Surface Water Research Articles

A database of nutritional strategies of nanoplankton genera present in North American lake surface waters

A database of nutritional strategies of nanoplankton genera present in North American lake surface waters

The Interaction and Lift-Off Forces of an Atomic Force Microscope Tip from Single Fibers Extracted from Protective Clothing Fabric.

The widespread use of engineered nanoparticles (ENPs) poses a potential health hazard to humans, especially to those involved in either nanoparticle manufacturing or the usage and assembly of a final product. In this study, we performed systematic force vs distance experiments (F(z)) using an atomic force microscope (AFM) on fibers commonly used in street clothing and protective laboratory clothing to better characterize the relevant interaction forces between engineered nanoparticles (ENPs) and the contacted fabric fibers. The intent of this study is to identify those factors that influence the interaction of ENPs with fabrics with an aim to improve the efficacy of protective clothing against ENP exposure and mitigate potential health risks. A ∼14 nm diameter AFM SiOx tip (with nanoscale radius of curvature) is considered as an effective oxide ENP. Features present (or absent) in a well-executed F(z) AFM experiment provide a fingerprint that distinguishes the relevant forces and interaction mechanisms in play. Measurements of F(z) as a function of relative humidity were also performed to assess the importance of thin surface water layers in binding nanometer-size oxide ENPs to a fabric fiber. The F(z) data indicate the dominant mechanism for adhesion of the oxide tip to the various fabric fibers (cotton, Tyvek (HD polyethylene), polypropylene, and polyester) can be attributed to a van der Waals interaction. The analysis provides no evidence for long-range electrostatic forces or capillary-induced adhesion of the AFM tip to the fibers studied.

Distribution characteristics and pollution evaluation of heavy metals in surface water of a uranium tailing area based on spatial interpolation

Distribution characteristics and pollution evaluation of heavy metals in surface water of a uranium tailing area based on spatial interpolation

Assessing surface water quality for sustainable irrigation in Tarim Basin: a study in the summer irrigation period

Water quality in arid regions is a crucial determinant of sustainable social and economic development. Combining traditional hydrogeochemical methods with ordinary least squares (OLS) and geographically weighted regression modeling (GWR), the suitability of surface water irrigation in the summer irrigation period was investigated in the Tarim Basin. The results indicated that all water samples belonged to three types of water: SO4 Cl–Ca•Mg, SO4 Cl–Na, and HCO3–Ca Mg. A convergence phenomenon occurred under long-term irrigation conditions, showing a similarity between the salt composition of soils and surface irrigation waters. Although the current quality of surface water is generally suitable for irrigation, the process of reverse ion exchange has a more important effect on surface water bodies and soil salinity, thereby resulting in an increase in the Na-ion content of the soil and subsequently enhancing alkaline hazards. Both the OLS and GWR models unequivocally indicate that nitrate nitrogen primarily originates from natural weathering processes and that the sources of this material exhibit spatial heterogeneity across distinct regions. The construction of irrigation reservoirs to effectively deal with agricultural water shortages will lead to a deterioration in the quality of irrigation. The overall findings suggest that the water quality can meet the irrigation needs at present, but to ensure the sustainable use of water resources in arid regions, the increasing nitrogen concentration caused by human activities and the decline in water quality caused by reservoir construction need to be addressed in future irrigation management.

Chemical and Physical Denudation Rates in the Poços de Caldas Alkaline Massif, Minas Gerais State, Brazil

