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Corcho-Alvarado JA, Díaz-Asencio M, Röllin S, Herguera JC. Distribution and source of plutonium in sediments from the southern Gulf of Mexico. Environ Sci Pollut Res Int 2022; 29:85766-85776. [PMID: 35079966 PMCID: PMC9668946 DOI: 10.1007/s11356-022-18770-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/17/2021] [Accepted: 01/17/2022] [Indexed: 06/14/2023]
Abstract
Here, we report on new data (75 analyses) of plutonium (Pu) isotopes to elucidate activity concentrations, inventories, sources, and their transport from the ocean surface to the seafloor from a collection of six deep-sea sediment cores (depths ranging from 257 to 3739 m) in the southern Gulf of Mexico. Sediment cores collected from the continental shelf and upper slope region of the Gulf of Mexico showed 240Pu/239Pu ratios of 0.15 to 0.26, and 239+240Pu-inventories ranging from 14.7 to 33.0 Bq m-2. Inventories and ratios are consistent with global fallout Pu for this tropical region. In contrast, sediment cores collected from the lower slope region and abyssal plain showed low 240Pu/239Pu ratios of 0.07 to 0.13 and much lower 239+240Pu inventories below 6.8 Bq m-2. This implies that only a small fraction of the expected global fallout Pu has reached the deep-sea sediments. The low 240Pu/239Pu isotope ratios indicate that fallout from the Nevada testing site was an important source of Pu in deep-sea sediments, and that this Pu was likely more efficiently scavenged from the water column than Pu from global fallout. We estimated that up to 44% of the total inventory of 239+240Pu in deep-sea sediments is due to the Nevada source. Low values and a progressive decrease of 240Pu/239Pu ratios and 239+240Pu inventories with increasing water depth have been previously reported for the Gulf of Mexico. Analysis of Pu isotopes in two sediment traps from the upper slope regions shows 240Pu/239Pu ratios comparable to those observed in global fallout. These results indicate that global fallout Pu is currently the main source of Pu in sinking particles in the water column. Therefore, a significant fraction of global fallout Pu must still be present, either in a dissolved phase, or as biologically recycled material in the water column, or scavenged on the shelf and shelf break. Our results bring to light important questions on the application of Pu isotopes to establish sediment chronologies in deep-sea sediments, since global fallout features such as the 1963 maximum are not available.
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Affiliation(s)
- José A Corcho-Alvarado
- Nuclear Chemistry Division, Spiez Laboratory, Federal Office for Civil Protection, CH-3700, Spiez, Switzerland.
| | - Misael Díaz-Asencio
- División de Oceanología, Centro de Investigación Científica y de Educación Superior de Ensenada (CICESE), Ensenada, Baja California, México
- Escuela Nacional de Estudios Superiores (ENES), Unidad Mérida, UNAM. Mérida, Yucatán, México
| | - Stefan Röllin
- Nuclear Chemistry Division, Spiez Laboratory, Federal Office for Civil Protection, CH-3700, Spiez, Switzerland
| | - Juan Carlos Herguera
- División de Oceanología, Centro de Investigación Científica y de Educación Superior de Ensenada (CICESE), Ensenada, Baja California, México
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Corcho-Alvarado JA, Guavis C, McGinnity P, Röllin S, Ketedromo T, Sahli H, Levy IN, de Brum K, Stauffer M, Osvath I, Burger M. Assessment of residual radionuclide levels at the Bokak and Bikar Atolls in the northern Marshall Islands. Sci Total Environ 2021; 801:149541. [PMID: 34418620 DOI: 10.1016/j.scitotenv.2021.149541] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Revised: 08/04/2021] [Accepted: 08/05/2021] [Indexed: 06/13/2023]
Abstract
The Bikar and Bokak Atolls, located in the northern Marshall Islands, are extremely isolated and consist of pristine marine and terrestrial ecosystems. Both atolls may have experienced significant radioactive deposition following the nuclear weapon testing conducted at Bikini and Enewetak proving grounds. Here we report activity concentrations of artificial radionuclides (239Pu, 240Pu, 241Pu, 241Am, 137Cs and 90Sr) in marine and terrestrial samples collected from Bikar and Bokak Atolls. Artificial radionuclides in soil from the Majuro Atoll are also reported and form a radiological baseline against which the levels at the other atolls can be compared. We observed low levels of artificial radionuclides in soil from Majuro and Bokak, but significantly higher levels in soil from Bikar. The residual radioactivity in the Bikar environment is comparable to the levels previously reported for other nearby atolls, including Taka and Utrik, but lower than for Rongerik, Rongelap, Bikini and Enewetak. An analysis of 240Pu/239Pu isotope ratios and estimations of the dates of contamination from 241Am/241Pu activity ratios both indicated that the Bikar Atoll was contaminated mainly by radioactive fallout from the Castle Bravo test in 1954. We compare the results of our measurements at Bikar and Bokak to data from other atolls in the Marshall Islands and to regions of the world affected by both global and regional fallout from atmospheric nuclear weapons testing and nuclear accidents.
