Soil Surface Research Articles

CAMELS-IND: hydrometeorological time series and catchment attributes for 228 catchments in Peninsular India

Abstract. We introduce CAMELS-IND (Catchment Attributes and MEteorology for Large-sample Studies – India), a dataset containing hydrometeorological time series and catchment attributes for 472 catchments in Peninsular India, of which 228 catchments have observed streamflow data available for over 30 % of the period between 1980 to 2020. Peninsular India covers 15 interstate river basins defined by the Central Water Commission (CWC), where river flow and water level datasets are available for several gauge stations through the open-source India Water Resources Information System (India-WRIS). However, many of these gauge stations lack reliable metadata, and data are not in an analysis-ready format for large-sample hydrological studies. Therefore, we utilized 472 gauge stations and their catchment boundaries, characterized as stations with reliable metadata, from the Geospatial dataset for hydrologic analyses in India (GHI) (Goteti, 2023). For each of these catchments, CAMELS-IND provides a catchment mean time series of meteorological forcings for 41 years (1980–2020) and 211 catchment attributes representing hydroclimatic and land cover characteristics extracted from multiple data sources (including ground-based observations, remote sensing-based products, and reanalyses datasets). CAMELS-IND follows the same standards of the previously developed CAMELS datasets for the USA, Chile, Brazil, Great Britain, Australia, Switzerland, and Germany to facilitate comparisons with catchments of those countries and inclusion in global hydrological studies. Notably, CAMELS-IND includes available observed streamflow and catchment mean time series of 19 meteorological forcings, including precipitation, maximum, minimum, average temperature, long-wave and short-wave radiation flux, U and V components of wind, relative humidity, evaporation rates from canopy and soil surface, actual and potential evapotranspiration, and soil moisture of four layers (covering depth up to 3 m below ground) for detailed hydrometeorological studies. We also derived catchment attributes representing human influences, including the number of dams and their utilization, total volume contents of dams in catchments, population density, and increases in urban and agricultural land covers to facilitate studies to understand human influences on catchment hydrology. Furthermore, the dataset includes predicted streamflow time series from a regionally trained long short-term memory (LSTM)-based hydrological model for all 472 catchments which can fill gaps in observed streamflow data or serve as a benchmark for testing and developing new hydrological models. We envision that CAMELS-IND will provide a strong foundation for a community-led effort toward gaining new hydrological insights from hydrologically distinct Indian catchments and solving pertinent issues related to water management, quantification and risk assessment of hydrologic extremes, unraveling regional-scale hydrologic functioning, and climate change impact assessment of catchments across India. The CAMELS-IND dataset is available at https://doi.org/10.5281/zenodo.14005378 (Mangukiya et al., 2024).

Rainfall distribution variability controls surface but not belowground litter decomposition in a semi-arid shrubland

IntroductionRainfall patterns are expected to become increasingly erratic as a result of global climate change, with more intense but less frequent rainfall events leading to an increased occurrence of drought events. This process may lead to significant declines in vegetation cover and subsequent increases in soil erosion, consequently accelerating the bury of detached litter by soil deposition and the mixture of residues from different plant species. Responses of litter decomposition to increasing rainfall variability in distribution and subsequent litter mixing or soil cover have scarcely received attention.MethodsTo fill this gap in our knowledge, we analyzed the influence of rainfall variability, soil cover, and litter mixing on shrub-species litter decomposition in a semi-arid shrubland. We explored the effects of redistributing the frequency and amount of precipitation on surface and belowground decomposition of litter from two separate or mixed predominant shrubs.ResultsDecomposition of belowground litter was consistently higher than that of surface litter over the entire field-incubation process. Mass loss significantly decreased in surface litter but not in belowground litter due to the lower frequency and larger amount of precipitation compared to the control treatment. Furthermore, exclusion of 30% precipitation had no significant effects on decomposition of either surface or belowground litter. We observed stronger synergistic effect for belowground litter mixture relative to surface litter mixture of the two shrubs, especially in the hotter months over the 5-month incubation.DiscussionThese findings support that rainfall variability in terms of distribution pattern rather than in the amount controls the litter decomposition on the soil surface in the semi-arid shrubland. Meanwhile, soil burial or litter mixing have greater effects on litter decomposition, individually or jointly. Together, our results highlight the need to consider rainfall distribution variability and incorporate soil-covering and litter-mixing as driving factors of organic matter turnover in drylands.

