Zone Water Research Articles

Application of the random forest algorithm for mapping potential fishing zones of Rastrelliger kanagurta off the east coast of peninsular Malaysia

Indian mackerel, Rastrelliger kanagurta, play an important role in the marine fisheries of Malaysia, and their distribution is reported to be influenced by various oceanographic conditions. In this study, a modeling framework of machine learning techniques (random forest [RF]) and spatial analysis with geographic information systems (hotspot analysis) was used to predict and map potential fishing zones of R. kanagurta in the exclusive economic zone (EEZ) waters off the east coast of peninsular Malaysia. The RF model was constructed with a training dataset (n = 2535) and externally validated by a testing dataset (n = 1087). Model validation using Lin’s concordance correlation coefficient (CCC) on the testing dataset indicated good agreement (CCC = 0.811) between the predicted and observed catch per unit effort (CPUE) of R. kanagurta. The variable importance plot revealed the relative importance of four predictors of potential habitat, ranked in decreasing order of importance: sea surface height anomaly (SSHA), eddy kinetic energy (EKE), sea surface temperature (SST) and surface chlorophyll-a (CHL) concentration. Partial dependence shows that R. kanagurta prefers a habitat with the following parameters: SSHA -0.05–0.20 m, EKE < 0.02 m2/s2 or > 0.07 m2/s2, SST 30–31 °C and CHL 0.1–0.3 mg/m3. Spatial distribution of predicted CPUE hotspots were found to be closely related to the thermal fronts, which influenced by the monsoonal wind and occurrence of upwelling event in the study area. Our study indicates that cost-effective satellite-derived products can be used to predict potential fishing zones of R. kanagurta and provide useful information on relationship between environmental factors and CPUE of R. kanagurta.

Diversity, habitat associations and stock structure of odontocete cetaceans in the waters of American Samoa, 2003-06

Little is known about the species composition, distribution, abundance or stock structure of odontocetes in the central and western tropical Pacific Ocean, including those inhabiting the US Exclusive Economic Zone (EEZ) waters of American Samoa. While some information on species presence in this region has been gleaned from anecdotal sightings and whaling and stranding records, odontocete diversity in the waters of American Samoa has never been formally investigated. This lack of information precludes efforts to determine the sustainability of cetacean populations within US EEZ waters. This paper reports on the first dedicated surveys to document the presence and distribution of odontocete cetaceans in the waters of American Samoa. A series of small-boat photo-identification and biopsy surveys for cetaceans were conducted in the nearshore waters of Tutuila during 2003-06. In addition, ship-based visual surveys were conducted in the waters surrounding the Manu‘a Islands, Rose Atoll and Swains Island in summer 2006. A total of 58 groups of odontocete cetaceans were encountered during both small-boat and ship-based surveys: spinner dolphins (Stenella longirostris, n=34), rough-toothed dolphins (Steno bredanensis, n=10), sperm whales (Physeter macrocephalus, n=3), false killer whales (Pseudorca crassidens, n=5), bottlenose dolphins (Tursiops truncatus., n=1), dwarf sperm whales (Kogia sima, n=1), short-finned pilot whales (Globicephala macrorhynchus, n=1), and three groups of unidentified odontocetes. Photographs were analysed for quality and individuals with distinctive markings were selected for entry into a photo-identification catalogue. The resultant catalogue included 46 spinner dolphins, 41 rough-toothed dolphins, 2 bottlenose dolphins, 5 false killer whales, 4 pilot whales, 1 dwarf sperm whale and 4 sperm whales. Thirteen spinner dolphins and 14 rough-toothed dolphins were sighted in multiple years. To investigate stock structure, spinner dolphin genetic data were used to compare mitochondrial control region genetic diversity and allele frequencies between American Samoa and the Hawaiian Islands. American Samoa had a higher genetic diversity, and populations at the two locations were genetically distinct (FST = 0.21). The high diversity at American Samoa indicates that spinner dolphins at this location are not reproductively isolated, but the data do not rule out the possibility that these dolphins may be demographically isolated on ecological timescales.

