Acid In Soil Research Articles

Biological Control of Melon Continuous Cropping Obstacles: Weakening the Negative Effects of the Vicious Cycle in Continuous Cropping Soil.

The continuous cropping obstacles of melons have become increasingly serious in recent years. To investigate this, we explored the effects and mechanisms of Bacillus subtilis C3 in control of the continuous cropping obstacles of melon. We provide a novel interaction model of the occurrence factors of continuous cropping obstacles. The dominant pathogen isolated from melon soil was Fusarium. Their hyphae were used as food to cultivate root-knot nematodes. The main phenolic acids in melon soil promoted the growth of Fusarium and indirectly increased the number of root-knot nematodes, but they also had direct toxic effects on melon root-knot nematodes. The simultaneous inoculation of the three had the strongest inhibitory effect on melon seedlings, while the inhibitory effect of paired inoculation was weaker than that of single inoculation. Therefore, the three balance each other, forming a vicious cycle. Bacillus subtilis C3 weakened the negative effects of this cycle on melon by eliminating phenolic acids and inhibiting the growth of Fusarium and root-knot nematodes. Simultaneously, they also alleviated the continuous cropping obstacles of melon by improving the composition and structure of the rhizosphere microbial community. Our results might be useful for the effective control of the continuous cropping obstacles of melon. IMPORTANCE The soil environment, crop growth and fruit quality of melons are negatively affected by long-term continuous cropping. It is important to study the mechanism of continuous cropping obstacles and their biological control. In this study, we propose a novel interaction model of the occurrence factors of continuous cropping obstacles. The dominant phenolic acids, pathogenic fungi, and root-knot nematodes from melon soil balance each other, forming a vicious cycle. Bacillus subtilis C3 weakened the negative effects of this cycle on melon by eliminating phenolic acids and inhibiting the growth of Fusarium and root-knot nematodes. In addition, C3 also improved the composition and structure of the melon rhizosphere microbial community. These results advance the study of the occurrence mechanism of continuous cropping obstacles and demonstrate an efficient and environmentally friendly biological control scheme.

Dynamic and Migration Characteristics of Soil Free Amino Acids in Paddy Soil Applied with Milk Vetch

To explore the attribution factors and migration characteristics of free amino acids (FAAs) in paddy soils after green manure application during the entire growth period of rice. Amino acid analyzer, quantitative PCR, and high-throughput sequencing were used to analyze the effects of different application rates of milk vetch on FAAs in paddy soil under equal nitrogen, phosphorus, and potassium conditions. Soil FAAs concentration at different growth stages was highest at the seedling stage and lowest at the tillering stage. The concentration of threonine, alanine, valine, isoleucine, leucine, and phenylalanine was most abundant during the growth period, accounting for 59.42–76.46% of the respective FAAs pool. The application of milk vetch was shown to increase the soil FAAs concentration, especially glutamic acid, which increased by 368.17–680.78%, but the excessive application had an inhibitory effect. Soil bacteria were critical factors affecting soil FAAs dynamics, among which Bacteroidetes, Firmicutes, and Nitrospirae contributed 56.89% to the FAAs dynamics. FAAs displayed significant vertical profile characteristics, and the mobility of serine, glycine, and proline was high. Conclusively, the application of milk vetch was able to significantly change the concentration and composition of soil FAAs, which were affected by soil bacteria.

Mobility assessment of 2,4-dichlorophenoxyacetic acid in andic soils of the department of Cauca, Colombia

El herbicida ácido 2,4 – diclorofenoxiacético (2,4-D) es un ácido selectivo y sistémico que, desde 1940, es ampliamente utilizado en suelo agrícolas, de todo el mundo. Su uso radica a su selectividad entre la vegetación de hoja ancha y cultivos de gramíneas y como regulador del crecimiento vegetal; sin embargo, este herbicida se puede acumular en el ambiente y, adicionalmente, puede ser transportado por lixiviación, a través del suelo, llegando a contaminar aguas subterráneas, lo que genera un alto riesgo para el ambiente y la salud del ser humano. El estudio de la movilidad del 2,4-D en suelos con alto contenido de materia orgánica permitió conocer, que no solo la materia orgánica se correlaciona indirectamente con la movilidad de este compuesto, sino que, también, influye la humedad, al reducir la lixiviación y el potencial de contaminación del recurso hídrico subterráneo, mientras que la conductividad hidráulica se relaciona, de manera directa, con la lixiviación de este herbicida.

