Flooded Soil Research Articles

Chemical composition and initial growth of soybean seedlings under flooding conditionat R5 growth stage

This work aimed to evaluate the chemical composition and the initial growth of soybean seedlings originated from seeds produced under influence of soil flooding in the crop reproductive period. The experimental design was totally randomized, organized in factorial scheme being two soybean cultivars x three soil-flooding periods, and the traits were disposed in four repetitions. When submitting soybean plants to flooding at R5 stage, the mass of thousand seeds was reduced independently of the cultivar. The shoot growth and length, shoot dry matter, and roots dry matter characters were negatively influenced due to soil flooding in R5 growth stage. The oxygen deficiency can cause alteration in roots and shoot protein concentration on soybeans seedlings. The aminoacids concentration was stimulated in roots and shoot of seedlings originated from seeds produced under hypoxia conditions.

Analysis of the content of heavy metal ions in the coastal zones of the northern part of the Apsheron peninsula

The article is devoted to studies of heavy metal pollution of the soil cover of the coastal zones of the northern part of the Apsheron Peninsula. Pollution of the coastal zones of the Caspian Sea, serving to a greater extent as a recreational area for the population, by toxic substances is of great concern and to solve this problem, periodic studies of these zones for the presence of heavy metals are necessary. For the first time, a comparative analysis of the content of heavy metals in different areas (Buzovna, Sumgait, Novkhany) of the northern part of the Apsheron peninsula was carried out and the presumable causes of their accumulation were outlined. The researched soils in the northwestern and northeastern part of the peninsula were grouped according to the degree of concentration of heavy metals depending on the depth of the researched soils. Zinc (77.0 mg/kg, at 0–16 cm depth, transect №03), copper, and cadmium (88 mg/kg and 0.36 mg/kg at 0–20 cm depth, transect №05) had the highest concentrations relative to other trace elements. Concentrations of zinc and copper in the northwestern direction of the peninsula increase by 1.5 and 3–3.5 times, respectively, as compared with the generally accepted norms. Average content of heavy metals, especially Ni, Cd, Pb in flooded soils at the depth of 0–100 cm increased 2.7 times on average as a result of coastal flooding by waters of Caspian Sea. The value of total heavy metals reaches a maximum in the northwestern direction.

Analysis of the content of heavy metal ions in the coastal zones of the northern part of the Apsheron peninsula

The article is devoted to studies of heavy metal pollution of the soil cover of the coastal zones of the northern part of the Apsheron Peninsula. Pollution of the coastal zones of the Caspian Sea, serving to a greater extent as a recreational area for the population, by toxic substances is of great concern and to solve this problem, periodic studies of these zones for the presence of heavy metals are necessary. For the first time, a comparative analysis of the content of heavy metals in different areas (Buzovna, Sumgait, Novkhany) of the northern part of the Apsheron peninsula was carried out and the presumable causes of their accumulation were outlined. The researched soils in the northwestern and northeastern part of the peninsula were grouped according to the degree of concentration of heavy metals depending on the depth of the researched soils. Zinc (77.0 mg/kg, at 0–16 cm depth, transect № 03), copper, and cadmium (88 mg/kg and 0.36 mg/kg at 0–20 cm depth, transect № 05) had the highest concentrations relative to other trace elements. Concentrations of zinc and copper in the northwestern direction of the peninsula increase by 1.5 and 3–3.5 times, respectively, as compared with the generally accepted norms. Average content of heavy metals, especially Ni, Cd, Pb in flooded soils at the depth of 0–100 cm increased 2.7 times on average as a result of coastal flooding by waters of Caspian Sea. The value of total heavy metals reaches a maximum in the northwestern direction.

