This study aims to reveal microplastic pollution. It is the first to be conducted in the South Aegean Region and one of the limited numbers of such studies in Turkey. To this aim, in September 2018 microplastic particles (MP's) pollution was evaluated on the sandy beaches along the coastline of the Datça Peninsula (Southern Aegean coast of Turkey) located at the intersection of the Aegean and Mediterranean Seas. MP's were analyzed using standard operating procedure along with some experimental techniques. Prior to the identification process, microplastics ranging from 1 to 5 mm were exposed to an experimental pre-treatment and efficient polymer scanning. The results showed that fragments (72%) were the dominant category from all the beaches exposed to dominant winds and surface currents and that MP contamination in the Datça Peninsula was higher than that reported in the literature from similar locations around the world (1154.4 ± 700.3 particles kg⁻¹ dw). More specifically the highest contamination was found in Aktur Beach (2073.3 ± 648.6 particles kg⁻¹ dw) which could be considered as a hotspot for the whole region in terms of MP pollution. As a result of the study, as sampling stations are remote from major cities and industrial zones, maritime activities increase during summer season and tar has been observed on particles during analyses, it can be asserted that the pollution may be caused by marine resources.

The complexity and scale of the sources, types and environmental impacts of persistent solid waste pollution (PSWP) continue to overwhelm the capabilities of government and private efforts to control it. Global cumulative production of virgin plastics is expected to quadruple by 2050 with a concomitant doubling of plastic waste. All nations must take significant steps to realize eventual mitigation of PSWP. These will include adopting a long-term PSWP elimination policy, creating an overarching authority to lead and coordinate a comprehensive national solid waste management program, and creating an International Convention for the Prevention of PSWP to enable global solutions for this global pollution. Initiating these changes will necessitate major, coordinated efforts on the part of environmental organizations, their supporting foundations and concerned citizens.

This research attempted to investigate the plant/soil concentration ratios (CRs) of ¹³⁷Cs and ⁴⁰K in plants that grow on the Anzali Lagoon of the Caspian coast, Iran. The activity concentrations of ¹³⁷Cs and ⁴⁰K were measured in soil samples, annual plants (Echinochloa crus-galli, Digitaria sanguinalis, and Trifolium repens), and perennial plants (Phragmites australis, and Cynodon dactylon). The relationship of activity concentration with soil particle density, and pH of soil samples, CR, and ¹³⁷Cs/⁴⁰K discrimination factor (DF) were determined. The activity concentration of ¹³⁷Cs in the soil, annual plants, and perennial plants ranged between 12- and 124 (Bq/kg dry weight), 2- and 17 (Bq/kg dw), and 2 - and 14 (Bq/kg dw), respectively. The geometric mean (GM) values of DF in annual and perennial plants were 0.57 and 0.55, respectively. The CR for ¹³⁷Cs and ⁴⁰K varied as a non-linear relation in annual plants and perennial plants. This study showed that the CRs for ¹³⁷Cs in annual plants were higher than the CRs for perennial plants.

Given the implications of microplastics contamination in aquatic ecosystems and information scarcity about microplastic abundances in estuarine sediments, this study aimed to quantify and describe the microplastics in the sublittoral sediments from Guanabara Bay. Sediment samples were collected at four sites and three months, microplastics were separated and classified according to type, color, size, and polymer composition. High abundances of microplastic (160 to 1000 items kg⁻¹ or 4367 to 25,794 items m⁻²) occurred independent of area or period, indicating microplastics are widely spread in Guanabara Bay. The dominant microplastic in the sediment was the translucent polyester microfiber of <1 mm size; which is a secondary microplastic, possibly coming from washing machines wastes. The extremely high availability of microplastics in Guanabara Bay, compared to the majority of studies around the world, suggests high risk of contamination to benthic organisms and demersal fish, as they may be ingesting microplastics.

The relative importance of organic nitrogen (ON) and inorganic nitrogen (IN) as nitrogen sources for the phytoplankton communities were studied through a seasonal time series of nitrogen species in the eastern Arabian Sea. Seasonal data on nitrogen species showed that ON dominates the system throughout the year and account for >90% of the total nitrogen (TN) during north east monsoon (NEM). The average ON concentration in the study region was 11.5 μM during NEM as compared to 7.2 μM during south west monsoon (SWM). The contribution of picoplankton to the total phytoplankton pool (fpico) increased from 19% during SWM to 36% in NEM. Along with cyanobacteria, the diatoms Thalassionema nitzchoides and Thalassiosira sp. and among the dinoflagellates Pronoctiluca sp. were found to proliferate in ON rich waters. We suggest atmospheric deposition, riverine-input, resuspension of bottom sediment and ground water intrusion as the possible sources of ON in the study region.