Chemical and physical denudation rates have been assessed in areas with different lithologies. Surprisingly, there are no studies that attempt to document these rates in the Poços de Caldas Alkaline Massif (PC), the largest alkaline magmatism in South America and an important Al supergene deposit in Brazil. Therefore, the chemical and physical denudation rates were assessed and explained in the PC. Surface water and rainwater samples were collected at the Amoras Stream basin, covering one complete hydrological cycle (2016). All samples were analyzed for dissolved cations, silica, anions, total dissolved solids (TDS), and total suspended solids (TSS). The results reflected the seasonal variation on discharge, water temperature, and electrical conductivity in the Amoras Stream, with most of the cations, anions, silica TDS, and TSS being carried in the wet season. Partial hydrolysis and silicate incongruent dissolution are the main water/rock interactions in the PC, with an atmospheric/soil CO2 consumption rate of 1.6 × 105 mol/km2/a. The annual fluxes of Cl−, PO43−, NO3−, and Al3+ were significantly influenced from rainwater. Chemical and physical weathering rates were 4 ± 0.8 and 3.0 ± 0.6 m/Ma in the PC, respectively, indicating that under the current climatic condition, the weathering profile is in dynamic equilibrium.

Toxic potential evaluation of liquid effluents discharged into nature by the university hospital centers (UHC) and mixed wastewater treatment station (WWTS) at Ouagadougou-Burkina Faso.

In Burkina Faso, several investigations have raised suspicions that hospital liquid effluents are the source of contaminants in porbeagle-culture products and surface water in urban and peri-urban areas. This study aimed to evaluate the hygienic quality of hospital liquid effluents discharged into nature by the UHC Bogodogo (UHC-BOG), Yalgado Ouédraogo (UHC-YO), and the WWTS of Kossodo (WWTS-KOS). Thus, 15 samples of liquid effluents (five per site) discharged into nature were collected. Within the physicochemical parameters, the pH, chemical oxygen demand (COD), biochemical oxygen demand (BOD5), suspended solids (TSS), conductivity, copper, iron, hafnium, silver, mercury, lead, and cadmium of these samples were determined using standard methods. The mean values of pH were 8.84 ± 0.42,8.06 ± 0.54, and 8.55 ± 0.53 for WWTS-KOS, UHC-BOG, and UHC-YO, respectively. Conductivity values were 1956.80 ± 81.30, 812.80 ± 45.22, and 956.00 ± 39.96 µS/cm, respectively. TSS were 338.20 ± 38.80, 45.00 ± 5.79, and 187.80 ± 27.58mg/L, respectively. COD were 274.80 ± 20.46, 35.00 ± 5.52, and 139.80 ± 25.53mg/L, respectively. BOD5 were 186.40 ± 68.68, 26.20 ± 4.82, and 81.80 ± 15.63mg/L, respectively. Mercury values were 1.93 ± 0.38, 4.04 ± 0.38, and 14.37 ± 1.65µg/L, respectively. Lead values were 434.70 ± 202.42, 310.50 ± 4.09, and 367.43 ± 94.01µg/L, respectively. Cadmium values were 79.59 ± 19.48, 109.94 ± 8.43, and 80.26 ± 7.85µg/L, respectively. Copper values were 27.66 ± 3.33, 30.84 ± 1.65, and 28.32 ± 2.36mg/L, respectively. Iron was detected only on the STEP-KOS with an average of 71.01 ± 37.83mg/L. Hafnium values were 50.27 ± 4.49 and 51.58 ± 4.61mg/L for WWTS-KOS and UHC-BOG, respectively. Silver values were 34.26 ± 3.06 for WWTS-KOS. On the three sites, the differences found were significant (p < 0.05). Liquid hospital effluents from Ouagadougou discharged into nature on the whole do not compile with the Burkinabè normative values for the discharge of wastewater into the environment.