Canopy structure modulates the sensitivity of subalpine forest stands to interannual snowpack and precipitation variability

Abstract. A declining spring snowpack is expected to have widespread effects on montane and subalpine forests in western North America and across the globe. The way that tree water demands respond to this change will have important impacts on forest health and downstream water subsidies. Here, we present data from a network of sap velocity sensors and xylem water isotope measurements from three common tree species (Picea engelmannii, Abies lasiocarpa and Populus tremuloides) across a hillslope transect in a subalpine watershed in the Upper Colorado River basin. We use these data to compare tree- and stand-level responses to the historically high spring snowpack but low summer rainfall of 2019 against the low spring snowpack but high summer rainfall amounts of 2021 and 2022. From the sap velocity data, we found that only 40 % of the trees showed an increase in cumulative transpiration in response to the large snowpack year (2019), illustrating the absence of a common response to interannual spring snowpack variability. The trees that increased water use during the year with the large spring snowpack were all found in dense canopy stands – irrespective of species – while trees in open-canopy stands were more reliant on summer rains and, thus, more active during the years with modest snow and higher summer rain amounts. Using the sap velocity data along with supporting measurements of soil moisture and snow depth, we propose three mechanisms that lead to stand density modulating the tree-level response to changing seasonality of precipitation: Topographically mediated convergence zones have consistent access to recharge from snowmelt which supports denser stands with high water demands that are more reliant and sensitive to changing snow. Interception of summer rain in dense stands reduces the throughfall of summer rain to surface soils, limiting the sensitivity of the dense stands to changes in summer rain. Shading in dense stands allows the snowpack to persist deeper into the growing season, providing high local reliance on snow during the fore-summer (early-summer) drought period. Combining data generated from natural gradients in stand density, like this experiment, with results from controlled forest-thinning experiments can be used to develop a better understanding of the responses of forested ecosystems to futures with reduced spring snowpack.

Global Perspectives on Lead Contamination and Health Risks in Surface Water, Rice Grains, and Soils

ABSTRACTLead (Pb), a pervasive and highly toxic metal, and poses significant environmental and health risks due to its extensive biogeochemical cycling, driven by anthropogenic activities. This review evaluates the health hazards allied with Pb contamination in surface water bodies, soils, and rice grains, based on a comprehensive analysis (2015–2024) of 118, 133, and 102 literature studies, respectively. The year‐wise assessment of Pb concentration in surface water bodies and soils frequently exceeded their permissible limits in 2015, 2017, 2018, 2019, 2020, and 2022. However, the mean Pb concentration in rice grains consistently surpassed the Codex Alimentarius limit (2.5 μg/g) across the analyzed years. Geographically, Bangladesh, India, Pakistan, and China surpassed their limits for surface water bodies, rice grains and soils, emphasizing regional vulnerabilities. Health risk analysis indicated hazard quotient values exceeding one for children and adults in surface water bodies and rice grains, exhibiting significant non‐carcinogenic risks. In soils, dermal exposure identified as the predominant pathways contributing to health hazard followed by ingestion, while inhalation presented the lower risk. These findings emphasize the imperative necessitate for implementing strict regulatory frameworks and preventive measures to mitigate Pb contamination in the environment and minimize its potential health impacts. This study advances understanding of Pb exposure pathways and risks, offering valuable insights for targeted mitigation strategies and public health interventions.