Biosorption of Pollutants in Diyala River by Using Irrigated Vegetables

In the absence of environmental regulation, food stays to be contaminated with heavy metals, which is becoming a big worry for human health. The present research focusses on the environmental and health effects of irrigating a number of crops grown in the soils surrounding the Al-Rustamia old plant using treated wastewater generated by the plant. The physicochemical properties, alkalinity, and electrical conductivity of the samples were evaluated, and vegetable samples were tested for Cd, Pb, Ni, and Zn, levels, and even the transfer factor (TF) from soils to crops and crop and multi-targeted risk, daily intake (DIM) of metals, and health risk index (HRI) was calculated. The findings found that the average contents of Zn, Pb, Ni, and Cd in soil and vegetation were less than the Food and Agriculture Organization’s standards of food safety enhancers. The flooded soil included Zn (56.5), Pb (15.1), Ni (9.30), and Cd (0.850) mg·kg-1. The heavy-metal concentration trend in all samples was Zn, Pb, Ni, and Cd. Daily metal intake in crops species was above acceptable limits for Zinc (0.011 – 0.019 mg·kg-1), Lead (2.010-5 – 5.910-5 mg·kg-1), Ni (2.410-4 – 5.210-4 mg·kg-1) and Cd (1.310-5 – 3.310-5 mgkg-1). The HRI for zinc varied between 0.037 and 0.063, for lead between 5.10-3 and 1.410-2, for nickel from 1.210-2 to 2.610-2, and for cadmium from 1.310-2 to 3.310-2. The HRI for such components was larger than one, suggesting that no possible health issue existed. Crop cultivation using wastewater is a typical solution for water-stressed nations; nevertheless, previous screening and processing of such industrial wastewaters is required to minimise its detrimental effects on the environment.

Fate characteristics of the chiral pesticide dufulin in flooded anaerobic soils and its interaction with soil microorganisms

Dufulin (DFL), a plant antiviral agent synthesized in China, has been widely used to control viral diseases in rice, tobacco, tomato, and other crops. However, its fate in flooded anaerobic soils, which is essential for environmental risk assessment, remains unknown. Using the 14C tracer technique, the fate of 14C-labeled DFL isomers in flooded anaerobic soils was systematically investigated in this study. Over the 100-day incubation, a small part of 14C-DFL enantiomer was mineralized to 14CO2 (< 10.44 %) or entered the surface water phase (< 6.69 %), with most of the 14C (> 80.40 %) remaining in the subsoil. The residues in all tested soils were gradually converted from extractable residues (ERs) to nonextractable residues (NERs). At the end of incubation, the fraction of 14C-NERs reached 5.38–23.77 %. The half-life (t1/2) of the DFL parent in soil is relatively long under submerged anaerobic conditions, especially in Fluvo-aquic soil, up to 277.26–315.07 days, which exceeds the risk threshold recommended by the Stockholm Convention (< 180 days). Soil type and microbial activity influenced the fate of DFL in flooded soils and microbial analysis showed that 2.0 mg kg−1 DFL had no obvious impact on soil bacterial richness and function. Pseudomonas spp. was estimated to be a potentially efficient degrading genus for DFL. No enantioselective behaviors were detected in this study. This research provides a theoretical basis for evaluating the environmental impact and ecological safety of DFL application.

Increasing phosphorus fertilizer value of recycled iron phosphates by prolonged flooding and organic matter addition

Iron (Fe) minerals are commonly used to remove phosphorus (P) from waste streams, producing P-loaded Fe(III) oxides or Fe(II) phosphate minerals (e.g., vivianite). These minerals may be used as fertilizers to enhance P circularity if solubilized in soil. Here, we tested the P fertilizer value of recycled Fe phosphates (FePs) in a pot trial and in an incubation experiment, hypothesizing that P release from FePs is possible under Fe(III)-reducing conditions. First, a pot trial was set up with rice (Oryza sativa) in all combinations of soil flooding or not, three P-deficient soils (acid, neutral, and calcareous), and six FePs (three Fe(III)Ps and three Fe(II)Ps) referenced to triple superphosphate (TSP) or zero amendments. Shoot P uptake responded to TSP application in all treatments but only marginally to FePs. The redox potential did not decrease to -200 mV by flooding for a brief period (13 d) during the pot trial. A longer incubation experiment (60 d) was performed, including a treatment of glutamate addition to stimulate reductive conditions, and P availability was assessed with CaCl2 extraction of soils. Glutamate addition and/or longer incubation lowered soil redox potential to < -100 mV. On the longer term, Fe(III) minerals released P, and adequate P was reached in the calcareous soil and in the neutral soil amended with Fe(III)P-sludge. It can be concluded that prolonged soil flooding and organic matter addition can enhance the P fertilizer efficiency of FePs. Additionally, application of FeP in powder form may enhance P availability.

