Formation (Caribbean coast of Panama)

The upper Miocene Chagres Formation, cropping out along the Caribbean coast of Panama, has been previously interpreted as the record of the last deep-water connection between the Caribbean and Pacific oceans based on bodyfossil paleodepth estimates. We test this interpretation by presenting an integrated ichnological and sedimentological analysis on eight coastal localities of the Chagres Formation (Toro Limestone and Chagres Sandstone members). The Toro Limestone Member accumulated under fully marine conditions in a mixed carbonate and siliciclastic marine shelf above storm wave base. Fluctuating high-moderate energy conditions modulated by a combination of tides and high energy currents likely led to the sparse bioturbation of Toro Limestone sediments, corresponding to an archetypal Cruziana ichnofacies assemblage. Bioturbation, dominated by Thalassinoides and Ophiomorpha isp., increases in the overlying Chagres Sandstone Member and corresponds to a proximal expression of the Cruziana ichnofacies. The Chagres Sandstone Member was deposited within the lower shoreface-upper offshore transition zone in a shelf with low sedimentation rates under combined storm, wave, and tidal influence, and includes fossils and sediments of continental origin suggesting proximity to a river mouth. Our results suggest that the Chagres Formation accumulated in shallow waters, contrasting with a previously proposed deep-water accumulation, and are consistent with deposition on a tectonically stable platform of the northern Canal Basin at the apex of the Panama orocline.

Correlation of wind waves and sea level variations on the coast of the seasonally ice-covered Gulf of Finland

Abstract. Both sea level variations and wind-generated waves affect coastal flooding risks. The correlation of these two phenomena complicates the estimates of their joint effect on the exceedance levels for the continuous water mass. In the northern Baltic Sea the seasonal occurrence of sea ice further influences the situation. We analysed this correlation with 28 years (1992–2019) of sea level data, and 4 years (2016–2019) of wave buoy measurements from a coastal location outside the City of Helsinki, Gulf of Finland in the Baltic Sea. The wave observations were complemented by 28 years of simulations with a parametric wave model. The sea levels and significant wave heights at this location show the strongest positive correlation (τ=0.5) for southwesterly winds, while for northeasterly winds the correlation is negative (−0.3). The results were qualitatively similar when only the open water period was considered, or when the ice season was included either with zero wave heights or hypothetical no-ice wave heights. We calculated the observed probability distribution of the sum of the sea level and the highest individual wave crest from the simultaneous time series. Compared to this, a probability distribution of the sum calculated by assuming that the two variables are independent underestimates the exceedance frequencies of high total water levels. We tested nine different copulas for their ability to account for the mutual dependence between the two variables.

Counterurbanisation, demographic change and discourses of rural revival in Australia during COVID-19

ABSTRACT The term ‘counterurbanisation’ is receiving renewed academic attention due to the Covid-19 pandemic. While not in vogue in popular discourse, the concepts invoked by the term counterurbanisation often appear uncritically in popular media as a Covid-19-induced rural renaissance. This article presents four arguments about using ‘counterurbanisation’ as a term and its applicability in the Australian context. I argue that ‘counterurbanisation’ emerged when categories of urban and rural were less theoretically problematic, and that being unidirectional it does not capture the diversity of migration dynamics. Third, in the Australian context, counterurbanisation is inaccurately often associated in the popular imagination with migration to rural productive landscapes. Fourth, the contemporary measurement and representation of counterurbanisation is flawed. While accepting that various forms of counterurbanisation are occurring, which is important in coastal and near-urban locations, the concept has little relevance for many Australian towns whose future will emerge outside the discourse of counterurbanisation.

