Major Water Bodies Research Articles

Occurrence, distribution, and ecological risk of psychoactive substances in typical lakes and rivers in Qinghai-Tibet Plateau

The occurrence, distribution, and ecological risks of psychoactive substances (PSs) in Qinghai-Tibet Plateau (QTP) was investigated in this study. The surface water samples were collected in July in 2020 from five major water bodies, and 9 PSs were determined by liquid chromatography-mass spectrometry. The mean concentrations of the total PSs were 2.19–96.86 ng/L in lakes and 4.56–34.47 ng/L in rivers. Amphetamine (AMP) was the predominant contaminant both in lakes and rivers with a mean concentration of 12.21 ± 22.76 ng/L and 9.83 ± 6.14 ng/L, respectively. The compositions of PSs in lakes and rivers were significantly different. AMP, methadone (MTD), 3,4-methylenedioxyamphetamine (MDA), and ketamine (KET) were the most detected contaminants in lakes, while in rivers AMP, MDA, heroin (HER), and methamphetamine (METH) were the most detected ones. Concentrations of AMP and MTD, the two predominant drugs, varied spatially, with the decreasing concentration of AMP in the order of Huangshui River > Yamzhog Yumco Lake > Qinghai Lake > Lhasa River > Namco Lake, and of MTD in the order of Qinghai Lake > Namco Lake > Huangshui River > Yamzhog Yumco Lake. The risk quotients (RQs) of PSs ranged from 4.44 × 10−6 to 4.32 × 10−2, indicating a low risk of PSs in the aquatic ecosystem in QTP. Compared with other research in the world, the contamination of psychoactive substances in the Qinghai-Tibet Plateau was at relatively low levels with low ecological risks.

Features of Pesticide-Contaminated Surface Water

This work aims to investigate the concentration indices of 14 pesticides in the major water bodies of the Southern Federal District of the Russian Federation. The study was conducted in 2019 using samples of bottom sediments and surface waters collected from three reservoirs (Krasnodar, Proletarian, and Veselovsky) and two rivers (Don and Sal). Concentrations of active pesticide substances were studied, and the results were benchmarked against 2018. In 2019, 14 active pesticide substances were detected in water and sediment samples from the three reservoirs under study. Maximum pesticide concentrations were observed in the spring of 2019 and autumn 2018. Total concentration indices in these time frames were similar, but autumn 2019 is 20 times lower than 2018 (0.7 versus 6.5, p ≤ 0.001). Total pesticide concentrations for rivers and reservoirs averaged about the same (0.15-0.80, p ≥ 0.05). There are different levels of pesticides in rivers and reservoirs. The detected pesticide concentrations did not exceed the maximum allowable concentrations, but the cumulative effect can have a harmful impact on hydrobionts in the future.

Bioavailability and health risk assessment of potentially toxic elements in salty water environment of Okposi, Southeastern Nigeria

This study is to determine some physicochemical parameters and potentially toxic elements (PTE) in water samples collected from a borehole, a stream and a lake in Okposi, Nigeria, for their quality status and the human health risk of exposure to the waters. The physico-chemical properties: pH, electrical conductivity (EC), salinity, nitrate and sulphate, were determined by standard methods, while the level of PTE contamination was analysed by Flame Atomic Absorption Spectroscopy (FAAS). The results show that the levels of physicochemical parameters in the water samples are within the World Health Organisation (WHO) permissible limit. The PTE concentrations (mg/L) in the samples are in the ranges of 0.12–0.35 (Cr); 0.06–0.19 (Cu); 0.24–2.45 (Fe); 0.0–0.06 (Mn); 0.00–0.75 (Pb); and 0.0–02 (Zn). The levels of Cr and Pb in all the samples, except Pb in the downstream water, are above the WHO permissible limits, indicating that the waters are contaminated and unsafe for drinking. PTE form complexes with anions in water at high EC and salinity which reduces availability of toxic metals to organisms. Therefore, toxicity of PTE in the samples is in decreasing order: Upstream > Downstream > Lake water > borehole water. Calculations of hazard quotients shows possible adverse effects on adults and children on dermal contact with the waters due to Cr. Children might get cancer due to Pb on ingestion of water from the studied borehole, the Lake and the Upstream waters. Statistical analysis suggests that the geology of the area influenced PTE contamination of the water bodies.Article highlightsEvaluation of the pollution status of the major water sources (borehole, lake, upstream and downstream) in the study area was conducted since the information will be useful for making decisions that will protect human health by the policy makers and the public.The samples from all the water bodies in the study area were contaminated by chromium. The borehole water samples were contaminated by Iron and Lead; the downstream samples were contaminated by Iron; while samples from the lake and the upstream were contaminated by Lead. They are contaminated because the concentrations of these metals in the water bodies were above the World Health Organisation’s permissible limit for those metals in drinking water. Human exposure to the level of these metals in the water bodies may lead to severe health problems.Based on the bioavailability studies of the metals and the physicochemical parameters of the major water bodies in the study area, the borehole water (ground water) is the safest (best) for drinking and domestic purposes, then, the lake water (safer), followed by the downstream water (safe), while the upstream water has the highest toxicity potential (not safe).

