Large dams have provided extensive benefits during the past 60 years but have also resulted in ec... more Large dams have provided extensive benefits during the past 60 years but have also resulted in ecological and social consequences that were unexpected or were deemed to have a lower societal importance than the design benefits. The management of large dams is still a relatively new scientific issue, compared to the timeframe necessary to detect and understand all the consequences occurring at the watershed scale. This paper summarizes the unforeseen or unanticipated environmental consequences of these projects and potential ramifications to the overall project performance. The value of a central knowledge base and the importance of a system-wide monitoring program to assess pre-and post-implementation conditions and adapt operational rules are presented. Knowledge developed in several basins is reviewed in the context of future strategies for Chile. Chile has a strong economy, looming energy crisis and is faced with balancing the long-term value of a renowned natural landscape with unique ecology and the largest salmon aquaculture industry in the world against the prospect of low cost hydropower to drive other sectors of the economy. This paper outlines the hydroinformatics technologies and scientifically based management approaches that can be applied to this complex issue.
Superficial sediments from Lenga estuary in the VIII region of central Chile were analysed for Po... more Superficial sediments from Lenga estuary in the VIII region of central Chile were analysed for Polychlorinated Biphenyls (PCBs) and Hexachlorobenzene (HCB). Organic carbon (OC) analysis was also performed and the statistical correlations (Pearson correlations) between compounds were also tested. Results showed the total PCB concentrations (ng g À1 d.w.) fluctuated from $20 to 10,000. These levels are higher than those reported in other coastal sediments of the world. The PCB profile was dominated by middle to highly chlorinated congeners (6-Cl = 40% and 7-Cl = 30%). HCB concentrations (ng g À1 d.w.), were lower than the PCBs and, fluctuated between 1 (at L1) and 870 (at L4). OC values ranged from 1% (L1) to 7% (L4) showing a significant positive correlations between OC% and PCBs (r = 0.86; p < 0.05) and for HCB (r = 0.71). These results are an important contribution to knowledge of levels of POPs levels in coastal Chilean environments.
Cytochrome P450-dependent monooxygenase (MFO) activity and levels of bile PAH metabolites were me... more Cytochrome P450-dependent monooxygenase (MFO) activity and levels of bile PAH metabolites were measured in fish (Oncorhynchus mykiss) exposed to Biobio river (Chile) water. Experiments were performed simultaneously in both the field and laboratory to investigate whether the river water contained notable bioavailable PAH fractions. The field experiment was conducted using fish caged for 41 days at La Mochita (Biobio river mouth) whereas the laboratory experiment involved a 21-day exposure treatment with water collected in the same area. Induction of hepatic MFO, assayed by benzo(a)pyrene monooxygenase activity (BaPMO), and levels of PAH metabolites in the bile were measured in groups of eight (field experiment) and four specimens (laboratory experiment) sampled after 5, 10, 21 and 41 days of exposure. BaPMO was induced by a factor of 23 and 25 in fish caged for 21 and 41 days, respectively. Likewise, a significant BaPMO induction was found in the fish group experimentally exposed to river water for 21 days. Biliary fluorescence measurements, recorded by fixed wavelength fluorescence (FF) and synchronous fluorescence spectroscopy (SFS), revealed significantly high levels of PAH metabolites in bile samples of fish caged for 21 and 41 days. A positive relationship was found between BaPMO activity and biliary PAH metabolites. This study provides evidences that (i) Biobio river water contains a significant bioavailable PAH fraction in terms of marked effects on fish and (ii) the biological indicators MFO activity and bile PAH metabolites represent an excellent screening methodology to assess PAH exposure.
