How many microplastics do you need to (sub)sample?

Analysis of microplastics in the environment requires polymer characterization as a confirmation step for suspected microplastic particles found in a sample. Material characterization is costly and can take a long time per particle. When microplastic particle counts are high, many researchers cannot characterize every particle in their sample due to time or monetary constraints. Moreover, characterizing every particle in samples with high plastic particle counts is unnecessary for describing the sample properties. We propose an a priori approach to determine the number of suspected microplastic particles in a sample that should be randomly subsampled for characterization to accurately assess the polymer distribution in the environmental sample. The proposed equation is well-founded in statistics literature and was validated using published microplastic data and simulations for typical microplastic subsampling routines. We report values from the whole equation but also derive a simple way to calculate the necessary particle count for samples or subsamples by taking the error to the power of negative two. Assuming an error of 0.05 (5 %) with a confidence interval of 95 %, an unknown expected proportion, and a sample with many particles (> 100k), the minimum number of particles in a subsample should be 386 particles to accurately characterize the polymer distribution of the sample, given the particles are randomly characterized from the full population of suspected particles. Extending this equation to simultaneously estimate polymer, color, size, and morphology distributions reveals more particles (620) would be needed in the subsample to achieve the same high absolute error threshold for all properties. The above proposal for minimum subsample size also applies to the minimum count that should be present in samples to accurately characterize particle type presence and diversity in a given environmental compartment.

Urban tropical freshwater ponds as microplastics hotspots-insight on abundance and characteristics using an improved sampling technique

This study elucidates the distribution and characteristics of microplastics (MPs) in 20 tropical freshwater ponds, located in the urban settlement of Raipur city in state of Chhattisgarh, India. The ponds were divided into 4 groups based on the habitat types to understand the influence of land use patterns and human activity on the distribution of MPs. Here, we provide an improved sampling technique that is economical, traditional, indigenous, independent of vessels or structures, and replicable for smaller waterbodies. The efficiency of the proposed method is closer to the traditional boat-based net sampling technique. MPs are ubiquitous in surface water samples of all 20 ponds. The average abundance of MPs was 2.52 ± 1.28 particles/L for bucket samples and 2.93 ± 1.34 particles/L for net samples. Among extracted MPs, fragments, films, and foams were dominant. MPs within size class 1 mm to 500 μm were prevailing for both bucket samples and tube-net samples. Color-wise, white/transparent and black MPs were abundant in both types of samples while the majority of MPs were polyethylene and polystyrene. The tube-net sampling method is economical and replicable and provides comparable results. This can help study MPs distribution in smaller inland waterbodies where boats and structures are not readily available to conduct net sampling. We provide the first insight into the distribution of MPs in urban ponds, and the results can be used to determine the ubiquity of MPs in urban ponds located in different regions of the subcontinent.

Microplastics in Landfills: A Comprehensive Review on Occurrence, Characteristics and Pathways to the Aquatic Environment

Microplastics, a multi-dimensional environmental stressor group, capable of transboundary migration, are a threat to the global ecosystem. Transboundary migration of microplastics across all environmental matrices is known to originate from a multitude of sources and acts in conjugation with each other. This inter-dependence of sources calls for a detailed scientific analysis of all the sources that are in play. Waste management facilities have already been established as a significant contributor of microplastics to the aquatic and terrestrial environment. A systematic overview of the scientific literature reveals that the existing body of scientific knowledge is mainly focused on wastewater treatment facilities as a source/pathway of microplastics in the environment. Recently the focus shifted towards solid waste management facilities through landfills. Poor plastic waste management practices made discarded plastics the most dominant component of solid wastes. This review elucidates the occurrence and distribution of microplastics, characteristics of microplastics, including size, shapes, colors, and polymer types, in leachate and refuse of landfills. Furthermore, we discussed the transport mechanisms and pathways used by microplastic present in landfills to migrate to subsurface or groundwater and adjacent aquatic bodies. Last, based on the findings, we summarized the gaps in existing studies and suggested future perspectives to be focused on the future. The abundance of microplastics is attributed to the volume of plastic waste in landfills, management of leachate originating from landfills, application of leachate, and age of landfills. Microplastics abundance and characteristics vary in leachate and refuse. Smaller microplastics are predominant in leachate while larger microplastics are predominant in refuse. Landfills are capable of generating secondary microplastics from fragmentation and degradation. Further studies on microplastics in landfills are necessa

A massive rock and ice avalanche caused the 2021 disaster at Chamoli, Indian Himalaya

On 7 February 2021, a catastrophic mass flow descended the Ronti Gad, Rishiganga, and Dhauliganga valleys in Chamoli, Uttarakhand, India, causing widespread devastation and severely damaging two hydropower projects. More than 200 people were killed or are missing. Our analysis of satellite imagery, seismic records, numerical model results, and eyewitness videos reveals that ~27 × 10⁶ cubic meters of rock and glacier ice collapsed from the steep north face of Ronti Peak. The rock and ice avalanche rapidly transformed into an extraordinarily large and mobile debris flow that transported boulders greater than 20 meters in diameter and scoured the valley walls up to 220 meters above the valley floor. The intersection of the hazard cascade with downvalley infrastructure resulted in a disaster, which highlights key questions about adequate monitoring and sustainable development in the Himalaya as well as other remote, high-mountain environments.

Biallelic mutations in FLNB cause a skeletal dysplasia with 46,XY gonadal dysgenesis by activating β-catenin

Filamin B (FLNB) functions as a switch that can affect chrondrocyte development and endochondral bone formation through a series of signaling molecules and transcription factors that also affect Sertoli cell development. Here, we report a subject with a novel skeletal dysplasia and co-existing 46,XY gonadal dysgenesis and biallelic mutations in FLNB. Whole exome sequencing was performed to identify mutations. Quantitative polymerase chain reaction (qPCR) and flow variant assays were performed to quantify RNA, proteins and phosphorylated proteins. The TOPFLASH reporter was performed to quantify β-catenin activity. Mutations were identified in the FLNB gene (FLNB:p.F964L, FLNB:p.A1577V). These mutations increased binding of FLNB protein to the MAP3K1 and RAC1 signal transduction complex and activated β-catenin and had different effects on phosphorylation of MAP kinase pathway intermediates and SOX9 expression. Direct activation of β-catenin through the FLNB-MAP3K1-RAC1 complex by FLNB mutations is a novel mechanism for causing 46,XY gonadal dysgenesis. The mechanism of action varies from those reported previously for loss of function mutations in SOX9 and gain-of-function mutations in MAP3K1.

Congenital Myotonic Dystrophy

We describe a case of severe congenital myotonic dystrophy (CDM). A 38-year-old primigravida, who was known to suffer from mild myotonic dystrophy (DM), conceived spontaneously and booked for confinement at 11 weeks in our unit. The couple had been fully counseled about the risks of transmission of this condition to their offspring before embarking on this pregnancy. Despite being fully aware of the risks, they declined prenatal diagnosis. The pregnancy was monitored by serial ultrasound scans. The diagnosis of CDM was suspected by ultrasound markers of borderline ventriculomegaly, polyhydramnios, and reduced fetal movements. The pregnancy ended prematurely at 33 weeks in an emergency caesarean section because of severe fetal compromise. The neonate died almost immediately after birth. The genetic analysis of cord blood confirmed severe DM. This case highlights the importance of ultrasound markers for the diagnosis of CDM in the absence of definitive prenatal diagnosis.