Underlying Mechanisms for Low-Molecular-Weight Dissolved Organic Matter to Promote Translocation and Transformation of Chlorinated Polyfluoroalkyl Ether Sulfonate in Wheat.

Dissolved organic matter (DOM) such as fulvic acid (FA) and humic acid (HA) in soil considerably affects the fate of per- and polyfluoroalkyl substances (PFASs). However, the effect of DOM on their behavior in plants remains unclear. Herein, hydroponic experiments indicate that FA and HA reduce the accumulation of an emerging PFAS of high concern, 6:2 chlorinated polyfluoroalkyl ether sulfonate (6:2 Cl-PFESA), in wheat roots by reducing its bioavailability in the solution. Nevertheless, FA with low molecular weight (MW) promotes its absorption and translocation from the roots to the shoots by stimulating the activity and the related genes of the plasma membrane H+-ATPase, whereas high-MW HA shows the opposite effect. Moreover, in vivo and in vitro experiments indicate that 6:2 Cl-PFESA undergoes reductive dechlorination, which is regulated mainly using nitrate reductase and glutathione transferase. HA and FA, particularly the latter, promote the dechlorination of 6:2 Cl-PFESA in wheat by enhancing electron transfer efficiency and superoxide production. Transcriptomic analysis indicates that FA also stimulates catalytic activity, cation binding, and oxidoreductase activity, facilitating 6:2 Cl-PFESA transformation in wheat.

Be-original break new ground: Fluorescence sensing of humic acid in natural water and soil by pitaya seed carbon dots

Pitaya seed carbon dots (P-CDs) with good biocompatibility were synthesized by hydrothermal method using natural biological matrix as carbon source, which applied to the detection of humic acid (HA) for the first time. So far, there is no report on the use of biomatrix-derived carbon dots for the detection of HA. This method can bring less pollution to the detection process of HA, which is very important to ensure lower cost, environmental safety and minimized energy consumption. In addition, it was worth noting that, based on the concept of green chemistry, the preparation process of P-CDs is simple, and the fluorescence method is used for analysis. Based on the fluorescence resonance energy transfer (FRET) mechanism, the detection of HA in water and soil can be realized in a short time. The results matched those of high-performance liquid chromatography (HPLC), suggesting that it shows great potential in water and soil quality monitoring.

Established methods and comparison of 10 organic acids based on reversed phase chromatography and hydrophilic interaction chromatography

ABSTRACT High performance liquid chromatography (HPLC) methods have been established for simultaneously determining the 10 organic acids in fruit or soil. Two liquid chromatographic (LC) columns with reversed phase (RP) (Titank C18) and hydrophilic interaction (HILIC) (Poroshell 120 HILIC-Z) were selected to separate organic acids in molecular or ionic state, respectively. Meanwhile, the mobile phases had different solvents and pH values in the two states. Results indicated that these two columns can complement each other and avoid various matrix interferences. The limits of detection (LOD) of organic acids (S/N ≥ 3) were 0.002–0.521 μg∙mL−1 in the molecular state and 0.003–0.459 μg∙mL−1 in the ionic state, and the corresponding limits of quantification (LOQ) (S/N ≥ 10) were 0.007–1.737 μg∙mL−1 and 0.009–1.530 μg∙mL−1. The above methods can provide a technical support for the analysis of organic acid components in other matrices.

