Burial of microplastics in freshwater sediments facilitated by iron-organo flocs

Microplastics are ubiquitous in standing freshwater bodies, consequently lakes and reservoirs may be important sinks for these contaminants. However, the mechanisms governing the deposition of microplastics and their interactions with the sediments are understudied. We demonstrate how aggregation-based transport facilitates the sinking and infiltration of buoyant microplastics into freshwater reservoir sediments by employing experiments with intact sediment cores. Buoyant polyethylene microplastics were rapidly (1–4 h) incorporated into sinking iron-organic aggregates, followed by swift deposition into sediments. Ingression of microplastic bearing flocs into sediments was completed within 6 days and led to stable deposition of the incorporated particles for at least 2 months. Most microplastics were deposited in the top 2 cm of the sediments and few particles (5–15%) were re-released into the water. Our results show at least 85% burial of microplastics, indicating the significant role of freshwaters with low flow velocities in reducing microplastic loads to the oceans.

Socio Economic Factors Responsible for Groundwater Consumption in Purba Bardhaman District of West Bengal

Groundwater is the biggest freshwater reservoir in the world. More than 95% of the unfrozen water comes from groundwater. Factors responsible for groundwater consumption by rice growers have been included in the study. For the study, Purba Barddhaman district was selected purposively considering the pattern of agriculture and extent groundwater use in the state. One community development block from the district has selected based on crop diversity, type of irrigation, amount of water extraction for irrigation purposes. From the selected block a big parcel of cultivating land (Math) were again selected randomly keeping the consideration of homogeneity in lad type, soil type, type of crops, variety and seasons. Farmers’ knowledge level, farmers’ attitude towards irrigation, economic motivation, improved water extraction mechanism and method of irrigation are the major contributing factors in predicting the amount of groundwater consumption when crop and land situation are constant.

Bioaccumulation of PCBs and PBDEs in Fish from a Tropical Lake Chapala, Mexico

Lake Chapala is the largest natural freshwater reservoir in Mexico and the third largest lake in Latin America. Lakes are often considered the final deposit of polluting materials; they can be concentrated in the organisms that inhabit them, the water, and the sediments. The PCBs and PBDEs are environmental pollutants highly studied for their known carcinogenic and mutagenic effects. PCB and PBDE bioaccumulation levels were determined in Chirostoma spp., Cyprinus carpio, and Oreochromis aureus. In addition, we monitored the concentrations of PCBs and PBDEs in sediment and water from Lake Chapala were monitored. Samples were collected during two periods, in October 2018 and May 2019. The samples were analyzed by gas chromatography coupled with mass spectrometry. Two bioaccumulation factors were determined in fish, one in relation to the concentration of PCBs and PBDEs in sediments and the other in relation to the concentration of PCBs and PBDEs in water. The PCB levels were 0.55–3.29 ng/g dry weight (dw) in sediments, 1.43–2.98 ng/mL in water, 0.30–5.31 ng/g dw in Chirostoma spp., 1.06–6.07 ng/g dw in Cyprinus carpio, and 0.55–7.20 ng/g dw in Oreochromis aureus. The levels of PBDEs were 0.17–0.35 ng/g dw in sediments, 0.13–0.32 ng/mL in water, 0.01–0.23 ng/g dw in Chirostoma spp., 0–0.31 ng/g dw in Cyprinus carpio, and 0.1–0.22 ng/g dw in Oreochromis aureus. This study provides information for a better understanding of the movement, global distribution, and bioaccumulation of PCBs and PBDEs. The results show that the fish, water, and sediments of Lake Chapala are potential risks to the biota and the local human population.

Analysis of the Snow Cover Area of the Gangotri and Surrounding Glaciers using Remote Sensing and GIS