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Affiliation(s)
- José A Corcho-Alvarado
- Nuclear Chemistry Division, Spiez Laboratory, Federal Office for Civil Protection, CH-3700 Spiez, Switzerland.
| | - Candice Guavis
- Marshall Islands Marine Resources Authority (MIMRA), Majuro, Marshall Islands
| | - Paul McGinnity
- International Atomic Energy Agency (IAEA), Environment Laboratories, Monaco
| | - Stefan Röllin
- Nuclear Chemistry Division, Spiez Laboratory, Federal Office for Civil Protection, CH-3700 Spiez, Switzerland
| | - Tuvuki Ketedromo
- Environmental Protection Authority (RMI EPA), Majuro, Marshall Islands
| | - Hans Sahli
- Nuclear Chemistry Division, Spiez Laboratory, Federal Office for Civil Protection, CH-3700 Spiez, Switzerland
| | - Isabelle N Levy
- International Atomic Energy Agency (IAEA), Environment Laboratories, Monaco
| | - Kalena de Brum
- Marshall Islands Marine Resources Authority (MIMRA), Majuro, Marshall Islands
| | - Marc Stauffer
- Nuclear Chemistry Division, Spiez Laboratory, Federal Office for Civil Protection, CH-3700 Spiez, Switzerland
| | - Iolanda Osvath
- International Atomic Energy Agency (IAEA), Environment Laboratories, Monaco
| | - Mario Burger
- Nuclear Chemistry Division, Spiez Laboratory, Federal Office for Civil Protection, CH-3700 Spiez, Switzerland
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Klemt E, Putyrskaya V, Röllin S, Corcho-Alvarado JA, Sahli H. Radionuclides in sediments of the Aare and Rhine river system: Fallouts, discharges, depth-age relations, mass accumulation rates and transport along the river. J Environ Radioact 2021; 232:106584. [PMID: 33744558 DOI: 10.1016/j.jenvrad.2021.106584] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Revised: 01/29/2021] [Accepted: 03/04/2021] [Indexed: 06/12/2023]
Abstract
The Aare-Rhine river system with its four nuclear power plants on the banks of these rivers and with its intermediate lakes and reservoirs provide the unique chance to analyze the input of radioactivity into the system thereby furnishing information on the sources, to analyze the transport within the sediment and along the rivers, and to refine unsupported 210Pb dating validated by known discharge maxima. At three locations (Lake Biel, Klingnau Reservoir, old branch of the Rhine) in the Aare and Rhine rivers system downstream of the older nuclear power plants (NPPs) Mühleberg and Beznau, the vertical distributions of 137Cs, 210Pb, 214Pb, 214Bi, 40K, 7Be, 239Pu, 240Pu, 241Am, and 237Np in sediment cores were determined. Depth-age relations using the excess 210 Pb were established with the raw and with the piecewise Constant Rate Supply (CRS) models. A comparison of the piecewise CRS method with the imprints of known discharges showed differences of up to two years. Besides typical 137Cs signals (about 100 Bq∙kg-1) from the atmospheric nuclear weapons testing (NWT) and the Chernobyl fallouts, imprints of known 137Cs discharges (10-70 Bq∙kg-1) from the NPPs were found in the sediments. The 237Np distributions (6-10 Bq∙kg-1) essentially follow the 137Cs NWT distributions. In the sediment downstream the NPP Mühleberg (Lake Biel) a239Pu distribution (<3 Bq∙kg-1) was found, which was solely due to the NWT fallout. Downstream the NPP Beznau (Klingnau Reservoir and an old branch of the Rhine), besides the NWT distribution, also imprints of 239Pu discharges (up to 7 Bq∙kg-1) were found within the time interval 1963 to 1986.240Pu/239Pu ratios revealed that the burn-up times of the nuclear fuel in the NPP (235U enrichment of 3.5%), from which the discharges stem, should be about 1 year or less. A comparison between the calculated and the measured 137Cs/239Pu ratio revealed no large discrepancies for the Lake Biel and Rhine positions, but in the Klingnau distribution, the calculated 137Cs/239Pu ratio is one order of magnitude larger than the measured one. The reason could be either a natural uranium research reactor as the source, or strong, short-range 239Pu precipitation after the discharge from the Beznau NPP. The largest 239Pu peak in the Rhine sediment (1968/70) corresponds to no major peak in the Klingnau sediment. For the NPP Mühleberg discharge of 1982 the ratio of the 137Cs deposition in sediments from Lake Biel, Klingnau Reservoir and the Rhine river is about 1 : 0.5 : 2.9. For the 1977/78 239Pu deposition the ratio is 1 : 0.02, for the Klingnau Reservoir and the Rhine sediments, respectively. These numbers indicate a long-range transport of Cs and a rather short-range transport of Pu.