Performance of ‘Sabiá’ Grass Irrigated with Drippers Installed in the Subsurface

ABSTRACTSubsurface irrigation, which provides greater water efficiency and reduces surface soil wetting, is an effective alternative for minimizing water losses through evaporation, especially under cultivation conditions that require greater resource conservation. The ‘Sabiá’ grass, an agronomically relevant forage species, may exhibit different responses when irrigated by subsurface systems. Thus, the objective of this study was to evaluate the performance of ‘Sabiá’ grass irrigated with drippers installed at different depths during different climatic seasons. The experiment was carried out from January to July 2022 under open‐air conditions in Viçosa, MG, Brazil, in a completely randomized design in split plots with four replicates. The plots consisted of four cycles of ‘Sabiá’ grass, and the subplots consisted of seven depths of dripper installation (superficial, 5, 10, 15, 20, 25, and 30 cm). ‘Sabiá’ grass was cultivated in pots, and the recommendations for irrigation were based on crop evapotranspiration (ETc), which was measured in two drainage lysimeters. The water consumption and morphogenetic and agronomic characteristics of ‘Sabiá’ grass were evaluated. The total water consumption of ‘Sabiá’ grass in cycles 1, 2, 3, and 4 was 42.4, 26.7, 14.9, and 11.5, respectively. The growth, development and productivity of ‘Sabiá’ grass decreased from cycle 1 (summer) to cycle 4 (winter). Morphogenic characteristics were slightly affected by the different dripper installation depths. ‘Sabiá’ grass presented lower shoot fresh mass, shoot dry mass and water use productivity at the greatest dripper depths. ‘Sabiá’ grass presented greater root system development when the dripper was installed between 10 and 15 cm deep. The normalized difference vegetation index (NDVI) proved to be a promising tool for estimating the biomass production of ‘Sabiá’ grass. In view of these results, drip tapes should be installed between depths of 10 and 20 cm for the cultivation of ‘Sabiá’ grass in clay soil.

Fugacity-based multimedia transport modeling and risk assessment of PAHs in Urumqi

Currently, there is a lack of a comprehensive understanding of the behavior of polycyclic aromatic hydrocarbons (PAHs) in complex multimedia urban environmental systems. Taking Urumqi City as a case study, we developed an integrated multimedia urban environmental model to simulate the inter-media transport processes of PAHs across air, water, soil, sediment, vegetation, and impervious surfaces. The predictive results of this model were in good agreement with the actual monitoring data from 2021, confirming its accuracy. Notably, the simulated data for 2021 indicate that the total amount of PAHs in the soil reached 1.06 × 106 kg, accounting for 97.44% of the total PAHs in Urumqi City, highlighting soil as the primary sink for PAHs. Further analysis of transport fluxes revealed that atmospheric transfer pathways to soil and vegetation are the main mechanisms driving the distribution of PAHs in urban environments. Additionally, sensitivity analysis identified temperature, soil, and vegetation-related parameters as the primary factors influencing PAHs. Based on the simulated concentration, the risk assessment results showed that soil PAHs had a higher risk of carcinogenesis to human body. This study deepens our understanding of the behavior of PAHs in urban environments and provides insights into how human activities affect the fate and transformation of these contaminants in multimedia urban systems.

Status of Different Forms of Nitrogen in Soils of Navsari District of South Gujarat, India

To study the nitrogen fraction under different cropping and management system, the present investigation was carried out at NAU, Navsari (Gujarat) during year 2022-2023. From each taluka of Navsari district, ten soil samples were collected randomly from 0-15 cm and 15-30 cm depth by using different cropping and management systems by GIS base grid sampling method. Soil samples were subjected to preliminary analysis for pH, EC, SOC and then analysis of different N-fractions was carried out. Nitrogen is one of the main limiting factors of crop productivity and many studies have sought possibilities to reduce the need for N application and extend the period of availability to plants. Organic N forms constitute up to 90% of the total N in the plow layer of mineralsoils and only about 1–4% is mineralized as plant- available N (NH4–N and NO3–N). Plant-available N released from soil organic N (SON) or applied in fertilizer is highly susceptible to loss from the soil– plant system through leaching and denitrification. The overall distribution of avail. N, NO3-N, NH4-N and total N in Navsari district was ranged from 72.80 to 375.20 mg kg-1, 5.60 to 92.40 mg kg-1, 30.80 to 114.80 mg kg-1 and 140.00 to 1036.00 mg kg-1, respectively for surface soils while, 61.60 to 364.00 mg kg-1, 8.40 to 72.80 mg kg-1, 25.20 to 100.80 mg kg-1 and 140.00 to 924.00 mg kg-1 for sub-surface soils, respectively. At surface layer, total N was correlated significantly and positively with SOC, CEC and it was negatively correlated with pH and EC. However, total N showed similar correlation with SOC and EC at sub-surface layer. NH4-N and NO3-N were positively and significantly correlated with each other at the same depth. The result also revealed that the N fractions were significantly decreased with increasing depth of soil. Overall, our findings suggest that vegetation restoration improved the soil N availability.

