Organic Matter Content Research Articles

Influence of straw degradation on consolidation of dredged sludge under vacuum preloading

Vacuum preloading with straw drainage has been used as an eco-friendly soil-reinforcement method to promote the consolidation of dredged sludge. In previous studies, the degradation of straw, an essential factor influencing dredged-sludge consolidation, has often been disregarded. In this study, laboratory tests were conducted to investigate the effects of straw degradation on the consolidation efficiency of dredged sludge. The vacuum level within the straw drainage was found to decrease with increasing degradation time, causing a reduction in water discharge and settlement. Consequently, the moisture content increased and the shear strength of the soil decreased. After 60 days of degradation, the water discharge and settlement decreased by 46% and 25%, respectively. The impact of degradation time was most significant during the first 15 days, which was when most straw degradation occurred. The average moisture difference in the first 15 days was 5.0%, whereas it was negligible (0.8%) from 45 to 60 days. The increase in organic matter content enhanced the Atterberg limits and hydrophilic properties of the soil. The findings of this study promote the engineering application of vacuum preloading with straw drainage and confirm it to be an effective and eco-friendly method for consolidating dredged sludge.

Safe Utilization Effect of Passivator, Foliar Inhibitor, and Their Combined Application on Cadmium-contaminated Farmland

This study sought to explore the effects of passivator, leaf inhibitor, and their combination on cadmium （Cd）-contaminated farmland and to realize the safe utilization of cultivated land. Coconut shell biochar and calcium magnesium phosphate fertilizer were selected as soil passivators and foliar selenium fertilizer was used as a foliar inhibitor. The best combination was selected through a wheat-maize rotation experiment. The results showed that： ① The soil pH, organic matter content, and CEC could be improved to varying degrees by the application of passivators. ② The grain yield of wheat and maize increased to different degrees after the application of the passivator and foliar inhibitor. ③ The BFL treatment （biochar 1 800 kg·hm-2 +calcium magnesium phosphate 600 kg hm-2 + foliar inhibitor 3 L·hm-2） during the maize season had the best effect, which was significantly lower than that in CK by 13.85%. The effect of the BF treatment （biochar 1 800 kg·hm-2 + calcium magnesium phosphate 600 kg·hm-2） in wheat season was the best, which was significantly reduced by 11.21% compared with that in CK. ④ The BF treatment （biochar 1 800 kg·hm-2 + calcium magnesium phosphate 600 kg·hm-2） had the best effect on reducing Cd content in roots, straws, and grains of maize and wheat, reducing Cd content in roots of wheat and maize by 20.55% and 27.81%, Cd content in straws by 11.39% and 13.70%, and Cd content in grains by 48.97% and 50.44%, respectively. Therefore, considering all the indexes, the combination of passivators and foliar inhibitor, especially biochar combined with calcium magnesium phosphate fertilizer and biochar and calcium magnesium phosphate fertilizer combined with foliar inhibitor, could more effectively reduce the absorption, transport, and enrichment of Cd in maize and wheat and could be popularized and applied in safe use cultivated land.

Effects of Different Fertilization Treatments on Bacterial Community and Citrus Quality in Yellow Soils of the Yunnan-Guizhou Plateau

