Water Pollution History of Switzerland Recorded by Sediments of the Large and Deep Perialpine Lakes Lucerne and Geneva

This review addresses the quantification of anthropogenic pollutants in lacustrine sediments by multidisciplinary analyses including: chronostratigraphy using radioisotopes (137Cs) and radiocarbon dates (14C), trace metal analysis, faecal indicator analysis, as well as antibiotic-resistant genes by molecular analysis. Sediment cores from lakes Lucerne and Geneva that are located at a distance of 150km from each other reveal a synchronous increase in anthropogenic trace metals (Pb, Cu, Zn, and Mn) following the industrial revolution in Europe about 1850. In both lakes, the peak of water pollution by toxic metals due to discharge of industrial wastewaters was reached in the middle of the twentieth century. During the second part of the twentieth century, both sites show a decrease in metal pollution following the implementation of wastewater treatment plants. On the contrary, the Vidy Bay of Lake Geneva where the treated wastewaters from the city of Lausanne are released since 1964 points out a dramatic increase in trace metal deposition. Later, a high increase in organic matter deposition, in bacteria (Escherichia coli and Enterococcus faecalis) activity as well as antibiotic-resistant genes and bacteria occurred into the bay, simultaneously with the eutrophication of the large and deep perialpine lakes in the 1970s due to excessive external nutrient loadin

Human impact on the transport of terrigenous and anthropogenic elements to peri-alpine lakes (Switzerland) over the last decades

Terrigenous (Sc, Fe, K, Mg, Al, Ti) and anthropogenic (Pb and Cu) element fluxes were measured in a new sediment core from Lake Biel (Switzerland) and in previously well-documented cores from two upstream lakes (Lake Brienz and Lake Thun). These three large peri-alpine lakes are connected by the Aare River, which is the main tributary to the High Rhine River. Major and trace element analysis of the sediment cores by inductively coupled plasma mass spectrometry (ICP-MS) shows that the site of Lake Brienz receives three times more terrigenous elements than the two other studied sites, given by the role of Lake Brienz as the first major sediment sink located in the foothills of the Alps. Overall, the terrigenous fluxes reconstructed at the three studied sites suggest that the construction of sediment-trapping reservoirs during the twentieth century noticeably decreased the riverine suspended sediment load at a regional scale. In fact, the extensive river damming that occurred in the upstream watershed catchment (between ca. 1930 and 1950 and up to 2,300m a.s.l.) and that significantly modified seasonal suspended sediment loads and riverine water discharge patterns to downstream lakes noticeably diminished the long-range transport of (fine) terrigenous particles by the Aare River. Concerning the transport of anthropogenic pollutants, the lowest lead enrichment factors (EFs Pb) were measured in the upstream course of the Aare River at the site of Lake Brienz, whereas the metal pollution was highest in downstream Lake Biel, with the maximum values measured between 1940 and 1970 (EF Pb>3). The following recorded regional reduction in aquatic Pb pollution started about 15years before the actual introduction of unleaded gasoline in 1985. Furthermore, the radiometric dating of the sediment core from Lake Biel identifies three events of hydrological transport of artificial radionuclides released by the nuclear reactor of Mühleberg located at more than 15km upstream of Lake Biel for the time period 1970-200

Assessment of pathogenic bacteria in water and sediment from a water reservoir under tropical conditions (Lake Ma Vallée), Kinshasa Democratic Republic of Congo

This study was conducted to assess potential human health risks presented by pathogenic bacteria in a protected multi-use lake-reservoir (Lake Ma Vallée) located in west of Kinshasa, Democratic Republic of Congo (DRC). Water and surface sediments from several points of the Lake were collected during summer. Microbial analysis was performed for Escherichia coli, Enterococcus (ENT), Pseudomonas species and heterotrophic plate counts. PCR amplification was performed for the confirmation of E. coli, ENT, Pseudomonas spp. and Pseudomonas aeruginosa isolated from samples. The results reveal low concentration of bacteria in water column of the lake, the bacterial quantification results observed in this study for the water column were below the recommended limits, according to WHO and the European Directive 2006/7/CE, for bathing water. However, high concentration of bacteria was observed in the sediment samples; the values of 2.65 × 103, 6.35 × 103, 3.27 × 103 and 3.60 × 108 CFU g−1 of dry sediment for E. coli, ENT, Pseudomonas spp. and heterotrophic plate counts, respectively. The results of this study indicate that sediments of the Lake Ma Vallée can constitute a reservoir of pathogenic microorganisms which can persist in the lake. Possible resuspension of faecal indicator bacteria and pathogens would affect water quality and may increase health risks to the population during recreational activities. Our results indicate that the microbial sediment analysis provides complementary and important information for assessing sanitary quality of surface water under tropical conditions

