Yona Chen

Phosphorus (P) nanoparticles (NPs) have been proposed as a promising alternative to conventional water‐soluble inorganic P (WSP) fertilizers, based on the hypothesized advantages of higher mobility and bioavailability in soils. However, systematic quantification of the mobility and bioavailability of P NPs in soils remains lacking. The transport (saturated and unsaturated), diffusion, and plant response of spherical polyacrylic acid‐coated nano‐hydroxyapatite (PAA‐nHAP) and WSP were evaluated in two low‐P soils: an alkaline sand (Alk) and an acidic sandy clay loam (Ac), targeting scenarios where P is surface‐applied without incorporation into the root zone. After systematically comparing 36 one‐site or two‐site kinetic models in HYDRUS‐1D, a model selection process was established for the first time. The results showed that two‐site kinetic models can capture the transport pattern, with distinct retention mechanisms across soils: reversible and time‐dependent at both sites for the Alk soil; reversible and depth‐dependent at one site and irreversible and time‐dependent at the other for the Ac soil. Because of the air‐water‐solid or air‐water interface, greater retention of the PAA‐nHAP was observed in the unsaturated transport than in the saturated transport. The diffusion capacity of the PAA‐nHAP was lower than that of the WSP in both soils, primarily due to NPs aggregation. Tomato bioassays further demonstrated that the bioavailability of PAA‐nHAP was not superior to, and in most cases, lower than that of conventional P fertilizers. The limited fertilization efficacy of the PAA‐nHAP was attributed to the low solubility of hydroxyapatite and the restricted diffusion of aggregated NPs, which prevented the macroscale transport advantage from translating into sustained plant‐available P supply. The framework of this study can be used to assess the agronomic benefits of nanofertilizers and the environmental risks posed by NPs in surface soils.

The semi-nomad Bedouin tribes who have inhabited the Negev Desert at least since the eighteenth century ce have historically practised nomadism with relatively little agriculture. In the current study, a comprehensive field survey and interviews were conducted with members of the Bedouin community, belonging to various tribes who lived in the Negev in the 1930s and 1940s, along with an evaluation of previous reports published by researchers and travellers who were active in this area at that time. Our study presents Bedouin nomadic activities, emphasising the geographic and historical factors that influenced their lifestyle, and highlights the transhumance corridors used by these semi-nomads in different regions of the Negev Desert. Our study indicates that during the period 1900–1948, in the Southern Negev and Negev Highlands, the agricultural potential of the ancient agricultural systems that were exploited by the Bedouin influenced their movement throughout the region. In contrast, in the Northern Negev, the most significant factors were the influence of climatic conditions on the agricultural potential of the region, and proximity to the town of Be‘er-Sheva. This article was published open access under a CC BY 4.0 licence: https://creativecommons.org/licenses/by/4.0/ .

Introduction: In Israel, desalinated water is a major source of drinking water. Previous studies have suggested that the levels of iodine in water provided by authorities may not accurately reflect the levels reaching end-users. Materials and Methods. We analyzed 21 tap water samples collected from different localities across Israel, 13 post-treated desalinated water samples from three of the largest Israeli desalination plants, and several natural water samples. An improved method of ICP-MS developed in our laboratory was used to analyze the content of iodine and other macro-elements, and determination of iodine was performed in alkaline media. Results: Our results showed that it is possible to distinguish between sample groups based on iodine concentration, water hardness, and Ca/Mg ratio. The median iodine concentrations for four groups of tap water samples ranged from 0.3 to 12.3 µg/L, which is lower than the concentrations previously reported by other researchers in Israel. Based on typical consumption, the water samples can provide no more than 3.39% of the recommended dietary allowance level for iodine. The analysis of post-treated desalinated water samples indicated that these waters comply with industrial specifications but contain only trace concentrations of iodine and much less magnesium than recommended by different public health authorities for public consumption of drinking water. Conclusion: The total iodine concentrations found were lower than several observations reported in previous years in the literature. There are currently no strict regulations regarding iodine and magnesium levels in drinking and/or softened (desalinated) water, but the intensive desalination plant application is already exhibiting a negative impact on public health. Further investigations are needed, but the present study provides useful insights for developing an effective policy to ensure adequate iodine supply for the population of Israel through drinking water.

