•The scientific knowledge on the southern Okhotsk Sea biogeochemistry and its relationship with its rich primary productivity was actualized.•The formation mechanisms of different water masses are ...starting to be revealed using chemical tracers, especially radionuclides.•The high seeding potential of Thalassiosira by ice–melting has been repeatedly featured, and it was placed as reason for its highest abundance in spring.•The total carbon mass flux is highest in April – June. Its maximum (up to 1165 mg C m−2 day−1) occurs several days after the sea ice retreatment•Further research is needed on the formation of the Intermediate Cold Water, the Cold Water Belt and the solubilization process of particulate Fe.
The southern Okhotsk Sea is one of the best fishing grounds in Japan, and the biogeochemistry, primary productivity, and physical aspects of this region have been heavily researched. However, a comprehensive review of the literature has not been written since that by doctor Takatoshi Takizawa more than 40 years ago (1982). This review actualizes the share–ground knowledge of the influence of oceanographic conditions on the primary productivity of the area. This review includes topics from physical/chemical oceanography and hydrobiology, focusing on the complex oceanological structures that support the high primary productivity of the southern Okhotsk Sea. It is known that the formation of all water masses is ultimately a consequence of the seasonal interchange of the Soya Warm Current and the East Sakhalin Current. However, it was revealed that there may be over- or under-estimations in different material and heat fluxes among water masses, especially regarding the dense Soya Warm Current. Recent studies have investigated the formation mechanisms of different water masses using chemical tracers, particularly radionuclides. Although promising if properly combined with traditional techniques, more isotopes or compounds are required to derive further conclusions. In terms of biological aspects, the high seeding potential of Thalassiosira after sea ice melting has been featured by many authors, and it was considered as the reason for its highest abundance in spring. The total carbon mass flux, which is essential for scallop farming, is highest in April–June, normally 120–160 mg C m−2day−1. The total carbon mass flux is maximum (up to 1165 mg C m−2day−1) after the spring bloom peak, and the spring bloom is strongly linked to sea ice retreatment. It was identified that the routes of 134Cs towards the Intermediate Cold Water, the formation mechanism of the Cold Water Belt, and the solubilization process of sea ice-carried particulate Fe require further research. Three major potential threats were identified, including the appearance of alien toxic species, a decrease in sea ice production in the northern parts of the Okhotsk Sea, and offshore gas and oil drilling northeastern of the Sakhalin Island. Publicly available scientific knowledge about the biogeochemistry of the southern Okhotsk Sea and its relationship with its rich primary productivity was actualized to 2022, anticipating that this work will become the starting line for many early career scientists endeavoring in interdisciplinary studies.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Releases of municipal waters, including drinking water and wastewater, can considerably alter urban stream chemistry. However, the relative contributions of drinking water versus wastewater to ...streams have not been quantified previously and are therefore the focus of this study. We sampled streams along a land use gradient that included watersheds with impervious surface areas (ISA) ranging from 1.6 to 62.6%. Samples were analyzed for F−, total B, δ11B, and optical brighteners to determine municipal water inputs to streams. We observed low F− (75 ± 20 μg/L), B (29 ± 6 μg/L), and optical brightener (3.66 ± 0.76 RFU) levels in rural streams, but their concentrations increased with urbanization (up to 475 μg/L, 227 μg/L, and 22.09 RFU, respectively). The δ11B values for drinking waters (16.52 ± 0.39‰) and wastewaters (untreated = 6.06 ± 0.88‰ and treated = 6.46 ± 0.93‰) were distinct, but there was poor correlation between δ11B and ISA for the streams (R2 = 1 × 10−5; p = 0.99), likely due to variable lithology in the study area. We used inverse and three-component mixing models to quantify municipal water inputs to the streams. In densely urbanized watersheds, drinking water and wastewater can respectively contribute up to 54% and 16% of the total streamflow. In addition to our spatial sampling, we collected weekly samples at a suburban stream to test the effects of discharge and seasonality on municipal water tracer behavior. We found that tracer levels did not change significantly (p ≥ 0.28) with discharge or season, suggesting that municipal water inputs are fairly constant. Understanding the relative proportions of differing municipal water types to streams is crucial in guiding infrastructure improvements to conserve drinking water and reduce harmful wastewater releases. The unique chemical signatures of municipal waters aid in the widespread applicability of our multi-tracer method for identifying water sourcing to urban streams.