Risk analysis of mechanical cross passage construction using work breakdown and fault tree

A subway cross passage is a connecting aisle between main tunnels. Owing to its narrow construction site, it is difficult to implement safety measures, and intensive construction techniques are often required. With the development of technology, the mechanical cross-passage technology has emerged. To address the risk problem of mechanical cross-passage construction, the construction process was systematically decomposed based on the work breakdown structure (WBS), and a fault tree of each construction process was established for qualitative analysis. Various factors leading to construction risks have been identified, such as head sinking of the excavation machine, spiral machine gushing, excavation deviation from axis, excavation surface soil instability, and ground deformation, and corresponding risk response measures have been proposed. The targeted measures were applied to the mechanical construction of Qingdao Subway Line 8, and the successful completion of the cross-passage verified the applicability of the risk analysis and the effectiveness of the response measures.

Assessment of forest soil contamination by heavy metals in the Polish National Park near Warsaw

The forest ecosystems are essential for human well-being development and reduction of the risk of natural disasters. Maintaining forest growth and ecosystem services is dependent on soil sustainability. The content of heavy metals is the main parameter determining the degree of soil contamination and degradation. The objective of the study was to assess the extent of soil contamination and identify the sources of potential anomalies. The content of the cadmium, lead, manganese and chromium (using atomic emission spectroscopy with induction-coupled plasma), as well as granulometric composition, pH value and nitrogen and total carbon content, were conducted on soil samples taken from the surface layer (0–10 cm) in the protected area of the Kampinos National Park in Poland. The soil quality assessment was conducted by calculating indicators of contamination including the geo-accumulation index, contamination factor, degree of contamination, ecological risk of individual heavy metals and potential ecological risk index. The results exhibited that the tested soils were very acidic or acidic sands. The content of the determined elements did not exceed the permissible limits as outlined in Polish standards, which are 2 mg/kg, 100 mg/kg and 150 mg/kg for cadmium, lead and chromium, respectively. The indicators show differences in the degree of contamination of the surface soil layer in the studied area, which is predominantly uncontaminated by heavy metals. However, the geochemical index values equal 0.42, 0.71 and 0.98 for certain samples suggesting the anthropogenic impact on the soils of the Kampinos National Park. The pollution appears to have been generated by the metallurgical industry, heating and power plants in the Warsaw agglomeration and transport.

Spatial distribution, environmental contamination and health risk assessment of metals in surface soils of Lesser Himalaya, Jammu and Kashmir, India

Spatial distribution, environmental contamination and health risk assessment of metals in surface soils of Lesser Himalaya, Jammu and Kashmir, India

Towards quantitative reconstruction of past monsoon precipitation based on tetraether membrane lipids in Chinese loess

Abstract. Variations in the oxygen isotope composition (δ18O) of cave speleothems and numerous proxy records from loess–paleosol sequences have revealed past variations in East Asian monsoon (EAM) intensity. However, challenges persist in reconstructing precipitation changes quantitatively. Here, we use the positive relationship between the degree of cyclization (DC) of branched glycerol dialkyl glycerol tetraethers (brGDGTs) in modern surface soils from the Chinese Loess Plateau (CLP) and mean annual precipitation (MAP) to quantify past monsoon precipitation changes on the CLP. We present a new ∼ 130 000-year-long DC-based MAP record for the Yuanbao section on the western edge of the CLP, which closely tracks the orbital- and millennial-scale variations in available records of both speleothem δ18O and the hydrogen isotope composition of plant waxes (δ2Hwax) from the same section. Combing our new data with existing brGDGT records from other CLP sites reveals a spatial gradient in MAP that is most pronounced during glacials, when the western CLP experiences more arid conditions and receives up to ∼ 250 mm less precipitation than in the southeast, whereas MAP is ∼ 850 mm across the CLP during the Holocene optimum. Furthermore, the DC records show that precipitation amount on the CLP varies at both the precession scale and the obliquity scale, as opposed to the primarily precession-scale variations in speleothem δ18O and δ2Hwax at Yuanbao and the 100 kyr cycle in other loess proxies, such as magnetic susceptibility, which rather indicates the relative intensity of the EAM. At the precession scale, the DC record is in phase with δ2Hwax from the same section and the speleothem δ18O record, which supports the hypothesis that monsoon precipitation is driven by Northern Hemisphere summer insolation.