Coastal toponyms of Iran

Abstract While the domain of toponymy has great research potential, it has so far gained little attention in Iran. The present paper is a typological study on a sample group of toponyms from two different provinces of Gilan (a northern coastal province next to the Caspian Sea) and Bushehr (a southern coastal province beside the Persian Gulf) within the framework of the Australian National Placenames Survey typology proposed by Tent and Blair. The two regions in question are similar in terms of adjacency to a major water body but different in language, culture, and geography. To determine whether the Australian proposed typology is applicable to Iranian toponyms, we collected 60 coastal placenames from Gilan and Bushehr and classified them according to their Specifics and Generics based on Tent and Blair’s (2009, 2011) typology. Further, we compared placenaming motivations and processes in the two regions. The results show that although the Iranian placenames differ from the Australian ones in terms of their structure, they fit well into the typology. Water-related features are among the top motivations for local namers in both Gilan and Bushehr. Nevertheless, Bushehr namers are more motivated by natural features while those from Gilan, in most cases, are non-naturally motivated.

Impact of Climate Change on Aquatic Plants Found in Major Lentic Water Bodies Located at Eastern Rajasthan

Climate change is one of the major challenges of the environment which is caused by the burning of fossilfuel, deforestation, increasing anthropogenic activities, release of greenhouse gases and global warming.The biggest factor of concern is increase in greenhouse gases mainly CO2 level which change the climateand weather pattern. In Rajasthan situation is as critical as continuous rain failure create the conditions ofdraught in Rajasthan. Some of the immediate effects of recent climate change are becoming apparent througheffects on aquatic flora. Vicissitudes of climate have a considerable impact on aquatic flora. The wetlandecosystems, which are most productive but most fragile, are great threat of extinction today, partly onaccount of their use for human activities and partly due to natural threats; such as frequent droughts,scantly rainfall, erosion and biotic effects caused by biotic intervention in maintaining them. The currentreview mainly focuses on how flora of eastern Rajasthan are likely responding to direct and indirect effectsof anthropogenic climate change. We aim to awareness rather than to be comprehensive. Rajasthan is thelargest state of India area-wise constituting 10.4% of country’s geographical area. East Rajasthan got one ofthe two Ramsar sites of Rajasthan, two national parks, and 7 wildlife sanctuaries and comprises about 9%geographical area of the state. Most of the lakes in east Rajasthan get fully dried up at least once in four tofive years. All aquatic ecosystems of this region suffer from periodic desiccation. We include extinction inaquatic plants, endangered species, and invasive species. However, all are important in providing insightsinto future state of aquatic ecosystems. We also highlight some of the management issues relevant toconserving aquatic communities and ecosystem in the face of anthropogenic climate change.

Lands Abutting Seas, Oceans, 85% of Worlds Coronavirus Deaths

The Worldometer Coronavirus registered six million deaths on March 03, 2022. 85% of the deaths occurred in lands directly abutting the World Seas and Oceans. The WHO, CDC and other World Public Health Organizations suggest that humidity can aid in the fight against COVID-19 [1]. The boundary of this comment is that it is directed at indoor air quality with perspective that 40-60% humidity is positive against COVID-19. The fact that almost all the World COVID-19 deaths are in lands directly abutting the Major World Seas and Oceans, with their inherent natural humidity, does not seem to be addressed in technical literature. There seems to be a conflict. This paper provides a breakdown of the World’s deadliest coronavirus regions at the six million death milestone, compares it to the earlier evaluation by the author captured in a WordPress website [2-10], and provides an in depth breakdown of the pandemic deaths and death rates in the lands abutting the Major World Seas and Oceans. Maps are provided showing the surrounding Countries or States of Countries with death and death rate tables for each of the World’s Major bodies of water. These are startling in similarity.