Remediating flooding paddy soils with schwertmannite greatly reduced arsenic accumulation in rice (Oryza sativa L.) but did not decrease the utilization efficiency of P fertilizer

Planting rice (Oryza sativa L.) in As-contaminated paddy soils can lead to accumulation of arsenic (As) in rice grains, while the application of phosphorus (P) fertilizers during rice growth may aggravate the accumulation effect. However, remediating flooding As-contaminated paddy soils with conventional Fe(III) oxides/hydroxides can hardly achieve the goals of effectively reducing grain As and maintaining the utilization efficiency of phosphate (Pi) fertilizers simultaneously. In the present study, schwertmannite was proposed to remediate flooding As-contaminated paddy soil because of its strong sorption capacity for soil As, and its effect on the utilization efficiency of Pi fertilizer was investigated. Results of a pot experiment showed that Pi fertilization along with schwertmannite amendment was effective to reduce the mobility of As in the contaminated paddy soil and meanwhile increase soil P availability. The schwertmannite amendment along with Pi fertilization reduced the content of P in Fe plaque on rice roots, compared with the corresponding amount of Pi fertilizer alone, which can be attributed to the change in mineral composition of Fe plaque mainly induced by schwertmannite amendment. Such reduction in P retention on Fe plaque was beneficial for improving the utilization efficiency of Pi fertilizer. In particular, amending flooding As-contaminated paddy soil with schwertmannite and Pi fertilizer together has reduced the content of As in rice grains from 1.06 to 1.47 mg/kg to only 0.38–0.63 mg/kg and significantly increased the shoot biomass of rice plants. Therefore, using schwertmannite to remediate flooding As-contaminated paddy soils can achieve the dual goals of effectively reducing grain As and maintaining the utilization efficiency of P fertilizers.

Synchronous response of arsenic methylation and methanogenesis in paddy soils with rice straw amendment.

Rice straw (RS) amendment promotes arsenic (As) methylation and methane (CH4) emissions from paddy soils, which can cause straighthead disease and climate warming. Although methanogens have been identified as critical regulators of methylated As concentrations in flooded soils, the mechanism of these microbial groups on As methylation in paddy soils with RS amendment remains unknown. In this study, paddy soil was incubated to test the response in As methylation and methanogenesis in flooded soil with RS amendment. Our results showed that RS amendment increased the accumulation of monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA) whether methanogenesis was inhibited or not. The methanogens inthe genera ofMethanocella probably played critical role in promoting As methylation in flooded soil with RS amendment. With the RS amendment, inhibition of methanogenesis led to the accumulation MMA and DMA by suppressing DMA demethylation. The demethylation of DMA was driven by methanogens possibly belonging to the genera of Methanobacterium. This study revealed a wealth of methanogens that dominate As methylation with RS amendment. It will provide guidance to RS amendment in As contaminated paddy soil and has important implications for rice quality and global climate change.

Reintroducing Vascular and Non-Vascular Plants to Disturbed Arctic Sites: Investigating Turfs and Turf Fragments

<h3>ABSTRACT</h3> Disturbed low-Arctic environments provide many challenges for ecological restoration, from harsh climates and remote locations to limited knowledge on plant establishment and successional pathways within tundra ecosystems. Due to limited commercially available materials for restoration of native low-Arctic plant communities, transplantation may provide an effective technique for revegetation in these difficult-to-restore environments. In this study, whole-turfs and shredded turfs were harvested from undisturbed upland-heath tundra near Rankin Inlet, Canada, and transplanted onto nearby disturbed gravel quarries to investigate species survivability and development of upland-heath vegetative communities. Two years following transplantation, turfs were found to maintain 85% of the initial vegetative cover and 91% of the initial species richness, with expansion up to 8 cm into the surrounding substrate, and production of seeds and spores. Although shredded turfs were unable to significantly establish vascular species, evidence suggests a shredded turf may establish non-vascular plant cover over a larger area than intact turfs, if given greater protection from environmental stressors. Our results demonstrate that whole-turfs are resistant to harvesting and transplantation stresses, flooding, drought, and poor soil conditions, and are an effective means of species transfer promoting development of vegetative cover on disturbed substrates. High species survivability indicates that turfs have the potential to provide disturbed areas with a wide array of native species, critical for the development of sustainable and self-organizing assemblages of native vegetation.