Effects of Straw Decomposition on Soil Surface Evaporation Resistance and Evaporation Simulation

As a prominent agricultural country, China has widely implemented returning straw to the field in agricultural production. However, as the decomposition of straw progresses, the physical properties of the soil change, inevitably leading to alterations in the soil surface evaporation model. This study investigated the variations in soil evaporation rate, soil moisture content over 60 days after returning straw to the field, and bare soil through two leaching pond experiments. Through soil moisture retention curves at different degrees of decomposition, this study analyzed the impact of straw decomposition on soil’s water retention capacity. Based on measured data, this study formulated models for the soil surface evaporation resistance of bare soil and varying degrees of straw decomposition. With the comparison and contrast between the models, this study clarified the impact of straw decomposition on soil surface evaporation resistance. The main conclusions are the following: The moisture content of the surface soil decreases exponentially over time and, after 40 days of straw decomposition, the water content of the soil under decomposition is higher than that of bare soil. As the moisture content decreases, the cumulative evaporation from the soil increases linearly. The cumulative evaporation of the decomposed straw soil is lower than that of bare soil, with a relative reduction ranging from 3.08% to 32.2%. The straw decomposition significantly enhances the water retention capacity of the soil in the medium-to-high suction range. The straw decomposition enhances the evaporation resistance of the soil surface, and the greater the degree of decomposition, the more significant the enhancement effect. The research findings not only provide a scientific basis for agricultural water management, but also possess practical implications for guiding farmers to adopt more effective moisture retention measures.

The effects of waterlogging duration on responses of above- and belowground organs of Pinus thunbergii seedlings after the release from waterlogging

ABSTRACT The tsunami in March 2011 heavily damaged the Pinus thunbergii Parlatore erosion-control coastal forests of northeastern Japan. The restoration is in process but has been challenged by waterlogging resulting from soil compaction of artificial growth bases. In this study, a pot experiment was conducted to elucidate the waterlogging responses of two-year-old P. thunbergii seedlings in terms of waterlogging duration. Three waterlogging durations were set (7 days, 17 days, and 32 days, water table at soil surface) during August, followed by a waterlogging-free recovery period (28 days) in September. In this experiment, the responses of both above- and belowground organs during waterlogging and after the release from waterlogging were elucidated, focusing on parameters, such as transpiration and photosynthesis rates, as well as fine root growth and morphology. As a result, we found that under the conditions of our experiment, if the waterlogging duration is within 17 days, P. thunbergii seedlings can recover physiological activity in about a week; however, if the waterlogging duration is over 32 days, recovery after the release from waterlogging largely varied among seedlings. For the seedlings that could recover, recovery took at least 2 weeks, which required new fine root growth. In cases where the damage was irreversible, seedlings showed an overall decline. These results suggest that it is important to manage the waterlogging conditions so that P. thunbergii seedlings can recover without prolonged negative effects.

Phosphorus release under short-term submergence of pasture soils in critical source areas.