Effect of land use on microplastic pollution in a major boundary waterway: The Arvand River

The occurrence of microplastics (MPs) was investigated in the Arvand River (Iran). The Arvand River (200 Km) is a major water body that flows through land with diverse use and it meets the Persian Gulf. This study constitutes the first assessment of MP pollution (prevalence and physico-chemical characteristics) in the Arvand river, both in the sediment and in the water. MP monitoring has been carried out in 24 stations located along the river. The MP pollution found ranged between 1 and 291 items·L−1 and 70 to 15,620 items·kg−1 (dw), in water and sediment, respectively. The majority of MPs were fibres, black/grey and yellow/orange in colour, and mainly 250–500 μm and >1000 μm in size. Polyethylene terephthalate (PET), polypropylene (PP), nylon (NYL), high-density polyethylene (HDPE), and polystyrene (PS) were found in sediment samples. All these polymers, except HDPE, were also identified in the water samples. PET and PP were dominant in the water samples; whereas PET and PS were the most abundant in the sediments. The vicinity of urban wastewater effluents could be behind MP pollution in both water and sediments. Significant differences (p < 0.05) of MP concentrations were affected by different land uses when comparing MP levels in undisturbed natural area with urban areas. A strong correlation between MP fibres and fragments found with PCA biplots revealed their similar distribution in water. In the sediment samples, fibre and fragment MP particles were significantly correlated with colloidal particles (e.g., clay and organic matter) suggesting a relevant role of colloidal particles in the aquatic ecosystem of the Arvand River in transporting MPs. This study contributes to the better understanding of the presence of MP in major rivers, which are systems that have been scarcely investigated for this type of pollution, and it can inform interventions to reduce MP inputs to the river and sea.

Quantification of archaea-driven freshwater nitrification from single cell to ecosystem levels

Deep oligotrophic lakes sustain large populations of the class Nitrososphaeria (Thaumarchaeota) in their hypolimnion. They are thought to be the key ammonia oxidizers in this habitat, but their impact on N-cycling in lakes has rarely been quantified. We followed this archaeal population in one of Europe’s largest lakes, Lake Constance, for two consecutive years using metagenomics and metatranscriptomics combined with stable isotope-based activity measurements. An abundant (8–39% of picoplankton) and transcriptionally active archaeal ecotype dominated the nitrifying community. It represented a freshwater-specific species present in major inland water bodies, for which we propose the name “Candidatus Nitrosopumilus limneticus”. Its biomass corresponded to 12% of carbon stored in phytoplankton over the year´s cycle. Ca. N. limneticus populations incorporated significantly more ammonium than most other microorganisms in the hypolimnion and were driving potential ammonia oxidation rates of 6.0 ± 0.9 nmol l‒1 d‒1, corresponding to potential cell-specific rates of 0.21 ± 0.11 fmol cell–1 d–1. At the ecosystem level, this translates to a maximum capacity of archaea-driven nitrification of 1.76 × 109 g N-ammonia per year or 11% of N-biomass produced annually by phytoplankton. We show that ammonia-oxidizing archaea play an equally important role in the nitrogen cycle of deep oligotrophic lakes as their counterparts in marine ecosystems.

Above‐ and below‐ground biodiversity responses to the prolonged flood pulse in central‐western Amazonia, Brazil

AbstractAmazonia encompasses extensive forests in areas that are periodically inundated by overflowing rivers. The inundation depth and duration vary according to the slope of the terrain and distance to major water bodies. This creates a flooding gradient from the lowest lying seasonally flooded forest up into the unflooded forest, which directly affects the biota. However, the effect of this gradient on soil organisms remains elusive. Here, we use DNA metabarcoding to estimate prokaryote and eukaryote diversity from soil and litter samples along the flooding gradient in central‐western Amazonia using 16S and 18S gene sequences, respectively. We characterize the below‐ground diversity and community composition based on amplicon sequence variants (ASVs). We examine relationships between the soil biota and the flooding gradient, soil properties, and above‐ground woody plant diversity. The flooding gradient does not explain below‐ground biodiversity, nor is below‐ground diversity explained by the above‐ground woody plant diversity. We uncover several taxonomic groups—such as Patescibacteria—not previously reported from Amazonian seasonally flooded forests. The flooding gradient and woody plant diversity partly explain the community composition of soil bacteria. Although the effects of the flooding gradient, soil properties, and above‐ground woody plant diversity are difficult to quantify, our results indicate that flood stress may influence below‐ground bacterial community composition.