Passive air samplers consisting of polyurethane foam (PUF) disks, were deployed in six locations ... more Passive air samplers consisting of polyurethane foam (PUF) disks, were deployed in six locations in Chile along a north-south transect to investigate gas-phase concentrations of polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs), and polybrominated diphenyl ethers (PBDEs). The study provides new information on air concentrations of these persistent organic pollutants (POPs) which is lacking in this region. It also provides insight into potential sources and long-range transport (LRT). The samplers were deployed for a 2-month period in five remote sites and one site in the city of Concepción. Mean concentrations (pg m -3 ) for ΣPCB were 4.7 ( 2.7 at remote sites and 53 ( 13 in Concepción. PCB levels at remote sites were related to proximity to urban source regions and/or air back trajectories. With the exception of endosulfan I, mean concentrations (pg m -3 ) of OCPs at background sites were consistently low: 5.4 ( 1.4 for R-HCH, 7.0 ( 1.1 for γ-HCH, 2.5 ( 0.5 for TC, 2.5 ( 0.6 for CC, 1.9 ( 1.2 for dieldrin, and less than 3.5 for toxaphene. Endosulfan I showed a decreasing concentration gradient from 99 to 3.5 pg m -3 from the north to south of Chile. Concentrations of OCPs in the Concepción City were generally 10-20 times higher than at the background sites suggesting continued usage and/or re-emission from past use. For instance, at remote sites, the R/γ ratio (0.76) was typical of background air, while the ratio in Concepción (0.12) was consistent with fresh use of γ-HCH. Levels of ΣPBDEs were below the detection limit of 6 pg m -3 at all sites.
This paper presents a first report on chlorinated pesticide deposition analyzed through sedimenta... more This paper presents a first report on chlorinated pesticide deposition analyzed through sedimentary records in a small mesotrophic lake (Chica de San Pedro) in central Chile. The sediment core was sliced and dated using 210Pb, 137Cs and pollen analyses. Organochlorine pesticides were analyzed by gas chromatography with electron capture detection (GC–ECD). From these results, pesticide deposition over the last 50 years was estimated. No pesticides were detected below the 1940 slice of the core. Concentrations were in the range 0.640–1.4 ng/g d.w. for total DDTs , 0.046–0.362 ng/g d.w. for lindane and 0.015–0.310 ng/g d.w. for α-hexachlorohexane. Highest concentrations of pp′DDT were found in 1993–1996 and higher concentrations of pp′-DDE and pp′-DDD were found in the seventies (1972–1978). Total organic carbon (TOC) normalized data were used for statistical analysis. Although significant correlation was observed between concentrations of DDE and DDD, no correlation was found for DDT, suggesting that it had a different source. Factorial analysis grouped DDE together with DDD, while DDT was grouped together with γ- and α-HCH. Total DDT fluxes were highest during the 1970s, while those for HCHs have been increasing in the 1990s. In Chile, organochlorine compounds were banned in 1985, and the historical deposition patterns seem to indicate that such measures have been effective. On the other hand, results point out a relatively new occurrence of pp′-DDT in the watershed, but the source remains unknown.
Passive air samplers consisting of polyurethane foam (PUF) disks, were deployed in six locations ... more Passive air samplers consisting of polyurethane foam (PUF) disks, were deployed in six locations in Chile along a north-south transect to investigate gas-phase concentrations of polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs), and polybrominated diphenyl ethers (PBDEs). The study provides new information on air concentrations of these persistent organic pollutants (POPs) which is lacking in this region. It also provides insight into potential sources and long-range transport (LRT). The samplers were deployed for a 2-month period in five remote sites and one site in the city of Concepción. Mean concentrations (pg m -3 ) for ΣPCB were 4.7 ( 2.7 at remote sites and 53 ( 13 in Concepción. PCB levels at remote sites were related to proximity to urban source regions and/or air back trajectories. With the exception of endosulfan I, mean concentrations (pg m -3 ) of OCPs at background sites were consistently low: 5.4 ( 1.4 for R-HCH, 7.0 ( 1.1 for γ-HCH, 2.5 ( 0.5 for TC, 2.5 ( 0.6 for CC, 1.9 ( 1.2 for dieldrin, and less than 3.5 for toxaphene. Endosulfan I showed a decreasing concentration gradient from 99 to 3.5 pg m -3 from the north to south of Chile. Concentrations of OCPs in the Concepción City were generally 10-20 times higher than at the background sites suggesting continued usage and/or re-emission from past use. For instance, at remote sites, the R/γ ratio (0.76) was typical of background air, while the ratio in Concepción (0.12) was consistent with fresh use of γ-HCH. Levels of ΣPBDEs were below the detection limit of 6 pg m -3 at all sites.