Critical source areas (CSAs) can act as a source of phosphorus (P) in surface waters by releasing soil P to porewater during frequent rainfall events. The extent of P release under short-term, frequent submergence has not been systematically studied in CSAs in New Zealand. A study was conducted to explore the potential of three contrasting dairy and sheep/beef farm soils (Recent, Pallic and Allophanic soils) to release P to porewater and pondwater under short-term and frequent submergence. Five undisturbed soil blocks (20×20×15cm) were sampled from each soil. Porewater samplers and half-cell platinum electrodes for in-situ redox potential measurements were installed at 2 and 10cm depths from the soil surface. Six submerged events were created by maintaining a 5cm waterhead. Porewater and pondwater samples were collected immediately and three days after each submergence event. After three days of submergence, the soil blocks were drained and maintained at 70% of water holding capacity for 10 days before the next submergence event. Dissolved reactive phosphorus (DRP), pH, dissolved organic carbon, cations, anions, and alkalinity of the water samples were measured. Soil chemical P fractions were assessed in initial soils and soils in the middle and end of the experiment. Thermodynamic modelling was used to infer dissolution and formation of P and P-associated minerals. The Recent soil released P to porewater at both depths and to pondwater. The Pallic soil released P to porewater at both depths but did not change pondwater DRP. Allophanic soil sorbed P and did not increase DRP either in porewater or pondwater. The average pondwater DRP of the three soils during submergence were 17 to 65-fold higher than the New Zealand lowland river target DRP concentration (0.01mg/L). The mechanisms of P release from the Recent and Pallic soils were desorption and reductive dissolution of Mn(Ⅱ) minerals. Reductive dissolution of Fe(Ⅱ) minerals was not supported by fractionation or modelling results. Decreases in labile, moderately labile and stable P fractions contributed to P release in the Recent soil, while increases in the labile and moderately labile P fractions contributed to P retention in the Pallic and Allophanic soils. This study highlighted that the Recent soil is riskier than the other two soils in releasing P upon short-term submergence and the potential use of Allophanic soil as a P sorbing material in CSAs to mitigate P loss.

Redox-induced phosphorus release from critical source areas following rainfall events in New Zealand.

Critical source areas (CSAs) can act as a source of phosphorus (P) during intermittent rainfall events and contribute to dissolved P loss via runoff. Dissolved forms of P are readily accessible for plant and algal uptake; hence it is a concern in terms of the eutrophication of freshwater bodies. The potential of CSAs to release dissolved P to surface runoff upon intermittent short-term submergence caused by different rainfall events has not been studied at a field-scale in New Zealand previously. A field study was conducted to investigate the potential of two different pastoral soil CSAs (Recent and Pallic soil) to release soil P over five rainfall events during winter and to explore the mechanisms of P release in these soils. Ten sampling stations were installed within each CSA in an area of 6×2m2. Each sampling station had two porewater samplers installed at two depths (2 and 10cm) below the soil surface. Two platinum half-cell electrodes were installed at the same two depths. Porewater and floodwater samples were collected following five rainfall events. Redox potentials were measured in-situ. Dissolved reactive phosphorus (DRP), pH, dissolved organic carbon, cations, anions, and alkalinity of the water samples were measured. Soil chemical P fractions were assessed at the beginning, middle and end of the experiment. Thermodynamic modelling was used to infer dissolution and formation of P and P-associated minerals. The average porewater DRP at the two depths during the rainfall events of the Recent and Pallic soils were 0.32-1.3mgL-1 and 0.26-2.31mgL-1, respectively. The average floodwater DRP concentrations of the Recent and Pallic soils were 35 and 43-fold higher than the target DRP concentration (0.01mgL-1) for the Manawatū River. The study highlights the substantial risk of P loss from CSAs to surface water, driven primarily by the reductive dissolution of Fe and Mn oxy(hydr)oxides. The findings underscore the importance of targeted management strategies to mitigate dissolved P runoff, particularly in high-risk CSAs frequent submerged during rainfall events. This study developed an effective method for monitoring soil porewater P and redox conditions, offering valuable insights and practical tools for resource managers seeking to reduce P contamination.

Spatial insights into microplastics and heavy metals levels, and risks in wastewater irrigated surface soils of Okara, Pakistan: Microplastics sizes impacts on heavy metals distribution using Structure equation model.