Human impact on the transport of terrigenous and anthropogenic elements to peri-alpine lakes (Switzerland) over the last decades

Terrigenous (Sc, Fe, K, Mg, Al, Ti) and anthropogenic (Pb and Cu) element fluxes were measured in a new sediment core from Lake Biel (Switzerland) and in previously well-documented cores from two upstream lakes (Lake Brienz and Lake Thun). These three large peri-alpine lakes are connected by the Aare River, which is the main tributary to the High Rhine River. Major and trace element analysis of the sediment cores by inductively coupled plasma mass spectrometry (ICP-MS) shows that the site of Lake Brienz receives three times more terrigenous elements than the two other studied sites, given by the role of Lake Brienz as the first major sediment sink located in the foothills of the Alps. Overall, the terrigenous fluxes reconstructed at the three studied sites suggest that the construction of sediment-trapping reservoirs during the twentieth century noticeably decreased the riverine suspended sediment load at a regional scale. In fact, the extensive river damming that occurred in the upstream watershed catchment (between ca. 1930 and 1950 and up to 2300 m a.s.l.) and that significantly modified seasonal suspended sediment loads and riverine water discharge patterns to downstream lakes noticeably diminished the long-range transport of (fine) terrigenous particles by the Aare River. Concerning the transport of anthropogenic pollutants, the lowest lead enrichment factors (EFs Pb) were measured in the upstream course of the Aare River at the site of Lake Brienz, whereas the metal pollution was highest in downstream Lake Biel, with the maximum values measured between 1940 and 1970 (EF Pb >3). The following recorded regional reduction in aquatic Pb pollution started about 15 years before the actual introduction of unleaded gasoline in 1985. Furthermore, the radiometric dating of the sediment core from Lake Biel identifies three events of hydrological transport of artificial radionuclides released by the nuclear reactor of Mühleberg located at more than 15 km upstream of Lake Biel for the time period 1970 to 200

Les résidus carbonés de feux dans les sédiments: Implications méthodologiques, climatiques et anthropiques