This paper presents a ®rst report on chlorinated pesticide deposition analyzed through sedimentar... more This paper presents a ®rst report on chlorinated pesticide deposition analyzed through sedimentary records in a small mesotrophic lake (Chica de San Pedro) in central Chile. The sediment core was sliced and dated using 210 Pb, 137 Cs and pollen analyses. Organochlorine pesticides were analyzed by gas chromatography with electron capture detection (GC±ECD). From these results, pesticide deposition over the last 50 years was estimated. No pesticides were detected below the 1940 slice of the core. Concentrations were in the range 0.640±1.4 ng/g d.w. for total DDTs, 0.046±0.362 ng/g d.w. for lindane and 0.015±0.310 ng/g d.w. for a-hexachlorohexane. Highest concentrations of pp H DDT were found in 1993±1996 and higher concentrations of pp H -DDE and pp H -DDD were found in the seventies (1972±1978). Total organic carbon (TOC) normalized data were used for statistical analysis. Although signi®cant correlation was observed between concentrations of DDE and DDD, no correlation was found for DDT, suggesting that it had a dierent source. Factorial analysis grouped DDE together with DDD, while DDT was grouped together with c-and a-HCH. Total DDT¯uxes were highest during the 1970s, while those for HCHs have been increasing in the 1990s. In Chile, organochlorine compounds were banned in 1985, and the historical deposition patterns seem to indicate that such measures have been eective. On the other hand, results point out a relatively new occurrence of pp H -DDT in the watershed, but the source remains unknown. Ó
El sistema fluvial Quilque (orden 3) recibe las descargas de aguas servidas de una población apro... more El sistema fluvial Quilque (orden 3) recibe las descargas de aguas servidas de una población aproximada de 115.000 habitantes y de 19 industrias. Estos residuos se vertían sin tratar directamente al curso del río hasta fines del año 2002, cuando se puso en marcha una planta de tratamiento de aguas servidas. Para analizar los efectos de estas descargas sobre la fauna de peces, se estudió la calidad del agua y estructura comunitaria de la ictiofauna a lo largo de ocho estaciones ubicadas desde aguas arriba de los vertidos hasta 300 m aguas abajo del efluente de la planta de tratamiento. Tanto la calidad del agua como la fauna de peces mostraron una leve mejoría luego de cinco meses de operación de la planta de tratamiento. Aun cuando se redujeron las concentraciones de DBO 5, sólidos suspendidos, nitrógeno y coliformes fecales, el río conduce una carga contaminante importante desde aguas arriba y mantiene remanentes en los sedimentos del lecho del río. La ictiofauna se encuentra empobrecida, pero evidencia un proceso de recolonización del sistema, desde las partes altas hacia el tramo inferior que recibía las descargas. Sin embargo, aún se mantienen sectores sin peces, debido a las altas concentraciones de DBO 5 . Las primeras especies en recolonizar aguas abajo son nativas (Trichomycterus areolatus y Percilia irwini).
In order to conserve the native ichthyofauna and as mitigation procedure to prevent the impact ge... more In order to conserve the native ichthyofauna and as mitigation procedure to prevent the impact generated by the interruption of the free displacement of fish in the Laja river (Biobio Region), a translocation program for native fish was carried out. Between the years 1997 ...
Abstract. Amarga Lagoon, lat. 50 29&amp;amp;#x27; S and long. 73 45&amp;amp;#x27; S, it i... more Abstract. Amarga Lagoon, lat. 50 29&amp;amp;#x27; S and long. 73 45&amp;amp;#x27; S, it is located at the Torres del Paine National Park, Chile. The physical, chemical, and biological features of the lake were studied. According to salinity, the lake is mesosaline. Sodium and chloride were the ...
The present paper focuses on the biological properties of Lake Chapo prior to the installation of... more The present paper focuses on the biological properties of Lake Chapo prior to the installation of a hydroelectric power station. Most of the biological parameters indicate that the lake is oligotrophic, i.e., it has very low values of chlorophyll a and primary production. The phytoplankton community of 73 species shows a predominance of only a few species in terms of density and biomass. The zooplankton community is poor in species, with one of the lowest densities measured in the North Patagonian lakes. The fish community is dominated by two introduced salmonid species. Comparison with other North Patagonian lakes reveals that Lake Chapo is the most oligotrophic.