The Heat Is On: Observations and Trends of Heat Stress Metrics during Florida Summers

Abstract Extreme heat is annually the deadliest weather hazard in the United States and is strongly amplified by climate change. In Florida, summer heat waves have increased in frequency and duration, exacerbating negative human health impacts on a state with a substantial older population and industries (e.g., agriculture) that require frequent outdoor work. However, the combined impacts of temperature and humidity (heat stress) have not been previously investigated. For eight Florida cities, this study constructs summer climatologies and trend analyses (1950–2020) of two heat stress metrics: heat index (HI) and wet-bulb globe temperature (WBGT). While both incorporate temperature and humidity, WBGT also includes wind and solar radiation and is a more comprehensive measure of heat stress on the human body. With minor exceptions, results show increases in average summer daily maximum, mean, and minimum HI and WBGT throughout Florida. Daily minimum HI and WBGT exhibit statistically significant increases at all eight stations, emphasizing a hazardous rise in nighttime heat stress. Corresponding to other recent studies, HI and WBGT increases are largest in coastal subtropical locations in central and southern Florida (i.e., Daytona Beach, Tampa, Miami, and Key West) but exhibit no conclusive relationship with urbanization changes. Danger (103°–124°F; 39.4°–51.1°C) HI and high (>88°F; 31.1°C) WBGT summer days exhibit significant frequency increases across the state. Especially at coastal locations in the Florida Peninsula and Keys, danger HI and high WBGT days now account for >20% of total summer days, emphasizing a substantial escalation in heat stress, particularly since 2000. Significance Statement Extreme heat is the deadliest U.S. weather hazard. Although Florida is known for its warm and humid climate, it is not immune from heat stress (combined temperature and humidity) impacts on human health, particularly given its older population and prevalence of outdoor (e.g., agriculture) work. We analyze summer trends in two heat stress metrics at eight Florida cities since 1950. Results show that heat stress is increasing significantly, particularly at coastal locations in central and southern Florida and at night. The number of dangerous heat stress days per summer is also increasing across Florida, especially since 2000. Our analysis emphasizes that despite some acclimation, Florida is still susceptible to a serious escalation in extreme heat as the climate warms.

Slow hospitality: Family perspectives of holiday experiences at beach fale in Samoa

In Samoa, customarily most tourism accommodation is locally owned and operated. Against a backdrop of increasingly foreign-owned large hotels and resorts, local families have built low-cost beach fale accommodation (consisting of thatched beach huts) in coastal locations. These beach fale, traditionally frequented by the backpacker market, are proving increasingly popular with visiting families from overseas. A major attraction at these beach fale is the local food experience. Yet, only a superficial understanding exists of the tourists’ perspective on food preferences and beach fale experiences, especially for families and their children. There have been several development research studies on fale operations but none on the growing international family tourism market. This article provides insights into the neglected family perspectives of social hospitality experiences at Samoan beach fale accommodation and to elicit the key elements of the emerging slow hospitality concept. This exploratory study is based on ten semi-structured whole-family group interviews conducted with New Zealand and Australian families (30 parents, grandparents and children [aged 7–17]). The findings support a trend towards families seeking more authentic, immersive and socially interactive experiences on holiday that are more akin to the local way of life or Fa‘asamoa. It emerged that beach fale tourism provides culturally, culinary, socially and sensually richer experiences as part of slow hospitality offerings for families. This study contributes to broader academic debates about whole-family perspectives on holiday, slow hospitality, beach fale accommodation, seaside or thalasso tourism and understandings of family well-being.

Egg production in the porcellanid crab Pachycheles laevidactylus Ortmann, 1892 (Decapoda: Anomura: Porcellanidae) in southern Brazil

