Surface Water Concentrations Research Articles

Stability Profile and Clinical Evaluation of an Innovative Hydrogel Containing Polymeric Micelles as Drug Delivery Systems with Oregano Essential Oil against Fibroepithelial Polyps.

Skin tags, also known as fibroepithelial polyps (FPs) or acrochordons, are soft, pigmented excrescences, with a prevalence of 50-60% in the population, occurring especially in the fourth decade of life. To date, FPs have been efficiently eliminated using minimum invasive methods such as surgical removal, cauterization, laser irradiation, and cryosurgery. Over-the-counter treatments are also of interest for patients due to their non-invasive character, but their clinical efficiency has not been clearly demonstrated. This study was designed in order to evaluate the efficacy of a modern-pharmaceutical-formulation-type poloxamer-based binary hydrogel, having Origanum vulgare L. essential oil (OEO-PbH) as an active ingredient in the management of FPs. The formulation has been shown to possess good qualities in terms of stability and sterility. Non-invasive measurements revealed changes in some physiological skin parameters. An increase in transepidermal water loss (TEWL) and erythema index was noted, while skin surface water content (SWC) decreased during eight weeks of treatment. The macroscopic evaluation revealed that the FPs dried and shrunk after topical treatment with OEO-PbH. Clinically, patients presented a lowering of the number of lesions on the treated area of 20-30% after one month of treatment and around 50% after the second month. Histopathological examination suggests that topical treatment with OEO-PbH may induce histological changes in the epidermis, dermis, and fibrovascular cores of FPs, including a loss of thickness, reduced size and number of blood vessels, and low cellularity. These changes may contribute to the observed reduction in size of FPs after treatment with OEO-PbH.

Concentrations and controls of dissolved inorganic carbon in Arctic summer sea ice and adjacent surface seawaters

The carbonate chemistry of sea ice plays a critical role in global ocean carbon cycles, particularly in polar regions which are subject to significant climate change-induced sea ice variation. However, less is known about the interaction of carbonate system between sea ice and its adjacent seawaters due to sparse sampling and disparities in reported results. Here we provide an insight into this issue by collecting and measuring dissolved inorganic carbon (DIC) and associated environmental parameters in Arctic sea ice during a cruise in the summer of 2014. Our observations show that DIC in Arctic summer sea ice has a mean concentration of 463.3 ± 213.0 μmol/kg and appears to be controlled mainly by the fraction of brine water in the ice. The low Chl a and nutrients content in sea ice indicate minor contribution of biological uptake to sea-ice DIC in the western Arctic Ocean. The DIC concentration in surface water (<100 m depth) decreased from a mean of 2108.3 ± 45.4 μmol/kg in 1994 to a mean of 2052.4 ± 98.6 μmol/kg in 2014, due to the enhanced sea ice melting that dilutes the DIC concentrations of surrounding seawaters.

A predictive risk map for human leptospirosis guiding further investigations in brown rats and surface water

ABSTRACT Leptospirosis is a zoonosis caused by the spirochete Leptospira spp. It is often not clear why certain areas appear to be hotspots for human leptospirosis. Therefore, a predictive risk map for the Netherlands was developed and assessed, based on a random forest model for human leptospirosis incidence levels with various environmental factors and rat density as variables. Next, it was tested whether misclassifications of the risk map could be explained by the prevalence of Leptospira spp. in brown rats. Three recreational areas were chosen, and rats (≥25/location) were tested for Leptospira spp. Concurrently, it was investigated whether Leptospira spp. prevalence in brown rats was associated with Leptospira DNA concentration in surface water, to explore the usability of this parameter in future studies. Approximately 1 L of surface water sample was collected from 10 sites and was tested for Leptospira spp. Although the model predicted the locations of patients relatively well, this study showed that the prevalence of Leptospira spp. infection in rats may be an explaining variable that could improve the predictive model performance. Surface water samples were all negative, even if they had been taken at sites with a high Leptospira spp. prevalence in rats.