Many researchers have shown the importance of water chemistry and benthic habitat characteristics... more Many researchers have shown the importance of water chemistry and benthic habitat characteristics for the conservation of the freshwater macroinvertebrate biodiversity. However, few authors have examined the physical effect of extreme water-level fluctuations in lakes. The present study set out to determine, through a comparative study between a regulated lake (Laja Lake, LL) and an unregulated lake (Icalma Lake, IL) of the Andean zone of southern Chile, how man-made disturbances of the natural hydrological regime affect the structure of the benthic macroinvertebrate community. The results showed LL had very low values for species richness, density and biomass in comparison with IL, and the community was composed mainly of few individuals belonging to opportunistic taxa such as Chironomidae and Naididae. We suggest that the low values in the regulated lake are potentially explained by littoral zone factors driven by the water-level fluctuations such as: desiccation, freezing of the biota, removal of organic particles from the sediment and absence of aquatic macrophytes.
A course for upper division undergraduate students was developed in response to a request for a c... more A course for upper division undergraduate students was developed in response to a request for a crossdisciplinary course in environmental sustainability with an emphasis on an international issue. The topic selected for the course focused on the energy needs for Chile and a proposal for five hydropower projects on the Baker and Pascua Rivers in the Patagonia area. Collaborations between the University of Michigan (USA) and the University of Concepción (Chile) to develop the course led to a plan to offer a parallel course at both universities, with the students of both courses participating in a site visit to Patagonia. The courses were structured to enhance learning through interdisciplinary team-based activities. The courses were taught in a seminar format, with invited lecturers to provide background information on technical, environmental, economic, social, and political issues surrounding hydropower development in general and the proposed projects in particular. The students combined this information with insights obtained during the site visit to prepare a variety of course products, notably an assessment of the concerns of the various affected stakeholder groups. Assessment of the course outcomes is discussed.
Hydropeaking dam operation and water extractions for irrigation have been broadly stated as alter... more Hydropeaking dam operation and water extractions for irrigation have been broadly stated as alterations to natural flow regimes, which have also been noticed in the Biobío Watershed, in Central Chile, since 1996. In the Biobío River, most of native fish species are endemic and very little is known about them. Their ecological and social values have never been estimated, and there is lack of information about their habitat preferences. Furthermore, changes on fish habitat availability due to natural and/or man-made causes have not been evaluated. In this study, eight native fish species, in a representative reach of the Biobío River, were studied and their preferred habitats were surveyed and characterized. A hydrodynamic model was built and linked to the fish habitat simulation model CASiMiR. Fuzzy rules and fuzzy sets were developed for describing habitat preference of the native fish species. CASiMiR was then used to simulate how physical habitat conditions vary due to flow control (i.e. upstream dams). Results show how overall habitat quality, expressed as weighted usable area (WUA) and hydraulic habitat suitability (HHS), changes and fluctuates due to the dam operation and how the daily hydropeaking is influencing quantity, quality and location of different habitats. The study suggests that the analysed fish are highly susceptible to flow control, as dams are currently operated, and fish habitat improvement suggestions are proposed.
O objetivo deste trabalho foi estudar o impacto de dois afluentes da barragem Santa Bárbara sobre... more O objetivo deste trabalho foi estudar o impacto de dois afluentes da barragem Santa Bárbara sobre o ambiente da mesma, utilizando a ocorrência de invertebrados bentônicos e características químicas da água. Durante nove meses foram realizadas coletas e análises da água e de invertebrados bentônicos nos afluentes Sanga da Barbuda e Sanga do Passo do Cunha e também no interior da bacia de acumulação da barragem. Os resultados mostram que, embora a Sanga da Barbuda e a Sanga do Passo do Cunha apresentem características químicas abaixo do recomendável, no limite aceitável pela legislação que determina os padrões de qualidade da água para abastecimento público, estes afluentes estão, ainda, sendo diluídos de forma satisfatória na bacia de acumulação da barragem. O estudo das relações entre variáveis químicas e invertebrados bentônicos mostra haver correlação significativa entre os baixos níveis de oxigênio dissolvido e a presença de Oligochaeta, sendo que o aumento do número de Oligochaeta indica uma situação de anoxia na barragem Santa Bárbara. Palavras-chave: zoobentos, saneamento ambiental, gestão hídrica.
RESUMEN Uno de los sistemas lóticos chilenos de mayor importancia de acuerdo a su caudal es el rí... more RESUMEN Uno de los sistemas lóticos chilenos de mayor importancia de acuerdo a su caudal es el río Biobío (ca. 37º S). Su estuario es reducido, especialmente en las épocas de máximo caudal. Con el objetivo de poner a prueba la hipótesis de que en verano la ...