Abstract We analysed the egg production of the porcellanid crab Pachycheles laevidactylus Ortmann, 1892 in two coastal locations (Tramandaí and Torres) in southern Brazil. The number of eggs and egg volume were analysed during one year and compared between locations and seasons. A total of 438 ovigerous females were collected from sand banks formed by the polychaete Phragmatopoma caudata Krøyer in Mörch, 1863. The eggs were measured, classified into three stages of development, and quantified. Females with stage-I eggs were more frequent than those with stages II and III, possibly because it is the longest-duration stage. A positive correlation between female body size and fecundity (stage I) was observed, represented by a power function. The ovigerous females of Tramandaí and Torres had the mean/median (Tramandaí) and the maximum (both locations) fecundity higher than previously recorded for the species, nevertheless they also reached the largest body sizes. Fecundity differences were found between locations and among seasons, all attributed mainly to female size, air exposure time, and temperature. Pachycheles laevidactylus did not follow the expected latitudinal pattern of fecundity. The volume of stage-I eggs fluctuated between seasons in Tramandaí only, showing a tendency to be smaller in the warmer seasons. Ovigerous females in Torres lost 36.8% of their eggs between stages II and III, whereas no egg loss was detected in Tramandaí. A similar increase in egg volume was found from stage I to III in both locations, 44.4% in Tramandaí and 41.2% in Torres.

Vegetation analysis and species diversity of the invasive plant Heliotropium curassavicum growing naturally in heterogeneous habitats

Heliotropium curassavicum is an invasive annual weed plant that spreads quickly, especially on disturbed saline soils and coastal locations in arid and semiarid habitats. This study aimed to assess the vegetation composition of invasive plant H. curassavicum. The soil factors and associated species of this plant were studied in natural coastal desert habitats (northern Nile delta coast) and inland habitats (farrow land and canal bank habitats). The floristic composition revealed the occurence of 109 species (67 annuals, 2 biennials and 40 perennials) belonging to 86 genera and related to 29 families. Asteraceae, Poaceae, Chenopodiaceae, and Fabaceae (53.21 % of all species reported) are the most abundant families. Therophytes and cryptophytes are the mainly abundant life forms and the Mediterranean chorotype is the most representative. The cluster analysis of stands expressed four vegetational groups (A, B, C and D). The most dominant species with group A was Polypogon viridis, with group B was H. curassavicum, with group C (the largest one) was Cynodon dactylon and H. curassavicum and with group D was Phragmites australis. Diversity indices expressed more richness and evenness of vegetation group B (H. curassavicum communities). The major soil factors influencing the studied invasive species are soil texture, WHC, organic carbon, cations (Na+, K+, Ca++, and Mg++), and SAR.

Analysis of Damage to Trees in the Coastal Mangrove Forest of East Lampung Regency

Mangrove forests must have health conditions to maintain forest functions and ensure benefits for the community's welfare and living creatures around them. Based on this, an evaluation of the health situation of the woodland is essential to ensure that the health situation of the mangrove forests is maintained. This research was conducted to assess and obtain data and information on the health of mangrove forests withinside the coastal regions of the East Lampung Regency. The levels on this look have been figuring out the measurement plot, making the forest health measurement plot, collecting data, identifying tree health, and analyzing forest health data. The results of the research that have been carried out show that of the 8 cluster plots that have been made, it was found that the dominant types of damage were open wounds, damaged leaves, shoots, and shoots, as well as broken/dead branches. Then, the locations of most damage were found in sprouts and shoots, branches, lower stems, leaves, and the tops and bottoms of stems. The average forest health condition within the coastal location of East Lampung Regency is within the medium class with a median NKH fee of 5,29. This indicates that the mangrove forests are correctly applied and controlled via way of the encompassing communities, especially those who depend on these mangrove forests. So far, the government and the community have worked together to conserve mangrove forests.

Key preferences of tourists during COVID-19 pandemic in luxury hotels: Evidence from qualitative data

There is a decline in revenue and occupancy rates in the hotels during the pandemic. For the sustainable and long-term recovery of the hotel industry, the guests need to be analyzed for their stay preferences. This study attempts to find the preferred attributes of the travelers visiting the Indian luxury hotels during the COVID-19 pandemic. The research investigated the post-visit experiences from the online reviews published by tourists on TripAdvisor.com. Thematic salience valence analysis and lexical salience valence analysis was used to identify the vital attributes of the hotel industry. The study revealed staff, location, food, hygiene, and rooms as the preferred hotel attributes, in which the coastal locations were highly considered for location based marketing of luxury hotels, and non-compliance of COVID-19 standards and complaints for upgradations in the rooms were the non-recommenders for the luxury hotels. The dashboard-based salience valence zone analysis was used to provide suggestions to the hotel authorities by revealing the significant and critical hotel attributes simultaneously for prompt handling of the issues during the COVID-19 pandemic.