Preliminary Research on Agricultural Cultivation Decreasing Amino Sugar Accumulation in Calcareous Soils in Subtropical Karst Region of China

Soil microbial residues play an important role in the formation and stabilization of soil organic matter and can be quantitatively characterized by amino sugars. However, the response of soil microbial residues to agricultural cultivation in karst areas remains unclear. In this study, we collected soil samples from natural reserved land as well as five plantation forests dominated by Citrus trees cultivated for 0, 1, 5, 15, 30 years to examine the effects of agricultural cultivation on the content of microbial residues (amino sugar analysis). Results showed that: (1) Soil Amino Sugars (ASs) contents were significantly reduced after agricultural cultivation along with the sharp decrease in soil organic carbon (SOC). After 30 years of cultivation, the contents of total ASs, glucosamine (GluN), galactosamine (GalN), and muramic acid (MurA) in cultivated soils decreased by 58.22%, 55.30%, 27.11%, respectively, compared with 0 yr.; (2) Microbial residual carbon contribution to SOC increased from 34.11% to 81.33% after 30 years of cultivation, including fungal residual carbon (FRC) (25.79% to 48.6%) and bacterial residual carbon (BRC) (8.32% to 32.72%); (3) Soil GluN/MurA values tended to decrease with increasing cultivation years. The results highlight the significant effect of cultivation years on amino sugar accumulation. It indicates that the years of reclamation in karst areas have different impacts on the organic fractions derived from various microbial communities in the soil organic matter pool, and the microbial residues indicated by amino sugar are of great significance for the interception of soil organic matter.

Characteristics of humic acids in sod-podzolic soil under long-term exposure to different fertilization systems

The elemental composition and structure of humic acids in the soddy-podzolic heavy loamy soil of the Cis-Urals were studied during long-term application of organic, mineral and organo-mineral fertilizers under conditions of a long-term stationary experiment. Mineral fertilizers contributed to the formation of humic acids with increased content of aliphatic components, the ratio H : C = 1.45 and a high degree of oxidation (ω = 0.41). The low content of nitrogen in humic acids (from 2.0 to 2.6 at.%), with various fertilizer systems, is primarily due to its low content in the plant biomass of crops cultivated in crop rotation.The organic fertilizer system resulted in the enrichment of the structural aggregates of humic acids with aromatic groups and nitrogen. The high intensity of absorption of the >C=O group of carboxylic acids in the region of 1 717 cm-1 and double bonds of carbon atoms at 1 627 cm-1 confirms this position. Humic acids of the “manure 10 t/ha” and “manure 5 t/ha + equiv. NPK” have the largest number of carboxyl groups in their composition. The vibrations of the >C=O group of carboxylic acids are most weakly expressed in soil humic acids with a mineral fertilizer system. Organo-mineral fertilizer system demonstrates intermediate results in terms of the content of the main constitutional elements in humic acids. Mineral fertilizers application reduces the amount and thermal stability of the structural components of humic acids, thereby contributing to the degradation of the most stable part of macromolecule, which can lead to the loss of potential soil fertility. Тhe use of mineral fertilizers on sod-podzolic heavy loamy soil led to the enrichment of humic acids with aliphatic fragments, and of organic ones – increased the content of stable components of aromatic nature, but lowered their thermal stability. According to thermographic analysis the ratio of weight loss in the low-temperature zone and the weight loss in the high-temperature zone (Z) during long-term use of mineral fertilizers is 0.9, i. e. the proportion of components of aliphatic nature in the structure of humic acids increases in comparison with unfertilized or manure fertilized soil.

Cadmium fractionation in soils affected by organic matter application: Transfer of cadmium to cacao (Theobroma cacao L.) tissues

Elevated cadmium (Cd) concentrations in cacao (Theobroma cacao L.) beans have concerned chocolate consumers worldwide because of the potential detrimental human health effects. Compost application on the soil surface could modify the labile Cd in soils and yet it could enhance Cd bound to humic and fulvic acids, forming an organo-metallic complex that could reduce the availability of Cd to plants. This study investigated the effect of surface compost applications at two rates, the chemistry and fractionation of Cd at two soil depths, and the relationship of these soil Cd pools with plant uptake. The research was carried out on four Ecuadorian cacao farms. The compost was applied at 6.25 Mg·ha−1 (low) and 12.5 Mg·ha−1 (high) per annum. There was also a control treatment with no compost application. Soil samples were collected at two depths, surface (0–5 cm) and below surface (5–20 cm). Leaf samples and cacao pots were collected from each treatment. Soil Cd was fractionated into five operational pools. Additionally, the Cd-bound to fulvic acids and humic acids in soils were extracted separately. The EDTA-extractable fraction showed the highest concentration of Cd at both depths. Cadmium bound to fulvic acids was higher in compost-applied soils than in the control (p < 0.05) in all farms. Leaf and bean-Cd were negative and significantly correlated with the Cd extracted by EDTA, NaOH, HNO3, and FA-Cd pools. The mobility of Cd in soils cultivated with cacao, based on plant uptake, was strongly associated with the soils’ chemical characteristics, especially pH and SOC. The surface application of organic matter facilitates the redistribution of Cd in soil fractions, mainly in EDTA-, NaOH-, and HNO3-extractable fractions, suggesting a reduction in Cd soil–plant transfer via adsorption or complexation processes. Apparently, the application of high-quality compost, i.e., high FA content, could aid in mitigating Cd contamination in cacao orchards. Experiments on perennial crops merit a longer evaluation time to better assess the changes in plant-Cd.