Microbial resistance in rhizosphere hotspots under biodegradable and conventional microplastic amendment: Community and functional sensitivity

Microplastics (MPs) are ubiquitous in the environment and can potentially damage microbes and plant root cells. Although the influence of MPs on soil parameters has been investigated, the response of microbiomes to soil microenvironments with contrasting limiting factors, particularly in flooded soil environments such as rice paddies, remains unknown. Using zymography and high-throughput sequencing, we conducted a mesocosm experiment with polylactide (PLA) and polyvinyl chloride (PVC) MPs to compare the effects of biodegradable and conventional MPs on rice growth, exoenzyme kinetics, and microbial communities. Both conventional and biodegradable MPs significantly inhibited rice growth, possibly by affecting nutrition. Compared with the control soils, both PLA- and PVC-amended soils exhibited higher enzyme activity in the hotspots. The enzymatic resistance to MPs was higher in ‘coldpots’ with PVC addition compared to that in PLA and control treatments. Bacterial biomass increased but diversity declined in PLA-amended soils, possibly because PLA particles act as carbon input inhabited the population of bacteria. Our findings suggest that co-occurrence networks among bacteria were strengthened by the addition of both MPs, with an increase in microbial functionality resilience and enhanced competition with neighboring roots for nutrient mining. This competition for nutrients may adversely affect plant growth.

Nature-Based Solutions for Flood Mitigation and Soil Conservation in a Steep-Slope Olive-Orchard Catchment (Arquillos, SE Spain)

The frequency and magnitude of flash floods in the olive orchards of southern Spain have increased because of climate change and unsustainable olive-growing techniques. Affected surfaces occupy &gt;85% of the rural regions of the Upper Guadalquivir Basin. Dangerous geomorphic processes record the increase of runoff, soil loss and streamflow through time. We report on ripple/dune growth over a plane bed on overland flows, deep incision of ephemeral gullies in olive groves and rock-bed erosion in streams, showing an extraordinary sediment transport capacity of sub-daily pluvial floods. We develop a novel method to design optimal solutions for natural flood management and erosion risk mitigation. We adopt physical-based equations and build a whole-system model that accurately reproduces the named processes. The approach yields the optimal targeted locations of nature-based solutions (NbSs) for active flow-control by choosing the physical-model parameters that minimise the peak discharge and the erosion-prone area, maximising the soil infiltration capacity. The sub-metric spatial resolution used to resolve microtopographic features of terrains/NbS yields a computational mesh with millions of cells, requiring a Graphics Processing Unit (GPU) to run massive numerical simulations. Our study could contribute to developing principles and standards for agricultural-management initiatives using NbSs in Mediterranean olive and vineyard orchards.

Elevated CO2 may increase the health risks of consuming leafy vegetables cultivated in flooded soils contaminated with Cd and Pb.

Elevated CO2 levels threat the crop quality by altering the environmental behavior of heavy metals (HMs) in soils. In reality, multiple HMs often co-exist in field, while details regarding coexisting HMs migration in flooded soil at elevated CO2 levels remain unclear. A pot experiment in open-top chambers (CO2 at 400 and 600μmolmol-1) was conducted to explore the uptake and transfer of cadmium (Cd) and lead (Pb) in water dropwort (Oenanthe javanica DC.) grown in flooded soils contaminated with Cd and Pb. Results showed that elevated CO2 significantly reduced soil pH, promoting the release of Cd and Pb (by 63.64-106.90% and 10.66-30.99%, respectively) into soil porewater. In the harvested O. javanica, elevated CO2 decreased the root uptake of Cd but promoted that of Pb. Further mechanism analysis showed that elevated CO2 promoted the formation of iron plaque on root surface by 44.60-139.57%, with lower adsorption capacity to HMs (0-34.93% and 63.61-67.69% for Cd and Pb, respectively). Meanwhile, Pb showed lower adsorbability in iron plaque but higher transfer capacity when compared with Cd. Ultimately, elevated CO2 increased the target hazard quotient values of Pb in O. javanica. These findings provide new insights on the effects of elevated CO2 on the transfer of coexisting HMs in soil-plant system, and the risk of HMs pollution under climate changes needs to be more fully assessed.

Mobility of arsenic and vanadium in waterlogged calcareous soils due to addition of zeolite and manganese oxide amendments.