Large dams have provided extensive benefits during the past 60 years but have also resulted in ec... more Large dams have provided extensive benefits during the past 60 years but have also resulted in ecological and social consequences that were unexpected or were deemed to have a lower societal importance than the design benefits. The management of large dams is still a relatively new scientific issue, compared to the timeframe necessary to detect and understand all the consequences occurring at the watershed scale. This paper summarizes the unforeseen or unanticipated environmental consequences of these projects and potential ramifications to the overall project performance. The value of a central knowledge base and the importance of a system-wide monitoring program to assess pre-and post-implementation conditions and adapt operational rules are presented. Knowledge developed in several basins is reviewed in the context of future strategies for Chile. Chile has a strong economy, looming energy crisis and is faced with balancing the long-term value of a renowned natural landscape with unique ecology and the largest salmon aquaculture industry in the world against the prospect of low cost hydropower to drive other sectors of the economy. This paper outlines the hydroinformatics technologies and scientifically based management approaches that can be applied to this complex issue.
Superficial sediments from Lenga estuary in the VIII region of central Chile were analysed for Po... more Superficial sediments from Lenga estuary in the VIII region of central Chile were analysed for Polychlorinated Biphenyls (PCBs) and Hexachlorobenzene (HCB). Organic carbon (OC) analysis was also performed and the statistical correlations (Pearson correlations) between compounds were also tested. Results showed the total PCB concentrations (ng g À1 d.w.) fluctuated from $20 to 10,000. These levels are higher than those reported in other coastal sediments of the world. The PCB profile was dominated by middle to highly chlorinated congeners (6-Cl = 40% and 7-Cl = 30%). HCB concentrations (ng g À1 d.w.), were lower than the PCBs and, fluctuated between 1 (at L1) and 870 (at L4). OC values ranged from 1% (L1) to 7% (L4) showing a significant positive correlations between OC% and PCBs (r = 0.86; p < 0.05) and for HCB (r = 0.71). These results are an important contribution to knowledge of levels of POPs levels in coastal Chilean environments.
Cytochrome P450-dependent monooxygenase (MFO) activity and levels of bile PAH metabolites were me... more Cytochrome P450-dependent monooxygenase (MFO) activity and levels of bile PAH metabolites were measured in fish (Oncorhynchus mykiss) exposed to Biobio river (Chile) water. Experiments were performed simultaneously in both the field and laboratory to investigate whether the river water contained notable bioavailable PAH fractions. The field experiment was conducted using fish caged for 41 days at La Mochita (Biobio river mouth) whereas the laboratory experiment involved a 21-day exposure treatment with water collected in the same area. Induction of hepatic MFO, assayed by benzo(a)pyrene monooxygenase activity (BaPMO), and levels of PAH metabolites in the bile were measured in groups of eight (field experiment) and four specimens (laboratory experiment) sampled after 5, 10, 21 and 41 days of exposure. BaPMO was induced by a factor of 23 and 25 in fish caged for 21 and 41 days, respectively. Likewise, a significant BaPMO induction was found in the fish group experimentally exposed to river water for 21 days. Biliary fluorescence measurements, recorded by fixed wavelength fluorescence (FF) and synchronous fluorescence spectroscopy (SFS), revealed significantly high levels of PAH metabolites in bile samples of fish caged for 21 and 41 days. A positive relationship was found between BaPMO activity and biliary PAH metabolites. This study provides evidences that (i) Biobio river water contains a significant bioavailable PAH fraction in terms of marked effects on fish and (ii) the biological indicators MFO activity and bile PAH metabolites represent an excellent screening methodology to assess PAH exposure.