Sediment ballast accelerates sinking of Alaska North Slope crude oil measured ex situ with surface water from Cook Inlet

Abstract Oil spilled into the ocean interacts with suspended matter forming aggregates that transport oil into subsurface layers and towards the bottom. We conducted a series of laboratory experiments to explore aggregation of oil with natural phytoplankton assemblages from Cook Inlet, Alaska at three times during a spring bloom. Oil and phytoplankton formed marine oil snow (MOS) that remained positively buoyant with a small fraction of MOS sinking to the bottom of our experimental bottles. Seawater treatments amended with suspended sediments formed oil-mineral aggregates (OMAs) with an oil capacity similar to MOS (~20% of aggregate area was covered with oil). OMAs accelerated oil sedimentation in our bottles relative to MOS sedimentation underlining the significance of suspended matter as ballast for sinking oil. Our results reveal potential transport mechanisms of oil in Cook Inlet which apply to other coastal systems with high productivity and sediment loads.&amp;#xD;

Predicting the Influence of Ammonium Toxicity Levels in Water Using Fuzzy Logic and ANN Models

The study aimed to address the complex and critical issue of surface water quality monitoring by proposing a diversified approach that incorporates a range of chemical indicators. (1) Background: the purpose of the study was to address the problem of surface water quality monitoring in relation to the toxic effects of ammonium on aquatic ecosystems by developing predictive models using fuzzy logic and artificial neural networks. (2) Water samples from the Styr River, influenced by the Rivne Nuclear Power Plant, were analyzed using certified standard methods and measured parameters, while fuzzy logic and artificial neural network models, including Mamdani’s algorithm and various configurations of activation functions and optimization algorithms, were employed to assess water quality and predict ammonium toxicity. (3) A fuzzy logic system was developed to classify water quality based on ammonia content and other parameters, and six Artificial Neural Network (ANN) models were tested, with the ANN#2 model (using ReLU activation and ADAM optimizer) showing the best performance. (4) This study emphasizes the critical need for precise monitoring and modeling of total ammonium in surface water, considering its variable toxicity and interactions with environmental factors, to effectively protect aquatic ecosystems, namely ichthyofauna.

Assessment of water mass distribution and intrusions of circumpolar deep water in the Amundsen Sea based on the ocean reanalysis product FOAM-GLOSEA5v13

The Amundsen Sea of West Antarctica is one of the regions of particularly interest to the oceanography community due to accelerated basal melting of its ice shelves. Quantitative estimates of the composition of water masses and their sources are essential for understanding the heat and salt budgets and the stability of ice shelves in this region. In this study, the water mass distributions on the Amundsen Sea continental shelf are estimated based on FOAM-GLOSEA5v13, a global oceanographic reanalysis product, using a modified statistical based optimal water mass analysis method. The reanalysis product effectively captures the signal of primary water masses, including the Winter Water (WW) and the Circumpolar Deep Water (CDW) below the Antarctic Summer Surface Water (SSW). The horizontal and vertical distributions and temporal evolution of three water mass endmembers (WW, CDW and DSW) and their mixing ratios are calculated, based on which an intrusion location detection method was established. Using the reanalysis product and intrusion detection method, all potential CDW intrusion sites along the shelf break are identified. Based on the reanalysis product, an intrusion site over the shelf break, away from major deep troughs was captured and confirmed by numerical particle tracking experiments.

Surface Microstructure Drives Biofilm Formation and Biofouling of Graphene Oxide Membranes in Practical Water Treatment.

Significant progress has been made previously in the research and development of graphene oxide (GO) membranes for water purification, but their biofouling behavior remains poorly understood. In this study, we investigated the biofilm formation and biofouling of GO membranes with different surface microstructures in the context of filtering natural surface water and for an extended operation period (110 days). The results showed that the relatively hydrophilic and smooth Fe(OH)3/GO membrane shaped a thin and spatially heterogeneous biofilm with high stable flux. However, the ability to simultaneously mitigate biofilm formation and reduce biofouling was not observed in the weakly hydrophilic and wrinkled Fe/GO and H-Fe(OH)3/GO membranes. Microbial analyses revealed that the hydrophilicity and roughness distinguished the bacterial communities and metabolic functions. The organic matter-degrading and predatory bacteria were more adapted to hydrophilic and smooth GO surfaces. These functional taxa were involved in the degradation of extracellular polymeric substances (EPS), and improved biofilm heterogeneity. In contrast, the weakly hydrophilic and wrinkled GO surfaces had reduced biodiversity, while unexpectedly boosting the proliferation of EPS-secreting bacteria, resulting in increased biofilm formation and aggravated biofouling. Moreover, all GO membranes achieved sustainable water purification during the entire operating period.