The effects of nitrogen and phosphorus nutrients on the bioremediation of oil-contaminated waters by Gracilariopsis persica in the coastal areas of Bandar Abbas

This study investigated the influence of nitrogen and phosphorus on the bioremediation of crude oil by Gracilariopsis persica in littoral zone waters. In order to determine the role of nitrogen in bioremediation, urea, ammonium, and nitrate were used with and without phosphorus, with the result that nitrogen had no significant effect on the degradation of oil by Gracilariopsis persica in the littoral zone. Nearly 90 % of the crude oil used in this study was degraded by treatments with added phosphorus and nitrogen. A significant increase in the degradation of oil-contaminated water was observed after the application of phosphorus. Comparatively to the application of phosphorus alone, nitrogen and phosphorus together increased the rate of biodegradation by the algal species. Based on the results of the study, nitrogen and phosphorus have complementary effects on the bioremediation of oil by Gracilariopsis persica.

Effects of rainfall characteristics on bromide leaching in a typical tobacco field in China's Yunnan Province

AbstractKnowledge about water and solute transport in the vadose zone is critical for agrochemical management, especially for the tobacco cultivation characterized by extensive fertilizer and pesticide applications. Under the field conditions, however, natural soil heterogeneity complicates and limits the analysis of water and solute transport. Applying the scale‐dependent treatment distribution in a rainfall simulation experiment, the objective was to evaluate the impact of rainfall characteristics on bromide (Br−) leaching in a typical tobacco field in China's Yunnan Province. On a transect established with 24 plots, rainfall amount, intensity, and time delay relative to solute application were arranged in cyclic patterns at different spatial scales. Soil samples in 10‐cm increments down to 50 cm depth were collected for Br− determination after the simulated rainfall. The results display a significantly decreasing trend of Br− concentration with depth, suggesting the predominance of matrix diffusion over preferential flow at the scale of investigation in the intensively cultivated tobacco field. The Pearson correlation analysis only detected significant associations of Br− with rainfall intensity at the 0–10 cm depth and with rainfall amount at the 20–30 cm. With the aid of frequency‐domain analysis, by comparison, strong spatial correlations were revealed with rainfall characteristics at each depth, even with the presence of a plow pan at the depth of 30–40 cm due to deep tillage. Although the dominant control of Br− distribution varied with depth, these findings demonstrate the profound effects of rainfall characteristics on solute leaching and the usefulness of scale‐dependent treatment distribution in field‐scale investigations of solute transport as well as other hydrological processes.

Virtual Scene Construction of Wetlands: A Case Study of Poyang Lake, China

Due to the complexity of wetland ecosystems, wetlands have a wide area of alternating land and water zones and complex vegetation composition, making it challenging to achieve dynamic displays of virtual wetland scenes using three-dimensional modeling. This study proposes a workflow of game engine-based virtual wetland scene construction for the rapid modeling of virtual wetland scenes. The virtual wetland scene construction work utilized Poyang Lake as the primary research area. It integrated unmanned aerial vehicle data collection technology and geographic information technology with 3D (three-dimensional) modeling of wetland elements and scene program modeling of the game engine to complete the construction and dynamic development of virtual wetland scenes. In addition, it used various virtual reality technologies to display the virtual wetland scene. The virtual scene of Poyang Lake combined with actual data was more realistic and had higher simulation. In reality, the digital wetland scene of Poyang Lake realizes multiple forms of virtual experience and provides users with a profoundly immersive virtual experience. This comprehensive virtual scene workflow in the study can serve as a technical resource for building 3D scenes. It can also provide a technical reference for the digital twin watershed project of Poyang Lake, which has practical application value.

Effects of plastisphere on phosphorus availability in freshwater system: Critical roles of polymer type and colonizing habitat

