Investigating the heterogeneous distribution pattern of plastic pollution in river systems is useful for better understanding the transport pathways of plastics from land to sea. Therefore, we analyzed samples from 17 sites to evaluate the distribution pattern of microplastics (MPs) in Minjiang River Watershed. The MP concentrations ranged between 0.12 and 2.72 n/L, with higher microplastic concentrations located in urban areas with greater population and gross domestic product (GDP) densities. MP concentrations were positively correlated with population density, GDP density, and built-up land use percentage, suggesting that increasing urbanization level will lead to greater plastic pollution. MP concentrations spanning the upstream and downstream sides of the SK Hydropower Dam showed decreasing trends, suggesting that MP settling would occur behind the dam and Shuikou Reservoir might serve as a sink for MPs. This study provides useful insight for revealing the effects of urbanization and dams on spatial distribution of riverine MPs.

Three species of mangroves and six species of salt marshes were collected from various locations along the Tuticorin coast for the estimation of metals like Cu, Cd, Pb, and Zn. The bioaccumulation of metals in mangroves is in the order of Cu > Pb > Zn > Cd, and the season-wise accumulation was higher in monsoon followed by summer, post-monsoon, and pre-monsoon seasons. The accumulation of metals in mangroves showed higher in Rhizophoraapiculata followed by Avicenniamarina, and Rhizophoramucronata. The concentration of metals in salt marshes is in the order of Pb > Zn > Cu > Cd, and the species-wise accumulation showed in the order of Suaeda maritime > Ipomoea sp. > Suaeda sp. > Spinifix littoreous > Sesuvium portacastrum > Ipomoea pes-capras. BAF in salt marhes and mangroves is as Cd < Pb < Cu < Zn and Cd < Cu < Pb < Zn, respectively.

²¹⁰Po in marine sediment from three peri-urban creeks in Mombasa was analyzed by alpha spectrometry in order to determine its baseline contamination levels. The mean ²¹⁰Po activity in marine sediment from Mtwapa, Tudor and Makupa creeks were 18.67 ± 1.8, 21.17 ± 2.2 and 13.09 ± 1.6 Bq Kg⁻¹ dw, for surface sediment and 37.56 ± 2.14, 28.64 ± 2.86 and 30.42 ± 2.1 Bq Kg⁻¹ dw respectively, for sediment cores. Comparison of ²¹⁰Po activity in surface sediment indicated that ²¹⁰Po in the creeks could be originating from the same source. However, comparison of activities in the entire cores from the three creeks indicated that ²¹⁰Po sources could have been different in the past. ²¹⁰Po activities in this study were relatively elevated compared to marine environments under similar anthropogenic influence and there is need to understand its source and fate.

The human health risk assessment associated with accumulation of nickel (Ni), cadmium (Cd), chromium (Cr), lead (Pb) and copper (Cu) in the tissues (gills, livers and muscles) of grey mullet (Mugil cephalus) collected from the creek in the Niger Delta region of Nigeria was investigated. Surface water, sediment and fish samples were collected and analysed from June to September 2019; estimated daily intake (EDI), target hazard quotient (THQ) and hazard index (HI) were determined. The mean concentration (mg/kg ww) of the tested metals followed the sequence: Cu (33.48 ± 15.54) > Cd (24.62 ± 12.11) > Pb (10.59 ± 9.12) > Cr (0.43 ± 0.66); while Ni was not detected in the sampled tissues. The HI for male and female (adults) are 7.612 and 7.840 respectively, while male and female (children) are 9.567 and 10.842 respectively.