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Affiliation(s)
- E Klemt
- Ravensburg-Weingarten University, Doggenriedstr., D-88250, Weingarten, Germany.
| | - V Putyrskaya
- Ravensburg-Weingarten University, Doggenriedstr., D-88250, Weingarten, Germany
| | - S Röllin
- Federal Office for Civil Protection, Spiez Laboratory, CH-3700, Switzerland
| | | | - H Sahli
- Federal Office for Civil Protection, Spiez Laboratory, CH-3700, Switzerland
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Díaz-Asencio M, Sanchez-Cabeza JA, Ruiz-Fernández AC, Corcho-Alvarado JA, Pérez-Bernal LH. Calibration and use of well-type germanium detectors for low-level gamma-ray spectrometry of sediments using a semi-empirical method. J Environ Radioact 2020; 225:106385. [PMID: 32979747 DOI: 10.1016/j.jenvrad.2020.106385] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/19/2020] [Revised: 06/24/2020] [Accepted: 08/09/2020] [Indexed: 06/11/2023]
Abstract
Gamma-ray spectrometry is a widely used technique to quantify the presence of numerous radionuclides in environmental samples. In this work, we describe a methodology for efficiency calibration of four well-type germanium detectors and their use for the determination of low-level activities of gamma emitters in sediment samples. An experimental efficiency calibration for each detector was built with three materials for 17 energies, ranging from 46.5 keV to 1460 keV. For efficiency transfer to different geometries and sample types, we used the effective solid angle approach (ET-Ω method). Final calibrations were calculated for all detectors, several counting geometries, and elemental composition of selected sample types. Calibrations were validated with six reference materials. This methodology allowed to reliably analyze nine gamma emitters (210Pb, 241Am, 234Th, 228Ac, 214Pb, 208Tl, 137Cs, 134Cs and 40K) in sediment samples. Using these calibrations, gamma emitter profiles of sediment cores from contrasting aquatic systems (lake, intertidal, marine and deep-sea areas) provided reliable profiles of 210Pb and artificial radionuclides useful for dating and stratigraphic interpretation. A protocol to implement this methodology is also presented.
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Affiliation(s)
- Misael Díaz-Asencio
- Unidad Académica Mazatlán, Instituto de Ciencias Del Mar y Limnología, Universidad Nacional Autónoma de México, Calz. Joel Montes Camarena S/N, 82040, Mazatlán, Mexico; División de Oceanología, Centro de Investigación Científica y Educación Superior de Ensenada, Carretera Ensenada-Tijuana #3918, Zona Playitas, 22860, Ciudad Ensenada, Baja California, Mexico
| | - Joan-Albert Sanchez-Cabeza
- Unidad Académica Mazatlán, Instituto de Ciencias Del Mar y Limnología, Universidad Nacional Autónoma de México, Calz. Joel Montes Camarena S/N, 82040, Mazatlán, Mexico.