Biofilm covered microplastics (BMPs) can act as vectors for the transport of exogenous microbial groups to aquatic ecosystem. However, a consensus regarding the formation and development of BMPs and their effect on phosphorus (P) availability has not been reached. Herein, plastic particles made of fuel-based (PET) and biobased polymers (PLA) were deployed in water and hyporheic zones of an urban river for biofilm colonization. Then, BMPs were transferred to lab incubation to study their effects on the P availability. The results showed that different microplastic biofilms had various bacteria and phytoplankton compositions. Additionally, BMPs induced a shift in the microbial co-occurrence patterns co-differentiated by polymer type and colonizing habitats. Network analyses revealed that the structure of PLA BMPs was more robust, while PET colonized in the hyporheic zone reduced network complexity with looser connections between species, and stronger negatively correlated interactions. However, PET formed denser biofilms by the excretion of extracellular polymeric substances from microalgae, which contributed to the better capacity of P utilization. PET colonized in the water/hyporheic zone significantly decreased soluble reactive phosphate by 42.5 % and 30.8 %, respectively. The abovementioned results indicated that BMPs have the potential to disrupt nutrient availability. This study broadens our perspectives for the ecological effects of BMPs in the aquatic environment.

Estimation of Primary Production in the Water of the Coastal Zone of Lake Baikal Based on Daily Variations in CO2 Concentration in Different Seasons of 2005–2021

Estimation of Primary Production in the Water of the Coastal Zone of Lake Baikal Based on Daily Variations in CO2 Concentration in Different Seasons of 2005–2021

A marine plastic cloud - Global mass balance assessment of oceanic plastic pollution

To improve our understanding and management of marine plastic pollution of the ocean, a total plastic budget is needed which quantifies the sources and sinks, as well as inputs and removal of plastic per unit time. The current state of knowledge indicates that the coastal zone and ocean water column are major locations for plastic pollution, but the fate of much of this must ultimately be the deep ocean floor. We reviewed 23 journal articles that provide 280 observations of deep-sea sediment microplastic concentration across six different off-shelf environments. We calculate the following mean concentrations of microplastic particles (number) per kg of sediment: continental slope 502; submarine canyons 784; submarine fans and continental rise 714; abyssal plains 217; trenches and troughs 2782; and abyssal hills, mountains and other ocean floor 165 particles kg−1. These figures are alarming because several exceed one estimate of ‘safe’ levels of microplastic concentration for benthic marine life (540 particles kg−1). Monitoring of the concentration of plastic particles in sediments of submarine canyons, fans and continental rise environments and in trenches and troughs should be a priority to ensure efficacy of policies and actions taken to curb ocean plastic pollution at both the national and global level. We estimate 3.05 million tonnes of microplastic resides in deep ocean sediments but acknowledge the uncertainties of this figure. If correct, this figure implies that the ocean water column (which may contain as much as 90 million tonnes of microplastic) is a major, transitory sink for MP, forming a suspended, marine plastic cloud. In addition to particle concentrations, further measurements of the size and mass of microplastic in deep-sea sediments and in the water column are needed to advance development of mass balance budgets for marine plastic pollution.

The lateral transport of zooplankton explains trophic and taxonomic similarities over the zonal gradient of central Chile

The highly productive upwelling zone in the Southeast Pacific provides inputs of C and N to the oceanic deep-water system via lateral transport, although the quality of this organic matter, the organisms being transported, and the controlling mechanisms are unclear. Here, we assessed whether the taxonomic and trophic structure of zooplankton over more oceanic offshore waters differ from that of zooplankton located in the upwelling zone, along with the characterization of the oceanographic processes and variables associated with the lateral transport. For this, epipelagic, mesopelagic, and bathypelagic zooplankton along with oceanographic variables and particulate organic matter (POM) were analyzed at the upwelling zone and adjacent oceanic stations off Central Chile (27–33°S), some of which were located over the Atacama trench, during September 2016. The community structure of size-fractioned zooplankton (<200 μm, 200–500 μm, 500–1000 μm, 1000–2000 μm, and >2000 μm size classes) was assessed by an automated method, along with the analysis of the isotopic niche computed from their δ 15 N and δ 13 C. The isotope signatures of POM indicated that diatoms contributed mostly to production of new organic C, being the main food source for small-sized zooplankton in coastal waters. The zooplankton community structure differed between the upwelling and oceanic areas, but their isotopic signature showed a large overlap (78%). Satellite-derived geostrophic flow and the depth of the mixed layer appeared as the main factors explaining the homogeneity in the isotopic and biogeochemical signatures of zooplankton between the upwelling zone and offshore waters. Cross-shelf advection is thus suggested as a key process promoting zooplankton export to the deep-water ecosystem, including the ultra-deep Atacama Trench. • The organic matter produced in the upwelling zone can be transported over the Atacama trench by strong offshore advection. • Isotopic niches of zooplankton from the Atacama Trench and the upwelling zone exhibit large overlapping (78%). • The upwelling systems acts as a C subsidiary for the offshore deep-sea ecosystem including the Atacama Trench.