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•Tracers were used to assess drinking water and wastewater inputs to streams.•Municipal waters have distinct tracer (F−, B, δ11B, and optical brightener) values.•Municipal water tracer levels were low in rural streams, but high in urban streams.•Drinking water and wastewater respectively contribute up to 54% and 16% of flow.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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•We evaluated hydrologic connectivity of distinct landscape units in 3-dimensions.•Hydrometric evaluations of catchment wetness revealed three distinct seasons.•End Member Mixing ...Analysis showed spatiotemporal shifts in source areas.•Upstream contributions were less important to downstream streamflow among seasons.•Local lateral contributions sustained streamflow through summer and fall seasons.
Montane ecoregions are important vehicles for downstream hydrologic function, but their dynamics are relatively understudied compared to alpine and subalpine catchments in the western United States. Montane catchments experience shifts in precipitation inputs seasonally, which results in spatiotemporal differences in source area contributions to the stream. We collected hydrometric and geochemical data between 2018 and 2021 from a 2.65 km2 semi-arid headwater catchment in the Front Range of Colorado, USA. Using a combined approach of hydrometric monitoring, geochemical characterization, and end-member mixing analysis (EMMA), we assess hydrologic connectivity between areas with high upslope accumulation and the stream. Within our study area, high upslope accumulation area corresponded to alluvial/ colluvial fans wherein we focused instrumentation and water sample collection. Using observed rainfall, and multiyear measurements of groundwater levels, soil moisture, and streamflow, we observed distinct hydrologic seasons within our catchment characterized by snowmelt during the spring, rainstorms during the summer, and a return to baseflow during the fall. Within this framework, we found that source areas to streamflow shift with longitudinal distance downstream, and among hydrologic seasons. Notably, our EMMA results indicate that contributions from upstream source areas become less important than lateral inputs from spring snowmelt into the fall return to baseflow. This was most pronounced at the upper catchment where upstream contributions to streamflow decreased up to 33.3% between spring and fall. These results suggest that streamflow is maintained by local source areas contributing laterally and vertically. Our results reflect dynamic shifts in hydrologic connectivity in space and in time, which are increasingly important to land and water resource management given rapid climate changes within the western United States.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
We demonstrated the great value of spatially distributed and temporally high-resolution hydro-chemical data to enhance knowledge about the intra-catchment variability of flow processes and the runoff ...composition of individual storms in a tropical alpine (Páramo) ecosystem. In this study, water sources (rainfall, spring water, and water from soil layers of Histosols and Andosols) and nested streams were sampled bi-weekly (2013–2014), including three storm high-resolution events (5–240 min). Water samples were analyzed for 14 tracers including electrical conductivity (EC) and rare earth trace elements and used as input to perform End-Member Mixing Analysis (EMMA). End-members identified for the outlet could explain the hydrological behavior of four out of the five tributaries, indicating similar hydro-geochemical processes and geomorphic features within the catchments. The runoff source contributions of the individual sub-catchments varied among (e.g. Andosols ~40% in tributaries and ~25% at the outlet) and within storm events (e.g. Histosols 15% higher in small peak discharge event), indicating a time-variable composition of streamflows. The latter was also reflected by the interaction of different sources and the chronology of flow paths in EMMA-space, evidencing a faster connectivity with hillslopes in the upper sub-catchments compared to the lower sub-catchments. We found counter-clockwise hysteresis patterns of storms in the lower catchments and clockwise hysteresis loops in the upper catchments. The latter bi-directionality can be related to lower slopes, wider riparian areas and the higher proportion of Histosols in the lower catchments compared to the upper sites.
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•High-resolution hydro-chemical data reveal chronology of flow processes in storms.•In upper and lower sub-catchments sources react oppositely during storm generation.•Soil water sources govern storms generation in tropical high-elevation catchments.•Hydro-chemical data are essential for precise conclusions about catchment functioning.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•Modeling of tracer transport in two-phase flow in capillary-dominated porous media.•Hydrodynamic dispersion, partition coefficient, and solute adsorption are examined.•Accurate modeling of tracer ...transfer by spontaneous imbibition in porous media.