Pakistan's freshwater shortage and climate events have caused soil nutrient leaching, prompting cities to adopt wastewater irrigation. This study investigates wastewater as a potential source of microplastics (MPs) and heavy metals (HMs), assessing contaminant levels in wastewater-irrigated surface soils (WISS) in district Okara, Pakistan. It further explores potential ecological and human health risks associated with HMs in soil and the impact of MPs on HMs distribution and physicochemical properties. The concentrations of HM in WISS were within permissible limits (Cd: 0.48, Cu: 17.99, Zn: 29.73, Pb: 19.65, Fe: 8559.5), except for Mn, which was 182.94 mg/kg. MPs abundance ranged from 1850 to 5300 particles/kg, with the most common physical characteristics being fragment shapes (49.6%); black color (40.1%), and small sizes (<500 μm) many physical properties depicted association with HMs and MPs sizes. The structural equation model (SEM) showed a significant impact of MPs on HMs distribution, risk index, and pollution load index, but no significant relationship with physicochemical properties. The pollution indices for HMs in WISS indicated low ecological risk and negligible non-carcinogenic health risks were predicted for both adults and children. However, regular monitoring, enforcement of management and implementation plans, and remediation strategies for HMs and MPs in WISS are highly recommended.

Bacterial Community Structure in Soils With Fire-Deposited Charcoal Under Rotational Shifting Cultivation of Upland Rice in Northern Thailand.

Rotational shifting cultivation (RSC) is a traditional agricultural practice in mountainous areas that uses fire to clear land after cutting vegetation for cultivation. However, few studies have assessed the effect of fire-deposited charcoal on the diversity and composition of soil microbial communities, and none have been conducted in Thailand. Therefore, this study was conducted 1 year after a fire in an abandoned 12-year RSC in Chiang Mai Province, northern Thailand. Charcoal samples were collected from the surface litter layer, while charcoal-soil mixtures were taken from the surface soil (0-2 cm). Soil samples from 2 to 7 cm captured the charcoal-soluble layer, and samples from 7 to 15 cm represented soil without charcoal incorporation. The results revealed that charcoal led to higher pH and electrical conductivity in the charcoal layer, with notable differences in soil texture across layers, including the highest sand and silt content in the charcoal-mixed soil layer (0-2 cm). Soil organic matter and total nitrogen were significantly higher in the charcoal-mixed layer compared to deeper layers, indicating improved nutrient retention due to charcoal presence. Enhanced microbial diversity was observed in the charcoal and charcoal-mixed soil layers, with Proteobacteria, Chloroflexi, and Planctomycetota dominating across all soil samples. The bacterial genus Ilumatobacter exhibited significant changes in abundance in the charcoal layer. Additionally, Pseudolabrys was more abundant in charcoal-leached soil, while JG30a-KF-32 showed greater abundance in soil without charcoal. Shifts in Proteobacteria and Planctomycetota abundance were evident in the charcoal leaching and non-charcoal layers. Network analysis indicated more complex bacterial interactions in the charcoal-mixed soil layer, with reduced network complexity observed in the charcoal leaching layer and the layer without charcoal. These findings imply that charcoal provides a favorable environment for diverse and interactive bacterial communities, potentially benefiting soil health and fertility recovery in RSC fields.

Impacts of Bioenergy Crop Cultivation on Regional Climate, Hydrology, and Water Quality in the U.S. Northern High Plains

AbstractThe cultivation of bioenergy feedstocks, such as miscanthus, or energycane, on marginal lands helps alleviate the competition between food and fuel. However, such land use conversion could lead to complex interactions among climate, vegetation, and water resources, resulting in positive or negative environmental impacts. In this study, we used the Climate‐Weather Research and Forecasting (CWRF) model to simulate the feedback from growing bioenergy crops on marginal lands to regional climate for the present and future scenarios and used the Soil and Water Assessment Tool (SWAT) to evaluate the climate and land use change impacts on the hydrological cycle and water quality in the U.S. Northern High Plains Aquifer region. CWRF projects a wetter and cooler regional climate by considering climate‐crop feedback as compared to a control scenario (no land use change and climate feedback), highlighting the importance of land‐atmosphere interactions in regional climate assessment. Our watershed‐scale assessment shows that although growing miscanthus increases local evapotranspiration and decreases surface runoff, soil moisture, and percolation on marginal lands, watershed‐scale streamflow substantially increases during the growing season in both present and future conditions due to increases in regional precipitation. The differences in the extent of marginal land use change between the Platte (4%) and Republican (20%) river basins result in different responses in streamflow and nitrogen loading. Overall, our study highlights the importance of assessing the regional climate‐crop feedback and environmental quality impacts of using marginal lands for future sustainable bioenergy production.