Development and prospect of downhole monitoring and data transmission technology for separated zone water injection

This article outlines the development of downhole monitoring and data transmission technology for separated zone water injection in China. According to the development stages, the principles, operation processes, adaptability and application status of traditional downhole data acquisition method, cable communications and testing technology, cable-controlled downhole parameter real-time monitoring communication method and downhole wireless communication technology are introduced in detail. Problems and challenges of existing technologies in downhole monitoring and data transmission technology are pointed out. According to the production requirement, the future development direction of the downhole monitoring and data transmission technology for separated zone water injection is proposed. For the large number of wells adopting cable measuring and adjustment technology, the key is to realize the digitalization of downhole plug. For the key monitoring wells, cable-controlled communication technology needs to be improved, and downhole monitoring and data transmission technology based on composite coiled tubing needs to be developed to make the operation more convenient and reliable. For large-scale application in oil fields, downhole wireless communication technology should be developed to realize automation of measurement and adjustment. In line with ground mobile communication network, a digital communication network covering the control center, water distribution station and oil reservoir should be built quickly to provide technical support for the digitization of reservoir development.

Pemanfaatan Air Hutan Oleh Desa Penyangga di Taman Nasional Bali Barat

Water is one of the most important elements in human life. Water resources are the most valuable gift from God Almighty because they provide benefits in realizing prosperity for the entire community. No one can deny that water is a basic need for all life, whether human, animal or plant, which cannot be replaced by other substances. So it must receive special attention because it involves not only human life but also other creatures, especially if we are talking within the scope of natural resource conservation, which in this case is a National Park. All parties involved in the management of the National Park as a conservation area must have a systematic effort in managing the area which is carried out by planning, protecting, monitoring, controlling, and utilizing which is carried out without destroying the landscape and changing the function of the area. management and utilization of existing water resources in the national park area, especially those used by buffer villages. The results obtained are the problem of using zones that are not in accordance with the established zoning and to overcome this, it is necessary to change the zoning from the core zone to the utilization zone so that the utilization of ground water in the core zone can be utilized as well as possible.

Marine heat waves in the Mediterranean Sea: An assessment from the surface to the subsurface to meet national needs

In the Mediterranean Sea, marine ecosystems and the resource-based economy are shared among many countries, making this a regional sea of important geopolitical and economic stakes. Over the last decades, marine heat waves (MHWs) in the Mediterranean Sea have caused mass-mortality events in various marine species and critical losses for seafood industries. MHWs are expected to become more intense, longer and more frequent through anthropogenic warming. This study proposes to better understand how much each Mediterranean country’s Exclusive Economic Zone (EEZ) waters may be affected by MHW changes, to contribute to decision support for management and adaptation at national scale. The variability of surface and subsurface MHWs is assessed over the 1987-2019 period in the Mediterranean EEZs, which are ocean areas where sovereign states have special rights. Combining high-resolution satellite observations and a regional reanalysis, sea surface temperature and ocean heat content are used to define surface and subsurface MHWs. The MHW characteristics selected in this study highlight the important differences between surface and subsurface extreme events. MHW frequency is higher at the surface than in the subsurface and has significantly increased in most EEZs both at the surface and in the subsurface, while MHW duration is longer in the subsurface than at the surface in all EEZs. MHW intensities decrease with depth, while its increase over time is more disparate throughout the basin. MHW maximum intensity displays significant positive trends with higher surface values in the western Mediterranean Sea, while in the subsurface it reaches its extreme values in the EEZs of the Levantine basin. In contrast, MHW cumulative intensity exhibits its extreme trend values in the eastern Mediterranean Sea both at the surface and in the subsurface. The choice of a “Top-Ten” list of EEZs shows that the impact to EEZs is different depending on the MHW characteristics and the depth, emphasizing the need to consider all MHW characteristics and to avoid focusing only on the surface. Overall, the results highlight the necessity of strengthening surface and subsurface observing systems in most national waters to better establish local-scale risk assessments and to respond to diverse stakeholder needs.

