A. Rendina

Comparison of soil tests to determine micronutrients status in Argentina soils

Abstract Soil extraction techniques to measure the status of available micronutrients for plants are important in the diagnosis of deficiency or toxicity. Mehlich 3 (M3), EDTA (pH=8.2), DTPA‐TEA, and Soltanpour and Schwab (SS) solutions were confronted for their ability to extract simultaneously copper (Cu), zinc (Zn), manganese (Mn), and iron (Fe). Argentinean soils from different taxonomic orders with widely varying properties were investigated. The values obtained showed that DTPA‐TEA and SS solutions extracted similar amounts of Zn, Fe, and Mn, while EDTA dissolved comparatively higher amounts of Fe and Mn. Mehlich 3 yielded the highest extractions for the four micronutrients. Soil pH not only affected the extraction of Mn by DTPA‐TEA, SS, and EDTA extractions, but also the extraction of Fe by EDTA. The organic carbon affected the determination of Fe and Zn in all cases. The correlations of the different tests for Cu, Zn, Mn, and Fe were significant. The results suggest that for the determination of t...

Genotoxicity of leachates from highly polluted lowland river sediments destined for disposal in landfill

The Matanza-Riachuelo is one of the most polluted rivers of Latin America. The complex chemical mixture of pollutants discharged into the river is accumulated in the river sediments. In this paper, Matanza-Riachuelo river sediment composition and genotoxicity were tested in order to develop a cost-effective, environmentally sound option for disposal and management of contaminated dredged materials. Sampling was performed in a rural area, in a solid waste dumpsite and also in an urban and industrial area. The concentrations of total heavy metals increased from the upper basin to the lower basin. The Ames Salmonella typhimurium test and the Saccharomyces cerevisiae D7 test were performed using toxicity characteristic leachate procedure (TCLP) leachates. The concentrations of copper, lead, and chromium in the leachates exceeded the guide levels for the protection of aquatic life. Low concentrations of organic chlorinated compounds were detected in the leachates. Genotoxic profiles were obtained by testing TCLP leachates from polluted sediment samples with Salmonella typhimurium, Saccharomyces cerevisiae D7, and water sediment suspension with Allium cepa test. No mutagenicity effects on Ames test were observed. Gene conversion and mitotic reversion in Saccharomyces cerevisiae D7 and chromosome aberration in Allium cepa were induced by the sediment samples. Results obtained suggest that dredged sediments could be classified as genotoxic hazardous waste.

Effect of phosphorus, copper, and zinc addition on the phosphorus/copper and phosphorus/zinc interaction in lettuce

Abstract The effect of phosphorus (P), copper (Cu), and zinc (Zn) addition on the P‐Cu and P‐Zn interaction in lettuce (Lactuca sativa L.) was analyzed following a factorial design. The experiment was conducted in a greenhouse. Two levels of P (62 and 224 ppm), three levels of Zn (0, 0.17, and 0.34 ppm), and three levels of Cu (0, 0.03, and 0.06 ppm) were applied in all combinations to lettuce grown in perlite. The influence of the different treatments on the leaf P concentration suggests that the P‐Cu interaction was positive, whereas P‐Zn was negative. An increase in root absorption and retention and a decrease in translocation to leaves were observed for Zn and Cu when the nutrient solution was supplied at a luxurious consumption level of P.

Heavy Metal Partitioning in Bottom Sediments of the Matanza-Riachuelo River and Main Tributary Streams

This study provides geochemical partitioning, potential bioavailability, and enrichment of Cd, Cu, Pb, and Zn in bottom sediments collected from the Matanza-Riachuelo River and its main tributary streams. A modified Tessier sequential extraction procedure, complemented with acid volatile sulfide (AVS) and simultaneous extracted metals (SEM) measurements, was applied to determine the partitioning of metals into four fractions (metals bound to amorphous sulfide, carbonate, and exchangeable), bound to Fe/Mn oxides (reducible), bound to organic matter/sulfide (oxidizable) and residual. Spatial and vertical distributions of metals were studied. The core sediments show a decreasing concentration of metals with depth. In top sediments, non-residual Cu was mainly associated with oxidizable phase, whereas Pb, Cd, and Zn were mainly associated with amorphous sulfide. Pb exhibited the highest enrichment in all sites. The ratio AVS/SEM was greater than one at sediment sections close to the water column, indicating that metals extracted with hydrochloric acid were mainly associated with the amorphous sulfide. The strong influence of amorphous sulfide in the retention of Cd, Pb, and Zn in anoxic sediments of Matanza-Riachuelo river system suggests that dredging and aeration could lead to the remobilization of metals from sediments to the water column, hence making the metals more available to the biota.

