Phosphate Fertilizer Research Articles

Composite hydrogels fabricated from konjac glucomannan and gellan gum: Rheological characterization and their potential application in sustainable agriculture

In this study, konjac glucomannan (KG) was incorporated in high acyl gellan (HAG) and low acyl gellan (LAG) hydrogels in different ratios. The addition of KG increased pseudoplasticity and thermal hysteresis values of the hydrogels. Improvement in elasticity and water holding capacity (WHC) was observed in KG-LAG hydrogels. The highest WHC (98.5 %) was observed for 1K1H (KG:HAG = 1:1) and 3K7L (KG:LAG = 3:7) hydrogels. The crystallinity of the composite hydrogels was lower than hydrogels prepared from individual biopolymers. The hydrogels exhibited a rough surface with minute pores in the cross-section, due to the aggregation of glucomannan on the gellan network in the composite hydrogels. While HAG and 1K1H hydrogels exhibited greater swelling at low pH (3.0), LAG and 3K7L exhibited greater swelling at high pH (11.0). At pH 7.0, the hydrogels exhibited swelling indices >300 %. Incorporation of 1K1H hydrogel at 10 % (w/w) in sandy loamy soil under semi-arid conditions increased the germination of fenugreek microgreens from 60 % to 80 % on the 15th day. Furthermore, the moisture evaporation rate of the soil reduced from 35 % to <15 %, positively impacting the physicochemical properties of the microgreens. The composite hydrogels were successful in achieving a controlled release of phosphate fertilizer.

Glyphosate residues in soil and phosphate fertilizer affect foliar endophytic microbial community composition and phytohormone levels in potato

Glyphosate, the active ingredient of glyphosate-based herbicide (GBH) controls the growth of weeds by inhibiting shikimate pathway, thereby interrupting amino acid biosynthesis in plants. However, several microbes have shikimate pathway and the action of glyphosate on these non-target organisms are ignored. Along with other agrochemicals such as phosphate fertilizers, the action of GBH is further complicated, often varying their mode of action depending on soil type or plant species. To address the impact of GBH and phosphate fertilizer, we simulated agricultural application of GBH and phosphate fertilizer in a field study, investigating the composition of endophytic microbial communities and correlation of phytohormone concentrations with the microbial diversity of potato (Solanum tuberosum). In leaves, glyphosate residues in soil from GBH treatment alone and in combination with phosphate significantly shifted bacterial community whereas phosphate alone and in combination with glyphosate significantly altered the composition of fungal community. There were no significant changes in microbial communities in roots and tubers. Plants treated with GBH showed higher ratios of potentially glyphosate-resistant bacteria, with Xanthomonadaceae and Moraxallaceae being more abundant. Additionally, phytohormone concentrations showed various correlations with bacterial and fungal diversity in different treatments. The study highlights the impact of GBH residues in soil, particularly in combination with phosphate fertilizers on the composition of plant-associated microbial communities. Together with changes in phytohormone concentrations, plant health may be affected. Moreover, future studies could provide insights to whether these agrochemicals influence plant microbiome, leading to changes in phytohormones or vice-versa.

Adubação fosfatada, biofertilizante e Bacillus sp. no cultivo de amendoim sob estresse salino

ABSTRACT Peanut (Arachis hypogaea) is an important agricultural crop in Brazil, considered one of the most important oilseed crops cultivated. The use of fertilizer-solubilizing bacteria can mitigate salt stress. The objective of this study was to evaluate the gas exchange, growth, and water use efficiency of the peanut crop irrigated with brackish water under phosphate fertilization and inoculated with bacteria of the genus Bacillus sp. The experimental design used in this study was completely randomized, in a 4 × 2 × 2 factorial scheme, with 5 replicates, referring to the forms of fertilization (F1 - 0% phosphorus, F2 - 50% phosphorus, F3 - 100% phosphorus, and F4 - bovine biofertilizer), presence and absence of the inoculant and two levels of electrical conductivity of the irrigation water (ECw - 0.3 and 4.0 dS m-1). Fertilization with organic fertilizer (100% biofertilizer) and mineral fertilizer (50 and 100% phosphorus) associated with Bacillus sp. mitigated the damage caused by salt stress and promoted greater water use efficiency, chlorophyll index, internal CO2 concentration and stem diameter. The control treatment (without phosphate fertilization and without salt stress) and the application of Bacillus sp. promoted greater performance in net photosynthesis, transpiration rate, stomatal conductance, and plant height in peanut plants.