To investigate the intrinsic driving mechanism of citrus yield and quality enhancement under different fertilizer applications, a field experiment was conducted to study the effects of biochar （SW）, organic fertilizer （YJ）, farmyard manure （NJ）, chemical fertilizer （HF）, and no fertilizer as the control （CK） on soil physical and chemical properties, bacterial community characteristics, and citrus quality of citrus orchards in the yellow soil area of the Yunnan-Guizhou Plateau. The results showed that compared with those in the CK treatment, the yield, single fruit weight, edible rate, juice rate, vitamin C content, and soluble solids of citrus increased under the different fertilization treatments. In contrast, the titratable acid content of citrus decreased, resulting in an increase in the solid-acid ratio of citrus. Among the different fertilization treatments, the most significant effective treatment was SW. The SW and YJ treatments significantly increased the soil pH value, while the HF treatment decreased soil pH. Different fertilization treatments could increase the contents of soil organic matter, hydrolyzable nitrogen, available phosphorus, and available potassium. The SW treatment exhibited the most obvious effect on the contents of soil hydrolyzable nitrogen, available phosphorus, and available potassium. The YJ treatment exhibited the most obvious effect on the soil organic matter content. The different fertilization treatments significantly affected soil bacterial community diversity and community structure, among which the SW treatment significantly increased the soil Chao1 index, observed species index, and Shannon index； optimized soil bacterial community structure； and made the bacterial symbiotic network simple and stable. By contrast, the HF treatment significantly decreased the soil Chao1 index, observed species index, and Simpson index and had less effect on bacterial community structure. Redundancy analysis showed that soil available potassium （96.47%）, Chao1 index （73.80%）, and Chujaibacter （55.92%） were the key factors in improving citrus yield and quality. Variance decomposition analysis indicated that the soil bacterial community structure was the largest contributor （17.00%） to the improvement in citrus yield and quality. In conclusion, fertilization can effectively improve soil physical and chemical properties, increase soil nutrient supply level, optimize bacterial community structure, and improve citrus yield and quality. Of these, biochar can be used as a priority for the fertilization and improvement of the soil in citrus orchards in the yellow soil area of the Yunnan-Guizhou Plateau.

Effects of Storm Runoff on Bacterial Community Structure and Metabolic Activity and Water Quality in a Drinking Water Reservoir

To explore the influence of storm runoff on bacterial metabolic activity and water quality in Jinpen Reservoir, three-dimensional fluorescence spectroscopy parallel factor analysis, high-throughput DNA sequencing technology, and Biolog technology were used to analyze variations in the components of dissolved organic matter, bacterial community composition, and microbial metabolic activity during three periods （before, during, and one month after runoff）. The results showed that after storm runoff into the reservoir, the water temperature decreased, and dissolved oxygen in the middle of the water column increased significantly. Finally, the aerobic and low-temperature state in the middle water and anaerobic and low-temperature state in the bottom water was formed. Simultaneously, the concentration of total nitrogen, total phosphorus, organic matter, and turbidity increased significantly. After one month of runoff, the concentration of pollutant decreased, however, was still higher than that before runoff. Further, during the runoff period, the proportion of Proteobacteria and Bacteroidetes increased significantly and the sum of their relative abundance accounted for 63.6% of the bacterial community. The bacterial metabolic activity was also higher than that before. One month after runoff, the bacterial population structure did not recover and the bacterial metabolic activity still remained at a high level.

Health Risk Assessment of Heavy Metals in Soil-crop System in Different Ecological Regions of Ningxia

Heavy metals are characterized by toxicity，non-biodegradability，and accumulation in the food chain；hence，o the distribution of heavy metals in farmland soils and crop food safety have attracted much attention. A total of 1 274 soil samples and crop samples were collected from farmland in Ningxia from 2017 to 2021 and bioconcentration coefficients were used based on the analysis of the elemental contents of Zn，Cr，Ni，Cu，Pb，As，Cd，and Hg. The ecological risk index and correlation analysis were used to characterize the heavy metal content and health risk assessment of the soil-crop system in Ningxia. The results showed that the soils in the study area were alkaline and the mechanical composition was dominated by pulverized and sandy grains，with a relatively small content of clay grains. The heavy metal contents in the soils were in the following order：Zn>Cr>Ni>Cu>Pb>As>Cd> Hg. Except for that of Cu and Ni，the contents of other heavy metals in the soils of the northern region were higher than those of the central and southern regions. The ecological risk index of soil heavy metals was Hg>Cd>As>Cu>Pb>Ni>Cr>Zn and the proportion of points with low and medium ecological risk index levels was high（98.58%），indicating that the soil environment was generally good. The average content of the eight heavy metals in crops did not exceed the limit value，and the average health risk index value was <1. However， the health risk index（HRI）of As in individual crops existed at points >1 in all three sub-regions and individual points with high values of HRI（HRI>1）for Cu and Ni were observed in crops in the northern region and for Pb in the north and south of the country，which require further attention. From the bioconcentration factor，crops showed no accumulation effect （BCF<1）for heavy metals such as As，Cd，Cr，Cu，Ni，Pb，and Zn and although the average uptake of Hg by crops did not show accumulation，a total of 31 crops in the three ecological zones showed some accumulation（BCF>1），which also requires further monitoring. Analysis using the Mantel's test showed that except for As and Ni in crops，which had a weak correlation with Cu content in the soil（0.05>Mantel's P>0.01），the other heavy metals in crops did not have a significant correlation with the corresponding soil heavy metals （Mantel's P≥0.05），indicating that the heavy metal contents in crops were less affected by soil heavy metals. RDA analysis showed that the sand content had a strong positive correlation with the transfer coefficients of heavy metals such as Hg，Ni，Pb，and Cd，while the powder content showed a strong negative correlation；however，the transfer coefficients of Cu，Zn，As，and Cr were not much affected by the mechanical composition of soils，and the correlation between the soil organic matter content and the transfer coefficients of heavy metals was also small. In summary，the quality of the soil environment and crops in the study area is generally good；however，attention must still be paid to the areas with high heavy metal content or exceeding the standard value to strictly control the input of pollutants，and at the same time，establishing long-term monitoring of the quality status of soil and agricultural products in the crop production area is a necessary control initiative.