Application of Machine Learning for Prediction and Monitoring of Manganese Concentration in Soil and Surface Water

This study explored the application of machine learning, specifically artificial neural network (ANN), to create prediction models for manganese (Mn) concentration in soil and surface water (SW) on the island province with two open mine pits overflowing to two major rivers that experienced mining disasters. The two ANN models were created to predict Mn concentrations in soil and SW from 12 and 14 input parameters for soil and SW, respectively. These input parameters were extracted from extensive field data collected at the site during sampling program in 2019, 2021, 2022, and initially processed with spatial analysis via geographic information system (GIS). All datasets were then divided for model training and validation, using 85% and 15% ratio, respectively. Performance evaluation of each model with mean absolute percentage error (MAPE) and root mean squared error (RMSE) confirmed the accuracy of both models. The soil Mn model achieved MAPE and RMSE values of 2.01% and 23.98, respectively. The SW Mn model was split into two models based on SW Mn values within the 0–1 mg/L range and &gt;1 mg/L range. The SW Mn model for &gt;1 mg/L performed better with MAPE and RMSE of 4.61% and 0.17, respectively. Feature reduction was also conducted to identify how the models will perform if some input parameters were excluded. Result showed sufficient accuracy can still be obtained with the removal of 4–5 input parameters. This study and these models highlight the benefit of ANN to the scientific community and government units, for predicting Mn concentration, of similar environmental conditions.

Metal Transport in the Mixing Zone of an Estuarine River to the Northern Gulf of Mexico

To better understand the pollution potential of metals in estuaries heavily concentrated with petrochemical industries, we measured concentrations of total recoverable metals in the lower Calcasieu River in southwestern Louisiana that flows into the northern Gulf of Mexico. Water samples were collected at six sites along the last 88 km reach of the river monthly between May 2013 and November 2015, during which salinity ranged from 0.02 to 29.5 ppt from upstream to downstream. The samples were analyzed for a series of total recoverable metals, including aluminum (Al), arsenic (As), boron (B), cadmium (Cd), calcium (Ca), cobalt (Co), chromium (Cr), copper (Cu), iron (Fe), lithium (Li), magnesium (Mg), manganese (Mn), nickel (Ni), silicon (Si), titanium (Ti), vanadium (V), and zinc (Zn), of which only Al, As, B, Ca, Fe, Li, Mg, Mn, Si, Ti, and Zn had a detection rate higher than 30% over the 31-month study period. In the freshwater portion of the river, Si, Ca, Al, Fe, and Mg showed the highest concentration (8, 5, 4, 2, and 2 mg/L, respectively), while Li, As, Zn, Ti, and B had the lowest concentration (6, 16, 27, 34 and 50 µg/L, respectively). The concentrations of Al and Si declined by more than 30% from the freshwater to the river mouth, but the concentrations of Li and B increased by 61 and 66 times, respectively. None of these metals’ concentrations were found to exceed US EPA standards, but the rapid increase in Li and B concentrations may indicate a potential anthropogenic influence. On average, the Calcasieu River discharged a total of 35,484 tons of the elements each year (or 8059 kg/km2/yr), of which Si, Al, Ca, Fe, and Mg contributed 98%. Three major components of factors were extracted explaining 34, 20, and 13% (cumulative 67%) of the total variation in the metal concentrations. Salinity and pH were the major (&gt;0.3) parameters in component 1 explaining the variability of B and Li; TSS was the major (&gt;0.3) parameter in component 2 explaining the variation of Al, Fe, and Ti concentration; and temperature and DO% were the major (&gt;0.3) parameters in component 3 explaining the variation of Mn concentration. Further studies on riverbed sediment metals and their effect on metal concentrations in surface water can help understand the metal sources and their potential effects on coastal aquatic ecosystems.

Polycyclic aromatic hydrocarbons in the water column of three hot spot areas, Jeddah coast, eastern of Red Sea

Jeddah coast receiving significant amount of persistent organic pollutants including polycyclic aromatic hydrocarbons (PAHs). Sources of PAHs mainly introduced to the coastal area from sewage influents, vehicle exhausts, industrial and Islamic harbor activates. In the present study, dissolved PAHs in the surface and near bottom waters were assessed in three highly polluted coastal areas in Jeddah city (Islamic Jeddah Port, Al-Arbaeen and Al-Shabab lagoons), eastern side of the Red Sea. The study aims to investigate vertical and horizontal distribution of PAHs in the water column, and explore the anthropogenic and environmental factors affecting their distribution. The total concentration of parent and methylated PAHs (∑25PAHs) in the near bottom waters were ranged between 377 and 1300 ng/L (average: 773 ± 329 ng/L), while the concentrations in surface waters (∑11PAHs) were ranged between 151 and 748 ng/L (average: 360 ± 174 ng/L). The concentrations of PAHs in the bottom waters were almost double those of surface waters. The area reached by particulate organic matter from sewage effluents that adsorbed low soluble high molecular weight PAHs from the surface waters on their way to the sediments then sediment-bottom water exchange released considerable amount of PAHs in bottom waters. The diagnostic ratios pointed out to a mixture of petrogenic and pyrogenic origins in the surface and near bottom waters. The toxic and mutagenic equivalent quotients for carcinogenic PAHs in the bottom waters were found 47 and 49 ng TEQ/L, respectively. The PAH levels in the study area indicated adverse effects are probable to occur.