Biomass burning in the tropics release about 25% of annual anthropogenic CO2 emissions, and large amounts of aerosol particles that play an important role in atmospheric chemistry and climate. The sedimentary carbonaceous particles emitted by plant organic matter combustion represent proxies of past fire activity. The analysis of refractory carbonaceous species behavior with different analytical methods has allowed to characterize with an increasing oxidation level : charcoal, refractory carbon and Black Carbon (BC). Despite that the analysis of the graphite concentration introduced in synthetic powders presents ca. 20% mass loss, the BC extractive methods indicate a satisfactory reproducibility and reliability to reconstruct sedimentary changes in biomass burning. Elemental analysis of carbon resistant to thermal and/or chemical extraction, combined with automatic-image analysis of charcoal, was applied to a marine record from the Western Pacific Warm Pool (WPWP) spanning the last 360 kyr and to a Tanzanian lacustrine record spanning the last 4 kyr. In the oceanic record, carbonaceous aerosols (charcoal and BC) display orbital precession plus its harmonics related frequencies, suggesting that fire activity closely responded to the variations in seasonal radiation forcing at the equator, but also that changes in high-latitudes forcing (Dansgaard-Oeschger periodicities) on the winter monsoon contribute to ENSO-like conditions. In addition, carbonaceous aerosol clearly registered human-induced fire-regime alteration in the Indo/Pacific area, with great increases in fire-activity between 53-43 and 12-10 kyr. Charcoal abundance and distribution in lake Masoko reveal that runoff and erosion on woodland soils are the dominant processes for charred particle transportation. However, the carbonaceous aerosol fraction (charcoal<1µm and BC) clearly illustrate fire activity. Its abrupt increase between 1,8 and 1,6 cal. kyr B.P. in lake Masoko testifies regional emissions from forest fires prior the local fire extend. This latter event is contemporaneous with an abrupt deforestation and coincides with the extend of Late Iron Age and agricultural activities in the East African Rift. These results demonstrate that carbonaceous residues analysis in sediments provides informations on past-climatic changes, human impact on the environment, and global carbon budget.Bien que les émissions de gaz à effet de serre et d'aérosols carbonés par les feux tropicaux, étroitement liées aux conditions de sécheresse et à l'action anthropique, aient un impact significatif sur le cycle du carbone et sur le climat global, la dynamique passée de ces émissions reste encore peu documentée. Cette étude a pour but de caractériser les produits de combustion carbonés piégés dans les sédiments lacustres et marins, afin d'établir des enregistrements fiables de la variabilité des feux tropicaux. L'analyse du comportement de standards carbonés sur des matrices synthétiques et naturelles à l'aide de différentes techniques d'extraction a permis de discriminer, selon un degré croissant de résistance à l'oxydation : le charbon, le carbone réfractaire, et le Black Carbon (BC). Bien que l'analyse de mélanges expérimentaux présente des pertes de masse d'environ 20% dans le cas du graphite mélangé à des poudres synthétiques, la méthode d'extraction et de mesure du BC s'avère reproductible et fiable pour reconstituer les changements de concentration enregistrés dans la plupart des sédiments. L'analyse du carbone élémentaire résistant aux traitements chimiques et/ou thermique, combinée au comptage automatisé des microcharbons, a ensuite été appliquée à une séquence pélagique du Pacifique Ouest (WPWP) couvrant les derniers 360 ka, et à un enregistrement lacustre Tanzanien couvrant les derniers 4 ka. L'enregistrement marin (carotte MD972140) montre que les émissions de BC sont fortement contraintes par les variations d'insolation en région intertropicale et équatoriale (cycles de précession et semi-précession). Elles sont également associées à la variabilité (pluri)millénaire du climat de l'hémisphère nord et de la mousson d'hiver est-asiatique, et suggèrent un couplage entre le gradient zonal des précipitations dans le Pacifique Equatorial et le climat des hautes latitudes. De plus, les aérosols carbonés enregistrent clairement l'action de l'homme sur le régime des feux dans la région Indo-Pacifique, avec une forte augmentation des apports de BC et de microcharbons entre 53-43 ka et 12-10 kyr. Au lac Masoko (carotte MM8), l'abondance et la nature des assemblages de particules de charbon reflètent en partie les apports détritiques liés au ruissellement des sols forestiers ou à l'érosion lors de bas niveaux lacustres. De plus, l'augmentation rapide des aérosols carbonés (microcharbons <1µm et BC) entre 1,8 et 1,6 ka BP suggère une intensification des incendies régionaux, contemporaine de l'expansion de la métallurgie et de l'agriculture dans le Rift Est Africain. L'identification et la quantification du carbone réfractaire piégé dans le réservoir sédimentaire montre ainsi que la dynamique des feux a été fortement contrainte par la variabilité du cycle hydrologique saisonnier et pluriannuel, et par l'action anthropique. Depuis plusieurs dizaines de milliers d'années, cette dernière est probablement déterminante vis-à-vis des quantités de carbone réfractaire émises dans l'environnement

Les résidus carbonés de feux dans les sédiments lacustres et océaniques intertropicaux (implications méthodologiques, climatiques et anthropiques)

Cette étude a pour but de caractériser les produits de combustion piégés dans les sédiments, afin d'établir des enregistrements de la variabilité des feux tropicaux. La méthode de mesure du Black Carbon (BC) est d'abord testée sur des standards puis appliquée aux sédiments. La séquence du Pacifique Ouest (carotte MD972140 ; 360 ka) montre que les feux sont contraints par les variations d'insolation en région intertropicale et équatoriale. Elle suggère aussi un couplage entre les précipitations équatoriales et le climat des hautes latitudes. De plus, l'augmentation en BC et microcharbons entre 53-43 et 12-10 ka atteste de l'impact de l'homme sur le régime des feux. Au lac Masoko (carotte MM8 ; 4 ka), les assemblages de charbon reflètent les apports détritiques liés au ruissellement ou à l'érosion des sols. Mais l'augmentation en microcharbons et BC ~1,8 ka BP suggère des incendies régionaux, contemporains de l'expansion de la métallurgie et de l'agriculture en Afrique de l'Est.AIX-MARSEILLE3-BU Sc.St Jérô (130552102) / SudocSudocFranceF

Water Pollution History of Switzerland Recorded by Sediments of the Large and Deep Perialpine Lakes Lucerne and Geneva

