Microplastics identification in water by TGA-DSC Method: Maharloo Lake, Iran

Nowadays, one of the biggest challenges is the lack of coordination between the microplastic identification methods used by researchers. To advance our global understanding of microplastic contamination and address the knowledge gaps, we require acceptable or similar identification methods or instruments designed to support the quantitative characterization of the microplastics data. In the current study, we focused on the thermogravimetric analysis (TGA) with differential scanning calorimetry (DSC) method which is usually used experimentally by other researchers, while we tried to look at this method in a real aquatic environment, Maharloo Lake and its Rivers. A number of 22 sites were chosen for sampling microplastics from water. The mean and median of total organic matter percentage for rivers samples (mean = 88%;median = 88%) was similar to the Maharloo lake (mean = 88.33%; median = 89%), suggesting the existence of a robust potential sink. The differentiation of the organic matter part into labile (e.g., carbon aliphatic and polysaccharides), recalcitrant (e.g., aromatic compounds and most plastics), and refractory fractions was implemented and the results indicated that labile organic matter was dominant in both the lake and the rivers, while recalcitrant and refractory fractions were lower. The river's average labile and refractory fractions were similar to the lake. Although the overall results of the study show combining TGA techniques with other analytical procedures can improve the technical quality of polymers, interpreting the complex information of those measurements requires a high level of expertise and the technology is still maturing.

Microplastics captured by snowfall: A study in Northern Iran

Samples of fresh snow (n = 34) have been collected from 29 locations in various urban and remote regions of northern Iran following a period of sustained snowfall and the thawed contents examined for microplastics (MPs) according to established techniques. MP concentrations ranged from undetected to 86 MP L^-1 (mean and median concentrations ~20 MP and 12 MP L^-1, respectively) and there was no significant difference in MP concentration between sample location type or between different depths of snow (or time of deposition) sampled at selected sites. Fibres were the dominant shape of MP and μ-Raman spectroscopy of selected samples revealed a variety of polymer types, with nylon most abundant. Scanning electron microscopy coupled with energy-dispersive X-ray analysis showed that some MPs were smooth and unweathered while others were more irregular and exhibited significant photo-oxidative and mechanical weathering as well as contamination by extraneous geogenic particles. These characteristics reflect the importance of both local and distal sources to the heterogeneous pool of MPs in precipitated snow. The mean and median concentrations of MPs in the snow samples were not dissimilar to the published mean and median concentrations for MPs in rainfall collected from an elevated location in southwest Iran. However, compared with rainfall, MPs in snow appear to be larger and more diverse in their shape and composition (and include rubber particulates), possibly because of the greater size but lower terminal velocities of snowflakes relative to raindrops. Snowfall represents a significant means by which MPs are scavenged from the atmosphere and transferred to soil and surface waters that warrants further attention.

Microplastic sampling techniques in freshwaters and sediments: a review

Pollution by microplastics is of increasing concern due to their ubiquitous presence in most biological and environmental media, their potential toxicity and their ability to carry other contaminants. Knowledge on microplastics in freshwaters is still in its infancy. Here we reviewed 150 investigations to identify the common methods and tools for sampling microplastics, waters and sediments in freshwater ecosystems. Manta trawls are the main sampling tool for microplastic separation from surface water, whereas shovel, trowel, spade, scoop and spatula are the most frequently used devices in microplastic studies of sediments. Van Veen grab is common for deep sediment sampling. There is a need to develop optimal methods for reducing identification time and effort and to detect smaller-sized plastic particles.

Scientific studies on microplastics pollution in Iran: An in-depth review of the published articles

This literature review was conducted to collect present data on microplastics pollution in Iran's ecosystems. Most of the studies performed in aquatic environment were conducted in Persian Gulf & Oman Sea (70%). The Persian Gulf, along with the beaches of Bushehr and Hormozgan Provinces, are the most studied areas. Moreover, most of the studies were conducted in aquatic environments and only four studies were conducted in terrestrial environment (4/42). One study has assessed microplastics in commercial salt and another study has reported the microplastics presence in Iranian bottled mineral water brands. The investigation of microplastics associated with biota was highlighted, customarily for fish species. Microplastics were also present in urban wastewater samples in Sari and Bandar Abbas cities. Three studies were performed in freshwater ecosystems until now (Haraz River, Anzali wetland, and Taleqan dam). The need for further studies in this field still exists, especially in terrestrial and freshwater compartments.