Velocity analysis of a lateral wave

In practice, the reflected EM signal cannot be clearly observed in GPR data due to the high water content and other reasons. However, the antenna coupling signal through the ground interface is dominated in all the GPR measurements. This direct coupling signal that travels through the ground interface is called a lateral wave. The properties of the lateral wave directly depend on the subsurface properties, especially electrical parameters. We have numerically analyzed a lateral wave and its velocity. Subsequently, the relationship between lateral wave and dielectric permittivity was determined by polynomial regression. Analytically, it is challenging to analyze a lateral wave due to the parameters that can influence wave propagation. Antenna characteristics, surface roughness, etc need to be considered. Numerically, we designed a GPR system with a subsurface layer and observed a lateral wave. This numerical analysis can give a chance to use a lateral wave for near-surface soil water content. This analysis gives a more precise estimation of surface water content. Moreover, we analyze the antenna height effect that influences radar signals. We numerically observed that the GPR signal is highly affected by antenna height. The antenna height effect depended on the wavelength of the applied electromagnetic wave. By adjusting the antenna height, the unobservable GPR signal can be clearly detected.

Temporal and Spatial Distribution Characteristics and Source Analysis of Nitrate in Surface Water of Wuding River Basin

The Wuding River Basin is a first-class tributary of the Yellow River, and the quality of its water ecological environment has a profound impact on the ecological protection and high-quality development of the Yellow River Basin. In order to identify the source of nitrate pollution in the Wuding River Basin, surface water samples of the Wuding River were collected from 2019 to 2021, and the temporal and spatial distribution characteristics and influencing factors of nitrate concentration in surface water in the basin were explored. Nitrogen and oxygen isotope tracer technology and the MixSIAR model were used to qualitatively and quantitatively determine the sources of surface water nitrate and their contribution rates. The results showed that there were significant spatial and temporal differences in nitrate concentrations in the Wuding River Basin. In terms of time, the mean concentration of NO-3-N in surface water in the wet season was higher than that in the flat-water period; spatially, the mean concentration of NO-3-N in the downstream surface water was higher than that in the upstream. The spatial and temporal differences in surface water nitrate concentrations were mainly affected by rainfall runoff, soil types, and land use types. The main sources of nitrates in the surface water of the Wuding River Basin during the wet season were domestic sewage, manure, chemical fertilizers, and soil organic nitrogen, whose contribution rates were 43.3%, 27.6%, and 22.1%, respectively, and the contribution rate of precipitation was only 7.0%. There were differences in the contribution rate of nitrate pollution sources in surface water of different river sections. The contribution rate of soil nitrogen in the upstream was significantly higher than that in the downstream, which was 26.5%. The contribution rate of domestic sewage and manure in the downstream was significantly higher than that in the upstream, which was 48.9%. To provide a basis for the analysis of nitrate sources and pollution control in Wuding River and even rivers in arid and semi-arid regions.

Environmental fate and ecological impact of the potentially toxic elements from the geothermal springs.

Potentially toxic elements from geothermal springs can cause significant pollution of the surrounding environment and pose potential risk to the ecosystem. The fate of potentially toxic elements in the water-soil-plant system in the Yangbajain geothermal field on the Tibetan Plateau, China was investigated to assess their impact on the eco-environment. The concentrations of Be, F, As, and Tl were highly elevated in the headwaters of the Yangbajain geothermal springs, and their concentrations in the local surface water impacted by the geothermal springs reached 8.1μg/L (Be), 23.9mg/L (F), 3.83mg/L (As), and 8.4μg/L (Tl), respectively, far exceeding the corresponding thresholds for surface and drinking water. The absence of As-Fe co-precipitation, undersaturated F-, and weak adsorption on minerals at high geothermal spring pH may be responsible for the As- andF-rich drainage, which caused pollution of local river. As concentrations in the leaves of Orinus thoroldii (Stapf ex Hemsl.) Bor were up to 42.7μg/g (dry weight basis), which is an order of magnitude higher than the allowable limit in animal feeds. The locally farmed yaks are exposed to the excessive amount of F and As with high exposure risk through water-drinking and grass-feeding.