Intercropping Land Kale on Hypopodium Leftover Oil Palm Fronds Pruning

The horticultural consumption of land kale in Indonesia is still quite high due to its complete nutritional content. However, limited cultivation land is an obstacle to the production of land kale. On the other hand, Indonesia has a very large area of oil palm plantations because it is a superior commodity as a foreign exchange earner. But it is unfortunate that the output obtained is only oil palm fresh fruit bunches (FFB). Therefore, it is necessary to create an integrated agricultural model such as intercropping so that the output obtained is more and profitable economically and environmentally sustainable. Intercropping is a method of agricultural cultivation by planting two or more commodities in the same area to maximise land use and maximise productivity. Intercropping in oil palm is not carried out in producing crops (TM) due to constraints on cultivation land area. However, by using a new agricultural cultivation method, namely cultivation on the hypopodium of the remaining leaf pruning, oil palm producing plants (TM) can still be intercropped. Hypopodium is the tip or base of the leaf that connects to the plant stem. The hypopodium area that is already wide enough in producing plants (TM) can be used as a place for kale plant growth. In addition, the content of organic matter in the hypopodium can be used as a source of nutrients and as an organic substrate. This type of primary research with qualitative methods shows the results that the intercropping method of kale with oil palm on the hypopodium of the remaining pruning of oil palm leaves can be done so that the output out of the farm is more.

Effect of Organic Matter on Soil Aggregate Stability in Rufunsa District of Zambia

Organic amendments have been known to improve soil physical and chemical properties in the sub Saharan Africa. However research information on how organic amendments affects aggregate stability and the degree of their effects in comparison to other is inadequate in Zambia.The study was therefore carried out to assess the effects of organic amendments on soil aggregate stability and organic matter content on soil from RUFUNSA District, Zambia

Synergistic Effects of Unmodified Tea Leaves and Tea Biochar Application on Remediation of Cr-Contaminated Soil

Hexavalent chromium (Cr(VI)) contamination in soil presents significant risks due to its high toxicity to both the environment and human health. Renewable, low-cost natural materials offer promising solutions for Cr(VI) reduction and soil remediation. However, the effects of unmodified tea leaves and tea-derived biochar on chromium-contaminated soils remain inadequately understood. In this study, tea tree pruning waste was converted into biochar at various temperatures, and the impacts of both unmodified tea leaves and tea biochar on soil Cr(VI) content, chromium fractionation, and soil biochemical properties were assessed using a soil incubation experiment. The results showed that the combined treatment of tea and tea biochar produced at 500 °C reduced Cr(VI) content by up to 49.30% compared to the control. Chromium fractionation analysis revealed a significant increase in the residual chromium fraction, accounting for 32.97% of total chromium, substantially reducing its bioavailability and mobility. Soil properties were markedly improved, with notable increases in pH (14.89%), cation exchange capacity (CEC; up to 100.24%), and organic matter content (up to 167.12%) under the combined treatments. Correlation analysis confirmed that Cr(VI) content reductions were positively correlated with increases in pH, nutrient retention, and enzyme activities, highlighting their role in chromium stabilization. This study underscores the synergistic potential of unmodified tea leaves and tea biochar as an innovative, eco-friendly strategy for Cr(VI) remediation, enhancing both soil quality and heavy metal stabilization.