Changes in the speciation, partitioning and phytoavailability of chromium induced by organic soil amendments

Abstract This study investigated the effect of two organic amendments (compost of cattle ruminai content and Sphagnum-moss peat) on the reduction of hexavalent chromium and the distribution of this metal among the main solid phases of a soil with low organic matter content treated with different levels of Cr(VI) (0–2000 mg Cr kg−1 soil). At the same level of added organic carbon, the peat reduced Cr(VI) added to the soil from 250 to 2000 mg kg−1, with 100% efficiency. The reduction efficiency of the compost, however, decreased with the increasing dose of Cr(VI) soil. The distribution of Cr between the different soil components was evaluated by a sequential chemical extraction procedure. The concentration of water-soluble and exchangeable Cr decreased with the addition of organic amendments to the soil, whereas Cr increased in the organic fraction. The effect of added organic material on the Cr absorption was examined with two ornamental plants (Melissa officinalis and Begonia semperflorens). The increased Cr(VI) in the soil increased the Cr concentration in plant tissues. The addition of organic matter produced a greater aerial biomass for each level of added Cr in comparison with unamended soil. Sphagnum moss peat was more effective than the compost to decrease the total Cr and the Cr(VI) concentration in the water-soluble and exchangeable fraction of soil, thereby reducing the Cr accumulation in plants tissues and phytotoxic symptoms.

Waterlogging effects on organic phosphorus fractions in a toposequence of soils

Organic P plays a key role as a source and sink of P in hydromorphic soils. Our objective was to study the influence of hydromorphism on the distribution of soil organic P fractions. The research was performed at 4 sites from a toposequence of the Flooding Pampa (Argentina), which varied from a never-flooded upland site to a lowland site that remains waterlogged most of the year. All the soils were of the same age, parent material, vegetation type (native grassland), and land use. Total P content was higher in the soil of the lowland site than in that of the upland site. In all sites, at the 0–10 cm depth, most soil P was found in the organic fraction (ranging from 68 to 80%). The sum of the moderately resistant and resistant to mineralization fractions was greater than the labile and moderately labile fractions. The differences in the relative distribution of organic P fractions were minimal among sites. As a consequence, in these soils developed from the same parent material and with the same vegetation type (native grassland) and land use, the duration of waterlogging had little influence on the fractionation of soil organic P.

Impact of the Moron stream on water quality of the Reconquista River (Buenos Aires, Argentina)

The Reconquista River basin is located in an urban area where 2.5 10 6 inhabitants and 4,242 industries are settled. The confluence with the Moron stream shows the largest anthropogenic impact. The effect of the Moron stream on the water quality of the Reconquista River was evaluated in relation to its organic, mineral and metal contribution. Bimonthly samplings were carried out in the Reconquista River upstream (GOR), and downstream (SMT) from the confluence with the Moron stream and in the latter (MOR). Dissolved oxygen, pH, conductivity, temperature, transparency, nutrients, major ions, suspended solids, particulate and total organic carbon, Kjeldahl nitrogen, total phosphorus and heavy metals were determined in water samples. Discharge ratios between the Reconquista and Moron streams were estimated based on chloride concentrations. The samplings were ordered from the Principal Component Analysis in: GOR, SMT and MOR according to a growing gradient of organic and mineral contamination. This gradient has a spatial component (related to the discharge point of the Moron stream) and one related with the flow of the Reconquista River. Mean levels of heavy metals were higher than the thresholds for aquatic life protection. The most important were: lead, zinc, copper and mainly chromium, all of them related to industrial activity. Their concentrations responded to an irregular and intermittent discharge. Sometimes, metal levels at SMT and GOR were higher than at MOR, indicating other sources of contamination besides the Moron stream.

Copper and molybdenum interaction in Elytrigia elongata growing on a halomorphic soil

Abstract The experiment was carried out in a greenhouse to investigate copper (Cu) and molybdenum (Mo) interaction in Elytrigia elongata. Three rates of Mo (0,0.5, and 1 mg kg‐1) and three rates of Cu (0,5, and 10 mg kg‐1) were applied to all combinations to Elytrigia elongata grown on a halomorphic soil. The plants were cut three times, the first one 60 days after seeding, and the other two 120 and 180 days later, respectively. The results indicated that an antagonistic interaction between Cu and Mo existed in the first and in the third cut, but there was no evidence of it in the second cut. The antagonism between the two micronutrients studied was evident in the aerial part of the plant beyond a Mo concentration of 2.5±0.5 mg kg‐1, proposed as “threshold”.