Response Two Cultivars of Chickpea (Cicer arietinum L) to Phosphate Fertilization Level and Bacterial Inoculum

The research was conducted during season 2020 in Al-Shallalat area, 5 km northeast of Mosul. The study included three factors, namely, the treatment of seed soaking with water and the bacterial inoculum, two local cultivars of chickpea: large seeds (Kabuli) and small seeds (Desi) and three levels of phosphate fertilization (zero, 50 kg, and 100 kg P2O5. h-1). The study was conducted according to the factorial experiment system, in (R. C. B. D) design. In three replication, some traits of plant are obtained such as: plant height (cm), the height of the first pod above the ground (cm), pod length (cm), number of seeds/ pod, number of pods/plant (total), number of pods/plant (full) number of pods cleavage (empty), percentage of yield, the weight of 100 seeds (g), biological yield (g/plant), Seed yield (g/plant) and harvest index. The results indicate a significantly excelled of the treatment of soaking with bacteria inoculum on the treatment of soaking with water for all the studied traits. And highly significantly excelled in most of the studied traits of Kabuli over Desi cultivar. Most of the binary and triple interactions recorded a significant difference between the bacterial inoculum and the seeds of the Kabuli cultivar.

Effect of BioNiK-Phos and Phosphorus-based fertilizers on yield of hybrid sunflower in Northern Uganda

The sunflower oil seed industry is one of the promising business sectors in Uganda for both domestic and export markets. Both open-pollinated varieties and hybrids are grown in Uganda. Average yields of open-pollinated varieties in farmers’ fields range from about 750-900 kg ha-1 and hybrids about 2,000 kg/ha. For high production and productivity, sunflower requires fertilizers. The objective of this study was to establish the effects of BioNik-Phos and di-ammonium phosphate (DAP) fertilizers micro-dosing on yield of sunflower hybrid (PAN 5057) in Northern Uganda in 2021b and 2022a seasons. Field experiments were laid using a randomized complete block design (RCBD) with 4 replications per location in 3 locations in Alebtong District (Abako, Aloi and Angeta). There were significant (P &lt; 0.05) differences in sunflower yields across treatments in all the three locations (Abako: 1,250-3,524 kg ha-1, Aloi: 1,274-3,488 kg ha-1 and Angeta: 1,238-3,369 kg ha-1) in 2021 with or without micro-dosing with BioNiK-Phos and DAP fertilizer. A similar trend was recorded for 2022a season (Abako: 1,268-3,500 kg ha-1, Aloi: 1,357-3,607 kg ha-1 and Angeta: 1,286-3,417 kg ha-1). The effect of DAP fertilizer micro-dosing on sunflower hybrid productivity was three folds in both years. BioNiK-Phos effect was, however, not significantly different (P &lt; 0.05) from the control. This is the first report of the effect of BioNiK-Phos and DAP fertilizers micro-dosing of sunflower in Northern Uganda.

Utilization of phosphogypsum and red mud in alfalfa cultivation

In this work, the utilization of phosphogypsum (PG), a waste coming from the manufacture of phosphate fertilizers, as fertilizer for alfalfa (Medicago sativa L.) crops was investigated using pot experiments. The objective of this study was to evaluate the effects of both phosphogypsum and red mud (RM) in two soils representative of the pasture production area in Southern Spain. The morpho-physiological parameters of biomass, plant height, number of stems and number of leaves, as well as the chemical parameters of soil content, were measured. High doses of PG inhibited seed germination in some treatments. In addition, the treatment substrate (2550 g soil + 50 g kg−1 PG + 100 g kg−1 RM) also affected seed germination, possibly due to the large amount of RM. The application of PG and RM to the soil increased the availability of important nutrients for alfalfa, such as phosphorus (P), calcium (Ca2+) and magnesium (Mg2+). The results demonstrate that the treatment with PG significantly improved the uptake of P in alfalfa.