Reconstructing groundwater storage variations from GRACE observations using a new Gaussian-Han-Fan (GHF) smoothing approach

This study focuses upon development of a new filter, referred to as Gaussian-Han-Fan (GHF) filtering, and its application within a comprehensive procedure for estimating groundwater changes. The Canadian Prairies was the study area. Variations in groundwater were estimated by using 15 years of Gravity Recovery And Climate Experiment (GRACE) twin-satellite observations (April 2002 to June 2017). Surface water storage (sum of soil moisture, snow water equivalent, canopy water, and surface water bodies) was subtracted from reconstructed GRACE-based Terrestrial Water Storage (TWS) changes through GHF filtering. To estimate the required hydrological parameters, both the Global Land Data Assimilation System (GLDAS) and Water Global Hydrology Model (WGHM) were used and evaluated. Water level changes for major surface water bodies were estimated using satellite altimetry-based products. The monthly average of GWS variations over the Prairies ranged between −200 mm and +230 mm. A positive trend was found for both TWS and GWS variations, with the highest values in the region surrounding Hudson Bay, particularly in northern Manitoba (about 55 mm/year). Estimated GWS anomalies error was equivalent to about 10% of its absolute value, with a mean of 19 mm. GWS variations results were validated using 116 active in-situ groundwater level measurements in five different river basins (Peace-Athabasca, Churchill, North Saskatchewan, South Saskatchewan, Missouri), which were all located in Alberta (Canada). Good agreement was achieved in each river basin (correlation > r = |0.70|, P < 10−4, RMSE < 55 mm). Regardless of hydrological system (GLDAS or WGHM), better statistical metrics were found when the average of the five basins was considered (r > |0.90|, P < 10−4), with lowest errors (RMSE or UnRMSE < 30 mm).

Reconstructing Kenya’s total freshwater fisheries catches: 1950–2017

Most freshwater fisheries occur in developing countries, where freshwater fish underpin local food security and small-scale fisheries livelihoods. Comprehensive catch data are fundamental to support the sustainable management of freshwater fisheries. However, freshwater catch data reported by the Food and Agriculture Organization of the United Nations (FAO) on behalf of countries under-represent freshwater fisheries because they are dominated by fragmented and highly dispersed small-scale sectors, often with no designated landing sites. Kenya is an emerging economy with socioeconomically important freshwater fisheries and ongoing food security concerns. We undertook a reconstruction of freshwater fisheries catch data for Kenya for the period 1950–2017, aiming to improve the comprehensiveness of existing reported baseline data and to provide a more ecologically and spatially relevant time series dataset for research and management uses. We reconstructed catches for 16 major waterbodies in Kenya and found catches to be 32% higher than the data reported by the FAO on behalf of the country. The subsistence sector (small-scale, non-commercial, personal consumption) accounted for 71% of unreported catches, compared with 29% for artisanal sector catches (small-scale, commercial), suggesting that non-commercial catches for direct local consumption are substantially under-represented in nationally reported statistics and should receive greater attention to support sustainable food security in Kenya.

Heronry distribution and site preference dynamics of tree-nesting colonial waterbirds in Tamil Nadu.