Recent Climatology (1991-2020) and Trends in Local Warm and Cold Season Extreme Temperature Days and Nights in Arabia.

The Arabian Peninsula (Arabia) is among the places to have experienced the greatest amount of warming during recent decades, and this trend is projected to continue. Specifics related to the characteristics (frequency, duration, and intensity) of extreme temperature events (ETEs) over Arabia as a whole are either largely outdated or limited only to specific areas. The seasonal ETE definitions commonly used in local studies are neither climatological- nor phenomenon-based. Using a novel and straightforward framework, the seasons of four extreme temperature types (extreme warm days/nights (EWDs/EWNs) and extreme cold days/nights (ECDs/ECNs)) were identified on the simultaneous basis of event occurrence and impact times. Assessments of ETE frequency, duration, and intensity and their recent changes were then provided based on the most recent climate data (1991–2020). Results showed that the use of traditional seasonal definitions (e.g., meteorological seasons) tends to assume a spatiotemporal homogeneity in the seasonality of ETEs and their potential risk levels throughout the year. The developed framework distinguished months with events that have larger potential impacts together with their local seasons. ETE seasons were found to vary at the regional and local scales and are better defined at both the local and phenomenon levels. Early extreme warm events were hotter, and those at locations with longer local warm seasons demonstrated higher intensities. ECDs tended to be more frequent at coastal locations, whereas ECNs were more frequent over southwestern Arabia. Early and late extreme cold events were much colder than those occurring mid-season. Trend analyses revealed generally increasing regional trends in the frequency of extreme warm events, whereas extreme cold events have declined. The duration (i.e., consecutive occurrences) and intensity of EWNs have been increasing at more locations, suggesting that urgent attention is needed within such an arid and hot climate type in which nighttime stress relief is already very limited.

Derivation of High-Resolution Meteorological Parameters for Use in Airport Wind Shear Now-Casting Applications

Methods for now-casting adverse weather conditions with the potential to cause disruption to aircraft landings often make use of real-time measurements at high temporal resolution. This paper describes processing methodologies developed to derive meteorological parameters from such measurements recorded in the vicinity of Hong Kong International Airport, specifically a radiometer in King’s Park, a wind profiler and surface anemometer on Cheung Chau Island and weather buoys in the Pearl River estuary. These parameters are suitable for use as input to a now-casting application of the computationally efficient airflow model, FLOWSTAR, which has previously been shown to predict mountain waves generated by flow over Lantau Island to the southeast of the airport. Radiosonde data from King’s Park have been used to test the radiometer processing method; the novel approach of using minimum and maximum potential temperature deviations from a series of height-dependent linear profiles to derive radiometer inversion layer parameters generates data that compares well with values derived from corresponding radiosonde profiles. Mountain wave strength depends on the magnitude of wind speed in the inversion layer; wind profiler data can be used to estimate typical and maximum wind speeds and associated wind directions using estimates of inversion layer depth derived from the radiometer data. With estimates of surface sensible heat flux appropriate for the airport’s coastal location calculated using a marine boundary layer scheme, a dataset of meteorological parameters at 20-min resolution has been derived for input into the FLOWSTAR model. The combination of automated meteorological data processing methods and flow field modelling has the potential to form part of a now-casting system for determining strong wind shear conditions at the airport.