Purification process and mechanism analysis of low-concentration phosphorus wastewater with novel electrodeposition - biochar filter bed

Phosphate‑phosphorus (PO43−-P) is a non-renewable resource. Rapid agricultural activities and inefficient use of phosphate fertilizers contribute to the contamination of natural water resources due to PO43−-P accumulation. PO43−-P recovery in natural water with a low PO43−-P concentration, is conducive to the sustainable utilization of phosphate. Electrodeposition using Ca2+ to recover PO43−-P in natural water has great potential. However, the limitations of low-concentration PO43−-P recovery need to be addressed. This study designed a novel electrodeposition-biochar filter bed (E-BFB) to investigate the removal and recovery ability of PO43−-P at low concentrations. Efficient removal and recovery of PO43−-P was achieved through electrodeposition, biochar adsorption, and accumulation by microorganisms. Effects of different parameters on the performance of E-BFB for PO43−-P removal were studied, including influent PO43−-P concentration, voltage, and electrode spacing. Results showed that 69.4 % PO43−-P was removed when the influent PO43−-P concentration was 0.8 mg/L by E-BFB, as the average removal rate in the biochar filter bed (BFB) was only 11 %. The PO43−-P recovery rate of cathodic electrodeposition was as high as 37.22 %, accounting for 57 % of the total PO43−-P removal amount. The PO43−-P electrodeposition precipitate mainly was amorphous calcium phosphate (ACP) through analysis. 16S rRNA results demonstrated that electrodeposition altered the microbial communities. At the genus level, such as Acinetobacter (26.6 %), Acidocella (11.7 %), and Pelomonas (7.2 %) were promoted in the biochar substrate of E-BFB. Overall, this novel E-BFB can remove PO43−-P at low concentrations effectively. It has great application prospects in the treatment of surface water by biofilters or constructed wetlands.

Glutamic Acid-Enhanced Phosphate Fertilizer Increases Phosphorus Availability in Fluvo-Aquic Soil via Phosphamide (O = P-N) Formation, Decreasing Phosphate Fixation and Increasing Soil Microbial Diversity

Glutamic Acid-Enhanced Phosphate Fertilizer Increases Phosphorus Availability in Fluvo-Aquic Soil via Phosphamide (O = P-N) Formation, Decreasing Phosphate Fixation and Increasing Soil Microbial Diversity

Lespedeza potaninii Vass seed yield response to plant density and phosphate fertilization in Northwest China

Lespedeza potaninii Vass is a highly drought-resistant China native legume plant, which plays an important role in animal husbandry and ecological restoration. However, there are few reports on the agricultural practices of its seed production. We evaluated the effect of four plant densities (33,333, 44,444, 66,666, and 133,333 plants ha−1) and five phosphate fertilizer rates (0, 45, 90, 135, and 180 kg ha−1) on seed yield, seed yield components and agronomic traits from the year 2020–2022. Correlation and structural equation model (SEM) analyses were used to determine the contribution of yield components to seed yield per plant. Year, plant density, phosphorus fertilizer rate and their interaction (P<0.05) significantly influenced the seed yield of L. potaninii Vass. The maximum average seed yield over 3 years (570 kg ha−1) occurred at the plant density of 44,444 plants ha−1 and phosphate fertilizer rate of 90 kg/ha. All the yield components, except 1000-seed weight, were significantly correlated with seed yield per plant. The racemes per stem, florets per raceme and pods per raceme had significant positive correlation, and stems per square meter and biomass had significant negative correlation with seed yield per plant. Increasing phosphorus fertilizer increased seed yield per plant. However, increasing plant density decreased seed yield per plant. Our findings enable further understanding of the mechanism of seed yield response to plant density and phosphorus fertilization in L. potaninii Vass and provide a reference for appropriate agronomic measures to improve seed yield of L. potaninii Vass and similar shrubs.