Rapid, sensitive analysis method for determining the nitrogen stable isotope ratio of total free amino acids in soil.

The amino acid-nitrogen (AA-N) isotope analysis of naturally abundant or isotope-labeled samples is indispensable for tracing nitrogen transfer in soil nitrogen biogeochemical cycling processes. Despite the usefulness of AA-N isotope analysis, the preparation methods are complex and time-consuming, and necessitate the use of toxic reagents. We present an improved, rapid method for AA-N isotope analysis with high precision. At a high pH, AA-N was released and oxidized to N2 O using ClO- under vacuum. Additionally, purge-and-trap isotope ratio mass spectrometry was used to analyze N2 O. Moreover, we investigated the effect of various factors on the N2 O conversion process with glycine and applied the results to seven representative single-N AAs (alanine, serine, cysteine, aspartic acid, glutamic acid, leucine, and phenylalanine) and five poly-N AAs (lysine, arginine, histidine, tryptophan, and asparagine), as well as side-chain analogs, blank reagent, and other N forms. The concentration of ClO- and the pH were determined to be crucial factors for achieving desirable AA-N to N2 O conversion efficiencies. Glycine-N had the highest N2 O yield of 70%, with isotopic results consistent with those of the reference values at a high precision (within 0.5‰ for natural abundance and 0.01 atom% for 15 N-enrichment) at the nanomolar N level. Additionally, the α-NH2 AAs were labile, and the single-N AAs were more easily converted to N2 O than poly-N AAs. With the exception of γ-aminobutyric acid, the N2 O conversion efficiencies of the side-chain N analogs were very low (below 5%). This method was also applicable to the 15 N analysis of the total free AAs in complex soil samples without interference from analytical blanks and other forms of N. Our method is highly selective for the α-NH2 groups of an amino acid, and the oxidation of the side chain is difficult. In addition, the method is sensitive, rapid, and convenient, and does not require toxic reagents.

Optimizing Phosphorus Application Rate and the Mixed Inoculation of Arbuscular Mycorrhizal Fungi and Phosphate-Solubilizing Bacteria Can Improve the Phosphatase Activity and Organic Acid Content in Alfalfa Soil

Alfalfa (Medicago sativa L.) is an important legume forage, and phosphorus is a significant nutrient element of alfalfa with high quality and high yield. However, the effect mechanism of different phosphorus application rates on soil bacteria, and the phosphorus efficiency of alfalfa are still unclear. Therefore, we present the results of a study in which alfalfa was inoculated with Funneliformis mosseae, Bacillus megaterium, double inoculated with Funneliformis mosseae and Bacillus megaterium, and given no inoculation bacteria. P2O5 was applied under the condition of bacterial inoculation, and the contents were 0, 50, 100, and 150 mg kg−1, respectively, to explore the effect of bacterial inoculation on alkaline phosphatase, organic acid, pH, organic matter, and the relationship between the indicators in alfalfa soil, under different phosphorus application rates. The effect of mixed inoculation was significantly higher than that of the non-inoculated control group (p < 0.05). The organic matter content of rhizosphere soil was higher than that of non-rhizosphere soil. When the phosphorus application rate was 100 mg kg−1, the content of alkaline phosphatase in the soil inoculated with Funneliformis mosseae and Bacillus megaterium was better than that in the single inoculation, and no inoculation. Principal component analysis showed that the top three treatments were: double inoculation bacteria and treatment group with phosphorus application rate of 100 mg kg−1 >; double inoculation bacteria and treatment group with phosphorus application rate of 50 mg kg−1 >; double inoculation bacteria and treatment group with phosphorus application rate of 150 mg kg−1. In addition, when P2O5 was 100 mg kg−1, the addition of Funneliformis mosseae and Bacillus megaterium to alfalfa soil could increase the content of organic matter in the soil, promote the metabolism of alfalfa root exudates, and increase the organic acid of the rhizosphere soil, compared with the control without inoculation, and without phosphorus application. At the same time, the phosphatase activity in the soil had a significant positive correlation with malic acid, oxalic acid, acetic acid, total organic acid, and soil pH, thereby improving soil fertility and promoting phosphorus absorption by plants. These findings provide new insights into alfalfa root soils and the effects of Funneliformis mosseae and Bacillus megaterium additions on soil nutrients.