This review addresses the quantification of anthropogenic pollutants in lacustrine sediments by multidisciplinary analyses including: chronostratigraphy using radioisotopes (137Cs) and radiocarbon dates (14C), trace metal analysis, faecal indicator analysis, as well as antibiotic-resistant genes by molecular analysis. Sediment cores from lakes Lucerne and Geneva that are located at a distance of 150 km from each other reveal a synchronous increase in anthropogenic trace metals (Pb, Cu, Zn, and Mn) following the industrial revolution in Europe about 1850. In both lakes, the peak of water pollution by toxic metals due to discharge of industrial wastewaters was reached in the middle of the twentieth century. During the second part of the twentieth century, both sites show a decrease in metal pollution following the implementation of wastewater treatment plants. On the contrary, the Vidy Bay of Lake Geneva where the treated wastewaters from the city of Lausanne are released since 1964 points out a dramatic increase in trace metal deposition. Later, a high increase in organic matter deposition, in bacteria (Escherichia coli and Enterococcus faecalis) activity as well as antibiotic-resistant genes and bacteria occurred into the bay, simultaneously with the eutrophication of the large and deep perialpine lakes in the 1970s due to excessive external nutrient loading

Les indicateurs de bactéries pathogènes résistantes aux antibiotiques dans les sédiments du Léman

L'évaluation des bactéries indicatrices de contamination fécale dans les lacs d'eau douce, et plus particulièrement l'occurrence de bactéries résistantes aux antibiotiques dans les sédiments, est primordiale. Cet intérêt est lié au risque potentiel de remise en suspension des agents pathogènes qui peuvent affecter la qualité de l'eau et dès lors présenter des risques pour la santé humaine, par exemple lors d'activités récréatives et/ou suite à la consommation d'eau potable contaminée. Deux stratégies ont été développées pour l'étude de l'accumulation de ces bactéries dans les sédiments lacustres contaminés. La première approche consiste à extraire et à quantifier les bactéries indicatrices de contamination fécale (FIB), y compris Escherichia coli (E. coli) et Enterococcus spp (ENT) à partir d'échantillons de sédiments, suivi par la caractérisation de bacteroides spécifiques pour l'homme par PCR en utilisant des amorces spécifiques et par matrix-assisted laser desorption ionization- time of flight mass spectrometry (MALDI-TOF MS). Une seconde approche est basée sur l'évaluation de la résistance multiple aux antibiotiques (MAR) à partir de FIB isolées. Malgré l'importance de cette thématique, de nombreuses questions restent en suspens, en particulier concernant le rôle des caractéristiques physico-chimiques des sédiments sur l'accumulation de FIB et les effets négatifs potentiels sur les écosystèmes et la santé humaine (risques de résistance aux antibiotiques FIB). Cet article présente un aperçu des méthodes récemment mises au point à l'Institut F.-A. Forel pour l'extraction et la quantification de FIB-MAR dans les carottes de sédiments prélèverecueillis dans la baie de Vidy qui est la zone la plus contaminée du Léman à cause des rejets des eaux traitées par la station d'épuration de la ville de Lausanne. Ces eaux usées proviennent de l'industrie, des hôpitaux et des activités domestiques. Notre recherche démontre que les sédiments qui se sont accumulés dans cette baie depuis 50 ans sont fortement contaminés et constituent un réservoir important de FIB, FIB-MAR et de gènes de résistance aux antibiotiques qui persistent dans les sédiments riches en matière organique

Pollen-based vegetation changes in southern Tanzania during the last 4200 years: climate change and/or human impact

The age-constrained pollen data of a sedimentary sequence from the crater Lake Masoko, southern Tanzania (9‡20PS, 33‡45PE, 770 m), display a continuous record of vegetation for the past 4200 years. This record provides evidence that wetter Zambezian woodlands always occupied this area during the late Holocene, reaching a maximum extent between 2800 and 1650 cal yr BP related to increase in summer monsoon intensity. However, three main episodes of decline have been detected, between 3450 and 2800 cal yr BP, between 1650 and 1450 cal yr BP and from 1200 to 500 cal yr BP, for which a climatic interpretation, decrease in the summer monsoon strength, was preferentially advanced. The first is synchronous with lowstand of many tropical African lakes and, so, mainly induced by increased aridity. In contrast, the abrupt change in the pollen record at 1650^1550 cal yr BP is marked by a large extension of grasslands at the expense of arboreal cover, further by an increase in Ricinus communis and an intensification of burning. It could thus indicate local clearance of vegetation by man. However, at the same time, the decline of montane forest suggests the impact of a more regional change. During the last episode, between 1200 and 500 cal yr BP, dry climatic conditions are inferred from a combination of pollen, diatom and magnetic proxies, although the occurrence of Late Iron Age settlements in the region means that local human interference cannot be excluded. This study illustrates the difficulties in deciphering ecological and anthropological changes from pollen data in African tropical regions.This work was supported by the European Community through the EEC Program Rukwa, the INSU-Variente and Eclipse (CLEHA) programs