Mineral Nanoparticle Aggregation Alters Contaminant Transport under Flow.

Iron oxyhydroxide nanoparticle reactivity has been widely investigated, yet little is still known on how particle aggregation controls the mobility and transport of environmental compounds. Here, we examine how aggregates of goethite (α-FeOOH) nanoparticle deposited on 100-300 μm quartz particles (GagCS) alter the transport of two emerging contaminants and two naturally occurring inorganic ligands-silicates and phosphates. Bromide tracer experiments showed no water fractionation into mobile and immobile water zones in an individual goethite-coated sand (GCS) column, whereas around 10% of the total water was immobile in a GagCS column. Reactive compounds were, in contrast, considerably more mobile and affected by diffusion-limited processes. A new simulation approach coupling the mobile-immobile equation with surface complexation reactions to surface reactive sites suggests that ∼90% of the binding sites were likely within the intra-aggregate zones, and that the mass transfer between mobile and immobile fractions was the rate-limited step. The diffusion-controlled processes also affected synergetic and competitive binding, which have otherwise been observed for organic and inorganic compounds at goethite surfaces. These results thereby call for more attention on transport studies, where tracer or conservative tests are often used to describe the reactive transport of environmentally relevant molecules.

Bladderwort Relationship to Zooplankton in Two Northern Michigan Lakes

Traditionally, most of our understanding of lake zooplankton dynamics is from data collected in the pelagic, open water zone. However, the littoral and benthic zones of lakes can play a role in zooplankton community interactions and relationships. Utricularia spp., or the bladderworts, inhabit littoral and shallow waters of lakes and consume zooplankton. Limited information exists on the dietary habits of bladderworts and how diet varies across lakes and seasonally. Bladderwort dietary assemblage in two Michigan, USA, lakes was quantified during the thermally stratified period of 2020, and was compared to zooplankton in the adjacent water column. Bladderwort trap size was positively related to zooplankton prey size, but not number of prey consumed or taxa richness. Bladderworts consumed a variety of prey, the majority dominated by littoral cladoceran and ostracod taxa. Seasonal change was observed, with significantly higher ostracod dominance earlier in the season, shifting into cladoceran dominance later in the season. Ostracods were more commonly found in traps than the water column, whereas Cladocera were more commonly found in the water column than the traps. These results shed light into the dietary habits of bladderworts, which can have consequences for food web dynamics and energy transfer in small lake systems.

Free water input into the New Britain subduction zone in Solomon Sea estimated from reflected seismic data

AbstractIt is of great significance to examine the distribution of the fluid within the subduction zone to estimate the water flux into the subduction zone and to study the motion state of the subducting plate. The interaction of the Western Pacific Plate and the Indo‐Australian Plate controls the subduction and expansion of the Solomon Basin where the mechanisms governing plate activity remain unclear but are typically associated with high pore fluid pressures and stabilizing frictional conditions. Combining the long streamer seismic data (200) and nine well logs inside the work area, we used constrained sparse spike inversion to obtain the P‐wave impedance profile. Then we constructed reservoir rock physics models to predict the fluids distribution in New Britain Trench subduction system in Solomon Sea. The genetic algorithm was used to guide the inversion of the pore fluid distribution. The water content profile revealed the shallow structure of the New Britain Trench subduction system in Solomon Sea, including the water content within the basalt layers. We determined that in certain cases, faults identified from the reflection data were associated with low‐impedance anomalies, and this may indicate that they are zones of high porosity that act as conduits for fluid flow. The continuity of the distribution of water content under the New Britain Trench suggests that there is a large amount of free water that subducts deeply and may be important in controlling the motion state of the subducting plate. We assume that the water saturation is 1. Therefore, the free water flux entering the deep circle with the subducting plate is estimated to be 158 Tg/Ma/m totally, including 53.724 Tg/Ma/m in the sediment and 105.06 Tg/Ma/m in the basalt. This study provides insight into the structure of free water in the New Britain subduction zone and reveals the potential for the direct estimation of the 2D structural distribution of water content using geophysical survey data.