Addition of manganese(IV) oxides (MnO2 ) and zeolite can affect the mobility of As and V in soils due to geochemical changes that have not been studied well in calcareous, flooded soils. This study evaluated the mobility of As and V in flooded soils surface-amended with MnO2 or zeolite. A simulated summer flooding study was conducted for 8 weeks using intact soil columns from four calcareous soils. Redox potential was measured in soils, whereas pH, major cations, and As and V concentrations were measured biweekly in pore water and floodwater. Aqueous As and V species were modeled at 0, 4, and 8 weeks after flooding (WAF) using Visual MINTEQ modeling software with input parameters of redox potential, temperature, pH, total alkalinity, and concentrations of major cations and anions. Aqueous As concentrations were below the critical thresholds (<100μgL-1 ), whereas aqueous V concentrations exceeded the threshold for sensitive aquatic species (2-80μgL-1 ). MnO2 -amended soils were reduced to sub-oxic levels, whereas zeolite-amended and unamended soils were reduced to anoxic levels by 8 WAF. MnO2 decreased As and V mobilities, whereas zeolite had no effect on As but increased V mobility, compared to unamended soils. Arsenic mobility increased under anoxic conditions, and V mobility increased under oxic and alkaline pH conditions. Conversion of As(V) to As(III) and V(V) to V(IV) was regulated by MnO2 in flooded soils. MnO2 can be used as an amendment in immobilizing As and V, whereas the use of zeolite in flooded calcareous soils should be done cautiously.

ВЛИЯНИЕ НЕОДНОРОДНОСТИ МЕХАНИЧЕСКИХ ХАРАКТЕРИСТИК СИСТЕМЫ «КРЕПЬ–МАССИВ ГРУНТА» НА НАПРЯЖЕННОЕ СОСТОЯНИЕ

The problem of a cylindrical hole in the soil massif at a great depth, in weak flooded soils, i.e. the array was considered as an incompressible material with a Poisson’s ratio . The calculation was carried out in order to determine the influence of the function of heterogeneity of the mechanical characteristics on the stress state of the “support-soil mass” system. The problem was considered as a one-dimensional case of a plane deformed state. In this work, we considered problems for all possible combinations of the three cases of functions of Young’s support modules and four cases of elastic moduli of the soil massif . Based on the calculation results, an analysis was carried out on the basis of which the following conclusions were made: the stress state of the lining - soil mass system is practically independent of the function of the Young’s modulus of the soil , which may be due to the rather low values that the modulus of elasticity of the soil massif assumes, in comparison with the modulus of elasticity of the lining. Functions of the modulus of support affect the stress state of the lining itself and have little effect on the stress state in the soil massif. When decreasing at the hole boundary, stresses also decrease. Based on the conclusions made, it can be said that when creating inhomogeneous lining it is possible to obtain a case of an equally stressed or equal strength state of lining [1, 8], which in turn can lead to a significant economic effect.

In situ mapping of ion distribution profiles and gene expression reveals interactions between hypoxia and Mn2+/Fe2+ availability in barley roots

Flooding stress affects soil properties thus altering the availability, uptake, and transport of mineral nutrients in plant roots. Flooding stress also increases the amount of soluble Mn2+ and Fe2+ in the soil and their uptake by plants, causing elemental toxicity. However, as oxygen profiles in plant roots are not uniform, it is still unclear how soil flooding will affect Mn2+/Fe2+ absorption and distribution in different cell types and tissues. In this study, waterlogging sensitive barley variety NasoNijo (NN) and tolerant variety TX9425 (TX) were exposed to hypoxia, metal (Mn2+ and Fe2+), and combined hypoxia + metal treatment to map the in situ ion profiles at different regions of barley root. We found that combined hypoxia and metal stress causes significantly more reduction in plant biomass compared with the single submergence or metal stress. Despite this, more Fe and Mn were accumulated under metal stress condition than those under combined stress, regardless of variety. Cultivar NN absorbed more Fe and Mn than TX in the cortical cells of the root meristem and in the mature zone under metal stress which was also verified by histochemical detection. In the mature zone, the expressions of Fe and Mn transporter genes including HvADPRibase-Mn (Manganese-dependent ADP-ribose), HvZIP1 (zinc-regulated transporter /Fe-regulated transporter-like protein 1), HvYS1 (yellow stripe 1), HvNRAMP5 (Natural Resistance-Associated Macrophage Protein 5) were significantly downregulated under all three treatments in both barley varieties except HvADPRibase-Mn HvZIP1 cortex of TX were unchanged under metal stress. Interestingly, the transcripts of HvMTP1 (metal tolerance protein 1) were significantly downregulated by metal and combined stress in stele and upregulated by hypoxia and metal stress in cortex of TX, but not affected in NN. It is concluded that Fe and Mn absorption involving HvMTP1is associated with the extent of waterlogging tolerance in barley.