Screening and identification of harmful bacteria associated with the accumulation of cinnamic acid in Wuyi Rock tea soil

Screening and identification of harmful bacteria associated with the accumulation of cinnamic acid in Wuyi Rock tea soil

Method validation for arsenic speciation in contaminated soil by HPLC-ICP-MS coupling method

In this work, we have highlighted the importance of the HPLC-ICP-MS for speciation of inorganic and organic species in trace amounts. The study employs a chromatographic separation prior to analysis of arsenic species by ICP-MS as a detection technique. The chromatographic conditions are selected to achieve excellent separation of the four main arsenic species. Several validation parameters such as linearity, detection limit, quantification limit, precision, accuracy and recovery were studied under optimized HPLC-ICP-MS conditions.The limits of quantification for AsIII, dimethylarsinic acid DMA, Monomethylarsonic acid (MMA) and AsV in soils were 0.047, 0.082, 0.168 and 0.167 μg g−1 respectively. The recovery tests and analysis of certified reference material demonstrate the excellent performance, accuracy and precision of HPLC-ICP-MS method. The satisfactory results of speciation by HPLC-ICP-MS showed that the majority form of arsenic in soil extracts is arsenate, but there are also arsenite and traces of DMA. Arsenic-species in the five soil samples ranged from 17.9 to 67.52 μg g−1. A good correlation was obtained from the comparison study between the sum of the arsenic species concentration and the total Arsenic (tAs).

Evaluating the Distribution of Perfluoroalkyl Substances in Rice Paddy Lysimeter with an Andosol.

The properties of potential emerging persistent contaminants, perfluoroalkyl substances (PFAS), in an andosol rice paddy lysimeter were analyzed to determine their mobility and leaching behavior regarding carbon chain length and functional groups. For this purpose, simulated contaminated water (ΣPFAS = 1,185,719 ng/L) was used in the lysimeter. The results showed that PFAS distribution in the paddy soil lysimeter was influenced by the migration of these substances into irrigation water and their adsorption into the soil. PFHxS (C6) and PFOS (C8), which are the main components of the simulated contaminated water, were mostly captured in the soil layers of the low-humic andosol layer (0–35 cm). PFAS distribution may depend on soil properties, such as total carbon (TC) content. Compared with perfluoroalkane sulfonic acids (PFSAs), the distribution of perfluoroalkyl carboxylic acids (PFCAs) in soil showed significant variation. The remaining PFCAs were distributed across all layers of the lysimeter, except for the longer-chain PFCAs. Moreover, the PFSA distribution was directly correlated with the carbon chain number, whereby longer- and shorter-chain PFSAs accumulated in the top and bottom soil layers, respectively. This study provides detailed information on the distribution, leaching, uptake, and accumulation of individual PFAS in andosol paddy fields in Japan.