Anthropogenic disturbance and climate change have significantly affected the distribution of wetlands globally and particularly in Asian countries. Various types of wetlands are harboured across all the biogeographic zones in India. These wetlands provide vital ecological services and are rich in biodiversity. However, anthropogenic pressures continue to be a threat to these wetlands by affecting the flora and fauna that depend on them. Tree-nesting colonial waterbirds are vulnerable to these pressures as their colonies are typically located in wetlands and associated areas. Disturbances to these areas have resulted in the loss or shifting of many heronries. The present study was conducted in the Indian state of Tamil Nadu during the period of 2017–2019 to document the existing and previously unknown heronries of the landscape. A total of 101 heronries were documented in 22 districts. The Little Cormorant was the most dominant species, occurring in 79% of the sites, with relative abundances of 24% and 26% during 2017–2018 and 2018–2019, respectively. A total of 23 tree species were utilized by the birds for nesting and Vachellia nilotica trees were used for nesting in about 25% of the heronries. 19% of the heronries were situated inside protected areas and 81% were located outside protected areas. Out of the 58 active nesting sites reported in 2005, 43 have been lost or are no longer active. Species distribution modelling with presence only data indicated that the sites with a high probability of occurrence were confined to the major waterbodies and rivers. Spatial correlation showed that the heronries were dispersed randomly across the landscape. The population dynamics within heronries and colonial nesting waterbirds’ response to various environmental factors must be monitored continuously to conserve these heronries.

Urban stormwater harvesting for domestic water supply: a water evaluation and planning approach.

Renewable groundwater and surface water supplies are insufficient for the current worldwide urban population as water demand is increasing rapidly. Usage per capita in urban areas transcends 160 liters per day. Climate change is projected to increase water demand even more. Sources of surface water from stormwater runoff can be used to fulfill this requirement. The main objective of this work is to assess the water supply and demand in the dry conditions of the Coimbatore region, Tamil Nadu, India, and to use the water evaluation and planning method to create a model for supply and demand in the future. There are more than three dozen surface water bodies in and around the metropolitan center. Most sources are heavily encroached upon. By linking stormwater runoff from its respective elevation to the accessible surface water bodies, an additional water supply source can be obtained. By using the water evaluation and planning framework as a guide, models were developed to determine potential needs, and to compare demand and supply, water usage, lack of water use, and population coverage. The enhanced stormwater drainage system for Coimbatore city was designed in such a way that the various roads were connected to the major water bodies. The domestic water demand in the future is predicted to be around 27 million cubic feet (MCFT). Meanwhile, the possible amount of stormwater collected in the selected water bodies is predicted to be 50 million cubic meter (MCM) to 320 MCM. This study concluded that 100% of urban domestic water demand can be met if the urban stormwater is utilized by harvesting and storing in surface water bodies.

Four decadal urban land degradation in Pakistan a case study of capital city islamabad during 1979–2019

The study of Land Use Land Cover (LULC) changes and their patterns enhance our understanding about various man caused phenomenon on earth surface. The Capital City of Pakistan, Islamabad has expereinced high rate of urbanization and population increase in the last 3-4 decades and as a result, the LULC changes have occurred in an unsustainable way. The accurate and reliable data of LULC changes for the study period is not available. The main aim of this study was to provide compatible data on LULC change during the last 40 years for the functional city Islamabad, Pakistan. LULC statistics were extracted from Landsat Multi-Spectral Scanner (MSS), Thematic Mapper (TM), Enhanced Thematic Mapper Plus (ETM+) and Operational Land Imager (OLI) images. For each of the target years (1979, 1989, 1999, 2009 and 2019) LULC information was obtained through a supervised classification algorithm. The study area was classified into five major landscape categories, namely built-up, agriculture, forest, water bodies and barren land. The results have indicated that the urban expansion has been increasing due to mass migration and uncontrolled urbanization in the city. The urban sprawl analysis revealed that built-up area and agricultural land has expanded by 41.7% and 5.20% respectively, during 1979–2019. On the other hand, the forest and water bodies declined by 9.03% and 1.21% respectively. The land use changes, have forced the planners to revise the original master plan of the city and including the agricultural sector in the housing area during 2019.

