Use of standardized procedures to evaluate metal leaching from waste foundry sands.

As part of the casting process, foundries create sand molds and cores to hold the molten metal to specific dimensional tolerances. Although most of the waste foundry sands (WFSs) from this process are land filled, there is great interest in diverting them for use in agricultural and geotechnical applications. One potential limitation to their beneficial use is concern that the WFSs will leach high levels of trace metals. The aim of this study was to quantify Ag, Ba, Cd, Cr, Cu, Ni, Pb, and Zn in leaching extracts from 96 waste molding and core sands from ferrous and nonferrous foundries. The procedures used to assess leaching in the WFSs were the Extraction Procedure, the Toxicity Characteristic Leaching Procedure, and the American Society for Testing and Materials water extraction procedure. The metal extract concentrations were compared with those found in virgin silica sands and Argentinean and U.S. hazardous waste laws to determine if the WFSs met toxicity limits. Regardless of metal cast and sand binder type, the majority of the WFS extracts analyzed contained metal concentrations similar to those found in virgin sand extracts and were below levels considered hazardous. However, 4 of 28 sands that used alkyd urethane binder were deemed hazardous because Pb concentrations in these sands were found to exceed regulatory thresholds. Although other regulated metals, such as As, Hg, and Se, were not analyzed in the extracts, this dataset provides additional evidence that many WFSs have a low metal leaching potential.

Analysis of total metals in waste molding and core sands from ferrous and non-ferrous foundries.

Waste molding and core sands from the foundry industry are successfully being used around the world in geotechnical and soil-related applications. Although waste foundry sands (WFSs) are generally not hazardous in nature, relevant data is currently not available in Argentina. This study aimed to quantify metals in waste molding and core sands from foundries using a variety of metal-binder combinations. Metal concentrations in WFSs were compared to those in virgin silica sands (VSSs), surface soils and soil guidance levels. A total analysis for Ag, Al, Ba, Be, Cd, Co, Cr, Cu, Fe, Mg, Mn, Mo, Ni, Pb, Sb, Te, Tl, V, and Zn was conducted on 96 WFSs and 14 VSSs collected from 17 small and medium-sized foundries. The majority of WFSs analyzed, regardless of metal cast and binder type, contained metal concentrations similar to those found in VSSs and native soils. In several cases where alkyd urethane binder was used, Co and Pb concentrations were elevated in the waste sands. Elevated Cr, Mo, Ni, and Tl concentrations associated with VSSs should not be an issue since these metals are bound within the silica sand matrix. Because of the naturally low metal concentrations found in most WFSs examined in this study, they should not be considered hazardous waste, thus making them available for encapsulated and unencapsulated beneficial use applications.

Levels of glyphosate in surface waters, sediments and soils associated with direct sowing soybean cultivation in north pampasic region of Argentina.

Levels of glyphosate were determined in water, soil and sediment samples from a transgenic soybean cultivation area located near to tributaries streams of the Pergamino-Arrecifes system in the north of the Province of Buenos Aires, Argentina. Field work took into account both the pesticide application and the rains occurring after applications. The pesticide was analysed by HPLC-UV detection, previous derivatization with 9-fluorenylmethylchloroformate (FMOC-Cl). In addition, SoilFug multimedia model was used to analyse the environmental distribution of the pesticides. In the field, levels of glyphosate in waters ranged from 0.10 to 0.70 mg/L, while in sediments and soils values were between 0.5 and 5.0 mg/Kg. Temporal variation of glyphosate levels depended directly on the time of application and the rain events. The results obtained from the application of the model are in accordance with the values found in the field.