Spatiotemporal variability of lake surface water temperature and water quality parameters and its interrelationship with water hyacinth biomass in Lake Tana, Ethiopia.

Urbanization, agriculture, and climate change affect water quality and water hyacinth growth in lakes. This study examines the spatiotemporal variability of lake surface water temperature, turbidity, and chlorophyll-a (Chl-a) and their association with water hyacinth biomass in Lake Tana. MODIS Land/ Lake surface water temperature (LSWT), Sentinel 2 MSI Imagery, and in-situ water quality data were used. Validation results revealed strong positive correlations between MODIS LSWT and on-site measured water temperature (R = 0.90), in-situ turbidity and normalized difference turbidity index (NDTI) (R = 0.92), and in-situ Chl-a and normalized difference chlorophyll index (NDCI) (R = 0.84). LSWT trends varied across the lake, with increasing trends in the northeastern, northwestern, and southwestern regions and decreasing trends in the western, southern, and central areas (2001-2022). The spatial average LSWT trend decreased significantly in pre-rainy (0.01 ℃/year), rainy (0.02 ℃/year), and post-rainy seasons (0.01℃/year) but increased non-significantly in the dry season (0.00 ℃/year) (2001-2022, P < 0.05). Spatial average turbidity decreased significantly in all seasons, except in the pre-rainy season (2016-2022). Likewise, spatial average Chl-a decreased significantly in pre-rainy and rainy seasons, whereas it showed a non-significant increasing trend in the dry and post-rainy seasons (2016-2022). Water hyacinth biomass was positively correlated with LSWT (R = 0.18) but negatively with turbidity (R = -0.33) and Chl-a (R = -0.35). High spatiotemporal variability was observed in LSWT, turbidity, and Chl-a, along with overall decreasing trends. The findings suggest integrated management strategies to balance water hyacinth eradication and its role in water purification. The results will be vital in decision support systems and preparing strategic plans for sustainable water resource management, environmental protection, and pollution prevention.

Hydrochemical characterization and health risk assessment of different types of water bodies in Fenghuang Mountain Area, Northeast China.

Groundwater, as an essential resource, holds significant importance for human production and livelihoods. With the deterioration of the water environment, the issue of groundwater quality has become an urgent international concern. This study focused on the Fenghuang Mountain Area (FMA) and collected a total of 41 sets of samples including pore groundwater (PGW), fissure groundwater (FGW), karst groundwater(KGW), and river water(RW). Hydrochemical analysis methods were employed to identify the hydrochemical characteristics and controlling factors. The entropy-weighted water quality index (EWQI) and health risk assessment model were utilized to assess the groundwater quality and nitrate health risk, respectively. The results indicated that the dominant anion and cation in both groundwater and surface water in the FMA were HCO3- and Ca2+, respectively, with the main hydrochemical type being HCO3-Ca. Groundwater and surface water in the FMA were primarily controlled by rock weathering process, with ion concentrations influenced mainly by the dissolution of halite, sylvite, carbonates (calcite and dolomite), silicates, and gypsum, as well as by reverse anion exchange process. PGW was significantly affected by agricultural activities, with NO3- concentration closely related to human activities. The water quality of FGW was relatively good, with Class I and Class II water accounting for the highest proportion, reaching 84.62%. The high-value area of EWQI in PGW was influenced by human activities. The impact of nitrate health risk on children was significantly greater than on adults, with FGW having the lowest health risk and PGW having the highest health risk. The research results can provide important guarantees for the rational development and utilization of water resources in the FMA and the sustainable development of the economy in Northeast China.