Recent Trends in Development of Nanomaterials Based Green Analytical Methods for Environmental Remediation

Background: In recent years, the occurrence and fate of environmental pollutants has been recognized as one of the emerging issues in environmental chemistry. A survey documented a wide variety of these pollutants, which are often detected in our environment and these are a major cause of shortened life spans and global warming. These pollutants include toxic metal, pesticides, fertilizers, drugs, and dyes released into the soil and major water bodies. The presence of these contaminants causes major disturbance in the balance of the eco-system. To tackle these issues, many technological improvements are made to detect minute contaminations. The latest issue being answered by scientists is the use of green nanomaterials as sensors which are economical, instant and give much better results at low concentrations and can be used for the field measurements resulting in no dangerous by-product that could lead to more environmental contamination. Nanomaterials are known for their wide bandgap, enhanced physical, and optical properties with the option of tuneability as per need, by optimizing certain parameters. They are proved to be a good choice for analytical/ optical sensors with high sensitivity. Objective: This review holds information about multiple methods that use green nanomaterials for the analytical assessment of environmental pollutants. UV-Vis spectrophotometry and electrochemical analysis using green and reproducible nanomaterials are the major focus of this review article. To date, there are a number of spectrophotometric and electrochemical methods available that have been used for the detection of environmental pollutants such as toxic metals, pesticides, and dyes. Conclusion: The use of nanomaterials can drastically change the detection limits due to having a large surface area, strong catalytic properties, and tunable possibility. With the use of nanomaterials, lower than the marked limit of detection and limit of quantification were seen when compared with previously reported work. The used nanomaterials could be washed, dried, and reused, which makes the methods more proficient, cost-effective, and environmentally friendly.

Eco Friendly Dye Extraction From Cyanophyta for Textiles

In countries like India there is always a scarcity for fresh water along with it polluting the available fresh water sources is a major threat. The major fresh water bodies are affected by eutrophication. It is the phenomenon in which algae forms a layer above the water surface and does not allow the sun light to enter into the water body. Due to this reason organisms which is present in the water body gets affected and the ecosystem gets damaged. The algae which are taken from the water bodies is dropped as waste in garbage or let to dry out on roads. “One man’s waste is other man’s treasure” so instead of wasting the collected algae, the algae can be used to prepare a dye which can be used to dye clothes for different uses. The collected algae are used as a raw material in an algal dying machine where the processes carried out are cleaning, drying the algae, grind it, boil them with water and other essentials, filter the residue and finally filtrate will be used to print on cloth.

New Insights into Hydrothermal Fluid Circulation Affected by Regional Groundwater Flow in the Asal Rift, Republic of Djibouti

The Asal Rift hosts a lake located in a depression at 150 m below sea level, where recharge is influenced by regional groundwater flow interacting with the Ghoubbet Sea along the coast of Djibouti. This regional groundwater flow is believed to influence hydrothermal fluid circulation, which we aim to better understand in this study, having the objective of developing concepts for geothermal exploration in the area. To this end, magnetotelluric data acquired in the Asal Rift were processed and analyzed. 1D inversion models of electrical conductivity were interpolated for interpretation. These data were then used to build a 2D hydrogeological model, allowing multiphase flow and heat transfer simulations to be performed, considering the regional groundwater flow near the surface and the site topography, in order to confirm the preferred path of fluid flow. Geophysical data analysis indicates the presence of normal faults, notably the H fault, which may act as a conduit for the circulation of hydrothermal fluids and where the hanging wall can be a hydrogeological barrier within the hydrothermal system of the Asal Rift. The results from the 2D numerical flow and heat transfer modelling show the importance of groundwater flow responsible for thermal springs located at the periphery of Asal Lake. Reservoir temperature inferred by means of geothermometry ranging from 200 to 270 °C was shown to correspond to simulated temperature at potential reservoir depth. Moreover, simulated temperature between 600 and 1700 m depth is close to the temperature profile measured in the geothermal well Asal 6 of the area, with less than 20 °C difference. Simulations indicate that hydrothermal fluid circulation is likely influenced by the regional groundwater flow controlled by the topography and the major water bodies, the Ghoubbet Sea and Asal Lake, feeding buoyant fluids interacting with a deep magmatic source and where tectonic activity created normal faults offering a preferred path for fluid circulation.