| | - Ana Carolina Ruiz-Fernández
- Unidad Académica Mazatlán, Instituto de Ciencias Del Mar y Limnología, Universidad Nacional Autónoma de México, Calz. Joel Montes Camarena S/N, 82040, Mazatlán, Mexico
| | | | - Libia Hascibe Pérez-Bernal
- Unidad Académica Mazatlán, Instituto de Ciencias Del Mar y Limnología, Universidad Nacional Autónoma de México, Calz. Joel Montes Camarena S/N, 82040, Mazatlán, Mexico
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Valcarcel Rojas L, Santos Junior JA, Corcho-Alvarado JA, Santos Amaral R, Röllin S, Ortueta Milan M, Herrero Fernández Z, Francis K, Cavalcanti M, Santos JMN. Quality and management status of the drinking water supplies in a semiarid region of Northeastern Brazil. J Environ Sci Health A Tox Hazard Subst Environ Eng 2020; 55:1247-1256. [PMID: 32567990 DOI: 10.1080/10934529.2020.1782668] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/09/2019] [Revised: 05/25/2020] [Accepted: 05/26/2020] [Indexed: 06/11/2023]
Abstract
Surface and groundwater resources in the Seridó Region (Brazilian semiarid) were investigated to evaluate their current quality conditions and suitability for domestic use. The water was characterized in terms of physical, chemical, and radiological parameters; including those required by the Brazilian Drinking Water Quality Standard (DWQS). Information about major and trace elements and radiological aspects of the water are reported for the first time. Salinization was confirmed as a key problem in the region, driven natural and anthropogenic. Overall, water has poor organoleptic characteristics. The concentration of most trace elements was below the recommended level, except for uranium and selenium in groundwater. Gross alpha and beta activities higher than the recommended levels were also recorded in several water samples, mostly from the investigated aquifers. In these samples, a detailed radionuclide analysis is required to estimate the effective dose received by the local population. Overall, the results show that water from the investigated region is not suitable for human consumption unless proper treatment is applied. Water requires proper treatment to decrease the content of dissolved salts, toxic elements, and radionuclides responsible for the high gross alpha and beta activities.
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Affiliation(s)
- Lino Valcarcel Rojas
- Radioecology Group, Nuclear Energy Department, Geoscience and Technology Center, Federal University of Pernambuco, Recife, PE, Brazil
| | - José Araujo Santos Junior
- Radioecology Group, Nuclear Energy Department, Geoscience and Technology Center, Federal University of Pernambuco, Recife, PE, Brazil
| | - José A Corcho-Alvarado
- Nuclear Chemistry Division, Spiez Laboratory, Federal Office for Civil Protection, Spiez, Switzerland
| | - Romilton Santos Amaral
- Radioecology Group, Nuclear Energy Department, Geoscience and Technology Center, Federal University of Pernambuco, Recife, PE, Brazil
| | - Stefan Röllin
- Nuclear Chemistry Division, Spiez Laboratory, Federal Office for Civil Protection, Spiez, Switzerland
| | - Marvic Ortueta Milan
- Radioecology Group, Nuclear Energy Department, Geoscience and Technology Center, Federal University of Pernambuco, Recife, PE, Brazil
| | - Zahily Herrero Fernández
- Radioecology Group, Nuclear Energy Department, Geoscience and Technology Center, Federal University of Pernambuco, Recife, PE, Brazil
| | - Kennedy Francis
- Radioecology Group, Nuclear Energy Department, Geoscience and Technology Center, Federal University of Pernambuco, Recife, PE, Brazil
| | - Marianna Cavalcanti
- Radioecology Group, Nuclear Energy Department, Geoscience and Technology Center, Federal University of Pernambuco, Recife, PE, Brazil
| | - Josineide M N Santos
- Radioecology Group, Nuclear Energy Department, Geoscience and Technology Center, Federal University of Pernambuco, Recife, PE, Brazil
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Putyrskaya V, Klemt E, Röllin S, Corcho-Alvarado JA, Sahli H. Dating of recent sediments from Lago Maggiore and Lago di Lugano (Switzerland/Italy) using 137Cs and 210Pb. J Environ Radioact 2020; 212:106135. [PMID: 31885363 DOI: 10.1016/j.jenvrad.2019.106135] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/18/2019] [Revised: 12/09/2019] [Accepted: 12/09/2019] [Indexed: 06/10/2023]
Abstract
This paper presents the results of 137Cs and 210Pb dating of sediments from the northern and western basins of Lago Maggiore and the southern basin of Lago di Lugano. Vertical distributions of 137Cs in sediment cores taken in 2017/18 were compared to those of the sediment cores taken almost two decades ago at the same positions. This comparison showed that 137Cs peaks do not alter their shape significantly over time and 137Cs remains a reliable time-marker for many decades. 210Pb dating using for the first time the piecewise "constant rate supply" (CRSPW) model constrained with 137Cs time-markers is performed for sediment cores of Lago Maggiore and Lago di Lugano. "Event-linked" mass accumulation rates (MARs) were derived from the CRSPW model. In combination with the dry bulk density, organic matter content, 40K and 210Pb activity concentrations, these "event-linked" MARs were used for the identification of one or more event layers (turbidites, detrital layers) in 1-cm thick sediment samples. "Continuous" mean MARs which are independent of the event layers were estimated: in Lago Maggiore sediment cores they are 0.066-0.090 g cm-2 yr-1; in Lago di Lugano they vary in the range of 0.032-0.057 g cm-2 yr-1 with higher values in the time interval 1963-1986 as compared to 1986-present.