Himalayas has one in every of the biggest resources of snow and ice, which act as a freshwater reservoir for all of the rivers originating from it. Monitoring of these sources is vital for the assessment of availability of water within the Himalayan Rivers. The mapping of Glaciers could be very tough undertaking due to the inaccessibility and remoteness of the terrain. Faraway sensing techniques are regularly the simplest way to research glaciers in remote mountains and to monitor a large range of glaciers in multitemporal manner. This paper presents the results obtained from the analysis of 5 set of Landsat 8 Band 3 - Green and Band 6 - SWIR 1 images from year 2017 to 2021 for the monitoring and analysis of approx 76% of Gangotri and Surrounding Glaciers (GSG) main snow covered area. It is seen in the analysis that there has been a down fall around 85 sq km of the Snow Cover of the Gangotri and Surrounding Glacier and Surrounding Glaciers (GSG) Area in the years of 2018 and 2019 respectively from the year 2017. In 2020 huge recovery has occurred with a drastic increase in snow cover area by approximately the same amount which has been previously depleted. After 2020, it seems that a gradual drop of 27 sq km occurred in 2021. Calculation shows a dip of 14.91% of snow cover area from 2017 to 2018 of the Gangotri and Surrounding Glaciers (GSG) which was recovered to original level in 2020. Slight dip of around 4.88% occurred in the current year 2021.

Characterization of Bacterial Communities From The Surface And Adjacent Bottom Layers Water of Billings Reservoir

Here, we describe the microbial diversity and physicochemical properties in freshwater samples from the surface and bottom layer of Billings reservoir in São Paulo state, Brazil. Twenty-two matched samples were characterized using the 16S rRNA gene Illumina MiSeq platform. Taxonomical composition revealed an abundance of Cyanobacteria phyla, followed by Proteobacteria, with 1903 and 2689 known bacterial genera in the surface and deep-water layers, respectively. Chroobacteria, Actinobacteria, Betaproteobacteria, Alphaproteobacteria, Sphingobacteriia, and Acidimicrobiia were the most dominant classes. Shannon diversity index ranging from 2.3 - 5.39 and 4.04 - 6.86 in the surface and bottom layer, respectively. Among the diverse pathogenic genera identified, Flavobacterium was the most predominant genus. Temperature and phosphorus concentration were among the most influential factors in shaping the microbial communities of both layers. Predictive functional analysis suggests that the reservoir is enriched in motility genes involved in the flagellar assembly. The overall results present new information on the significantly altered diversity composition of the bacterial community detected in Billings freshwater reservoir.

Evidence of Anthropogenic Gadolinium in Triangle Area Waters, North Carolina, USA

Gadolinium (Gd), a member of the rare earth elements (REE), is becoming an increasingly observed microcontaminant in waters of developed regions. Anthropogenic Gd anomalies were first noted in 1996 and were determined to be sourced from Gd-based contrast agents used in magnetic resonance imaging (MRI). This study investigates Gd anomalies in North Carolina’s Triangle Area, focusing on surrounding wastewater treatment plants (WWTPs). Samples were obtained from upstream and downstream of selected WWTPs as well as a freshwater reservoir that supplies part of the region’s drinking water. The PAAS-normalized samples indicate Gd anomalies in the influent, effluent, and downstream samples. We quantify the anthropogenic Gd in wastewater samples to constitute between 98.1% to 99.8%. Sample comparisons show an average increase of 45.3% estimated anthropogenic Gd between samples upstream and downstream of WWTPs. This research contributes to the existing database demonstrating the presence of anthropogenic Gd in developed regions. Although current Gd concentrations are not near toxic levels, they should be continuously monitored as a micropollutant and serve as a wastewater tracer.

Molecular Identification of an Invasive Sarotherodon Species from the Atchakpa Freshwater Reservoir (Ouémé River Basin, Benin) and Comparison within S. melanotheron Using COI Markers

The Atchakpa freshwater reservoir (Ouémé Basin, Benin) was found to harbour an unexpected population of a cichlid species that was presumed to be Sarotherodon melanotheron. This species became dominant in the reservoir and became the main fisheries target species. We applied DNA barcoding to identify this population. Besides specimens from the reservoir, we also sequenced S. melanotheron from its native range in Benin at the lower Ouémé and Sô Rivers, and from Lake Nokoué, and Porto-Novo Lagoon. High sequence similarity indicated that all specimens were conspecific. Hence, we cannot exclude that a natural range extension led to the presence of the species in the reservoir. A comparison with sequences from NCBI GenBank confirmed that all samples belonged to the subspecies S. m. melanotheron, which is native to Benin. This comparison also showed that this subspecies was previously introduced in the Philippines. We call for further studies to investigate the socioeconomic, ecological and environmental impacts of the species in the Atchakpa reservoir.