Hydrologic classification of Tanzanian rivers to support national water resource policy

AbstractClassifying rivers into homogeneous categories based on hydrological and/or environmental attributes supports the implementation of environmental flows to sustain aquatic ecosystems and support the resource needs of society. Hydrological classifications provide decision‐makers with a pragmatic number of water management units by grouping individual rivers or river segments expected to exhibit similar biophysical responses to flow alteration. Such classifications are particularly useful across broad geographies and in data‐limited contexts, such as in Tanzania, where the legal requirement to implement environmental flows for all major waterbodies remains constrained by scant data. We present a two‐level hydrological classification of all Tanzanian basins and the Rufiji River Basin. For the Rufiji River Basin, the largest river basin in the country, we performed an inductive classification based on the availability of long‐term time series of daily average discharge. We clustered 28 gauging stations into seven classes according to ecologically relevant hydrological metrics and used boosted classification trees to predict the hydrological class of all 95,909 river segments in the basin based on environmental attributes that influence flow regimes. In the absence of consistent, readily‐available gauged flow data, we conducted a deductive classification of all Tanzanian rivers whereby segments were directly grouped by multivariate similarity using the same environmental attributes. This analysis revealed 10 river classes reflecting the diversity of ecohydrological conditions characterizing the 486,681 river segments draining in and out of Tanzania. The new hydrological classifications presented here provide the foundation to guide implementation of management practices within the water policy framework of Tanzania.

The Formation and Balance of the Atmospheric Precipitations, Surface Water, and Groundwater on the Southern Slopes of the Khibiny Massif (Based on Data on the Isotopic Composition of Oxygen and Hydrogen)

The δ2H and δ18O values of the atmospheric precipitations in the Khibins vary within the range –147 ≤ δ2H ≤ –37‰, –20 ≤ δ18О ≤ –4‰ and are close to the global line of the precipitations for the northern hemisphere; the light values (with a positive deuterium excess) are typical of snow, while the heavy values are typical of rains. The data on the isotopic composition of water in open water bodies and groundwaters suggest their formation from the precipitations. Their flow (and subsurface migration) is accompanied by mixing of snowmelt and rain water; the efficiency of mixing can be evaluated by a decrease in the variation range of the values of δ2H and δ18О. According to isotopic data, the water of Lake Imandra, the major water body in the region, has formed through mixing of snowmelt and rain water in a proportion close to 1 : 1.

Strontium and Oxygen Isotope Analyses Reveal Late Cretaceous Shark Teeth in Iron Age Strata in the Southern Levant

Skeletal remains in archaeological strata are often assumed to be of similar ages. Here we show that combined Sr and O isotope analyses can serve as a powerful tool for assessing fish provenance and even for identifying fossil fish teeth in archaeological contexts. For this purpose, we established a reference Sr and O isotope dataset of extant fish teeth from major water bodies in the Southern Levant. Fossil shark teeth were identified within Iron Age cultural layers dating to 8–9th century BCE in the City of David, Jerusalem, although the reason for their presence remains unclear. Their enameloid 87Sr/86Sr and δ18OPO4 values [0.7075 ± 0.0001 (1 SD, n = 7) and 19.6 ± 0.9‰ (1 SD, n = 6), respectively], are both much lower than values typical for modern marine sharks from the Mediterranean Sea [0.7092 and 22.5–24.6‰ (n = 2), respectively]. The sharks’ 87Sr/86Sr are also lower than those of rain- and groundwater as well as the main soil types in central Israel (≥0.7079). This indicates that these fossil sharks incorporated Sr (87Sr/86Sr ≈ 0.7075) from a marine habitat with values typical for Late Cretaceous seawater. This scenario is in line with the low shark enameloid δ18OPO4 values reflecting tooth formation in the warm tropical seawater of the Tethys Ocean. Age estimates using 87Sr/86Sr stratigraphy place these fossil shark teeth at around 80-million-years-old. This was further supported by their taxonomy and the high dentine apatite crystallinity, low organic carbon, high U and Nd contents, characteristics that are typical for fossil specimens, and different from those of archaeological Gilthead seabream (Sparus aurata) teeth from the same cultural layers and another Chalcolithic site (Gilat). Chalcolithic and Iron Age seabream enameloid has seawater-like 87Sr/86Sr of 0.7091 ± 0.0001 (1 SD, n = 6), as expected for modern marine fish. Fossil shark and archaeological Gilthead seabream teeth both preserve original, distinct enameloid 87Sr/86Sr and δ18OPO4 signatures reflecting their different aquatic habitats. Fifty percent of the analysed Gilthead seabream teeth derive from hypersaline seawater, indicating that these seabreams were exported from the hypersaline Bardawil Lagoon in Sinai (Egypt) to the Southern Levant since the Iron Age period and possibly even earlier.