Poly(ε-caprolactone)-grafted-chitosan copolymers: Synthesis and use as tunable and biodegradable coating for water soluble fertilizers

The urgent need for efficient agriculture to increase crop and food has fueled the development of coated fertilizers with a slow-release kinetics, water economy and full degradability to avoid negative environmental impact. In this context, we herein report the synthesis of poly(ε-caprolactone) (PCL) grafted from chitosan (CS) as a new class of biodegradable coating materials. The CS-g-PCL were prepared following a one-pot, two-step strategy, in which the primary amines of CS first react with ε-caprolactone (CL) to form CL-oligomers linked to CS via amide bonds terminated with hydroxyls, which together with the native hydroxyls of CS initiate the ring-opening polymerization of CL after addition of Sn(C ≡ CPh)4 as catalyst. Owing to the great stability of the used catalyst, the high molar mass of PCL grafted onto CS was successfully obtained under trivial open-air conditions. Different copolymers (CS-g-PCL) were prepared by varying the CS content. The structural characterization of CS-g-PCL was carried out using FTIR, 1H NMR, X-ray diffraction, contact angle and size exclusion chromatography (SEC) while the thermal and mechanical characterization of the prepared CS-g-PCL were compared to the neat PCL. Next, using a laboratory rotary drum, CS-g-PCL was implemented to uniformly coat granular diammonium phosphate fertilizer (DAP). Consequently, the kinetic releases of nitrogen and phosphorus were significantly delayed compared to that observed from uncoated DAP (conventional fertilizers). Finally, the degradation of CS-g-PCL was examined under aerobic conditions and showed a significant increase in their biodegradability with respect to neat PCL.

The Use of Magnesium Fertilizer Can Improve the Nutrient Uptake, Yield, and Quality of Rice in Liaoning Province

In this study, the effects of the soil application and foliar spraying with magnesium fertilizers on rice yield and quality in Liaoning Province were investigated. Field experiments were conducted at Kaiyuan, Xinmin, and Dawa in 2022 and 2023. Magnesium fertilizers were used in the soil as magnesium sulfate monohydrate and silicon–magnesium fertilizer and on leaves was magnesium sulfate heptahydrate. The results showed that the application of 12 kg magnesium hm−2 in the soil at the Kaiyuan site can significantly increase rice yield by 14.8% compared with sites without magnesium fertilizer. The use of silicon–magnesium fertilizer showed a more obvious yield increase of 22.2%. The application of 3 kg magnesium hm−2 or 6 kg magnesium hm−2 on the leaf surface increased the rice yield at Kaiyuan by 19.4% and 21.6% and at Xinmin by 17.8% and 5.4%, respectively. The yield increase was more significant under the optimal fertilization treatment compared with the conventional fertilization treatment. The application of magnesium fertilizer increased the magnesium, nitrogen, and phosphorus contents in rice shoots and the potassium and crude protein contents in rice grains. The effect of foliar spraying with magnesium fertilizers was more obvious than soil application. Therefore, the magnesium fertilizer used on the leaf surface plays an important role in improving rice yield and quality in rice-growing areas with relatively rich soil magnesium content. Magnesium fertilizer can compensate for the yield decrease caused by the reduced use of nitrogen and phosphorus fertilizers by promoting nitrogen and phosphorus absorption in rice. Conclusively, the application of magnesium fertilizer is a promising measure to improve rice production in Liaoning province under a reduced nitrogen and phosphate fertilizer background.

The Enzyme Activity of Dual-Domain β-Propeller Alkaline Phytase as a Potential Factor in Improving Soil Phosphorus Fertility and Triticum aestivum Growth