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Affiliation(s)
- V Putyrskaya
- Hochschule Ravensburg-Weingarten, University of Applied Sciences, Doggenriedstr., D-88250, Weingarten, Germany.
| | - E Klemt
- Hochschule Ravensburg-Weingarten, University of Applied Sciences, Doggenriedstr., D-88250, Weingarten, Germany
| | - S Röllin
- Federal Office for Civil Protection, Spiez Laboratory, CH-3700, Switzerland
| | | | - H Sahli
- Federal Office for Civil Protection, Spiez Laboratory, CH-3700, Switzerland
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Corcho-Alvarado JA, Balsiger B, Sahli H, Astner M, Byrde F, Röllin S, Holzer R, Mosimann N, Wüthrich S, Jakob A, Burger M. Long-term behavior of (90)Sr and (137)Cs in the environment: Case studies in Switzerland. J Environ Radioact 2016; 160:54-63. [PMID: 27132253 DOI: 10.1016/j.jenvrad.2016.04.027] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2015] [Revised: 04/13/2016] [Accepted: 04/20/2016] [Indexed: 06/05/2023]
Abstract
We present long-term records of the (137)Cs and (90)Sr activity concentrations in soil, grass and milk from two lowland and two alpine pastures of Switzerland. The data is used for better understanding the long-term behavior of these radionuclides in the environment. Transfer factors between compartments are used as qualitative indicators of the magnitude of transfer and as a way to compare different elements (e.g. Cs and Sr) in similar conditions. The long-term behavior was quantified by means of the effective half-life which integrates all processes that cause a decrease of activity in a given medium such as leaching, fixation, erosion and radioactive decay. Our study shows that (90)Sr is more likely transferred from alpine soil to grass than (137)Cs. This is explained by a stronger fixation of Cs in the soils. We observed higher transfers of (90)Sr to grass in soils with lower Ca concentrations, and vice versa. In contrast, the transfer of (137)Cs to grass was not affected by the variations of the K content in the soil. We provide evidence that shows that (137)Cs, after intake by dairy cattle, is more likely transferred to milk than (90)Sr. However, as the (90)Sr and Ca transfers to milk are influenced by parameters/processes that were not taken into account in our study, our result cannot be entirely validated. The effective half-lives of (137)Cs and (90)Sr in soil, grass and milk corresponded with previous estimates in alpine soils. We have found that processes other than radioactive decay are responsible for a major decrease of the (90)Sr activity in soil. For (137)Cs, on the other hand, radioactive decay is among the most relevant process. Our data shows to be of interest in studying the trends of behavior of radionuclides in alpine regions.