Transport of chemical tracers in porous media is an important physical mechanism for applications in oil reservoir characterization, aquifer remediation, and CO2 storage. Although numerous analytical solutions exist to model the flow of solutes under single-phase flow, the modeling of solute transport in two-phase media driven by imbibition has been insufficiently examined. In tight porous media and the matrix of fractured reservoirs, spontaneous imbibition (SI) represents a key driving mechanism for fluid infiltration because the low permeability in these systems results in negligible transport by advection. Here, we present a new semi-analytical solution to model the transport of chemical tracers under one-dimensional countercurrent SI in oil–water porous media.
The model presented is derived from the analysis of fluid imbibition driven by capillarity and numerically solved as a function of water distribution. We model ideal and partitioning tracers to examine the contacted region and estimate the average oil saturation in capillary-dominated media under countercurrent SI. The concentration profiles obtained with the derived model show an excellent agreement against numerical simulation results, verifying that the semi-analytical solution accurately models the mechanisms of partitioning, hydrodynamic dispersion, and adsorption. The concentration profiles exhibit a significant delay in displacement behind the imbibition front when hydrodynamic dispersion is ignored and for high partitioning coefficients, demonstrating the importance of determining these properties under two-phase flow conditions. We consider that our solution derived represents an accurate alternative to time-consuming simulations that can be extended for the analysis of tracers in fractured reservoirs to estimate oil saturation in the matrix medium.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Evaluating the performance of source apportionment (SA) models is difficult due to the non-observable nature of source contribution in reality. Here we propose a new approach to assess the ...performance of Chemical Transport Models (CTMs) for SA based on wavelet time-frequency spectral analysis and Grey Incidence Analysis (GIA). For each source category, certain species that better reflect the periodic characteristics of the emission sources were selected as the chemical tracers. The consistency of the time series between the simulated source contributions and the observed source-specific chemical tracers was then examined using a GIA model based on the perspective of similarity, and characterized by the GIA scores. By applying this method to six typical pollution episodes, we evaluated the performance of the Comprehensive Air Quality Model with Extensions-Particle Source Apportionment Technology (CAMx-PSAT) model for PM2.5 SA from different temporal and spatial scales. The source- and episode-dependent optimal average time and main source regions were obtained. This approach is robust for facilitating a relatively meticulous evaluation of the performance of CTMs for PM2.5 SA, and provides additional insight for decision-making for heavy pollution emergencies.
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•A novel approach to assess the performance of CTM-based SA model is proposed.•It is applied to evaluate the performance of CAMx-PSAT model for haze episodes.•The source- and episode-dependent optimal ∆t and main source regions are obtained.•For secondary sources, better performance is found at longer ∆t and spatial distance.•Model performance is more sensitive to ∆t than distance for primary emission sources.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•Correlation between flow and hydrological data shows the effect of external sources.•Stable isotopes are efficient parameters for quantifying infiltration in networks.•Temperature can be used as an ...indicator for infiltration and inflow detection.•Combining various methods of assessments ensures the robust interpretation of data.
The failure of sewage network systems can lead to the introduction of external water, impacting the capacity, performance, and environmental sustainability of urban infrastructures. This study examined methods for identifying and quantifying external water in a sewage system in cold climate conditions through the analysis of stable isotope of oxygen (δ18O) and hydrogen (δ2H) from samples, and continuous temperature monitoring, followed by the simulation of the network's hydraulics and temperature profile. The assessment was conducted during periods of low and high groundwater levels, specifically during dry weather flow. In comparison, the yearly trends of infiltration and inflow rates were assessed utilizing the moving minimum method. Using δ18O as a tracer, daily infiltration rates of 5.8 % and 35 % were estimated for periods of low and high groundwater levels, respectively. Using the outputs of the thermodynamic model, temperature was used as a tracer and the daily infiltration rates were found to be 1.5 % and 21.9 % for the same periods. The infiltration and inflow rate for the year in question was estimated to be 23 % using the moving minimum method. The findings of this study demonstrate the temporal variability of infiltration in networks and highlight the need for, as well as the potential of, a multi-faceted approach and continuous monitoring for the accurate estimation of external water before sewage network renovations are carried out.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Fronts in the NO parameter, a semiconservative tracer combining nitrate and dissolved oxygen, and dynamic height were observed in the central East Siberian Sea that distinguished Atlantic and Pacific ...contributions to the upper halocline of the Amerasian Basin during the summer of 2015. The NO front was aligned with the Transpolar Drift, and its position over the Mendeleyev Ridge indicates that Pacific waters were generally restricted to the Canada Basin and did not spread to the central Arctic. This interpretation lies in contrast to the distribution of Pacific water fractions, calculated using established relationships between nitrate and phosphate, and indicates that traditional tracers used to quantify Pacific water contributions to the Arctic Ocean are no longer accurate.