The widespread use of non-renewable phosphate fertilizers in agriculture poses a significant pollution threat to soil, necessitating the exploration of sustainable alternatives for phosphate fertility. Releasing phytate phosphorus through microbial phytases presents an eco-friendly solution for sustainable phosphate fertility in agriculture. This study directly inoculated dual-domain β-propeller alkaline phytase (phyHT) derived from Bacillus sp. HJB17 into the soil. The study analyzed the impact of inoculated phyHT on the physicochemical properties of the soil, assessed the variations in enzyme activity of phyHT within the soil, and examined the effects of the treated soil on wheat growth. Additionally, the study explored the enhancement of the available phosphorus in the soil through the inoculation of phyHT in both crop residues and organic fertilizer. PhyHT exhibited the highest catalytic activity at 37 °C and pH 8.0. After soil adsorption, phyHT maintained stable enzymatic activity. PhyHT markedly boosted the available phosphorus in the soil while reducing the soil phytate content by about 20%, increasing the phosphorus levels and enhancing soil fertility. PhyHT effectively degraded phytates in an organic fertilizer and crop residues, increasing the available phosphorus. PhyHT supplementation enhanced growth, biomass, and phosphorus content in both the shoot and root weights of Triticum aestivum. This study establishes phyHT as a viable and eco-friendly method to enhance phosphorus fertility in soil. The direct application of microbial phytases can serve as a sustainable source of phosphate fertility in soil.

Low-cost eggshell-fly ash adsorbent for phosphate recovery: A potential slow-release phosphate fertilizer

Fly ash (FA) and eggshells (ES) are common solid wastes with significant potential for the recovery of phosphorus from water. This study focuses on synthesizing a low-cost and environmental-friendly phosphate adsorbent called eggshell-fly ash geopolymer composite (EFG) using eggshells instead of chemicals. The CaO obtained from the high-temperature pyrolysis of eggshells provides active sites for phosphate adsorption, and CO2 serves as a pore-forming agent. The phosphate adsorption performance of EFG varied with the eggshell-fly ash ratios and achieved a maximum of 49.92 mg P/g at an eggshell-fly ash ratio of 40 %. The adsorption process was well described by the pseudo-second-order model and the Langmuir model. EFG also exhibited a good regeneration performance through six-cycle experiments and achieved the highest phosphate desorption at pH 4.0. The results of the column experiment showed that EFG can be used as a filter media for phosphorus removal in a real-scale application with low cost. Soil burial test indicated saturated EFG has a good phosphate slow-release performance (maintained for up to 60 days). Overall, EFG has demonstrated to be a promising adsorbent for phosphorus recovery.

Closed-loop purification process of industrial phosphoric acid: Selective recovery of heavy metals and rare earth elements via solvent extraction

Phosphate fertilizers are produced using phosphoric acid as a vital chemical component. This essential ingredient is typically derived from phosphate rock, through a wet process phosphoric acid (WPPA). However, the WPPA contains impurities, including heavy metals (HMs) like cadmium (Cd), zinc (Zn) and copper (Cu), as well as unwanted elements like iron, and other valuables elements, notably rare earth elements (REEs) such as yttrium (Y), holmium (Ho) and ytterbium (Yb). The current study aims to develop a novel process for a simultaneous and selective recovery of HMs and REEs through solvent extraction from WPPA. Single-stage extraction, cascade extraction and synergistic extraction were explored to gain a deeper understanding of the mechanisms and identify the most efficient process. 90, 80 and 99 % for Y, Ho and Yb, respectively, were extracted using D2EHPA. While 89 % for Zn, 99 % for Cu and Cd were removed using Cyanex 301. On the other hand, 60 % of Yb, 74 % of Y and 78 % of Ho were stripped using H2SO4, while 98 % of Cd and 99 % of Zn were stripped using HCl. The organic phase can be successfully reused with an effective extraction and stripping. Oxalic acid (C2H2O4) was employed to precipitate REEs. However, sodium carbonate (Na2CO3) was used to precipitate HMs. Finally, solvent extraction was carried out on WPPA solution to ensure the extraction performance under industrial conditions.