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Affiliation(s)
- J A Corcho-Alvarado
- Federal Office for Civil Protection, Spiez Laboratory, Physics Division, 3700 Spiez, Switzerland.
| | - B Balsiger
- Federal Office for Civil Protection, Spiez Laboratory, Physics Division, 3700 Spiez, Switzerland
| | - H Sahli
- Federal Office for Civil Protection, Spiez Laboratory, Physics Division, 3700 Spiez, Switzerland
| | - M Astner
- Federal Office for Civil Protection, Spiez Laboratory, Physics Division, 3700 Spiez, Switzerland
| | - F Byrde
- Federal Office for Civil Protection, Spiez Laboratory, Physics Division, 3700 Spiez, Switzerland
| | - S Röllin
- Federal Office for Civil Protection, Spiez Laboratory, Physics Division, 3700 Spiez, Switzerland
| | - R Holzer
- Federal Office for Civil Protection, Spiez Laboratory, Physics Division, 3700 Spiez, Switzerland
| | - N Mosimann
- Federal Office for Civil Protection, Spiez Laboratory, Physics Division, 3700 Spiez, Switzerland
| | - S Wüthrich
- Federal Office for Civil Protection, Spiez Laboratory, Physics Division, 3700 Spiez, Switzerland
| | - A Jakob
- Federal Office for Civil Protection, Spiez Laboratory, Physics Division, 3700 Spiez, Switzerland
| | - M Burger
- Federal Office for Civil Protection, Spiez Laboratory, Physics Division, 3700 Spiez, Switzerland
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Alonso-Hernández CM, Tolosa I, Mesa-Albernas M, Díaz-Asencio M, Corcho-Alvarado JA, Sánchez-Cabeza JA. Historical trends of organochlorine pesticides in a sediment core from the Gulf of Batabanó, Cuba. Chemosphere 2015; 137:95-100. [PMID: 26051863 DOI: 10.1016/j.chemosphere.2015.05.044] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2014] [Revised: 05/12/2015] [Accepted: 05/15/2015] [Indexed: 06/04/2023]
Abstract
Sediments can be natural archives to reconstruct the history of pollutant inputs into coastal areas. This is important to improve management strategies and evaluate the success of pollution control measurements. In this work, the vertical distribution of organochlorine pesticides (DDTs, Lindane, HCB, Heptachlor, Aldrin and Mirex) was determined in a sediment core collected from the Gulf of Batabanó, Cuba, which was dated by using the (210)Pb dating method and validated with the (239,240)Pu fallout peak. Results showed significant changes in sediment accumulation during the last 40 years: recent mass accumulation rates (0.321 g cm(-2) yr(-1)) double those estimated before 1970 (0.15 g cm(-2) yr(-1)). This change matches closely land use change in the region (intense deforestation and regulation of the Colon River in the late 1970s). Among pesticides, only DDTs isomers, Lindane and HCB were detected, and ranged from 0.029 to 0.374 ng g(-1) dw for DDTs, from<0.006 to 0.05 ng g(-1) dw for Lindane and from<0.04 to 0.134 ng g(-1) dw for HCB. Heptachlor, Aldrin and Mirex were below the detection limits (∼0.003 ng g(-1)), indicating that these compounds had a limited application in the Coloma watershed. Pesticide contamination was evident since the 1970s. DDTs and HCB records showed that management strategies, namely the banning the use of organochlorine contaminants, led to a concentration decline. However, Lindane, which was restricted in 1990, can still be found in the watershed. According to NOAA guidelines, pesticides concentrations encountered in these sediments are low and probably not having an adverse effect on sediment dwelling organisms.
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Affiliation(s)
- C M Alonso-Hernández
- Centro de Estudios Ambientales de Cienfuegos, AP 5, Ciudad Nuclear, Cienfuegos, Cuba.
| | - I Tolosa
- International Atomic Energy Agency - Marine Environment Laboratories, 4, Quai Antoine 1er, MC 98000, Monaco
| | - M Mesa-Albernas
- Centro de Estudios Ambientales de Cienfuegos, AP 5, Ciudad Nuclear, Cienfuegos, Cuba
| | - M Díaz-Asencio
- Centro de Estudios Ambientales de Cienfuegos, AP 5, Ciudad Nuclear, Cienfuegos, Cuba
| | - J A Corcho-Alvarado
- Spiez Laboratory, Federal Office for Civil Protection, CH-3700 Spiez, Switzerland; Institute of Radiation Physics (IRA), Lausanne University Hospital, Rue du Grand Pré 1, 1007 Lausanne, Switzerland
| | - J A Sánchez-Cabeza
- Instituto de Ciencias del Mar y Limnología, Universidad Nacional Autónoma de México, 04510 Ciudad de México, Mexico
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