Cs and

Various studies have been conducted during the fast decade onto atmospheric deposited 210Pb and caesium isotopes in soils in order to quantify soil erosion rates. In North Morocco (Tangier area), erosion is a real problem leading to silting up of artificial lakes. Soil profiles were collected in cultivated areas from the catchment basin of one of this lake in order to quantify the erosion. 137Cs and 210Pb concentrations and inventories were measured and their spatial distribution was studied in relation with other parameters : granulometry, pH, organic matter content. Mean 137Cs inventory in stable soils was found to be 2582 Bq.m-2 in 1999, in agreement with literature data for Spanish and Portuguese soils. Depth profiles were usual, showing an exponential decrease with depth for 210Pb and a subsurface peak for 137Cs in reference soils where it was found until 30 cm depth. No clear relations appeared with organic matter content or pH and the distribution of the inventories is probably linked to erosion process. Estimated erosion rates varied from 5 to 66 t.ha-1y-1, but the use of different models for such estimation led to important differences

Aerosols in Northern Morocco: Input pathways and their chemical fingerprint

International audienc

Quaternary palaeoclimates in the eastern Canary islands

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Sedimentology and geochemistry of lacustrine terraces of three Middle Atlas lakes: Paleohydrological changes for the last 2300 cal BP in Morocco (western Mediterranean region)

International audienceIn the Moroccan Middle Atlas Mountains, three lakes were used to characterize climate variability in the late Holocene. The methodology is based on sedimentological, geochemical, and mineralogical analysis of lacustrine terraces. Lake Ifrah is a natural lake. Waters are calc-magnesian, relatively very alkaline and oxygenated. Lake Afourgagh is of karst origin, with maximum depth 1.5 m. Lake Iffer is a smaller lake, sub-circular and relatively deep. Its area is 3.5 ha. Its maximum depth is 6.5 m at the center of the lake. Seven terraces located in the borders of the lakes were sampled and studied. Seven radiocarbon dates were obtained on organic matter and shells. The time period concerned is between 2300 cal BP and 400 cal BP. The results show high lake levels at about 2300 cal BP related probably to the wetter Iberian - Roman period in northern Mediterranean. Lake Iffer was deeper by about 30 m from its current level. 1000 cal BP probably marks the beginning of the decline with a drop in lake level of 20 m, which is ongoing in connection with drier climate and the beginning of the medieval climate anomaly. (C) 2015 Elsevier Ltd and INQUA. All rights reserved

Recent environmental changes and human impact since mid 20th century in Mediterranean Lakes : Ifrah, Iffer and Afourgagh, Middle Atlas Morocco.

International audienceThe multidisciplinary study of sediment cores from three middle Atlas lakes (central Morocco) provides a detailed record of environmental, climatic and anthropogenic changes. The paleohydrological reconstructions show fluctuating lake level since the mid-20th century. Human activities have played a significant role in the lakes' hydrological changes. The sedimentology, geochemistry and mineralogy results show three main periods. The first period between 1900 and 1920 is humid with high lake levels, with fine particle size and relatively high contents of organic matter. The second period between 1920 and 1965 is very unstable with varying humidity. The last period between 1965 and 2000 is characterised by increasing human activities (clearing of forest and development of agricultural techniques). This last phase was interrupted by some humid years or sub-periods (between 1976 and 1980, between 1995 and 1996) and dry years (between 1980 and 1990, between 1994 and 1995). This study provides an opportunity to evaluate the relative significance of human and climatic factors in middle Atlas lakes during the 20th century

Impacts climatiques et anthropiques sur le fonctionnement hydrogéochimique du Lac Ifrah (Moyen Atlas marocain)

International audienceMonitoring hydrogeochemical seasonality of Lake Ifrah (Morocco) was carried out between 2003 and 2006 in order to characterize the hydrogeochemical processes in the context of climatic and anthropogenic impacts. Lake Ifrah has declined significantly over the last decade. The waters are fairly alkaline, oxygenated, fairly turbid and oversaturated alkaline. The suspended load is moderately high. The hydrogeochemical facies is typically chloro-sodium bicarbonate magnesium. The lake is experiencing a significant water deficit as a result of recurrent droughts over the last three decades and marked human pressure. This is reflected by the increase in salinity manifested primarily by increased electrical conductivity and alkali contents (Na+ and K+) and chloride. This deficit is also assessed by lower levels of alkaline earth (Ca2+ and Mg2+) as a result of their precipitation as endogenic carbonates. The saturation index of calcite, aragonite and dolomite is always greater than zero. The increase in nutrients (phosphorus and nitrates) and degradation of water oxygenation reflect the acceleration of the eutrophication of the lake which is also evident from the increased particulate load and turbidity of the water

Human impact on fluvial regimes and sediment flux during the Holocene: review and future research agenda

There is a long history of human–riverine interactions throughout the period of agriculture that in some regions of the world started several thousand years ago. These interactions have altered rivers to human dominated systems with often negative impacts on fluvial environments. To achieve a good ecological and chemical status of rivers, as intended in the European Water Framework Directive (WFD), a better understanding of the natural status of rivers and an improved quantification of human–riverine interactions is necessary. Over the last decade the PAGES-LUCIFS (Land Use and Climate Impact on Fluvial Systems) program has been investigating both contemporary and long-term (centuries tomillennia) river responses to global change with the principal aims of: 1) quantifying land use and climate change impacts of river-borne fluxes of water, sediment, C, N and P; 2) identification of key controls on these fluxes at the catchment scale; and 3) identification of the feedback on both human society and biogeochemical cycles of long-termchanges in the fluxes of these materials. Here, we review recent progress on identifying fluvial system baselines and quantifying the response of long-term sediment budgets, biogeochemical fluxes and flood magnitude and frequency to Holocene global change. Based on this review, we outline the future LUCIFS research agenda within the scope of the PAGES-PHAROS (Past Human-Climate-Ecological Interactions) research program. Key research strategies should be focused on: 1) synthesising the data available from existing case studies; 2) targeting research in data-poor regions; 3) integrating sediment, C, N and P fluxes; 4) quantifying the relative roles of allogenic and autogenic forcing on fluvial regimes, extreme events and sediment fluxes; 5) improving long-term river basin modelling; and 6) integration of LUCIFS with other research communities within PHAROS, namely HITE (land cover) and LIMPACS (water quality and biodiversity).status: publishe