Lignin-rich extracts as slow-release coating for phosphorus fertilizers

Lignin (L) is the most abundant three-dimensional polymer with versatile yet attractive structural features and chemical properties for applicability as a coating. The properties of lignin are mainly related to its botanical origin, structure and extraction method. Although there has been a lot of interest in using lignin in fertilizing systems, only limited attempts have been dedicated to studying the effect of the lignin structure and origin on the release of P fertilizer. Thus, the aim of this work was to study the effect of lignin polymers, extracted from different plant biomass, as coating materials for P fertilizers. Thus, the effect of the structural features originating from the botanical origin on the properties of coated fertilizers and their slow release were established. To this end, three lignocellulosic biomass, namely olive pomace (OP), barley straw (BS) and wood shavings (WS) were used as feedstock to extract lignin polymers. Those chemical compositions and thermochemical properties were characterized prior to their application as coating for triple super phosphate (TSP) fertilizer. Coated fertilizers were characterized for their morphology and coating thickness prior to their evaluation as slow release P-based fertilizer. A distinct slow P release behavior was reported for lignin-coated fertilizers with TSP@L-OP being the slowest as compared to TSP@L-WS, TSP@L-BS as well as pristine TSP, which confirm that the botanical origin and most likely the chemical structures of lignin has significant impact on the properties of the coating materiel. A 100 % release of P from the uncoated TSP was observed after 3 days, while the released amount ranged from only 16.9 % for TSP@L-OP up to 33.4 % for TSP@L-BS. The impact of these coated fertilizers on nutrients uptake and wheat growth was also scrutinized and an noticeable improvement of wheat shoot biomass was observed with the coated TSP treatments reaching up 57.8 % for TSP@BS, 78.1 % for TSP @WS and 93.7 % for TSP @OP, compared to uncoated TSP. This was concomitant to a slight increase of P concentration in shoots, roots and rhizosphere soil, which confirmed the positive effect of slow release P fertilizers on plant growth.

Applications of humic and fulvic acid under saline soil conditions to improve growth and yield in barley.

Enriching the soil with organic matter such as humic and fulvic acid to increase its content available nutrients, improves the chemical properties of the soil and increases plant growth as well as grain yield. In this study, we conducted a field experiment using humic acid (HA), fulvic acid (FA) and recommended dose (RDP) of phosphorus fertilizer to treat Hordeum vulgare seedling, in which four concentrations from HA, FA and RDP (0.0 %, 50 %, 75 % and 100%) under saline soil conditions . Moreover, some agronomic traits (e.g. grain yield, straw yield, spikes weight, plant height, spike length and spike weight) in barley seedling after treated with different concentrations from HA, FA and RDP were determined. As such the beneficial effects of these combinations to improve plant growth, N, P, and K uptake, grain yield, and its components under salinity stress were assessed. The findings showed that the treatments HA + 100% RDP (T1), HA + 75% RDP (T2), FA + 100% RDP (T5), HA + 50% RDP (T3), and FA + 75% RDP (T6), improved number of spikes/plant, 1000-grain weight, grain yield/ha, harvest index, the amount of uptake of nitrogen (N), phosphorous (P) and potassium (K) in straw and grain. The increase for grain yield over the control was 64.69, 56.77, 49.83, 49.17, and 44.22% in the first season, and 64.08, 56.63, 49.19, 48.87, and 43.69% in the second season,. Meanwhile, the increase for grain yield when compared to the recommended dose was 22.30, 16.42, 11.27, 10.78, and 7.11% in the first season, and 22.17, 16.63, 11.08, 10.84, and 6.99% in the second season. Therefore, under salinity conditions the best results were obtained when, in addition to phosphate fertilizer, the soil was treated with humic acid or foliar application the plants with fulvic acid under one of the following treatments: HA + 100% RDP (T1), HA + 75% RDP (T2), FA + 100% RDP (T5), HA + 50% RDP (T3), and FA + 75% RDP (T6). The result of the use of organic amendments was an increase in the tolerance of barley plant to salinity stress, which was evident from the improvement in the different traits that occurred after the treatment using treatments that included organic amendments (humic acid or fulvic acid).

Effect of various phosphorus levels on the extraction of Cd, the transformation of P, and phosphorus-related gene during the phytoremediation of Cd contaminated soil