Hydrological setting controls 137Cs and 90Sr concentrations in a headwater catchment in the Chornobyl Exclusion Zone

Concentration-discharge relationships are widely used to understand the hydrological processes controlling river water chemistry. This study investigates how hydrological processes affect radionuclide (137Cs and 90Sr) concentrations in surface water in headwater catchments within the Chornobyl Exclusion Zone (ChEZ) in Ukraine. In the flat wetland catchments, the depth of the saturated soil layer changes little throughout the year, but changes in the saturated soil surface area during snowmelt and immediately after rainfall affect water chemistry by changing the opportunities for contact between the surface water and the soil surface. On the other hand, in the slope catchments where there are few wetlands, the water chemistry of river water is governed by changes in the relative contributions of “shallow water” and “deep water” due to changes in the catchment water supply pathways feeding the rivers. In this study, no correlations were observed between dissolved or suspended 137Cs concentrations and either discharge rates or competitive cations, but the solid-liquid ratio of 137Cs was found to be significantly and negatively correlated with water temperature. However, 90Sr concentrations in surface water were found to be strongly related to the water pathways for each of the catchments. Moreover, contact between the surface water and the soil surface and changes in the relative contributions of shallow and deep waters to stream water were correlated with changes in 90Sr concentrations in surface water in wetland and slope catchments, respectively. The study concludes that 90Sr in rivers inside the ChEZ are strongly affected by the water pathways in headwater catchments. Additional studies will be necessary to clarify the details of sorption/desorption reactions.

The environmental impact of pharmaceuticals on surface waters and its estimation through drug utilisation data.

Human use of pharmaceuticals is their primary way of entering the environment. Once consumed, pharmaceuticals are released, through urine and faeces, into wastewater and consequently into surface waters. Furthermore, veterinary use and inappropriate disposal also contribute to the accumulation of these substances in surface waters. These quantities of pharmaceuticals, although small, can cause toxic effects on aquatic flora and fauna, e.g., causing growth and reproduction problems. To estimate pharmaceutical concentration in surface waters, different data sources can be used, such as drug utilisation data, and wastewater production and filtration. Applying a method to estimate aquatic concentrations of pharmaceuticals at national level could allow the implementation of a monitoring system. to prioritize water sampling.

Bioavailability-based Environmental Quality Standards for metals under the Water Framework Directive

Metals are naturally present in surface waters. By considering the bioavailability of a metal in an aquatic environment, we can more precisely predict the effect of a selected metal on aquatic organisms. This enables us to make a more reliable assessment of the compliance of the metal's concentration in inland surface waters with the environmental quality standard for that metal. In addition to complex-forming inorganic and organic ligands, the bioavailability of metals in water is also influenced by physicochemical conditions in the water. Metals occur in different concentrations and in different forms in aquatic environments. This is referred to as metal speciation. The bioavailability of a metal in water depends mainly on its speciation. Normally, a dissolved free metal ion is more bioavailable than a metal ion bound in a complex. The risks posed by given metals to aquatic environments are addressed under EU legislation in the Water Framework Directive (Council of the European Union, 2000) (WFD). The WFD’s purpose is to direct Member States to protect and improve the status of all water bodies throughout the European Union. Directive 2013/39/EC (Council of the European Union, 2013), which refers to priority substances as regards water policy, supplements the WFD and the Directive on environmental quality standards (Council of the European Union, 2008). For nickel and lead, Directive 2013/39/EC sets the annual average environmental quality standards (AA-EQS) for inland surface waters, which refer to biologically available concentrations of metals (AA-EQSbioavailable). In this way, uniform environmental quality standards for the entire European Union are determined for metals, allowing for a compliance assessment of metals for surface waters. In the article, we have presented an analysis of inland surface water monitoring data for nickel and lead, examining how the introduction of AA-EQSbioavailable affects the consistency of monitoring data for these metals. We used monitoring data from 2018 to 2021. To calculate bioavailable concentrations for nickel and lead, we used the bioavailability assessment model bio-met bioavailability tool v.2.3 (Bio-met, 2017). Additionally, for lead, we used equations (1), (2), and (3) to calculate the bioavailable concentration (European Commission, 2019). Based on the analysis conducted, we recommend the utilization of the bio-met model instead of the equations for calculating the concentration of bioavailable lead in the context of the annual compliance assessment of inland surface water monitoring data carried out by ARSO. Using the mentioned bioavailability assessment model, we have provided an upgrade in the methods used to assess metal’s concentration compliance with the EQS for that metal for surface waters. As a result, the requirements of Directive 2013/39/EC relating to biologically available concentrations of metals could be transferred to the Slovenian legal system.