Glyphosate and aminomethyphosphonic (AMPA) contents in Brazilian field crops soils

Because of a lack of direct measurements, the presence and persistence of glyphosate and its main metabolite aminomethylphosphonic acid (AMPA) in agricultural soils of Brazil remains unknown. This paper aims at reporting glyphosate and AMPA contents in Brazilian field crop soils at the country scale from southern states to eastern Amazon. Brazilian field crop farmers are among the highest users of glyphosate-based herbicides (GBH) in the world. Soybean and corn field crop soils from 17 sites were collected at two depths (i.e. 0-20 cm and 20-40 cm) in 2016 and 2018. The study area encompasses three regions of Brazil: southern Brazil, central-west Brazil and eastern Amazon, all having in common intensive, conventional, large-scale grain farming. ßGlyphosate and AMPA contents were measured using a GC-ECD following soil extraction. Both chemicals were ubiquitously detected in soils cultivated under various agricultural practices ranging from ploughing to no-till ones. Average measured glyphosate and AMPA contents were 0.08 ± 0.09 µg/g and 0.17 ± 0.16 µg/g respectively with maximum values of 0.57 µg/g and 0.98 µg/g. Glyphosate plus AMPA contents in the top 40 cm of soils presented cumulated amounts exceeding the annual glyphosate inputs via GBH. This is interpreted as a multiannual persistence of these chemicals in Brazilian agricultural soils. Downward migration of glyphosate and AMPA is also suspected with regard to the vertical distribution of these chemicals along with deeper soil horizons. This study highlights the backlash of conservation agriculture as far as glyphosate and AMPA presence in agricultural soils are concerned. These compounds persistence in Brazilian soils appear to be longer than what is usually reported in the literature, especially so for tropical environments. The worldwide concern about the ubiquitous presence of glyphosate and AMPA in the environment needs a broader screening in Brazilian field crop soils since the majority of the available data comes from Argentina, Europe and to a lesser extent North America.

Enhancement of humic acid on plant growth in a Cd-contaminated matrix: performance, kinetics, and mechanism.

Phytoremediation of heavy metal-contaminated sites has been widely used. Nonetheless, the destruction of chloroplasts and plant growth enzymes by heavy metals leads to a low germination rate and high mortality of plants. To address these issues, an experiment was conducted in which plants were grown with (SHC) and without humic acid (SC) in actual Cd-contaminated soil from the site of an industrial pollution source. The results showed that the average germination rates of SC and SHC samples were 94.17% and 98.33%, respectively, and the plant heights were approximately 5 and 7cm after 42days of planting, respectively. It was discovered that humic acid (HA) enhanced plant growth by increasing urease and invertase content of the soil. The Shannon index and Venn diagram revealed that SHC had the richer population diversity. High-throughput analysis demonstrated that HA increased the content of plant growth-promoting bacteria in the soil from 5.01 to 34.27%. The experimental results revealed that HA increased microbial activity and diversity, thereby providing a favorable environment for plants to thrive. This study develops an effective method to enhance the phytoremediation performance of heavy metal-contaminated soils.

Chemical fumigants control apple replant disease: Microbial community structure-mediated inhibition of Fusarium and degradation of phenolic acids

Fusarium and phenolic acids in apple replant soil have deleterious effects on soil, which affects the growth of young replanted apple trees. Here, we studied the effects of different chemical fumigants (metham sodium, dazomet, calcium cyanamide, 1,3-dichloropropene, and methyl bromide) on Fusarium and phenolic acids in soil. The chemical fumigants disturbed the apple replant soil microbial community to different degrees in the order from highest to the lowest as methyl bromide > 1,3-dichloropropene > dazomet > metham sodium > calcium cyanamide. Compared with the control, the total numbers of Operational Taxonomic Unit (OTU) were 104.63 % and 9.38 % lower in the methyl bromide and calcium cyanamide treatments, respectively while the average contents of Fusarium were 88.04 % and 59.18% lower in these treatments, respectively. Higher disturbance degrees resulted in a slower recovery rate of the soil microbial community, which facilitated the transformation of the soil into a disease-suppressing state. During the recovery process, the roots recruited Streptomyces OTU2796 and Bacillus OTU2243, which alleviated Fusarium-induced stress via the synthesis of polyketones and macrolides. The roots also recruited Sphingomonas OTU3488, OTU5572, and OTU8147, which alleviated phenolic acid-induced stress through the degradation of benzoate and polycyclic aromatic hydrocarbons.

Comparison of Ion Chromatography Conductivity Detection (IC-CD) and Ion Chromatography Inductively Coupled Plasma Mass Spectrometry (IC-ICP-MS) for the Determination of Phosphonic Acid in Grapevine Plant Parts, Wine, and Soil.