Arsenic (As) is a naturally occurring element in the Earth’s crust. Both anthropogenic and natural processes can release As into sources for drinking water supply. A substantial epidemiological evidence is available to support that the chronic exposure to high concentrations in drinking water (> 10 μg/L) is associated with several detrimental effects on human health including skin lesions [1] and cancer of the lung [2], bladder [3], kidney [4], and liver [4]. Furthermore, dermatological, developmental, neurological [5], respiratory [6], cardiovascular [7], immunological [8], and endocrine effects [9] as a result of chronic exposure to high As concentrations have been reported. However, there remains considerable uncertainty on the chronic risks due to As exposure at low concentrations (< 10 μg/L) and the shape of the dose-response relationship [10, 11]. It is therefore crucial to question whether the 10 μg/L limit ensures protection of human health from the adverse health effects of As.

In the last few years extreme weather events, including changes to storm frequency and intensity, have increased across all continents. In this note we assessed, for the first time in the Mediterranean Sea, the impact of a violent storm and consequent flood on offshore water contamination and benthic community along the Calabrian coast (Ionian Sea). Three sites (at 500, 1000, and 2000 m off the coast) were sampled along three parallel transects in 2013, 2014 (before), and 2015 (after the flood). After the flood, metals (especially Al, CrVI, Ni, Cu, Zn) in the water column increased in concentration. The flood affected the structure of the benthic community, causing a decrease of diversity, the dominance of few opportunistic species, and the decrease of M-AMBI values.

Estimates of marine debris are often based on beach surveys. Few studies have documented the veracity of these observations and the factors that may affect accuracy. Our laboratory-scale experiment identified potential sources of error associated with visual identification of marine debris (1–2 cm long) during shoreline surveys of sand beaches. Characteristics of the survey site (beach characteristics), observer (personal characteristics), and debris (color and size) may be important factors to consider when analyzing data from shoreline surveys. The results of this study show that the ability of individuals to accurately identify plastic fragments depends on the plastic and sand color, and density of shell fragments. Most suggestively, the high accuracy of blue plastic counts (95%) and the under-counting of white (50%) and clear plastic counts (55%) confirmed the hypothesis that a significant amount of clear and white plastic fragments may be missed during shoreline surveys. These results highlight the need for further research and possible modifications of visual shoreline survey methodologies in order to optimize this cost-effective method of marine debris monitoring.

The diversity of free-living dinoflagellates in the coastal areas of the central Red Sea, Saudi Arabia, was studied from April 2016 to March 2017. A total of 106 dinoflagellates belonging to 36 genera, 20 families and 7 orders were identified and characterized using light microscopy. Of these, 47 taxa were potentially harmful, and 60 taxa were recorded for the first time from the Red Sea. The unexpectedly high species diversity, including new records, was due to the benthic species. The monthly variability of planktonic species records exhibited negative correlations with temperature and salinity, although in most cases, the links between them were insignificant. Subsequently, the dinoflagellates checklist for the entire Red Sea was updated and showed that there were currently 395 taxa and 66 genera. The results of this study provide a solid foundation for future studies of dinoflagellate biodiversity in the Red Sea, particularly for benthic and harmful species.

There is a reasonably extensive body of literature recording mass loss of polyhydroxyalkanoates (PHAs) (a class of biodegradable plastics) in the natural marine environment. However, to date, this research has been very disparate. Thus, it remains unclear what the timeframe for the biodegradation of such marine biodegradable plastics actually is. The aim of this work was to determine the rate of biodegradation of PHA in the marine environment and apply this to the lifetime estimation of PHA products. This provides the clarification required as to what ‘marine biodegradation of PHA’ means in practicality and allows the risks and benefits of using PHA to be transparently discussed. It was determined that the mean rate of biodegradation of PHA in the marine environment is 0.04–0.09 mg·day⁻¹·cm⁻² (p = 0.05) and that, for example, a PHA water bottle could be expected to take between 1.5 and 3.5 years to completely biodegrade.