Phytoremediation has emerged as a common technique for remediating Cd pollution in farmland soil. Moreover, phosphorus, an essential element for plants, can alter the pectin content of plant cell walls and facilitate the accumulation of Cd in plant tissues, thereby enhancing phytoremediation efficiency. Therefore, pot experiments were conducted in order to investigate the effect of phosphorus levels on Cd extraction, phosphorus transformation and phosphorus-related genes during phytoremediation. The results revealed that an optimal application of suitable phosphate fertilizers elevated the soil's pH and electrical conductivity (EC), facilitated the conversion of soil from insoluble phosphorus into available forms, augmented the release of pertinent enzyme activity, and induced the expression of phosphorus cycling-related genes. These enhancements in soil conditions significantly promoted the growth of ryegrass. When applying phosphorus at a rate of 600 mg/kg, ryegrass exhibited plant height, dry weight, and chlorophyll relative content that were 1.27, 1.26, and 1.18 times higher than those in the control group (P0), while the Cd content was 1.12 times greater than that of P0. The potentially toxic elements decline ratio and bioconcentration factor were 42.86% and 1.17 times higher than those of P0, respectively. Consequently, ryegrass demonstrated the highest Cd removal efficiency under these conditions. Results from redundancy analysis (RDA) revealed a significant correlation among pH, total phosphorus, heavy metal content, phosphorus forms, soil enzyme activity, and phosphorus-related genes. In conclusion, this study suggests applying an optimal amount of suitable phosphate fertilizers can enhance restoration efficiency, leading to a reduction in soil Cd content and ultimately improving the safety of crop production in farmlands.

Geospatial analysis of groundwater arsenic and fluoride in Quaternary aquifers of southern Ontario, Canada

The geological setting of an area plays a critical role in the transfer and ultimate distribution of hydrochemical constituents present in groundwater. In southern Ontario, Canada, the present physiography was significantly influenced by glacial processes during the Quaternary period. The heterogeneous nature and complex pattern of shallow subsurface glacial overburden sediments, likely affect the fate of different groundwater constituents. In this study, arsenic (As) and fluoride (F−) concentrations from 515 water wells, that are constructed within overburden sediment, were analyzed with the physiographic map of southern Ontario along with other related variables. Geospatial mapping and several spatial statistical analyses were performed to examine the possible geological influence on As and F− distribution and water-well susceptibility at a regional scale. Key findings suggest four physiographic settings were significant variables influencing the distribution of As and F− in differently constructed bored/dug and drilled wells. Bored/dug wells in Bevelled Till Plains and bored/dug wells in Undrumlinized and Bevelled Till Plains were found to be relatively susceptible to As and F− contamination respectively. In contrast, bored/dug and drilled wells in Drumlinized Till Plains and Drumlins and drilled wells in Sand Plains seemed to be relatively safe from F− and As respectively. The statistical regression analyses suggested that other variables, such as the application of phosphate fertilizer and the textures of till, influenced the spatial distribution of As and F− as well as which types of wells (bored/dug or drilled) were impacted. The geospatial mapping and statistical cluster analysis indicated that the possible sources of elevated As and F− in drilled wells are the clasts of underlying bedrock. The relationship between physiographic settings and impacted overburden wells in southern Ontario provides planners with an approach to water-well susceptibility assessments at the regional scale, which in turn can guide further local analysis for water resource management.

The impact of phosphate fertilizer factory on the chemical and radiological pollution of the surrounding marine area (seawater and sediments) in northwestern Greece

Phosphogypsum, a waste of phosphate fertilizers production, contains heavy metals and especially radionuclides as 238U, 226Ra and 232Th. It is usually deposited in stacks close to coastal zones and the leachates with seawater result in chemical and radiological pollution. In this work the pollution in the coastal environment surrounding a phosphate fertilizer factory in northwestern Greece was investigated by measuring the activity of radionuclides (238U, 226Ra and 232Th) and the concentrations of heavy metals (Pb, Zn, Cu, Ni, Cd and As) in seawater and sediments samples. The measurements were performed by nuclear spectrometry and chemical techniques in two seasons and radiation risks were estimated, by determination of indexes asRaeq, Hin, Hex and Iγ as well as absorbed dose rate D. The values were in the range of worldwide indicating low hazard. Moreover, several environmental indicators (HPI, MPI, CF, Cd and EF) were applied to evaluate the water and sediment quality for heavy metal contamination and the average concentrations of the investigated heavy metals, showed that there is no danger for humans.

Evaluation of soil quality following phosphate fertilization on leguminous crops in the Mitidja region, Algeria

Evaluation of soil quality following phosphate fertilization on leguminous crops in the Mitidja region, Algeria