Perception, knowledge and attitudes towards environmental issues and management among coastal users of the most important beach destination in Argentina

This study was designed to address coastal users' perception in the largest seaside summer resort in Argentina regarding beach physical features and quality assessments, including issues related to the impacts of marine pollution, particularly litter on local beaches. We also explore the dependence of answers in certain traits of coastal users' profile (i.e. users’ age, gender and residence status). There was a strong relationship of predictor variables pertaining to the respondents' profile on the users' perception about environmental related aspects as well as beach quality assessment related topics. Virtually all respondents stated acknowledging that pollution by beach litter harms marine aquatic life, with plastics being the most commonly identified litter item. Interestingly, though, the users' perception about topics related to beach litter was not affected by residence status, gender or age. Addressing the issues linked to responsible and sustainable use of the environment in coastal localities in northern Argentina like Mar del Plata should include the participation of beachgoers, as these can help to improve beach management plans and assist managers and stakeholders identifying key issues in environmental policy to be implemented by coastal jurisdictions.

An Extreme High Temperature Event in Coastal East Antarctica Associated With an Atmospheric River and Record Summer Downslope Winds

AbstractHigh surface temperatures are important in Antarctica because of their role in ice melt and sea level rise. We investigate a high temperature event in December 1989 that gave record temperatures in coastal East Antarctica between 60° and 100°E. The high temperatures were associated with a pool of warm lower tropospheric air with December temperature anomalies of >14°C that developed in two stages over the Amery Ice Shelf. First, there was near‐record poleward warm advection within an atmospheric river. Second, synoptically driven downslope flow from the interior reached unprecedented December strength over a large area, leading to strong descent and further warming in the coastal region. The coastal easterly winds were unusually deep and strong, and the warm pool was advected westwards, giving a short period of high temperatures at coastal locations, including a surface temperature of 9.3°C at Mawson, the second highest in its 66‐year record.

Were prehistoric coastal sites more intensively occupied than inland sites? Using an agent-based model to understand the intensity of prehistoric coastal occupation, and what it means for studies on the evolution of the coastal adaptation

The origins and significance of an aquatic diet in hominin evolution is a scientific research topic of high significance. Some have argued that marine shellfish collection was a key ingredient in the emergence of modern human behavioral and cultural complexity. The collection of marine resources, which can be productive and predictable, may have evolved into a coastal adaptation that led to reduction in residential mobility and other important changes in behavior and culture. Therefore, studying the emergence and intensity of coastal occupations is important to understand the rise of this particular aspect of modern humans' behavioral and cultural evolution. In this article, we use an agent-based model to explore the interaction between foraging behavior and the environment, and the impact of such interaction on sites' length of occupation, which in turn affects the accumulation of artifacts and ecofacts. The results of the model suggest that the intensive occupation of coastal sites is likely to be influenced by their position within a restricted band of productive coastal habitat. Even when foragers spend most of their time in other habitats, the cyclical reoccupation of coastal sites – due to the coast's cyclical productivity as well as the low number of locations that can be occupied there – could naturally result in higher artifact density in coastal than inland sites. Here, we argue that, given those results, coastal locations should accumulate large and dense deposits of occupation debris. These will be obvious features on the landscape and should be easier to find than inland occupations because of the coastal habitats' confined space. Finally, given the higher find densities of those sites, this may lead archaeologists to overestimate the contribution of marine resources in prehistoric diets. Therefore, what archaeologists have interpreted as intensive coastal adaptation in the past may be more the result of geographical constraints rather than important evolutionary changes.

Evaluation of machine learning models for predicting daily global and diffuse solar radiation under different weather/pollution conditions