Water, Sanitation and Hygiene practices in areas affected by Cyclone Idai in Zimbabwe

ABSTRACT This study was aimed to investigate the association between Cyclone Idai and the Water, Sanitation and Hygiene (WASH) practices in Chimanimani and Chipinge districts in Zimbabwe. The WASH parameters assessed included the main water source, the type of toilet in the household, the number of households sharing a toilet and the presence of a handwashing facility for use after using the toilet. The highest proportion of households that were mostly affected used piped water, while those not affected mainly used community boreholes (42.9%), protected wells (24.2%) and surface water (18.7%). Most households that were relocated to camps (70%) used the pit latrine with slabs, while most of the households that were not affected (41.8%) used the bush as their toilet facility. Only households relocated to camps shared toilets. Only the most affected and resettled population groups (in camps) had better access to improved WASH infrastructure. However, the sharing of toilets was high and the use of handwashing facilities was low in all settlement types. There was a significant association between the severity of Cyclone Idai and the main water source, adequacy of drinking water, sharing of toilets and the ability to purify drinking water.

First lacustrine application of the diatom‐bound nitrogen isotope paleo‐proxy reveals coupling of denitrification and N2 fixation in a hyper‐eutrophic lake

AbstractPast changes in the input/output, and internal cycling, of bioavailable nitrogen (N) in marine and lacustrine environments can be reconstructed by analyzing the N isotopic composition (δ15N) of organic matter in the sedimentary record. To verify, and eliminate, potential biases of bulk sedimentary δ15N (δ15Nbulk) signatures by diagenetic alteration and external N inputs, we applied, for the first time, the diatom‐bound N isotope (δ15Ndb) paleo‐proxy to lake sediments. By comparing δ15Nbulk and δ15Ndb in a sedimentary record from eutrophic Lake Lugano (Switzerland), we demonstrate that changing redox conditions influence the degree of N‐isotopic alteration of the bulk sediment, emphasizing the need for caution when interpreting δ15Nbulk in paleolimnological studies. Furthermore, in combining δ15Ndb measurements with X‐ray fluorescence scanning and state‐of‐the‐art molecular biomarker analyses, we reconstruct nutrient cycling and paleoenvironmental conditions in the lake over the past ~ 125 yr. Coeval with the period of severe eutrophication in Lake Lugano in the 1960s, our proxy data indicate that export production, δ15Ndb, and the concentration of heterocyst glycolipids (a biomarker for N2‐fixing cyanobacteria) increased simultaneously. Together, these data suggest that the rise in δ15Ndb is likely the result of enhanced water‐column denitrification in response to increased phytoplankton productivity. We hypothesize that greater export production during eutrophication led to anoxic conditions in the hypolimnion as a result of enhanced organic matter remineralization, raising water‐column denitrification. Enhanced N loss and remobilization of phosphorous (P) from the sediments under anoxic conditions lowered the N : P ratio in the lake, fostering cyanobacterial N2 fixation in surface waters.

Preferential Partitioning of Per- and Polyfluoroalkyl Substances (PFAS) and Dissolved Organic Matter in Freshwater Surface Microlayer and Natural Foam.

Per- and polyfluoroalkyl substances (PFAS) are surfactants that can accumulate in the surface microlayer (SML) and in natural foams, with potential elevated exposure for organisms at the water surface. However, the impact of water chemistry on PFAS accumulation in these matrices in freshwater systems is unknown. We quantified 36 PFAS in water, the SML, and natural foams from 43 rivers and lakes in Wisconsin, USA, alongside measurements of pH, cations, and dissolved organic carbon (DOC). PFAS partition to foams with concentration ranging 2300-328,200 ng/L in waters with 6-139 ng/L PFAS (sum of 36 analytes), corresponding to sodium-normalized enrichment factors ranging <50 to >7000. Similar enrichment is observed for DOC (∼70). PFAS partitioning to foams increases with increasing chain length and is positively correlated with [DOC]. Modest SML enrichment is observed for PFOS (1.4) and FOSA (2.4), while negligible enrichment is observed for other PFAS and DOC due to low specific surface area and turbulent conditions that inhibit surfactant accumulation. However, DOC composition in the SML is distinct from bulk water, as assessed using high-resolution mass spectrometry. This study demonstrates that natural foams in unimpacted and impacted waters can have elevated PFAS concentrations, whereas SML accumulation in surface waters is limited.