Physical, chemical, and microbiological parameters of soil under different tillage types.

Objective: To determine the effect on the chemical, physical and biological properties of soils under minimum tillage and conservation tillage in different locations in Sinaloa. Design/methodology/approach: The treatments were evaluated using a completely randomized experimental design, with a total of eight treatments or sampling sites, where five samples per site were collected at a depth of 30 cm. A total of 40 samples were obtained, which were preserved in a thermal box and were transferred to the microbiology laboratory of the Faculty of Agronomy (UAS). The variables evaluated included the quantification of bacteria on plates, where the number of total bacterial colonies (TB), phosphate solubilizing bacteria (PSB), nitrogen-fixing bacteria (NF) and indole-promoting bacteria (IPB) were determined. In addition, organic matter, electrical conductivity and pH were determined. Results: Soils under minimum tillage modality significantly promoted higher percentage of organic matter, a greater number of bacterial colonies and higher electrical conductivity compared to soils with conventional tillage modality. Limitations on study/implications: Findings/conclusions: Agricultural tillage intervenes in the physical, chemical and microbiological properties of soils, as the sampling sites where minimum tillage is practiced show a higher concentration of organic matter and therefore leads to greater microbiology and electrical conductivity in those evaluated soils.

Impact of vegetation type on the content and spectroscopic properties of soil organic matter in the subalpine zone of the Bieszczady Mountains (Eastern Carpathians)

Impact of vegetation type on the content and spectroscopic properties of soil organic matter in the subalpine zone of the Bieszczady Mountains (Eastern Carpathians)

Analyzing the impact of variations in land use and elevation on selected soil microbial indices and spatial distribution.

Soil biological characteristics are highly sensitive to land use changes, making them valuable indicators of soil quality. This study assesses the effects of three land use types (agriculture, rangeland, and forest) and elevation variations on soil microbial parameters and their spatial distribution in the Khaneghah region. Standard physicochemical and biological properties of the soil were measured on a total of 72 soil samples collected using systematic and random sampling techniques. Spatial distribution maps of the biological indices were generated using geostatistical techniques, specifically the Kriging method, within a geographic information system (GIS). The results revealed significantly higher values for microbial biomass carbon (MBC = 900 mg Cmic-CO2 kg-1), nitrogen (MBN = 8.97 mg Nmic kg-1), basal respiration (BR = 25.1 mg C-CO2 g-1 day-1), and the total microbial population (MPN = 0.63 × 109 cells g-1) in forest soils compared to rangeland and agricultural soils. The alignment between land use maps and biological index maps reinforced these findings. Although the correlations between biological indices and physicochemical properties were generally weak (positive or negative), organic matter content, field capacity moisture, and silt percentage exhibited a slight positive correlation with most of the microbial indices evaluated. The comparison of soil microbial indices with the digital elevation model map indicated higher levels of MBC, MBN, BR, and MPN at elevated regions. However, the microbial quotient and metabolic quotient (qCO₂) did not show significant changes with increasing elevation. The study also confirmed the effectiveness of Kriging interpolation in mapping specific soil microbial indices, as the correlation between Kriging estimates and measured values at sampling points exceeded 0.2, demonstrating statistical significance at a 5% confidence level.

Field evaluation of a simple infiltration test and its relationship with soil physical properties of three different types of land uses

Infiltration capacity is an important variable for understanding and predicting arange of soil processes. A study was conducted to assess infiltration rates across three distinct land types: forested areas, grasslands, and construction zones. The infiltration rate of the soil was assessed utilizing a mini disk infiltrometer, with a subsequent analysis of soil physical properties to establish a correlation with its infiltration capacity. The infiltration rates were observed to be the highest for forestland, followed by grassland, and then construction land. The cumulative infiltration values further support this trend, indicating that forestland exhibits the highest cumulative infiltration, followed by grassland and construction land. Soil physical properties, including particle size distribution, moisture content, and organic matter content, significantly influenced infiltration rates. Soil compaction, characterized by a higher dry bulk density, was associated with reduced infiltration capacity, particularly in construction land. Conversely, higher moisture and organic matter content enhanced infiltration rates. These findings underscore the importance of considering soil properties, land use, and vegetation cover when managing landscapes to mitigate soil erosion and preserve water quality. Understanding the intricate relationship between these factors is crucial for sustainable land use practices and environmental conservation.