View, download and discuss this poster on Peeref: Determination of total iodine using ICP-MS in Israeli bottled and tap water: method development and application. Peeref makes academic exchange simple.

Phosphorus (P) nanoparticles were hypothesized to exhibit greater mobility in soils than water-soluble P (WSP) and were therefore proposed to be used as a P fertilizer. Unsaturated transport is the main pathway from the application site to plant roots. Though its importance to fertilizer efficacy, quantitative evaluation of unsaturated transport of P nanoparticles has been overlooked to date. Mobility of spherical nano-hydroxyapatite particles coated with polyacrylic acid (PAA-nHAP) suspension and WSP (a mixture of KH₂PO₄ and K₂HPO₄) was evaluated in breakthrough column experiments under unsaturated states using three soils: alkaline sand (sandy-alk), acidic sandy clay loam (sandy-ac) and clayey soils. Next, P retention was determined by total P extraction layer-by-layer from the disassembled soil columns. In all soils, PAA-nHAP exhibited faster transport compared to WSP. In the sandy-alk soil, earlier breakthrough but lower plateau of the final relative P concentration of PAA-nHAP (64.0% vs. 100% of the input P concentration) and consistent low P retention with depth after washing with 10 mM KBr solution for the two sources were observed. In the other two soils, PAA-nHAP displayed greater retention near the inlet and decreased retention with depth. In the sandy-ac soil, no WSP and low final relative concentrations of PAA-nHAP (11.6%) were transported through the soil column. The retention of PAA-nHAP was much lower than that of WSP with depth. In the clayey soil, the breakthrough (relative P concentration >1%) occurred earlier (~35 pore volumes vs. ~45 pore volumes) and the eluted P concentration increased more rapidly (~2.6 times) for PAA-nHAP compared to WSP. The difference between the two sources mainly occurred at the soil surface with higher retention of WSP. Soil properties affected the P retention capacity of the two P sources, but for all soils, P mobility was increased by changing from the common soluble fertilizers to nanoparticles. Adsorption and size exclusion effect are suggested as the major factors affecting nHAP mobility. We suggest that the nHAP transport can be improved by modifying its coating with more negative zeta-potential to decrease coagulation and adopting drip flows with short hydraulic retention time. The design of the nanoparticles needs to take into account soil properties.

The application of treated wastewater (TWW) via pressurized drip irrigation (DI) systems, specifically micro-irrigation, is an effective solution to mitigate water scarcity. TWW contains a higher concentration of nutrients and microbial activity compared to fresh water (FW) and poses a larger danger of fouling and subsequent clogging to DI systems. The goal of this paper was to characterize the effectiveness of chemical treatments, specifically hydrogen peroxide (H₂O₂) in preventing clogging in DI systems utilizing secondary (ST) and tertiary (TT)_TWW. A novel field model was employed to compare the flow rate (FR), fouling accumulation and composition in laterals and emitters of different treatments. Under ST_TWW irrigation, control treatment performance quickly declined while regular low concentration H₂O₂ treatments exhibited the lowest amounts of fouling and maintained nominal FR and coefficient of variation (CV). Shock treatments, defined as periodical applications of concentrated chemicals combined with lateral flushing, were ineffective in maintaining satisfactory irrigation performance.

The application in agriculture of treated wastewater (TWW) is expanding worldwide and in particular in dryland regions such as the Mediterranean region in general and the Middle East in particular. Freshwater, which was formerly directed to agriculture, is increasingly being utilized by the ever‐increasing municipal sector as a result of population increase and improved the standard of living. A major source that can account for the demand in the agricultural sector is TWW. Therefore, the percentage of wastewater that undergoes treatment is constantly increasing. This article will focus on the need to not only increase the quantity of TWW but to thoroughly enhance their quality prior to application. This article will focus on potential adverse effects related to TWW irrigation and will briefly discuss means that can be employed to reduce or avoid their effects. A number of undesired traits are higher in TWW than in their freshwater (FW) source. Of these, the most important ones are (i) organic – suspended and dissolved organic matter (DOM) and micro pollutants; and (ii) inorganic – total soluble salts, sodium, chloride, boron, and heavy metals. All of the above pose a threat to soil quality, as well as to plant and human health.