PURPOSE OF REVIEW: Cyanobacteria, commonly known as blue-green algae, are often seen as a problem. Their accumulation (bloom) in surface water can cause toxicity and aesthetic concerns. Efforts have been made in preventing and managing cyanobacterial blooms. By contrast, purposeful cultivation of cyanobacteria can create great opportunities in food, chemical and biofuel applications. This review summarises the current stage of research and the socio-economic impacts associated with both the problems and opportunities induced from the presence of cyanobacteria in surface water. RECENT FINDINGS: Insightful knowledge of factors that trigger cyanobacterial blooms has allowed for the development of prevention and control strategies. Advanced technologies are utilised to detect, quantify and treat cyanobacterial biomass and cyanotoxins in a timely manner. Additionally, understanding of cyanobacterial biochemical properties enables their applications in food and health industry, agriculture and biofuel production. Researchers have been able to genetically modify several cyanobacterial strains to obtain a direct pathway for ethanol and hydrogen production. Cyanobacterial blooms have been effectively addressed with advances technologies and cyanobacterial research. However, this review identified a knowledge gap regarding cyanotoxin synthesis and the relevant environmental triggers. This information is essential for developing measures to prevent cyanobacterial blooms. Additionally, this review affirms the promising opportunities that cyanobacteria offer in the food, cosmetics, pigments and agriculture. Biofuel production from cyanobacterial biomass presents an immense potential but is currently constrained by the cultivation process. Thus, future research should strive to achieve effective mass harvesting of cyanobacterial biomass and obtain a profound understanding of cyanotoxin production.

Previous studies indicate coastlines are at risk of wastewater contamination from injection wells, cesspools, and septic systems. In this study, common marine algae were used to ground-truth modeled loading of wastewater-derived N to coastlines of Oʻahu, Hawaiʻi. Macroalgae were collected and/or deployed at 118 sites and analyzed for tissue δ¹⁵N and N %. Wastewater source locations were used to estimate wastewater-derived N in groundwater with the modeling software MT3DMS/MODFLOW. Algal bioassays identified six coastal regions subjected to elevated wastewater-derived N loading. In a case study, submarine groundwater discharge (estimated by ²²²Rn mass balance) was related to wastewater loading from onsite sewage disposal systems (OSDS) and municipal wastewater injection wells in Waimānalo. The highest ²²²Rn-derived SGD rate and N flux were 21.4 m³/m/d and 62.6 g/m/d, respectively. The results of this study suggest that OSDS and injection wells discharge substantial volumes of wastewater and N across broad regions of coastal Oʻahu.

We report the presence of ‘plasticrusts’ and ‘pyroplastic’ from coastal habitats in Giglio island, Tyrrhenian Sea, Italy. These novel plastic debris types have only recently been described for the first time from Madeira island (NE Atlantic Ocean) and the United Kingdom, respectively. While ‘plasticrusts’ are generated by sea waves smashing plastic debris against intertidal rocks, ‘pyroplastic’ derives from (un)deliberately burnt plastic waste. Using Fourier-transform infrared (FTIR) spectroscopy, we identified the ‘plasticrust’ material as polyethylene (PE) and the ‘pyroplastic’ material as polyethylene terephthalate (PET). These polymers are widely used in everyday products and, therefore, contribute heavily to plastic pollution in aquatic and terrestrial environments worldwide. Furthermore, our field surveys suggest that ‘plasticrust’ abundance is related to wave-exposure and that the ‘pyroplastic’ derived from beverage bottles which we frequently found along the Giglio coast. Overall, our findings corroborate the notion that ‘plasticrusts’ and ‘pyroplastic’ are common debris types in marine coastal habitats.

The level of heavy metals (HMs) in coastal sediments has attracted the environmental researchers due to their persistence, abundance, biomagnification and toxicity. The present study was conducted to assess the contamination and ecological risk assessment of HMs in Jazan coastal sediments, Red Sea, Saudi Arabia utilizing pollution indices and multivariate statistical analyses. A total of 32 surface samples were collected for Cu, Sb, Zn, Cr, Cd, Pb, Fe, Co, Ni, Al, and total organic matter analysis using an atomic absorption spectrophotometer. The results indicate the following descending order of metal concentrations: Al > Fe > Cr > Cu > Zn > Ni > Co > Pb > Cd > Sb. Average level of Cd is significantly higher than those from many neighboring and worldwide coastal sediments; and recorded very severe enrichment, severe contamination and very high risk in the investigated sediments. The pollution indices and statistical analyses revealed that proportion of Zn, Fe, Ni, Cr, Al, Cu, Sb and Pb were formed from lithogenic sources of weathering Quaternary units and atmospheric deposition. Most of the Cd, Sb, and Pb levels were derived from anthropogenic sources of industrial, agricultural, and fishing activities. The higher contribution of organic matter may be attributed to the mangrove roots and organic fertilizers; and played a key role in adsorbing, transferring and accumulating of elements.