Continuous fixation of dissolved arsenite from flooded soil by cooperating ferrihydrite with Geobacter sulfurreducens

The fixed arsenic in soil is easy to be released into the aquatic environment in the form of arsenite (As(III)) with high toxicity and mobility due to the eutrophication of environment under anaerobic conditions. However, As(III) is difficult to be fixed in situ continuously by traditional methods, especially for the most efficient fixation method by iron ores. Based on that Fe(II) could promote the fixation of As(III), this study investigated the possibility that Geobacter sulfurreducens (G. sulfurreducens) cooperates with ferrihydrite to fix released As(III) from flooded soil in a glass column continuously under anaerobic conditions. During 42 days of operation of reactors that simulated the actual flooded soil environment, the concentration of released As(III) in the reactor with adding G. sulfurreducens and ferrihydrite is always lower than that in reactors with adding ferrihydrite or no treatment. Compared with reactors without treatment, the accumulated content of released As(III) (2455.0 ± 313.1 μg) decreased by 39.4% in the reactor with adding G. sulfurreducens and ferrihydrite on the last day, while that in reactors with adding ferrihydrite only decreased by 11.6%, respectively. These were caused by the cooperation of G. sulfurreducens and ferrihydrite, which increased the relative abundance of iron-reducing microorganisms to inhibit metabolisms of As-reducing microorganisms, inhibited the quick release of As(III) from solid soil, and promoted the release of iron to accelerate the formation of stable secondary ores with As. This study could provide an environmentally friendly method to fix dissolved As(III) pollutants from soil continuously.

Effect of Dam Emplacement and Water Level Changes on Sublacustrine Geomorphology and Recent Sedimentation in Jackson Lake, Grand Teton National Park (Wyoming, United States)

Dam installation on a deep hydrologically open lake provides the experimental framework necessary to study the influence of outlet engineering and changing base levels on limnogeological processes. Here, high-resolution seismic reflection profiles, sediment cores, and historical water level elevation datasets were employed to assess the recent depositional history of Jackson Lake, a dammed glacial lake located adjacent to the Teton fault in western Wyoming (USA). Prograding clinoforms imaged in the shallow stratigraphy indicate a recent lake-wide episode of delta abandonment. Submerged ∼11–12 m below the lake surface, these Gilbert-type paleo-deltas represent extensive submerged coarse-grained deposits along the axial and lateral margins of Jackson Lake that resulted from shoreline transgression following dam construction in the early 20th century. Other paleo-lake margin environments, including delta plain, shoreline, and glacial (drumlins, moraines) landforms were likewise inundated following dam installation, and now form prominent features on the lake floor. In deepwater, a detailed chronology was established using137Cs,210Pb, and reservoir-corrected14C for a sediment core that spans ∼1654–2019 Common Era (CE). Dam emplacement (1908–1916 CE) correlates with a nearly five-fold acceleration in accumulation rates and a depositional shift towards carbonaceous sediments. Interbedded organic-rich black diatomaceous oozes and tan silts track changes in reservoir water level elevation, which oscillated in response to regional climate and downstream water needs between 1908 and 2019 CE. Chemostratigraphic patterns of carbon, phosphorus, and sulfur are consistent with a change in nutrient status and productivity, controlled initially by transgression-driven flooding of supralittoral soils and vegetation, and subsequently with water level changes. A thin gravity flow deposit punctuates the deepwater strata and provides a benchmark for turbidite characterization driven by hydroclimate change. Because the Teton fault is a major seismic hazard, end-member characterization of turbidites is a critical first step for accurate discrimination of mass transport deposits controlled by earthquakes in more ancient Jackson Lake strata. Results from this study illustrate the influence of dam installation on sublacustrine geomorphology and sedimentation, which has implications for lake management and ecosystem services. Further, this study demonstrates that Jackson Lake contains an expanded, untapped sedimentary archive recording environmental changes in the American West.

Responses of key root traits in the genus Oryza to soil flooding mimicked by stagnant, deoxygenated nutrient solution.

