The very wide use of glyphosate to control weeds in agricultural, silvicultural and urban areas throughout the world requires that special attention be paid to its possible transport from terrestrial to aquatic environments. The aim of this review is to present and discuss the state of knowledge on sorption, degradation and leachability of glyphosate in soils. Difficulties of drawing clear and unambiguous conclusions because of strong soil dependency and limited conclusive investigations are pointed out. Nevertheless, the risk of ground and surface water pollution by glyphosate seems limited because of sorption onto variable-charge soil minerals, e.g. aluminium and iron oxides, and because of microbial degradation. Although sorption and degradation are affected by many factors that might be expected to affect glyphosate mobility in soils, glyphosate leaching seems mainly determined by soil structure and rainfall. Limited leaching has been observed in non-structured sandy soils, while subsurface leaching to drainage systems was observed in a structured soil with preferential flow in macropores, but only when high rainfall followed glyphosate application. Glyphosate in drainage water runs into surface waters but not necessarily to groundwater because it may be sorbed and degraded in deeper soil layers before reaching the groundwater. Although the transport of glyphosate from land to water environments seems very limited, knowledge about subsurface leaching and surface runoff of glyphosate as well as the importance of this transport as related to ground and surface water quality is scarce.

Fate of glyphosate in soil and the possibility of leaching to ground and surface waters: a review.

This contribution critically reviews the state of knowledge on interactions of natural colloids and engineered nanoparticles with natural dissolved organic materials (DOM). These interactions determine the behavior and impact of colloids in natural system. Humic substances, polysaccharides, and proteins present in natural waters adsorb onto the surface of most colloids. We outline major adsorption mechanisms and structures of adsorption layers reported in the literature and discuss their generality on the basis of particle type, DOM type, and media composition. Advanced characterization methods of both DOM and colloids are needed to address insufficiently understood aspects as DOM fractionation upon adsorption, adsorption reversibility, and effect of capping agent. Precise knowledge on adsorption layer helps in predicting the colloidal stability of the sorbent. While humic substances tend to decrease aggregation and deposition through electrostatic and steric effects, bridging-flocculation can occur in th...

Interactions of Dissolved Organic Matter with Natural and Engineered Inorganic Colloids: A Review

Kinetics and thermodynamic study of phosphate adsorption on iron hydroxide-eggshell waste

Magnetite nanoparticles of 40 nm in size have been phosphated in orthophosphoric acid. Large phosphatation rates, equivalent to goethite capacity, have been pointed out, and the possibility of phosphatation−dephosphatation cycles has been proved. Phosphatation occurs rapidly, inhibits the dissolution of magnetite and does not modify the structure and the magnetization of magnetite. IR spectroscopy, X-ray photoelectron spectroscopy (XPS) analysis, and Mossbauer spectrometry have shown that phosphatation occurs by interaction with both positively charged groups and hydroxyl sites at the surface of magnetite and more precisely with Fe3+ in octahedral sites. The main surface species would be a protonated binuclear species and the top layer would be in the (111) plane. The chemical stability of magnetite during cycling and its magnetic macroscopic moment allowing an easy recycling are promising for technological uses.

Phosphate Adsorption Properties of Magnetite-Based Nanoparticles

The addition of iron is a convenient way for removing phosphorus from wastewater, but this is often considered to limit phosphorus recovery. Struvite precipitation is currently used to recover phosphorus, and this approach has attracted much interest. However, it requires the use of enhanced biological phosphorus removal (EBPR). EBPR is not yet widely applied and the recovery potential is low. Other phosphorus recovery methods, including sludge application to agricultural land or recovering phosphorus from sludge ash, also have limitations. Energy-producing wastewater treatment plants increasingly rely on phosphorus removal using iron, but the problem (as in current processes) is the subsequent recovery of phosphorus from the iron. In contrast, phosphorus is efficiently mobilized from iron by natural processes in sediments and soils. Iron–phosphorus chemistry is diverse, and many parameters influence the binding and release of phosphorus, including redox conditions, pH, presence of organic substances, and...

B. Raben-Lange

Papers

Influence of humic substances on phosphate adsorption by aluminium and iron oxides