THE ECHELONED MINE BARRIERS BREACHING PROPOSALS BASED ON THE EXPERIENCE OF THE RUSSIAN-UKRAINIAN WAR

The echeloned mine barriers system of the russian occupying forces became a real challenge for the Ukrainian military. The first days of the Ukrainian offensive in the Zaporozhye direction revealed that the russians had created very dense minefields on their defense lines. The occupiers used continuous mining of the area, that is several times higher than the normative values for laying mines. The solution to this problem can be found in the application of non-standard technical solutions and tactical techniques that will allow to break through the echeloned mine barriers system of the russian occupying forces. Regarding the technical aspect of this issue solving, there was an interesting technical solution in the history of weapons and military equipment. We are talking about a hovercraft, that is supported above a supporting surface (land or water) on a compressed air layer (cushion) created by ship fans (superchargers). This principle of movement allows them to overcome underwater engineering structures and to break through mine barriers, to move on ice and swampy terrain, to go to the shore equipped in the anti-landing position, to overcome ditches and trenches. These tactical properties of hovercraft can be taken as a basis for the creation of a new generation of armored vehicles based on new principles of movement. In theory, the combat use of a whole series of armored vehicles on an air cushion (tanks, combat vehicles, armored personnel carriers, mortars, demining machines, evacuation vehicles, etc.) will expand the capabilities of mechanized units, will allow to improve existing methods and techniques for breaking through the echeloned mine barriers, forcing water obstacles, swampy and desert terrain. The issue of creating armored vehicles on an air cushion to break the mine barrier requires further research.

Assessing Potential Bias in PFAS Concentrations in Groundwater and Surface Water Samples

AbstractPer‐ and polyfluoroalkyl substances (PFAS) encompass a large group of recalcitrant anthropogenic compounds that have been used in a variety of consumer and industrial products and processes over many decades. Drinking water standards were recently finalized for two PFAS at low nanogram per liter concentrations. Due to the widespread use of PFAS and low health‐based thresholds, a literature review and laboratory and field studies were conducted to assess several potential sources of bias in PFAS concentrations. Fluoropolymers are commonly present in equipment, products, and materials used during field sampling, potentially leading to false positive results. Laboratory results confirmed the presence of PFAS in multiple commonly used field materials. However, best practices can be used to limit pathways for cross contamination. Laboratory‐specified hold times and sample storage temperatures are scientifically founded and adequately prevent bias due to PFAS sorption to sampling containers or partial degradation of some PFAS to form others. PFAS are also known to accumulate at the air‐water interface and other interfaces. Results from laboratory and field studies indicate that PFAS enrichment in foam and in the surface microlayer does occur. However, the effect of this phenomenon is within the range of analytical and spatial sampling variability and therefore a change in sampling procedures is not needed. Findings were distilled into science‐based and practical recommendations to minimize bias during PFAS sampling without incurring unnecessary cost and effort.