Assessment of resin systems as solution for well integrity challenge in carbonate reservoirs

Well integrity is defined as technical, operational, and organizational solutions specifically aimed at the reduction of the risk of formation fluids release throughout a well's life cycle. Cement integrity is one of the main aspects that comprises well integrity. Cement integrity must be ensured throughout a well's life cycle as well as after abandonment. If the cement was to lose its integrity, the consequences for the personnel, the equipment, and the environment could be severe. Cement failures might lead to leakages that can seep through the cement pathways; sealant materials are used to plug these pathways. The actual and real-time disputes are mainly dependent on the technical approaches currently available to limit the main causes of well integrity deficiency. These include cementing jobs, substantial design based on downhole conditions, material selection criticality, well construction performance, and technological resources. Additionally, in this specific context, well integrity also refers to the control of the flow inside the wellbore (between different horizons) and the flow from the well (especially in the annulus behind the casing). The worst-case scenario would be the loss of wellbore integrity, and it would be identified as the collapse of the well caused by failure of the construction material. The focal point of the research presented in this paper is the cement quality and its role in developing the most vigorous well casing possible. The focus was centered around resin additives such as microbond, latex, and crystal seal. Microbond is a white mineral cement-based liquid with exceptional performances when combined with cement. Latex is composed of rubber particles dispersed in water, usually found in white liquid form. Crystal seal is a yellow colloidal material highly regarded for sealing properties when mixed with concrete mixtures. These additives were individually incorporated into cement-based samples, in varying concentrations, for testing the changes in properties suitable for well integrity considerations. Highly specialized and sophisticated cement testing apparatuses, such as the ultrasonic cement analyzer (UCA), static gel Strength machine (SGSM), and curing chamber, have been used to perform qualitative and quantitative property gradient tests. Based on the performed experimental tests results, the optimal additive resin for a class G cement slurry is the microbond additive at a concentration of 7.5%. The results highlighted its ability to enhance the cement compressive strength by 52%. Additionally, the transit time showed a 26–42% range decrease in the travel period, indicating that the cement was stronger under increased pressure and temperature. This can clear up the permeable section of the well wherein the cement-resin slurry could efficiently close off wellbore intersecting faults and, therefore, prevent possible connections between the wellbore and water zones in the subsurface. As a result, microbond, latex, and crystal seal, respectively, show the effect of varying controlled conditions as functions of the increase in concentration, curing time, and temperature to its comparable properties such as breakload, compressive strength, and ultimate break force. This study can further support future analysis in improving the reliability of petroleum well constructions.

Mantle mineralogy limits to rocky planet water inventories

ABSTRACT Nominally anhydrous minerals in rocky planet mantles can sequester multiple Earth-oceans’ worth of water. Mantle water storage capacities therefore provide an important constraint on planet water inventories. Here we predict silicate mantle water capacities from the thermodynamically-limited solubility of water in their constituent minerals. We report the variability of upper mantle and bulk mantle water capacities due to (i) host star refractory element abundances that set mantle mineralogy, (ii) realistic mantle temperature scenarios, and (iii) planet mass. We find that transition zone minerals almost unfailingly dominate the water capacity of the mantle for planets of up to ∼1.5 Earth masses, possibly creating a bottleneck to deep water transport, although the transition zone water capacity discontinuity is less pronounced at lower Mg/Si. The pressure of the ringwoodite-perovskite phase boundary defining the lower mantle is roughly constant, so the contribution of the upper mantle reservoir becomes less important for larger planets. If perovskite and postperovskite are relatively dry, then increasingly massive rocky planets would have increasingly smaller fractional interior water capacities. In practice, our results represent initial water concentration profiles in planetary mantles where their primordial magma oceans are water-saturated. This work is a step towards understanding planetary deep water cycling, thermal evolution as mediated by rheology and melting, and the frequency of ocean planets.