Passive air samplers consisting of polyurethane foam (PUF) disks, were deployed in six locations ... more Passive air samplers consisting of polyurethane foam (PUF) disks, were deployed in six locations in Chile along a north-south transect to investigate gas-phase concentrations of polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs), and polybrominated diphenyl ethers (PBDEs). The study provides new information on air concentrations of these persistent organic pollutants (POPs) which is lacking in this region. It also provides insight into potential sources and long-range transport (LRT). The samplers were deployed for a 2-month period in five remote sites and one site in the city of Concepción. Mean concentrations (pg m -3 ) for ΣPCB were 4.7 ( 2.7 at remote sites and 53 ( 13 in Concepción. PCB levels at remote sites were related to proximity to urban source regions and/or air back trajectories. With the exception of endosulfan I, mean concentrations (pg m -3 ) of OCPs at background sites were consistently low: 5.4 ( 1.4 for R-HCH, 7.0 ( 1.1 for γ-HCH, 2.5 ( 0.5 for TC, 2.5 ( 0.6 for CC, 1.9 ( 1.2 for dieldrin, and less than 3.5 for toxaphene. Endosulfan I showed a decreasing concentration gradient from 99 to 3.5 pg m -3 from the north to south of Chile. Concentrations of OCPs in the Concepción City were generally 10-20 times higher than at the background sites suggesting continued usage and/or re-emission from past use. For instance, at remote sites, the R/γ ratio (0.76) was typical of background air, while the ratio in Concepción (0.12) was consistent with fresh use of γ-HCH. Levels of ΣPBDEs were below the detection limit of 6 pg m -3 at all sites.
This paper presents a first report on chlorinated pesticide deposition analyzed through sedimenta... more This paper presents a first report on chlorinated pesticide deposition analyzed through sedimentary records in a small mesotrophic lake (Chica de San Pedro) in central Chile. The sediment core was sliced and dated using 210Pb, 137Cs and pollen analyses. Organochlorine pesticides were analyzed by gas chromatography with electron capture detection (GC–ECD). From these results, pesticide deposition over the last 50 years was estimated. No pesticides were detected below the 1940 slice of the core. Concentrations were in the range 0.640–1.4 ng/g d.w. for total DDTs , 0.046–0.362 ng/g d.w. for lindane and 0.015–0.310 ng/g d.w. for α-hexachlorohexane. Highest concentrations of pp′DDT were found in 1993–1996 and higher concentrations of pp′-DDE and pp′-DDD were found in the seventies (1972–1978). Total organic carbon (TOC) normalized data were used for statistical analysis. Although significant correlation was observed between concentrations of DDE and DDD, no correlation was found for DDT, suggesting that it had a different source. Factorial analysis grouped DDE together with DDD, while DDT was grouped together with γ- and α-HCH. Total DDT fluxes were highest during the 1970s, while those for HCHs have been increasing in the 1990s. In Chile, organochlorine compounds were banned in 1985, and the historical deposition patterns seem to indicate that such measures have been effective. On the other hand, results point out a relatively new occurrence of pp′-DDT in the watershed, but the source remains unknown.
Passive air samplers consisting of polyurethane foam (PUF) disks, were deployed in six locations ... more Passive air samplers consisting of polyurethane foam (PUF) disks, were deployed in six locations in Chile along a north-south transect to investigate gas-phase concentrations of polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs), and polybrominated diphenyl ethers (PBDEs). The study provides new information on air concentrations of these persistent organic pollutants (POPs) which is lacking in this region. It also provides insight into potential sources and long-range transport (LRT). The samplers were deployed for a 2-month period in five remote sites and one site in the city of Concepción. Mean concentrations (pg m -3 ) for ΣPCB were 4.7 ( 2.7 at remote sites and 53 ( 13 in Concepción. PCB levels at remote sites were related to proximity to urban source regions and/or air back trajectories. With the exception of endosulfan I, mean concentrations (pg m -3 ) of OCPs at background sites were consistently low: 5.4 ( 1.4 for R-HCH, 7.0 ( 1.1 for γ-HCH, 2.5 ( 0.5 for TC, 2.5 ( 0.6 for CC, 1.9 ( 1.2 for dieldrin, and less than 3.5 for toxaphene. Endosulfan I showed a decreasing concentration gradient from 99 to 3.5 pg m -3 from the north to south of Chile. Concentrations of OCPs in the Concepción City were generally 10-20 times higher than at the background sites suggesting continued usage and/or re-emission from past use. For instance, at remote sites, the R/γ ratio (0.76) was typical of background air, while the ratio in Concepción (0.12) was consistent with fresh use of γ-HCH. Levels of ΣPBDEs were below the detection limit of 6 pg m -3 at all sites.