Due to the rapid development of solar energy and photovoltaic industries in China, it is crucial to provide the reliable and accurate solar radiation predictions. In this work, three commonly used machine learning models for predicting global and diffuse solar radiation were assessed in eight Chinese cities, representing different geoclimatic and pollutant conditions. According to the results; regarding the nRMSE, nMAE, nMBE and R values, coastal locations (such as Shanghai, Guangzhou, etc.) obtained higher values than inland locations (such as Lanzhou and Wuhan). Moreover, the SVM (support vector machine) highly outperformed the other models in all locations, regardless of whether the study area was arid, semiarid, semihumid or humid, followed by GLMNET (generalized linear modeling) and RF (random forest). In addition, when assessing the SVM in different locations under different climatic and pollution conditions, it was indicated that the accuracy of solar radiation prediction was closely related to the weather and pollution condition levels. In general, the global solar radiation prediction error was in line with the weather condition levels. The prediction error increased as the weather level increased. However, the relationship between the pollution condition levels and the global solar radiation prediction showed a non-linear relationship. Moreover, for the prediction results of diffuse solar radiation, its variation law with different weather and pollution condition levels was almost different from that of global solar radiation. The maximum high error occurrence probability of global solar radiation and diffuse solar radiation appeared at pollution levels 5 and 1, respectively. Overall, the SVM model demonstrated its reliability in radiation prediction under slight pollution and stable weather conditions. This is crucial in locations with scarce meteorological data and can be used to optimize the selection of geographical locations for photovoltaic power station construction.

Seawater browning alters community composition and reduces nutritional quality of plankton in a subarctic marine ecosystem

Inflows of coloured terrestrial organic matter cause seawater browning and reduced phytoplankton production in subarctic coastal ecosystems, potentially deteriorating the nutritional quality of marine food webs. We analyzed the fatty-acid (FA) compositions of seston and the zooplankton taxa Eurytemora affinis and cladocerans at three locations of the northern Baltic Sea. At the coastal and northerly locations, salinity and phosphorus concentrations were low, while concentrations of humic substances (i.e., terrestrial organic matter) were high. The southerly location showed the opposite trend. The ratio between alga-specific ω3 polyunsaturated FA and terrigenous monounsaturated FA (MUFA) in Eurytemora decreased from south to north, as did the ratio between the alga-specific docosahexaenoic acid (DHA) and terrigenous MUFA in cladocerans. With increasing humic substances, the biomass of DHA-rich phytoplankton decreased and the zooplankton MUFA content increased. Our results indicate that coloured terrestrial organic matter alters the phytoplankton composition, consequently affecting the zooplankton nutritional quality.

Nitrogen Isotope Sclerochronology—Insights Into Coastal Environmental Conditions and Pinna nobilis Ecology

Pinna nobilis is a large bivalve endemic to the Mediterranean Sea that lives in shallow coastal areas. Due to its size and relatively fast shell growth rates, it is an interesting taxon for high-resolution study of nitrogen isotopes of carbonate bound organic matter (δ15NCBOM). In this study we tested if P. nobilis shells can be used as an indicator of the nitrogen isotope baseline of the system, if it can provide high-resolution data on environmental δ15N variability, and if the chemical properties of the shell and biomineralization process change in response to mass mortality events spreading in the Mediterranean. Shells were opportunistically collected during 2019 and 2020 by skin diving, as a part of a project on mortality monitoring, from four shallow coastal localities in the eastern Adriatic. Shell powder for δ15NCBOM analysis was collected by milling sample swaths from the internal (low-resolution) and external (high resolution) shell surface. Significant differences in δ15NCBOM, obtained from the internal shell surface, were observed between sampling localities with different anthropogenic influences, with lowest values (∼3–4‰) recorded for shells obtained from Pag Bay, and highest (∼6–8‰) for shells sampled in Lim and Kaštela Bays. High-resolution samples from the external shell surface of Pinna nobilis showed spatial and temporal variations in δ15NCBOM values, with temporal resolution of 1–3 weeks. High-resolution δ15NCBOM data obtained from the shell Kas1 corresponded to a time interval from spring 2018 to summer 2019 and had a pronounced increase of δ15NCBOM values closest to the shell margin coupled with a decrease in δ13Cshell values, indicating that this animal was experiencing stressful conditions several months prior to its death. According to our findings, δ15NCBOM values from P. nobilis shells can serve as an indicator of the isotopic baseline of the ecosystem potentially as a powerful tool to study bivalve physiology.