STATISTICAL ANALYSIS OF RADON CONCENTRATION IN BOREHOLE WATERS; CORRELATION TO GEOLOGICAL FORMATIONS KATSINA STATE, NORTH WESTERN NIGERIA

Radon in borehole water serves as a source of natural radioactivity exposure through indoor air. Determination of naturally occurring radionuclides concentration in ground and surface waters is useful as a contribution to environmental health studies. In this research, statistical analysis of radon concentration in (borehole) water was conducted in Katsina state. The aim of this study is to analyse statistically the concentration of radon in borehole water in Katsina state and to establish a possible relationship between radon activity concentration in borehole water and underlying rock types. A total of 110 water samples were collected and analysed using Tri-carb 1000 Liquid Scintillation Counter (LSC) at the Centre for Energy Research and Training, Ahmadu Bello University. The overall average concentration of 222Rn was found to be 69 ± 3 Bql-1 with geological formations, G8 and G7 having the highest and lowest concentrations with values of 75 ± 10 Bql-1 and 57 ± 4 Bql-1 respectively, which are higher than the world average values of 10 Bql-1 set by WHO and 11.1 Bql-1 set by USEPA. The results showed that radon concentrations are clearly correlated to rock types with acidic intrusive rocks associated with values which sedimentary rocks are associated with lower concentrations.

Exploration of the factors that influence total phosphorus in surface water and an evaluation of surface water vulnerability based on an advanced algorithm and traditional index method

Due to the continuous influence of human activities, phosphorus pollution in surface water has become a persistent problem that needs to be addressed since phosphorous entails certain risks and degrees of damage to ecosystems and humans. The presence and accumulation of total phosphorus (TP) concentrations in surface waters is the result of a combined effect of many natural and anthropogenic factors, and it is often difficult to intuitively identify the individual importance of each factor in regard to the pollution of the aquatic environment. Considering these issues, this study provides a new methodology to better understand the vulnerability of surface water to TP pollution and the factors that influence TP pollution through the application of two modeling approaches. This includes the boosted regression tree (BRT), an advanced machine learning method, and the traditional comprehensive index method (CIM). Different factors, such as natural variables (including slope, soil texture, normalized difference vegetation index (NDVI), precipitation, and drainage density) and point and nonpoint source anthropogenic factors were included to model the vulnerability of surface water to TP pollution. Two methods were used to produce a vulnerability map of surface water to TP pollution. Pearson correlation analysis was used to validate the two vulnerability assessment methods. The results showed that BRT was more strongly correlated than CIM. In addition, the importance ranking results showed that slope, precipitation, NDVI, decentralized livestock farming and soil texture had a greater influence on TP pollution. Industrial activities, scale livestock farming and population density, which are all contributing sources of pollution, were all relatively less important. The introduced methodology can be used to quickly identify the area most vulnerable to TP pollution and to develop problem specific adaptive policies and measures to reduce the damage from TP pollution.

Dissolution behavior of ZnO nanoparticles at environmentally relevant low concentrations in surface waters: Equilibrium and kinetics

Environmentally relevant fate parameters are essential in accurate prediction of nanomaterial's exposure. This study investigates the dissolution kinetics and equilibrium of ZnO nanoparticles (ZnONPs) using environmentally relevant low concentrations (50–200 μg/L) of ZnONPs in river water and lake water samples, and a seawater-influenced river water. We found that ZnONPs at an initial concentration of 50 μg/L completely dissolved independent of water matrices, while at 100 and 200 μg/L the dissolution level of ZnONPs was strongly dependent on the water chemistry. Carbonate alkalinity was found to control the dissolution levels, and can react with dissolved Zn ion to form secondary solid product hydrozincite. An analysis of our kinetic data and comprehensive literature results reveals that the dissolution kinetic coefficients largely increased with decreased initial ZnONP concentrations especially in environmental water matrices. The result highlights the importance to measure and derive representative dissolution parameters of nanomaterials using environmentally relevant concentrations.