Nature loofah network‐inspired rapid thermal‐conductive and thermochromic‐based nanocomposites for efficient heat management in advanced electronic devices

AbstractThe development of 5G technology has raised concerns about the heat buildup in microelectronic components, which can hinder device performance and integration. Inspired by the structure of loofah, we designed thermally conductive substrates using polydimethylsiloxane (PDMS) and graphene oxide (GO) incorporated into copper foam (F‐Cu). We also created nano‐thermal management composites with organic thermochromic material‐GO/PDMS/F‐Cu. The composites had a thermal conductivity of 1.02 Wm−1 K−1 with 15 wt% content of (35‐, 45‐, and 65‐) organic thermochromic materials (OTM), showing efficient heat dissipation. Practical testing showed significantly improved cooling effects compared to pure copper foam, with a CPU temperature drop of 9.6°C. Additionally, the surface color changes at specific temperature thresholds, offering an innovative way to determine the temperature range of electronic devices. This material also provides a solution for monitoring the temperature of densely integrated electronic devices.Highlights Enables temperature visualization in microelectronics. The nanocomposite achieves a value of 1.08 Wm−1 K−1. Nanocomposites predict heat source temperature via thermochromic coating. The cyclic test exhibits commendable stability and reliability.

Chemical composition and carbohydrates of seaweed Sargassum sp. with different drying methods

Sargassum sp., a brown seaweed abundant in Semau Island, East Nusa Tenggara, Indonesia, has potential as an alternative feed source in animal nutrition due to its rich chemical composition. This study aimed to determine Sargassum sp.'s chemical and carbohydrate composition using different drying methods to evaluate its suitability as livestock feed. A Completely Randomized Design (CRD) with three treatments—sun drying, oven drying at 60°C, and air drying—and five replications were employed. Using standard proximate analysis, fresh seaweed samples were dried according to the treatments and analyzed for dry matter, organic matter, crude protein, crude fat, crude fiber, and carbohydrate content. The results showed that the drying method significantly affected (P &lt; 0.05) the dry matter, moisture content, ash content, organic matter, crude protein, and crude fat of Sargassum sp. but had no significant effect (P &gt; 0.05) on crude fiber and carbohydrate content. Air-dried samples exhibited the highest crude protein content (6.38%) compared to sun-dried (4.71%) and oven-dried (4.94%) samples, indicating better preservation of protein at lower temperatures. Crude fat content was highest in sun-dried samples (0.56%) and lowest in air-dried samples (0.24%). Carbohydrate content ranged from 52.83% to 54.00% across all treatments without significant differences. These findings suggest that air drying is the most effective method for retaining the nutritional components of Sargassum sp., enhancing its potential as a valuable ingredient in animal feed formulations. The drying method significantly influences Sargassum sp. seaweed's chemical composition. Air drying preserves key nutritional components, making it the recommended method for processing Sargassum sp. for use in animal nutrition.

