CONICET | Buscador de Institutos y Recursos Humanos

Environmental contamination caused by Persistent Organic Pollutants (POPs) is a global rather than a regional concerning issue. Defined in the Convention on Long-Range Transboundary Air Pollution (CLRTAP, Europe), POPs accumulate in the environment (soils, sediments, water and air) and subsequently in living organisms and humans. As regards of the increasing concern about these contaminants, international treaties were agreed at international level, in e.g., the United Nations Environmental Program (UNEP) Stockholm Convention, signed by 127 countries in 2001 -reaffirmed in 2007- and also the UNECE Protocol for the selection of new POP substances in 1998. On the other hand, trace metals are persistent contaminants which are introduced into the estuaries through river runoff, atmospheric deposition, hydrothermal venting, diagenetic remobilization, agricultural activities, and industrial and urban waste-waters discharges. As the process of industrialization and urbanization is stepping rapidly in South America, and in particular in Argentina -a developing country-, the potential increase in persistent pollutants loads is a concern. The present work is focused on the Bahía Blanca Estuary (38 º 40´ S and 62º 09´ W) as a presently monitored coastal environment case study. It has a total surface of 2300 km2, including about 410 km2 of islands and 1150 km2 of intertidal sector. It is a mesotidal system with very little fluvial input covered by extensive tidal flats and salt marshes. This estuary has a large length/width ratio, low mean depth and a very large tidal prism in relation to a small freshwater input. The inner part of the estuary shows high primary production values due to a bloom of diatoms during winter and spring. On the one hand, it presents intensive anthropogenic activity at the north shoreline: oil, chemical and plastic factories, two commercial harbours, a 12-m over-all length ships fishing fleet with a total catch of 600 t/yr and a big industrial city with more of 350 000 inhabitants, whose pre-filtered effluents are directly introduced into the estuarine waters. On the other hand, the inner part of the estuary presents low urbanized / rural lands, a tourist area and an artisanal fishing / recreational port. Polycyclic aromatic hydrocarbons (PAHs) are a unique class of POPs contaminating the aquatic environment. PAHs are not released to the environment from a single source of origin, as are most industrial, petro or agricultural chemicals; in fact, they are formed in at least three ways: pirogenically, petrogenically and diagenetically and unlike other harmful organic chemicals that have been banned or regulated in discharges, PAHs continue to be released into the environment because of their widespread formation during the burning of fossil fuels and escape during petroleum recovery, transport and use. As concentrations of PAHs in seawater and sediments are of toxicological importance to both benthic and pelagic marine organisms, this work reviews relevant available information about PAHs in sediments, water and organisms (Brachidontes sp., Tagelus sp. and Odonthestes sp.) at this strategic coastal area. Organochlorine compounds were widely used in agriculture and disease control programs from the 1940s to 1960s with dramatic benefits; they fell into disfavor because of their persistence in the environment, wildlife, and humans. However, the relatively low cost of these pesticides and unavailability of complete substitutes (particularly for DDT), ensured their continued use in several developing countries. As an agricultural country, Argentina was estimated from 26 to 30 million hm2 of farmland using OCs in the period 2005-2008. In particular, the area of study is located at Buenos Aires Province, one of the most important agriculture regions of Argentina (17.5 to 19.2 million hm2 of sowed land from 2005 to 2008). Based on long term monitoring data, the present work review the most relevant findings on levels, spatial and seasonal distribution and putative input sources of several OCs in the surface sediments of the study area. In aquatic ecosystems, plankton and suspended particulate matter have an affinity for most of the trace metals, thus, these fractions play important roles in their biogeochemical cycle. Suspended particulates are instrumental in controlling the reactivity, transport and biological impacts of substances in aquatic environments, and provide a crucial link for chemical constituents between the water column, bed sediments and food chain. This section aims to review the monitoring of some heavy metals in water (dissolved and particulate) and in the mesozooplankton fraction (200um-2mm), in order to highlight the major findings in the heavy metals transport at the estuary. TBT derivatives were introduced into the international market of antifouling paints during the 1960s and rapidly expanded due the high benefit/cost relation. Generally, the purpose of TBT coatings is to save fuel and to avoid excessive careenage in dry docks. A few years later, the high toxicity of butyltin compounds was widely demonstrated in non-target organisms, such as gastropods, bivalves, fish, and even mammals. This work presents a review of the TBT and derivatives monitoring at the estuary, which for the first time demonstrated levels of concern. As the environmental behavior of persistent pollutants depends on the complex interaction of many factors, any significant environmental alteration is likely to affect their distribution and fate. Such is the case of Temperature, which plays an important role in affecting pollutants mobility. A 30 years database at the area of study shows a warming environment, with consequences in several linked physicochemical variables. Some changing examples are given by pH, salinity, precipitation distribution, lands cover characteristics, etc. The alteration of any of these factors will in turn influence the parameters controlling the environmental distribution and fate of persistent pollutants, such as partitioning and degradation rates, the release rates from secondary sources, uptake rates, bioaccumulation dynamics, etc. The reviewed pollutant monitoring set the bases that would provide support on modeling the upcoming new scenario in a changing world.

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