Using Stakeholders’ Perception to Evaluate the Prospects of Establishing Marine Protected Areas in the Niger Delta Coastal Ecosystem

This study assesses the Political, Economic, Social, Technical, Legal, and Environmental (PESTLE) factors for establishing Marine Protected Areas (MPAs) in the Niger Delta coastal waters. Interview and questionnaire methods were used to collect the needed information from locals and environmental experts. The locals include fishermen from four (4) coastal locations in the Niger Delta while experts include relevant government institutions, researchers, and Non-Governmental Organizations (NGOs). Data collected from the survey were analyzed and used to determine the state of 18 PESTLE sub-criteria, and Analytical Hierarchical Process (AHP) was used to find the sub-criteria weights (importance). The stakeholder’s perceptions on potential MPAs were analyzed and compared with Relative Importance Index (RII). Results show stakeholders agree more on the prioritization of MPA implementation criteria and expected benefits but agree less on the MPA objectives and beneficiaries. Environmental prospects for MPAs in the Niger Delta have the highest performance score and vice versa for the political and technical capacity for MPA implementation and management. The study concludes Niger Delta has potentials for MPAs which can be achieved through addressing the identified weaknesses and threats.

Thermohaline Temporal Variability of the SE Mediterranean Coastal Waters (Israel) – Long-Term Trends, Seasonality, and Connectivity

The high variability of coastal waters together with the growing need for assessing the state of the marine coastal ecosystem, require continuous monitoring at exceptional resolution and quality, especially during the Anthropocene changing seas. We perform a comprehensive analysis of a decadal (March 2011 to June 2021) thermohaline variability of the East Levantine Basin (LB) coastal waters (continuous measurements), its predominating temporal trends and their linkage with atmospheric forcing and advection. We identify statistically significant long-term warming and salinification trends with yearly rates of 0.048°C and 0.006, respectively. Through the use of the X11-ARIMA method temperature and salinity inter-annual trends are examined and associated with previously published open ocean dynamics as well as model reanalysis. We study the linkage between Northern and Southern coastal locations, and identify the along shore northward current as a primary cause of positive temperature anomalies arriving from the south. The coastal salinity long-term trend demonstrates a connection to local precipitation. A less coherent seasonal sequence is found with a bimodal behavior, where, salinity values drop in August on several summers. This drop is attributed to the intensification of the along shore current in the period of June-July, potentially advecting more Atlantic Water. The observations presented here emphasize the relatively strong coupling between coastal water and the open ocean, the influence of the general surface circulation of the LB on the coastal zone and the faster response time and higher sensitivity of the coastal environment to atmospheric forcing.

Water-soluble matter in PM2.5 in a coastal city over China: Chemical components, optical properties, and source analysis

Although marine and terrestrial emissions simultaneously affect the formation of atmospheric fine particles in coastal areas, knowledge on the optical properties and sources of water-soluble matter in these areas is still scarce. In this work, taking Qingdao, China as a typical coastal location, the chemical composition of PM2.5 during winter 2019 was analyzed. Excitation-emission matrix fluorescence spectroscopy was combined with parallel factor analysis model to explain the components of water-soluble atmospheric chromophores of PM2.5. Our analysis indicated that NO3−, NH4+ and SO42− ions accounted for 86.80% of the total ion mass, dominated by NO3−. The ratio of [NO3−]/[SO42−] was up to 2.42 ± 0.84, suggesting that mobile sources play an important role in local pollutants emission. The result of positive correlation between Abs365 with K+ suggests that biomass burning is an important source of water-soluble organic compounds (WSOC). Six types of fluorophores (C1-C6), all humic-like substances, were identified in WSOC. Humification index, biological index and fluorescence index in winter were 1.66 ± 0.34, 0.51 ± 0.44 and 1.09 ± 0.78, respectively, indicating that WSOC in Qingdao were mainly terrestrial organic matters. Overall, although the study area is close to the ocean, the contribution of terrestrial sources to PM2.5, especially vehicle exhaust and coal combustion, is still much higher than that of marine sources. Our study provides a more comprehensive understanding of chemical and optical properties of WSOC based on PM2.5 in coastal areas, and may provide ground for improving local air quality.