Key Points
The NO parameter was used to separate upper halocline waters originating on the Chukchi versus East Siberian Sea shelves
Traditional methods of identifying and separating Pacific from Atlantic waters in the central Arctic may no longer be reliable
Pacific water was generally restricted to the Canadian Basin side of the Mendeleyev Ridge during summer 2015
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Since a few years, land use management aims to reduce and control water erosion processes in watersheds but there is a lack of quantitative information on the contribution of the sources of ...transported sediment. This is most important in agricultural areas where soils are sensitive to erosion. The geology of these areas is often characterized by large expanses of relatively homogeneous quaternary silts. The possibility of distinguishing the sources of erosion according to their geological substratum is thus very delicate. This information is important because its lack can lead to the mis-implementation of erosion control measures. To address this request, a confluence-based sediment fingerprinting approach was developed on the Canche river watershed (1274 km2; northern France), located in the European loess belt, an area that is affected by diffuse and concentrate erosion processes. Suspended particulate matter was collected during five seasonal sampling campaigns using sediment traps at the outlet of each tributary and confluence with the main stream of the Canche river. The final composite fingerprint was defined using physico-chemical and statistical analyses. The best tracer parameters for each tributary were selected using stepwise discriminant function analyses. These parameters were introduced into a mass balance mixing model incorporating Monte-Carlo simulations to represent the uncertainty. Estimates of the overall mean contributions from each tributary were quantified at different temporal scales. The annual sediment flux tributaries contributions range from 3 to 22% at the outlet of the Canche river, and annual sediment flux range from 0.87 to 40.7 kt yr−1. The Planquette and the Créquoise tributaries appear to be those producing the largest sediment flux. In contrast, tributaries with the highest number of erosion control on their area exhibit the lowest values of sediment flux. Our results indicate a positive impact of recent land management policies in the Canche river watershed.
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•Confluence-based sediment fingerprinting was developed in a homogeneous geological context.•Mass balance mixing model was applied using chemical sediment fingerprinting.•Tributaries relative contributions of the Canche river range from 3 to 22%.•Tributaries annual sediment flux ranges from 0.87 to 40.7 kt yr−1.•Results confirm the efficiency of erosion control policies in Northern France.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The extent of summer Arctic sea ice has reduced dramatically in recent years and, simultaneously, we have observed surface freshening over the Canada Basin in 2006 and 2007. In order to identify the ...source of this fresh water, either meteoric or sea ice meltwater, salinity, δ18O, and alkalinity were analyzed. Results show that sea ice meltwater increased in the surface water over the central part of the basin in 2006 and 2007, corresponding to the melting of an additional 2.7 m (1.3 m a−1) of sea ice. Anomalously fresh surface water observed in the southern part in 2007, however, was mostly attributed to Mackenzie River water extending into the basin interior, a source that was mainly absent in the early 2000s. Comparison with previous data shows that the meltwater component of surface water in the southern part of the Canada Basin has progressively increased at a mean rate of 0.27 m a−1 since 1987. This can be explained by a reduction of winter sea ice formation rate by 0.45 m or more during the past two decades. The runoff component showed larger variability in the southern basin but no obvious temporal trend. In the central basin, the river runoff component showed an increasing trend of 0.7 m a−1.
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