Searching for hotspots of neustonic microplastics in the Canary Islands

In this study, we investigated the concentration, distribution, and characteristics of neustonic MPs in the Canary Islands, with a particular focus on the island leeward zones, where a high accumulation of floating marine microplastics is expected. Samples were collected with a manta net at 15 different sites from Alegranza to La Gomera during the IMPLAMAC expedition. The microplastic concentration in surface waters ranged from 0.27 MPs/m3 in Alegranza to 136.7 MPs/m3 in the south of Gran Canaria. The highest concentration of MPs found was due to the presence of a sea-surface slick, also called “marine litter windrow”, formed in the south of Gran Canaria. The most abundant zooplankton group in the neuston was copepods, except at the marine litter windrow where fish larvae and eggs predominated. This indicates that coastal areas where marine litter windrows are formed have a high risk of MP ingestion and potential adverse effects on biota.

Per- and polyfluorinated alkyl substances (PFAS) in Pennsylvania surface waters: A statewide assessment, associated sources, and land-use relations

The objectives of this study are to identify per- and polyfluoroalkyl substances (PFAS) in Pennsylvania surface waters, corresponding associations with potential sources of PFAS contamination (PSOC) and other parameters, and compare raw surface water concentrations to human and ecological benchmarks. Surface water samples from 161 streams were collected in September 2019 and were analyzed for 33 target PFAS and water chemistry. Land use and physical attributes in upstream catchments and geospatial counts of PSOC in local catchments are summarized. The hydrologic yield of the sum of 33 PFAS (∑PFAS) for each stream was computed by normalizing each site's load by the drainage area of the upstream catchment. Utilizing conditional inference tree analysis, the percentage of development (>7.58 %) was identified as a primary driver of the ∑PFAS hydrologic yields. When percentage of development was removed from analysis, ∑PFAS yields were closely related to surface water chemistry associated with landscape alteration (e.g., development or agricultural cropland), such as concentrations of total nitrogen, chloride, and ammonia, but also to count of water pollution control facilities (agricultural, industrial, stormwater, and/or municipal waste pollution abatement facilities). In oil and gas development regions, ∑PFAS yields were associated with combined sewage outfalls. Sites surrounded by ≥2 electronic manufacturing facilities had elevated ∑PFAS yields (median = 241 ng/s/km2). Study results are critical to guide future research, regulatory policy, best practices that will mitigate PFAS contamination, and the communication of human health and ecological risks associated with PFAS exposure from surface waters.

The Use of Isotopic Techniques to Determine the Sources of Groundwater Recharge and Interaction with Surface Water in Southern Baghdad –Iraq

Isotope Hydrology has become a widely used technique for managing the global water crisis. The study of the Isotopic content of Groundwater and surface water and the study of chemical analysis is an important source of water sustainability. The study area is located south of Baghdad- Iraq three regions (Al-Dora, Al- Rustumiya and Al-Tuwaitha). Many samples were taken in the study area (15) samples Groundwater (well) and surface water (Rivers Tigris and Diyala). The results of the isotopic study indicated that there is a clear interaction in the values of the two stable isotopes between groundwater and surface water (Tigris and Diyala Rivers). In the wells (-41.5,-42.95 ‰) for deuterium (2H) (-6.77, -7.15 ‰) Oxygen-18 (18O) and the Tigris and Diyala rivers (-40 , - 39.47 - -7.34,-7.2 ‰) respectively ((2H), ((18O)) in the study area. Depending on these variables, indicates isotopic signatures similar between groundwater and surface water in the study area, helped in this the geological structures of the city of Baghdad (the sedimentation of the sedimentary plain). Through the results of isotope Tritium (H-3), (indicator to know the age of water and Recharge of water) we showed a clear convergence between the concentrations of tritium in the surface water of the rivers (Tigris and Diyala) (4.8 ± 0.064) TU and the wells (4.5 ±0.045) TU in the region, which indicates that the supply of water from wells is modern and continuous, and confirms the overlap between surface water and groundwater in the study area. It also indicated the high values of electrical conductivity in wells samples because most of the wells in the study area are shallow, where salt concentrations are high due to increased evaporation and are not suitable for drinking.