This paper presents a ®rst report on chlorinated pesticide deposition analyzed through sedimentar... more This paper presents a ®rst report on chlorinated pesticide deposition analyzed through sedimentary records in a small mesotrophic lake (Chica de San Pedro) in central Chile. The sediment core was sliced and dated using 210 Pb, 137 Cs and pollen analyses. Organochlorine pesticides were analyzed by gas chromatography with electron capture detection (GC±ECD). From these results, pesticide deposition over the last 50 years was estimated. No pesticides were detected below the 1940 slice of the core. Concentrations were in the range 0.640±1.4 ng/g d.w. for total DDTs, 0.046±0.362 ng/g d.w. for lindane and 0.015±0.310 ng/g d.w. for a-hexachlorohexane. Highest concentrations of pp H DDT were found in 1993±1996 and higher concentrations of pp H -DDE and pp H -DDD were found in the seventies (1972±1978). Total organic carbon (TOC) normalized data were used for statistical analysis. Although signi®cant correlation was observed between concentrations of DDE and DDD, no correlation was found for DDT, suggesting that it had a dierent source. Factorial analysis grouped DDE together with DDD, while DDT was grouped together with c-and a-HCH. Total DDT¯uxes were highest during the 1970s, while those for HCHs have been increasing in the 1990s. In Chile, organochlorine compounds were banned in 1985, and the historical deposition patterns seem to indicate that such measures have been eective. On the other hand, results point out a relatively new occurrence of pp H -DDT in the watershed, but the source remains unknown. Ó
El sistema fluvial Quilque (orden 3) recibe las descargas de aguas servidas de una población apro... more El sistema fluvial Quilque (orden 3) recibe las descargas de aguas servidas de una población aproximada de 115.000 habitantes y de 19 industrias. Estos residuos se vertían sin tratar directamente al curso del río hasta fines del año 2002, cuando se puso en marcha una planta de tratamiento de aguas servidas. Para analizar los efectos de estas descargas sobre la fauna de peces, se estudió la calidad del agua y estructura comunitaria de la ictiofauna a lo largo de ocho estaciones ubicadas desde aguas arriba de los vertidos hasta 300 m aguas abajo del efluente de la planta de tratamiento. Tanto la calidad del agua como la fauna de peces mostraron una leve mejoría luego de cinco meses de operación de la planta de tratamiento. Aun cuando se redujeron las concentraciones de DBO 5, sólidos suspendidos, nitrógeno y coliformes fecales, el río conduce una carga contaminante importante desde aguas arriba y mantiene remanentes en los sedimentos del lecho del río. La ictiofauna se encuentra empobrecida, pero evidencia un proceso de recolonización del sistema, desde las partes altas hacia el tramo inferior que recibía las descargas. Sin embargo, aún se mantienen sectores sin peces, debido a las altas concentraciones de DBO 5 . Las primeras especies en recolonizar aguas abajo son nativas (Trichomycterus areolatus y Percilia irwini).
In order to conserve the native ichthyofauna and as mitigation procedure to prevent the impact ge... more In order to conserve the native ichthyofauna and as mitigation procedure to prevent the impact generated by the interruption of the free displacement of fish in the Laja river (Biobio Region), a translocation program for native fish was carried out. Between the years 1997 ...
Abstract. Amarga Lagoon, lat. 50 29&amp;amp;#x27; S and long. 73 45&amp;amp;#x27; S, it i... more Abstract. Amarga Lagoon, lat. 50 29&amp;amp;#x27; S and long. 73 45&amp;amp;#x27; S, it is located at the Torres del Paine National Park, Chile. The physical, chemical, and biological features of the lake were studied. According to salinity, the lake is mesosaline. Sodium and chloride were the ...
The present paper focuses on the biological properties of Lake Chapo prior to the installation of... more The present paper focuses on the biological properties of Lake Chapo prior to the installation of a hydroelectric power station. Most of the biological parameters indicate that the lake is oligotrophic, i.e., it has very low values of chlorophyll a and primary production. The phytoplankton community of 73 species shows a predominance of only a few species in terms of density and biomass. The zooplankton community is poor in species, with one of the lowest densities measured in the North Patagonian lakes. The fish community is dominated by two introduced salmonid species. Comparison with other North Patagonian lakes reveals that Lake Chapo is the most oligotrophic.