Effect of rice hull amendment in green roof substrates

The use of waste and locally available materials could improve the sustainability of green roofs. Therefore, a study was conducted to evaluate the potential of a rice hulls in the organic and inorganic portion of green roof substrates. Three substrate mixtures were prepared at the site by mixing locally available materials. The substrate mixtures were designated as RPZV (rice hulls 6:1; pumice and zeolite mixture 2:1; vermicompost 2:1 by volume), PZR (rice hulls 2:1; pumice and zeolite 8:1), and PZV (pumice and zeolite 8:1; vermicompost 2:1). Measurements were performed including plant growth index, chlorophyll fluorescence, biomass accumulation on native and exotic plant species. Increased amounts of rice hulls in the substrate mixture had a significant effect on reducing bulk density up to 24%, increasing organic matter content up to 67% and maximum water holding capacity (WHC) of the substrate, but also had the lowest volumetric moisture values in the field measurements due to increased porosity and permeability of the substrate. Adversely, substrate mixtures with higher rice hull content experienced greater temperature fluctuations during the study period, which have resulted in increased plant mortality and stress for certain plant species during the study. As the organic part of the substrate, rice hulls caused a decrease on the salinity of the substrate by about 28% and provided higher survival rates and lower stress levels for A.schoenoprasum, C.creticus, L.spectabilis, D.chinensis and Sedum species. The results of the study suggested that, rice hulls may have the potential to be used in appropriate proportions due to their low bulk density, low salinity and resistance to degradation, leading to a reduction in the environmental impact of green roof construction.

IoT-Based Tryptophan-like Fluorescence Portable Device to Monitor the Indicators for Microbial Quality by E. coli and Biochemical Oxygen Demand (BOD5)

Tryptophan-like fluorescence (TLF) is a key indicator of water contamination, particularly of microbial origin and biodegradable organic compounds. This study introduces an Internet of Things (IoT)-enabled portable device (IoT-TLF-PD) for real-time monitoring of microbial quality and biochemical oxygen demand (BOD5). The device was tested using surface water (S1), secondary wastewater (S2), and final wastewater effluents (S3). Results showed significant correlations between TLF intensity, Escherichia coli (E. coli) counts, and BOD5, with R2 values of 0.77 (S1), 0.61 (S2), and 0.76 (S3) for BOD5, and 0.60 (S2) to 0.68 (S3) for E. coli. Considering various water samples, a strong correlation was found between E. coli and BOD5 with TLF intensity normalized by total organic carbon (TOC) concentration (TLF intensity/TOC). The R2 value for E. coli was 0.92, and for BOD5, it was 0.77. This indicates the necessity of accounting for organic matter concentration when interpreting TLF intensity in water quality assessments. The study confirmed the potential of the IoT-TLF-PD to serve as a cost-effective, real-time indicator for assessing water quality, especially for detecting microbial contamination. This technology offers a valuable tool for environmental monitoring and water management.

The Impact of Exogenous Organic Matter on the Properties of Humus Compounds of Soils Developing on a Reclaimed Fly Ash Landfill

Fly ash does not contain organic matter to initiate soil-forming processes and the proper development of plant cover. Therefore, in the reclamation of fly ash landfills, an integrated approach is required, including the introduction of exogenous organic matter into the top layer of ash. This study assessed changes in the content and quality of organic matter in soils developing on a reclaimed fly ash landfill. This study included reclaimed areas without the introduction of EOM (RV_1—the direct introduction of plants) and with the introduction of EOM (RV_2—surface humus and RV_3—sewage sludge). In samples taken 15 years after reclamation, the contents of total organic carbon (TOC) and total nitrogen (TN), the fractional composition of organic matter, the susceptibility of organic matter to oxidation, and soil carbon management indices (carbon pool index (CPI), C lability (L), lability index (LI), and carbon management index (CMI)) were determined. The study results showed that the use of EOM in the reclamation of the ash dump significantly increased the content and improved the quality parameters of organic matter and thus influenced the initiation of the process of organic matter accumulation. In RV_1 soil, the accumulation of carbon resources was only found in the topsoil. An increase in carbon resources in the 15–40 cm layer was only noted in the variants in which EOM was introduced (RV_2 and RV_3). Carbon management indices showed that organic matter transformations covered only the top layers of these soils and were closely related to the EOM inflow. The interdependence of the CPI and L was most beneficial in the soil reclaimed with sewage sludge. In the soil of this reclaiming variant, the CMI had a value above 100, which indicates the initiation of the soil-forming process. Significant differences between the assessed reclamation variants were confirmed by means of PCA based on organic matter quality indicators. The organic matter content and quality indicators were the most favorable in the soil of variant RV_3. The obtained results confirmed that the introduction of EOM into the top layer of fly ash has a beneficial effect on the accumulation and quality indicators of organic matter and thus on the development of the soil-forming process in Technosols developing on a reclaimed fly ash landfill.