Excess water can induce flooding stress resulting in yield loss, even in wetland crops such as rice (Oryza). However, traits from species of wild Oryza have already been used to improve tolerance to abiotic stress in cultivated rice. This study aimed to establish root responses to sudden soil flooding among eight wild relatives of rice with different habitat preferences benchmarked against three genotypes of O. sativa. Plants were raised hydroponically, mimicking drained or flooded soils, to assess the plasticity of adventitious roots. Traits included were apparent permeance (PA) to O2 of the outer part of the roots, radial water loss, tissue porosity, apoplastic barriers in the exodermis, and root anatomical traits. These were analysed using a plasticity index and hierarchical clustering based on principal component analysis. For example, O. brachyantha, a wetland species, possessed very low tissue porosity compared with other wetland species, whereas dryland species O. latifolia and O. granulata exhibited significantly lower plasticity compared with wetland species and clustered in their own group. Most species clustered according to growing conditions based on PA, radial water loss, root porosity, and key anatomical traits, indicating strong anatomical and physiological responses to sudden soil flooding.

Evaluation of the fertility status of flooded soils in the Saharsa District, Bihar

The sampling location was Saharsa, which is one of Bihar's most flood-prone area Flooding is the leading source of soil degradation in the district. The current study was carried out in the Soil Science and Agricultural Chemistry laboratory at Sam Higginbottom University of Agriculture Technology and Sciences. 27 samples were collected from several farmer's fields, and composite sampling was carried out from three depths of 0-15, 15-30, and 30-45 cm. The results revealed that the texture was sandy loam to sandy clay, bulk density ranged from 1.11 to 1.59 Mg/m3, particle density ranged from 2.22 to 2.85 Mg/m3, pore space ranged from 52.60 to 66.50 % and water holding capacity ranged from 61.11 to 78.12 %. The pH ranged from 6.58 to 7.65, E.C. from 0.17 to 0.39 dS/m,(Due to Flooding) Soil Organic Carbon ranged from 0.74 to 1.20 %, Soil has acceptable Bd, Pd, pore space, and water holding capacity. As a result of the beneficial electrical conductivity for plants, the pH of the soil is neutral to alkaline. Sodium is low to medium in range. Low to medium levels of macronutrients are found in nitrogen, phosphorus, potassium, calcium, magnesium, and sulphur. By employing the proper management techniques and supplying the soil with enough nourishment for plant growth, farmers must maintain the health of their soil.

Mechanisms of S cooperating with Fe and Mn to regulate the conversion of Cd and Cu during soil redox process revealed by LDHs-DGT technology

The activity changes of Cd and Cu in paddy field were strongly influenced by the transformation of S, Fe and Mn species. However, in the process of soil redox, how S cooperates with Fe/Mn to regulate the law and mechanism of Cd and Cu speciation transformation still needs to be studied. In this study, we used DGT technology based on layer double hydroxides (LDHs) combined with pore water sampling to investigate soil redox changes, rice growth, and the effects of different forms of sulfur (S0, SO42−) on soil Cd and Cu activities. The results showed that the concentrations of CDGT-Cd and Cu in the soil decreased rapidly in the anaerobic stage, but increased slowly in the oxidative stage. Multiple regression analysis showed that the changes of Cu and Cd concentrations mainly depended on the changes of Fe/Mn morphology. Sulfur treatment promoted the dissolution of Fe/Mn oxides in the short term (<48 h), and the activities of CDGT-Fe, Mn, and Cd increased simultaneously, but CDGT-Cu was not affected. However, after long-term anaerobic conditions (>10 d), sulfur addition reduced the activities of CDGT-Cd and Cu, and decreased the uptake of Cd and Cu by rice. During sulfate reduction, the sulfur addition treatment group resulted in a 24.5–50.2 % decrease in CDGT-Fe, indicating that sulfur addition may delay the release of Cd and Cu after rice planting by promoting the formation of FeS/FeS2. In addition, in the anaerobic stage, Cu formed sulfide before Cd and was fixed, and the higher thermodynamic stability of CuS would promote the dissolution of CdS in the oxidation stage. Overall, soil flooding with sulfur to enhance the generation of metal sulfides and secondary iron ores provides an opportunity to use sulfur as an environmentally friendly modifier to coordinate Fe, Mn to improve heavy metal-contaminated soils.