The Bahia Blanca Estuary is located in southern Buenos Aires province, Argentina. The area is linked to a petrochemical industrial complex, whose raw materials and final products contaminate the surrounding areas via atmospheric pollution and effluents, which are dumped in the estuary waters. To establish the effects of the industrial waste disposal on the nearest coastal soils, 17 samples were taken at different distances from the loading dock and the outfall pipes of the industrial complex. Later, the physicochemical characteristics of the soil samples, their hydrocarbon contents, sulfides, sulfates, Zn, Cu, and Pb were analyzed and a comparison was made to control samples, which were not affected by the industrial outfall. Hydrocarbons, Zn, Cu, and Pb contents were found at levels that modified the physical and chemical characteristics of the soils. The resistance to penetration shows that the thinner the film of water that surrounds the particles or aggregates, the smaller the migration of organic micelle, which settle on the surface of the contact material. This is demonstrated by the degree of cohesion reached by the particles and the strong influence on the index of hydrophobicity. The high porosity shows that the continuity of the porous space of the soil matrix is impeded by the presence of pollutants, which generate areas that are highly limiting to water flow. The oxidation-reduction potential and the low concentrations of soluble forms of Cu and Pb compared with their concentrations precipitated as sulfides confirm the action of the pollutants.

The land around Bahía Blanca, Argentina, has been farmed intensively for six decades. We report the concentrations of a number of organochlorine pesticides (DDT, dieldrin, endrin, heptachlor epoxide and lindane), and of DDT metabolites (DDD + DDE) in three different layers (0–5, 5–10 and 10–20 cm) of the soils in 44 fields of eight farms that have been devoted to horticulture for periods ranging from 15 to 60 yr. In spite of the horticultural use of these substances having been banned for the past 13–35 yr, high concentrations were found – up to nearly 12 mg kg-1 for DDT + DDD + DDE, 17 mg kg-1 for dieldrin, 4 mg kg-1 for endrin, 7 mg kg-1 for heptachlor epoxide and 0.8 mg kg-1 for lindane. The highest concentrations of DDT, dieldrin, endrin and heptachlor epoxide were found on the oldest farms, the highest levels of DDD + DDE on middle-aged farms (35–40 yr), and the hi ghest levels of lindane on 15–40-year-old farms that had rather lower soil pH than the older farms. Concentrations invariably decreased slightly with increasing depth, and for DDT, dieldrin and heptachlor epoxide they exhibited significant positive correlation with soil organic matter content. Principal components analysis confirmed the distinguishability of three groups of analytes: one comprising DDT, dieldrin, endrin and heptachlor epoxide associated with higher soil organic matter and clay contents; and two singletons, DDD + DDE associated with higher pH and lindane. We conclude that these pesticides have very limited mobility in these semiarid alkaline soils. Key words: Organochlorine, semiarid soils, horticulture, depth variation.

The Bahia Blanca Estuary is located in southern Buenos Aires province, Argentina. The area is linked to a petrochemical industrial complex, whose raw materials and final products contaminate the surrounding areas via atmospheric pollution and effluents, which are dumped in the estuary waters. To establish the effects of the industrial waste disposal on the nearest coastal soils, 17 samples were taken at different distances from the loading dock and the outfall pipes of the industrial complex. Later, the physicochemical characteristics of the soil samples, their hydrocarbon contents, sulfides, sulfates, Zn, Cu, and Pb were analyzed and a comparison was made to control samples, which were not affected by the industrial outfall. Hydrocarbons, Zn, Cu, and Pb contents were found at levels that modified the physical and chemical characteristics of the soils. The resistance to penetration shows that the thinner the film of water that surrounds the particles or aggregates, the smaller the migration of organic micelle, which settle on the surface of the contact material. This is demonstrated by the degree of cohesion reached by the particles and the strong influence on the index of hydrophobicity. The high porosity shows that the continuity of the porous space of the soil matrix is impeded by the presence of pollutants, which generate areas that are highly limiting to water flow. The oxidation-reduction potential and the low concentrations of soluble forms of Cu and Pb compared with their concentrations precipitated as sulfides confirm the action of the pollutants.

No abstract

No abstract