Variable effects of soil organic matter on arsenic behavior in the vadose zone under different bulk densities

The nonstationary nature of water and oxygen content in the vadose zone determines various biogeochemical reactions regarding arsenic (As) therein, which affects the groundwater vulnerability to As contamination at a site. In the present study, we evaluated the effect of soil organic matter (OM) on the behavior of As using specifically designed soil columns that simulated the vadose zone. Three wet-dry cycles were applied to each of the four columns with different OM contents and bulk densities. OM was found to exhibit variable effects, either inhibiting or accelerating the mobilization of As, depending on bulk density. At a moderate bulk density (< 1.27 g/cm3), OM slightly lowered the pH of pore water, which enhanced the sorption of As onto the iron (Fe) oxides, promoting the retention of As in soil. In the soil column with a relatively higher bulk density (1.36 g/cm3), however, the dissimilatory reduction of iron oxides was triggered by rich OM under oxygen-limited conditions. X-ray absorption spectroscopy analysis revealed that alternate wetting and drying transformed the Fe oxides in the soil by reductive dissolution and subsequent re-precipitation. Consequently, As was not stably retained in the soil, and its mobilization downwards was further accelerated.

Relationship between hydrogeochemical characteristics of hot springs and seismic activity in the Jinshajiang fault zone, Southeast Tibetan Plateau

Significant anomalous hydrogeochemical changes in hot spring water are detected during strong seismic cycles. It is now necessary to clarify the relationship between tectonic movements, earthquakes and the evolution of hot springs. In this paper, laboratory analyses of major, trace elements, δD, δ18O and 87Sr/86Sr values of 28 hot spring waters in the Jinshajiang fault zone (JSJFZ) in the northwestern boundary of the Sichuan-Yunnan block were conducted. The results showed that the primary source of water for JSJFZ hot springs was atmospheric precipitation. The geothermal reservoir temperature variation based on the silicon enthalpy mixing model ranged from 73 to 272°C. And the circulation depth range was 1.2–5.4 km. The segmentation characteristics of the 87Sr/86Sr values were related to the influence of source rocks on groundwater cycle processes. A conceptual model of the hydrologic cycle of hot springs explained the spatial distribution of earthquakes associated with tectonic movements. The Batang segment had the strongest water-rock reaction, the highest reservoir temperature and the deepest circulation depth; meanwhile, it was also an earthquake prone area. The fluid circulation of the JSJFZ corresponds well with the seismicity, which indicates that the hydrological characteristics of the hot spring water in a fracture zone play a crucial role in receiving information on seismic activity.

Water Budget of Urban Turf Field and Optimal Irrigation Schedule Simulation in an Ecotone between Semi-Humid and Semi-Arid Regions, Northern China

Water security in the ecotone between semi-humid and semi-arid regions (EHA) is very vulnerable and sensitive to climate change and human interferences. Urban turf irrigation is a primary consumer of urban water resources in the EHA, which places huge pressures on water security by substantial irrigated water use due to the expansion of urban turf planting. Based on a 2-year (2020–2021) turf experiment in Zhangjiakou City, a typical water-deficit city in the EHA of northern China, the water budget for turf was measured and analyzed. Furthermore, the Root Zone Water Quality Model (RZWQM2) was employed to evaluate the optimal irrigation scheme for turf. The results showed that the average volumetric water content in the 0–40 cm soil layer was maintained above 23% in 2020–2021. The evapotranspiration in growth period of turf accounted for more than 70% of the annual evapotranspiration, and the deep seepage in turf soil accounted for 49.67% and 60.28% of the total precipitation and irrigation in 2020 and 2021, respectively, during the vigorous growth period of the turf from May to September. The calibrated RZWQM2 showed a robust ability to simulate the water changes in turf. The d-values (consistency index) between the simulated and observed volumetric water contents and evapotranspiration were both greater than 0.90. In the aspects of irrigation scenarios, the T60%-12 scenario (TA-B, where A is 100%, 80%, 60% or 40% of the total irrigation amount and B is the number of irrigation events corresponding to A) was determined as the best irrigation schedule in our study area because of lower evapotranspiration, seepage and higher turf soil water storage under this irrigation scenario, also resulting from the comparison of different irrigation scenarios using the entropy-weight-TOPSIS method. In such an optimal scenario, T60%-12 irrigation treatment reduced the irrigated water requirement of turf by 40% (142.06 mm) and the seepage amount by 28.07% (39.05 mm), and had the lowest negative impacts on the turf growth.