Effectiveness of the Sustainable Manure Pile Model for Ammonia Emission and Soil

In order to reduce odor emissions and surface water pollution while storing manure in field heaps near a barn, there is a challenge in properly designing manure-storage areas. Therefore, it is important to assess what solutions and conditions, considering environmental requirements, should be considered when storing manure in field heaps. The goal of the research is to determine the impact of various factors on the risk of nutrient leaching, soil, and gas emissions from solid manure heaps, considering climatic factors in the environment. Through various scientific studies, a manure pile model has been developed and evaluated for its impact on the risk of potential leaching and odor emissions (using hyperspectral gas emission analysis mass flow method) from manure and the dynamics of the 0–80 cm soil layer properties (nitrate (N-NO3) and nitrite (N-NO2), ammonia (NH3), mineral, and total N). Based on the research results, requirements for manure management and storage during the prohibited fertilization period were established, considering the requirements for nitrates from agricultural sources in Lithuania. An optimal new manure heap model has been identified—a layer of not less than 20 cm of compacted straw (density 150–200 kg m−3) or a 10 cm layer of peat for absorbing manure slurries is formed on the soil surface, the manure heap is surrounded by an earth embankment not less than 30 cm high, the manure heap is covered with a layer of finely chopped straw not less than 10 cm thick, or 5 cm of sawdust, or 5 cm of peat. The manure is stored in the heap for 6–12 months. Following the research results, requirements for manure management and storage during the prohibited fertilization period were established, considering the requirements for nitrates from agricultural sources in Lithuania, applicable to the northern part of the temperate climate zone and applying similar requirements to the relevant countries.

Microplastic pollution and ecological risk assessment of a pond ecosystem.

Microplastic (MP) pollution has been observed in various ecosystems as a result of the rapid increase in plastic production over the past half-century. Nevertheless, the extent of MP pollution in different ecosystems, particularly in freshwater ecosystems, has not been well-studied, and there are limited investigations on this particular topic, specifically in Türkiye. Here, we quantify the occurrence and distribution of MPs in surface water samples collected from Topçu Pond (Türkiye) for the first time. Water samples were collected at five stations and filtered (30 L for each station) through stacked stainless steel sieves (5mm, 328µm, and 61µm mesh size) with a diameter of 30cm. The abundance, size, color, shape, and type of collected debris samples were analyzed after the wet peroxide oxidation process. MP particles were observed in all samples at an average abundance of 2.4 MPs/L. The most abundant MP size class and type were 0-999µm and fiber respectively. On the other hand, prevalent colors were black and colorless in general. According to the Raman analysis results, the identified MP derivatives were polypropylene (40%), polyamide (30%), ethylene acrylic acid (20%), and polyvinylchloride (10%). Moreover, the pollution load index (PLI) index was used to determine the pollution status. PLI values were determined as 1.91 at station S1, 1.73 at station S2, 1.31 at station S3, 1 at station S4 and 1.24 at station S5. The PLI value determined for the overall pond was 1.4. The results of this research show that MP pollution is present in Topçu Pond and contributes to the expanding literature on MP pollution in pond ecosystems.

Diatomite evidence for a small palaeo mountain lake at 3400 m asl, Lesotho, southern Africa

ABSTRACTThe Eastern Lesotho Highlands experience an excess of rainfall sufficient to form the country's primary export, supplying the economic hub of southern Africa, Gauteng South Africa. However, there is currently only one natural lake in the country, Letšeng‐la Letsie, and evidence of palaeolakes in the region is therefore of particular interest. This study presents the analysis of a diatomite outcrop from a depression northwest of Mafadi Summit, at 3400 m asl. The presence of diatomite, dominated by the facultative planktonic species Staurosirella pinnata and Staurosira construens and abundant planktonic Aulacoseira ambigua, is indicative of the continuous presence of a shallow lake between ~4600 and 100 cal a bp. Comparative analysis of rainfall for the Mafadi and Letšeng‐la Letsie regions from CHIRPS gridded rainfall data demonstrates sufficient rainfall for a lake of comparable size, if not larger, as Mafadi receives considerably more rainfall than Letšeng‐la Letsie. Analysis of the SRTM 30‐m Digital Elevation Model and Topographic Position Index calculations demonstrate the feasibility of a shallow surface water feature at Mafadi. The conversion of this palaeolake into the contemporary wetland is hypothesized to be the result of post‐industrial warming, possibly augmented by migration of livestock into the Eastern Lesotho Highlands.