Melamine - A PMT/vPvM substance as a generic indicator for anthropogenic activity and urbanisation? An explorative study on melamine in the water cycle and soil.

Melamine has a high production volume today and is spread ubiquitously in the anthropogenic technosphere. It is released steadily to the water cycle by many sources. Even though melamine has low direct toxicity, chronic exposure can cause nephrolithiasis and disrupt the endocrine system. Most data on melamine is based on case studies with, when compared, partially contradictive implications. As melamine is a compound of many sources (SMS), very persistent, mobile (vPvM), and toxic (PMT) it has the potential to break through natural barriers posing a potential risk to drinking water resources. This study combines existing data with own measurements gathered through various individual monitoring campaigns with the aim to gain new insights into its environmental behaviour and hotspots. Samples from surface water bodies, groundwater, wastewater (treated, untreated), and soil samples were analysed regarding their melamine concentration via liquid chromatography coupled with tandem mass spectrometry (LC-MSMS). Besides three drinking water samples, melamine could be found in all water samples (n=632) of this study, with a maximum concentration of 1289ng/L in drinking water and 1120ng/L in groundwater. While a constant baseline melamine concentration with an event-based release could be observed in most surface water bodies, higher concentrations towards Western Europe (urbanisation and chemical industry) was observed for wastewater. A similar pattern was found in the spatial distribution of melamine in agricultural soils towards an urban/suburban area. As, in general, melamine concentrations were higher towards urbans centers melamine can also be classified as an indicator of anthropogenic activity and urbanisation, but also spotlights on these areas as hotspots for potentially many compounds of the human technosphere. We call policy to shift from the existing one-size-fits-all solution to more flexible and risk-based approaches to prepare for future challenges.

An objective methodology for waterlogging risk assessment based on the entropy weighting method and machine learning

Waterlogging disasters are one of the most severe and widespread agricultural meteorological disasters. They affect about 15% of land surface globally, causing a significant reduction in crop growth and yields. This paper presents an objective methodology for assessing waterlogging risk, primarily in non-urban, predominantly agricultural areas. The waterlogging risk was assessed by evaluating vulnerability and hazard based on key environmental, anthropogenic, and climatic factors. The weights of factors affecting the waterlogging vulnerability were determined using the entropy weight method (EWM), assuring the objectivity of the overall evaluation results. The obtained waterlogging risk map was validated by comparing it with observed and detected waterlogged sites using Sentinel-2 imagery and Random Forest classification. The key novelties of this study are the use of the entropy weight method to objectively determine the relative importance of factors influencing waterlogging vulnerability, and a two-step validation process which includes field-based comparison and remote sensing validation. The presented methodology was demonstrated in the Vojvodina region, Serbia. The following waterlogging vulnerability factors were used: soil properties, geomorphology, surface depressions, average phreatic water table depth, and land cover. The EWM shows that surface depressions and soil properties have the most significant influence on waterlogging vulnerability. The highest waterlogging hazard classes occur in about 31% of the analyzed territory. The waterlogging hazard was estimated based on water balance for the non-vegetation season and maximum daily precipitation in spring, both modeled using the Generalize Extreme Value distribution function. The highest waterlogging hazard classes occur in about 31% of the analyzed territory. The final risk map shows that the high waterlogging risk occurs in about 11% of the territory. Those are mainly areas in the central, eastern, and southeastern parts of the Vojvodina region, usually along the main watercourses. High agreement between the detected waterlogged areas and the produced waterlogging risk map was achieved, validating the proposed methodology. The presented waterlogging risk assessment methodology is valuable for planning and policy-making for various water management and environmental activities. Although it is demonstrated in Vojvodina, by selecting the appropriate factors of vulnerability and hazard, it can be applied to any other region.