Many researchers have shown the importance of water chemistry and benthic habitat characteristics... more Many researchers have shown the importance of water chemistry and benthic habitat characteristics for the conservation of the freshwater macroinvertebrate biodiversity. However, few authors have examined the physical effect of extreme water-level fluctuations in lakes. The present study set out to determine, through a comparative study between a regulated lake (Laja Lake, LL) and an unregulated lake (Icalma Lake, IL) of the Andean zone of southern Chile, how man-made disturbances of the natural hydrological regime affect the structure of the benthic macroinvertebrate community. The results showed LL had very low values for species richness, density and biomass in comparison with IL, and the community was composed mainly of few individuals belonging to opportunistic taxa such as Chironomidae and Naididae. We suggest that the low values in the regulated lake are potentially explained by littoral zone factors driven by the water-level fluctuations such as: desiccation, freezing of the biota, removal of organic particles from the sediment and absence of aquatic macrophytes.
A course for upper division undergraduate students was developed in response to a request for a c... more A course for upper division undergraduate students was developed in response to a request for a crossdisciplinary course in environmental sustainability with an emphasis on an international issue. The topic selected for the course focused on the energy needs for Chile and a proposal for five hydropower projects on the Baker and Pascua Rivers in the Patagonia area. Collaborations between the University of Michigan (USA) and the University of Concepción (Chile) to develop the course led to a plan to offer a parallel course at both universities, with the students of both courses participating in a site visit to Patagonia. The courses were structured to enhance learning through interdisciplinary team-based activities. The courses were taught in a seminar format, with invited lecturers to provide background information on technical, environmental, economic, social, and political issues surrounding hydropower development in general and the proposed projects in particular. The students combined this information with insights obtained during the site visit to prepare a variety of course products, notably an assessment of the concerns of the various affected stakeholder groups. Assessment of the course outcomes is discussed.
Hydropeaking dam operation and water extractions for irrigation have been broadly stated as alter... more Hydropeaking dam operation and water extractions for irrigation have been broadly stated as alterations to natural flow regimes, which have also been noticed in the Biobío Watershed, in Central Chile, since 1996. In the Biobío River, most of native fish species are endemic and very little is known about them. Their ecological and social values have never been estimated, and there is lack of information about their habitat preferences. Furthermore, changes on fish habitat availability due to natural and/or man-made causes have not been evaluated. In this study, eight native fish species, in a representative reach of the Biobío River, were studied and their preferred habitats were surveyed and characterized. A hydrodynamic model was built and linked to the fish habitat simulation model CASiMiR. Fuzzy rules and fuzzy sets were developed for describing habitat preference of the native fish species. CASiMiR was then used to simulate how physical habitat conditions vary due to flow control (i.e. upstream dams). Results show how overall habitat quality, expressed as weighted usable area (WUA) and hydraulic habitat suitability (HHS), changes and fluctuates due to the dam operation and how the daily hydropeaking is influencing quantity, quality and location of different habitats. The study suggests that the analysed fish are highly susceptible to flow control, as dams are currently operated, and fish habitat improvement suggestions are proposed.
O objetivo deste trabalho foi estudar o impacto de dois afluentes da barragem Santa Bárbara sobre... more O objetivo deste trabalho foi estudar o impacto de dois afluentes da barragem Santa Bárbara sobre o ambiente da mesma, utilizando a ocorrência de invertebrados bentônicos e características químicas da água. Durante nove meses foram realizadas coletas e análises da água e de invertebrados bentônicos nos afluentes Sanga da Barbuda e Sanga do Passo do Cunha e também no interior da bacia de acumulação da barragem. Os resultados mostram que, embora a Sanga da Barbuda e a Sanga do Passo do Cunha apresentem características químicas abaixo do recomendável, no limite aceitável pela legislação que determina os padrões de qualidade da água para abastecimento público, estes afluentes estão, ainda, sendo diluídos de forma satisfatória na bacia de acumulação da barragem. O estudo das relações entre variáveis químicas e invertebrados bentônicos mostra haver correlação significativa entre os baixos níveis de oxigênio dissolvido e a presença de Oligochaeta, sendo que o aumento do número de Oligochaeta indica uma situação de anoxia na barragem Santa Bárbara. Palavras-chave: zoobentos, saneamento ambiental, gestão hídrica.
RESUMEN Uno de los sistemas lóticos chilenos de mayor importancia de acuerdo a su caudal es el rí... more RESUMEN Uno de los sistemas lóticos chilenos de mayor importancia de acuerdo a su caudal es el río Biobío (ca. 37º S). Su estuario es reducido, especialmente en las épocas de máximo caudal. Con el objetivo de poner a prueba la hipótesis de que en verano la ...
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