Potassium dihydrogen phosphonate had been allowed as a plant strengthener in organic viticulture in the European Union only until 2013, supporting the control of grapevine downy mildew. Therefore, low or nondetectable levels are a prerequisite for marketing of organic wines and, consequently, validated analytical methods are of major interest. Herein, two methods based on ion chromatography conductivity detection (IC-CD) or ion chromatography inductively coupled plasma mass spectrometry (IC-ICP-MS) for the determination of phosphonic acid (H3PO3) from 14 different plant matrices of Vitis vinifera L., wine, and soil were developed, validated, and compared. Extraction recoveries ranged from 95.1 to 99.3%. Limits of quantification (LOQ) ranged in liquid and solid samples from 3.8 to 16.8 μg/kg and 0.08 to 2.41 mg/kg for ICP-MS detection and from 39.9 to 593.7 μg/kg and 3.51 to 58.7 mg/kg for CD, respectively. Data on a current anonymized selection of 100 conventionally and 30 organically produced wines are briefly presented to demonstrate the suitability of the method.

Retrieval of trivalent chromium by converting it to its dichromate state from soil using a bipolar membrane electrodialysis system combined with H2O2 oxidation

When a bipolar membrane electrodialysis (BMED) system is used to remove Cr(III) from the soil, the existing metal cations easily affect this removal owing to the migration competition of metal cations. To address this problem, herein, a BMED system combined with H2O2 oxidation was used to recover Cr(III) from soil in the form of Na2CrO4. The experimental results show that H2O2 can oxidise Cr(III) to Cr(VI), which can be recovered as Na2CrO4. The concentrations of electrolyte and humic acid in soil, current densities and addition time of H2O2 influenced Cr(III) recovery, current efficiency and specific energy consumption. Under optimal experimental conditions of a current density of 2 mA/cm2 and H2O2 addition time of 2 h after the BMED system was powered on, more than 69 % of Cr(III) could be recovered. When the number of equipped soil compartments increased from one to two and then to three, the current efficiency increased from 9.9 % to 19.8 % and then to 29.1 % and the specific energy consumption of chromium removal decreased from 7.04 × 10−2 to 5.51 × 10−2 and then to 4.72 × 10−2 kW∙h/g, respectively. When the BMED system was used to recover Cr(III) from actual soil, the recovery rate decreased to 55.9 % owing to the low Cr(III) oxidation rate resulting from more residual state Cr(III) being present in actual soil. Following treatment, the remaining Cr(VI) in soil can be reduced to Cr(III) by adding a reductant. Therefore, the BMED system combined with H2O2 oxidation can be regarded as an effective method for recovering Cr(III) from soil.

Irrigation water salinity structures the bacterial communities of date palm (Phoenix dactylifera)-associated bulk soil.

The irrigation of date palms (Phoenix dactylifera) with saline groundwater is routinely practiced in the agroecosystems of arid environments because of freshwater scarcity. This leads to salts deposition in topsoil layers and increases soil salinization. However, how different irrigation sources affect soil microbiota is poorly understood. Bulk soil samples were collected from date farms receiving non-saline water and saline groundwater to examine bacterial communities using metabarcoding. Overall, bacterial diversity measures (Shannon diversity index, richness, and evenness) did not vary between irrigation sources. Bacterial communities were structured based on irrigation water sources and were significantly associated with their electrical conductivity. Of 5,155 operational taxonomic units (OTUs), 21.3% were unique to soil irrigated with saline groundwater, 31.5% received non-saline water irrigation, and 47.2% were shared. The Proteobacteria abundance was higher in soil under saline groundwater irrigation while Actinobacteriota abundance was lower. A compositional shift at the genera level was also evident; the abundance of Subgroup_10 and Mycobacterium was higher under saline groundwater irrigation. Mycobacterium was a key indicator of OTU under saline groundwater irrigation while Solirubrobacter was an indicator of non-saline water irrigation. Functional gene analyses showed enrichment of fatty acid, cell wall, and starch biosynthesis pathways in soil under saline groundwater irrigation. These findings provide insights into how “salinity filtering” influences bacterial communities, key taxa, and the potential metabolic function in soil under increasing irrigation water salinities, and have broad implications for arid agroecosystems.