Hydrobiological and Geochemical Responses to Trout Cage Aquaculture in Lake Ecosystem

This study investigates the seasonal dynamics and interrelationships between geochemical and hydrobiological parameters in lake ecosystems impacted by fish cage farming in Lake Ladoga, Russia. Environmental conditions at three trout farms were assessed, focusing on water and sediment quality as well as benthic and zooplankton communities. For each farm, two categories of sampling sites were designated: cage sites and reference sites located 100–600 m away from the cages. Fieldwork was carried out across four seasons in 2023: February, June, August, and November. The findings indicate that intensive fish feeding results in significant organic waste accumulation beneath trout cages, altering the composition and abundance of planktonic and benthic organisms. The organic matter content in sediments beneath the cages during periods of intensive feeding was found to increase 2–5 times compared to the reference sites. In winter, accumulated organic matter in the sediments underwent mineralization, bringing hydrobiological indicators closer to the reference values. The geochemical and hydrobiological parameters analyzed in this study serve as valuable indicators for developing ecological monitoring approaches in freshwater cage aquaculture.

Evaluation of boron toxicity in soil and influencing factors: A case study of sodic soils of Panipat, India.

Boron toxicity is an increasingly serious problem leading to soil degradation and vegetation loss in arid and semi-arid environments worldwide. The soils of solonetzic complexes often display this characteristic. This study aimed to investigate the vertical distribution of hot water soluble-boron (hws-B) in the sodic and agricultural soils of Israna block in Haryana, India. The study also examined the influence of various soil variables on hws-B. The samples were collected at six depths to assess the availability of B. Additionally, an assessment was conducted to ascertain the appropriateness of the water sources for irrigation. The findings of our study revealed a notable disparity in the hws-B content between sodic soils and control agricultural soils, with the former exceeding the toxic thresholds. The levels of B available to plants were highest in the upper layers of soil and reduced as the depth increased. A number of variables influenced the water-soluble B content in sodic soils, particularly pH, calcite content, electrical conductivity (EC), organic matter (OM), and calcium-boron ratio (Ca/B). The results indicated that the boron levels in both surface and groundwater were within acceptable limits for irrigation purposes, suggesting that boron toxicity may not be directly attributed to these sources. Our study suggests that sodic soils contain high levels of boron, which can be toxic, and consequently, proper management of these soils is recommended. It is essential to have a comprehensive understanding of boron levels in surface and sub-surface soils, as well as in irrigation water, in order to effectively manage soil and improve crop productivity.

Polycyclic aromatic hydrocarbons in surface sediments of the western Bay of Bengal: Distribution, sources, and ecological risk assessment

This study investigated the distribution, sources, and ecological risk of polycyclic aromatic hydrocarbons (PAHs) in the surface sediments of the Western Bay of Bengal (WBoB). Coastal, shelf and slope sediments from the WBoB, collected from different research cruises, were analysed for 16 priority PAH pollutants. Total PAHs (TPAHs) were in the range of 1.87–918.79 ng/g and exhibited a significant association with organic matter and silt content with a predominance of high molecular weight (HMW) PAHs congeners. The preferential degradation of the labile low-molecular-weight (LMW) PAHs resulted in the sedimentary accumulation of HMW congeners. A comparison with reported values from other oceanic areas revealed a relatively low concentration of PAHs in WBoB. The isomeric ratios of PAHs could suggest a pyrogenic or petrogenic (crude oil) origin of PAHs. Principal component analysis indicated the dominance of HMW PAHs (petrogenic or combustion) over the LMW fraction. Based on sediment quality guidelines, four congeners [Pyrene (Py), Benzo[a]anthracene (BaA), Chrysene (Ch), and Dibenzo[a,h]anthracene (DbA)] exceeded the threshold effect levels, indicating an adverse impact of these PAHs on the benthic fauna occasionally. The corresponding risk quotients further indicated a moderate risk caused by Py, BaA, and Benzo[b]fluoranthene (BbF) to the biota. This study underscores the importance of proactive management and mitigation strategies to safeguard these vital oceanic ecosystems from the adverse effects of PAHs and other hazardous materials.