Chlorinated hydrocarbons in Coastal Lagoon of the Pacific Coast of Nicaragua
A screening for persistent chlorinated hydrocarbons was carried out in December 1995 in the main coastal lagoons on the Pacific side of Nicaragua, where most of the country’s agriculture and pesticide use has been taking place for decades. Results for a wide range of organochlorine pesticides in...
| Autores Principales: | Carvalho, F.D, Montenegro Guillén, Salvador, Villeneuve, J. P, Cattini, C, Bartocci, J, Lacayo Romero, Martha, Cruz Granja, Adela del Carmen |
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| Formato: | Artículo |
| Idioma: | Español Español |
| Publicado: |
1999
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| Materias: | |
| Acceso en línea: |
http://repositorio.unan.edu.ni/2654/ http://repositorio.unan.edu.ni/2654/1/618.pdf http://repositorio.unan.edu.ni/2654/7/88x31_cc.png |
| Sumario: |
A screening for persistent chlorinated hydrocarbons
was carried out in December 1995 in the main coastal lagoons
on the Pacific side of Nicaragua, where most of the country’s
agriculture and pesticide use has been taking place for decades.
Results for a wide range of organochlorine pesticides in lagoon
sediments show levels that generally were very low in Estero
Real, Estero Padre Ramos, and estuary of San Juan del Sur. For
example, total DDTs in these lagoons averaged 4.5 6 3.4 ng
g21 dry weight, which may be considered a baseline level for
the region. Other compounds such as HCHs, BHC, endosulfan,
heptachlor, endrin, toxaphene, and aroclors were present in
concentrations even lower, generally below 1 ng g21 dry
weight. However, sediments of the Esteros Naranjo–Paso
Caballos system at Chinandega district contained pesticide
residues in much higher levels, attaining maximum values of
1,420 ng g21 and 270 ng g21 dry weight, respectively, for
toxaphene and total DDTs. Other compounds such as aroclors,
chlordane, endosulfan, and dieldrin were also present in the
sediments of this lagoon system, but in lower concentrations.
The very high concentrations of toxaphene and DDTs in this
lagoon are a result of the intensive use of these pesticides in
cotton growing in the district of Chinandega. Due to the long
environmental half-lives of these compounds (t1⁄2 . 10 years in
temperate soils), their concentrations in lagoon sediments will
likely remain high for years to come. Based on these results, the
development of the new shrimp farming activities in the Pacific
coastal lagoons should be restricted to selected areas.
The intensive use of pesticides in Nicaragua, which for decades
has been one of the biggest pesticide importers and users in
Central America (Appel 1991; Castillo et al. 1997), is likely to
cause severe contamination of aquatic systems. In particular
halogenated hydrocarbons, including chlorinated pesticides and
industrial chemicals such as the polychlorinated biphenyls
(PCBs), are lipophilic toxic compounds that bioaccumulate and
transfer in the food chain. Introduced in aquatic environments
these chemicals may compromise the health of the ecosystems
(Tardiff 1991). This is the case for the coastal lagoons of the
Pacific coast of Nicaragua, where most of the country’s
agriculture and population have been concentrated. In particular,
cotton growing, a pesticide intensive agriculture started in
the 1950s, was developed in this region of Nicaragua (Appel
1991).
The degradation of these coastal lagoon systems, especially
the reduction of mangrove forest and overexploitation of fishery
resources, has received focused attention from national authorities.
Agrochemical residues are suspected in the degradation of
these lagoons, but have not been investigated. Furthermore,
with the plans for developing shrimp rearing farms in these
coastal lagoons (esteros), contamination by agrochemical residues
becomes a matter of much concern for the future of this
industry. To provide information on the potential impacts from
agriculture and urban development, a screening of the contaminants
was carried out in the main lagoons of the Pacific coast.
This paper presents the results of the analyses of chlorinated
hydrocarbons in lagoon sediments and discusses the ecotoxicological
hazard posed by the current levels of persistent pesticide
residues to aquatic biota. |
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