A meta-analysis of the occurrence of alkylphenols and alkylphenol ethoxylates in surface waters and sediments in the United States between 2010 and 2020

Nonylphenol (NP), Octylphenol (OP), and their ethoxylates (NPEO and OPEO) have been the subject of considerable scientific and regulatory attention, primarily due to concerns about their aquatic toxicity and endocrine activity. Environmental monitoring has been conducted and reported for these substances in the United States (U.S.) for several decades. This paper develops an updated statistically based meta-analysis of the occurrence and ecological relevance of these substances in fresh and marine surface waters and sediments in the U.S. between 2010 and 2020. The overall objectives of this study were: (1) to evaluate the impact of analytical detection limits (DLs) and treatment of censored or non-detected (ND) samples on reported results, (2) to summarize and evaluate recent (2010–2020) occurrence and concentrations of these substances in surface waters and sediments, (3) to conduct an ecological screening assessment of the potential risks of these substances to aquatic organisms in surface waters and sediments for this same period, and (4) to examine temporal trends of these substances in surface waters and sediments relative to previous investigations. Given that a large proportion of all NP, NPEO, OP and OPEO samples in recent (2010–2019) U.S. monitoring studies were below their respective method Limit of Detection/Limit of Quantification (LOD/LOQ) detection frequency ranging from 0 to 24%), proxy values were imputed using robust regression of order statistics (ROS). Nationally, NP and OP concentrations in fresh surface waters and sediments have decreased from 2010 to 2019. In contrast, changes in NP and OP concentrations in marine waters and sediments were more variable with some increases noted. A screening environmental risk assessment indicated that less than 1% of all samples exceeded U.S. or Canadian environmental quality guidelines. No exceedances were noted after 2016 which indicates a low potential for risk to aquatic organisms.

Physical and biogeochemical drivers of solute mobilization and flux through the critical zone after wildfire

A nine-year time series of nutrient cation and anion concentration and efflux from three forested catchments in the Jemez River Basin Critical Zone Observatory (JRB-CZO) in northern New Mexico was used to quantify the pulse of chemical denudation resulting from varying levels stand-replacing wildfire intensity in May-June of 2013. The 3 years of pre-fire and 6 years of postfire data were also probed to shed light on the mechanisms underlying the pulsed release and the subsequent recovery. The initial large solute pulse released to the streams—K+, Ca2+, Mg2+, SO42-, Cl−, dissolved inorganic carbon (DIC), dissolved organic carbon (DOC), and total dissolved nitrogen (TDN)—was caused by leaching of hillslope ash deposits during the first monsoon storms post-fire. Debris flow following the wildfire likely redistributed much of the ash-containing sediments along streams and valley bottoms. Sustained elevated solute concentrations observed in the surface waters throughout the post-fire period relative to pre-fire baselines is consistent with these soluble materials being periodically flushed from the soils during wet seasons, i.e., snowmelt and summer monsoons. As microbial mediated reactions and biotic uptake—due to plant regrowth—recover after fire, nutrient ion export (e.g., NO3-, Cl− and SO42-) steadily decreased toward the end of the post fire period, but remained above pre-fire levels, particularly for NO3- and SO42-. Surface water concentrations of polyvalent cations (e.g., Al and Fe) decreased significantly after the fire. Our observations suggest that changes in organic matter composition after fire (e.g., increased humification index—HIX) and the presence of pyrogenic carbon may not favor organo-metal complexation and transport. Finally, differences in burn severity among the three watersheds presented in this study, provide insights of the relative impact of solute exports and resilience. The catchments that experienced high burn severity exhibited greater solute fluxes than the less severely burn. Moreover, despite these differences, toward the end of the post-fire period these surface waters presented low and similar solute effluxes, indicating system recovery. Nonetheless, magnitudes and rebounds were solute and process specific. The results of this study highlight the importance of surface and near surface physical and biogeochemical processes on the long-lasting geochemical denudation of forested catchments following wildfires of varying intensities.