Sedimentary and diagenetic features in saline lake deposits of the Monegros region, northern Spain

The Monegros region in northern Spain is marked by the occurrence of a large number of ephemeral to dry lake basins, occupying small karstic depressions. The lacustrine sediment fill of these basins contain various carbonate and silicate minerals whose origin and palaeoenvironmental significance is poorly understood. For the present study, 14 lake basins were sampled in order to establish vertical, lateral and regional variations in mineralogical and textural characteristics, aimed at determining the mode of formation of the various mineral phases present. In nearly all basins, the same sequence of three lithological units is recognized, including a basal clayey unit, a middle magnesite-bearing and gypsum-rich unit, and a calcite- and dolomite-dominated surface unit. Distribution patterns of carbonate minerals indicate that magnesite is a synsedimentary precipitate, dolomite formed as a diagenetic authigenic phase, and calcite is partly authigenic and partly allogenic. All clay minerals, including sepiolite and smectite, appear to be allogenic. Regional variations are marked by similarities between groups of neighbouring basins, but no overall trend related to regional drainage patterns is recognized. The middle lithological unit records a lake stage with predominantly chemical sedimentation (Unit II), overlying a less well documented interval corresponding to a perennial lake stage with lower salinity (Unit III), whereas the surface unit formed during a period with predominantly clastic sedimentation. Based on a comparison with other regional records, the middle unit is attributed to an Early Holocene humid stage, separated from the overlying Late Holocene deposits by a hiatus that corresponds to a Mid Holocene arid stage.     

Mercury Bioaccumulation in Rainbow Trout (Oncorhynchus mykiss) and the Trout Food Web in Lakes Okareka,Okaro, Tarawera,Rotomahana and Rotorua,New Zealand

Methyl mercury (Hg) was determined in rainbow trout (Oncorhynchus mykiss) and organisms in the lower tropic levels: smelts (Retropinna retropinna), bullies (Gobiomorphus cotidianus), koura (Paranephrops planifrons); and zooplankton (Daphnia carinata and Calamoecia lucasi) in Lakes Okareka, Okaro, Tarawera, Rotorua and Rotomahana, New Zealand. Water concentrations of total Hg (Hg_T) and methyl Hg were also measured. Mean methyl Hg concentrations in the trout, the prey species (smelts, bullies and koura) and zooplankton increased linearly with mean Hg_T and methyl Hg chloride (CH₃HgCl) concentrations in water. Most of the bio-magnification of methyl Hg occurred in the lower trophic levels of the trout food web (10^4.72) between the zooplankton and water. The bioaccumulation factors between the forage fish and zooplankton were 10^0.73 for bullies and 10^1.06 for smelt. Methyl Hg was 10^0.41 to 10^0.95 times greater in the trout then their prey.     

Comparative Analysis of Metal Concentrations and Sediment Accumulation Rates in Two Virginian Reservoirs,USA: Lakes Moomaw and Pelham

Water, Air, &; Soil Pollution - Agricultural chemicals from nonpoint sources in groundwater are present in the major provinces of the High Plains aquifer in Nebraska. Nitrate and...     

Heavy Metals in the Aerosols Collected at Two Stations in Mallorca (Spain)

An extensive study of the different heavy metals (Fe, Mn Ni, Cr, Zn, Cd, Pb, Cu) present in the atmospheric aerosols collected at two stations in Mallorca located in the evirons of a new incinerator plant has been carried out. The aim of this study is to establish the quality of the air surrounding this new MSW (Municipal Solid Waste) incinerator on the island of Mallorca prior to its setting up. Besides, a study of the distribution of the analyzed metals in both the fine (diameter ≤1.5 μm) and coarse (diameter ≥1.5 μm) fractions of the aerosol has been performed. Concentrations of heavy metals in the atmospheric aerosols prior to the running of the new incinerator plant were found to be very low and similar to the values obtained at other Mediterranean stations.     

Historical Variations in Lead Fluxes in the Pyrenees (Northeast Spain) from a Dated Lake Sediment Core

Variations in Pb concentration in lake sediments reflect changes in the fluxes of this element in the past. A sediment core from a lake in the Pyrenees (Lake Redó at 2,240 m a.s.l., NE Spain) was studied, with the aim of reconstructing past environmental and climatic conditions in the lake and its catchment area. The core was dated using both 210Pb and 14C. A surface peak of Pb concentration, which was about 10 times higher than the background level, was found. This peak is attributed to mining activities since the beginning of this century. Although Pb pollution due to the combustion of gasoline is expected to be present, no evidence can be deduced from Pb isotope ratios of sediment due to the masking effect of Pb from mines. A second peak appeared in a deeper layer, with a maximum Pb concentration of about 17 times higher than the background level. The origin of this peak is unclear. All evidence suggests that the ancient peak is due to mining operations in the central Pyrenees area, which were not documented historically.     

Main Environmental Features Leading to Recent Land Abandonment in Murcia Region (Southeast Spain)

Land abandonment is a global phenomenon whose environmental consequences are difficult to assess. The Murcia region is one of the most arid regions in southern Europe and also one of the most prone to land abandonment. This study researches which environmental features are more relevant to explain abandonment at the agricultural plot scale. Geomorphometric features were measured at different scales to investigate which scales could be more relevant. Two different models have been used: logistic regression, a statistical model that allows the interpretation of the involved features, and Random Forest, a machine learning model with a higher predictive power but lower interpretability. The combined use of both such models allows a set of predictors to be selected, which, when used with Random Forest, produce a map that is highly accurate for predicting abandonment and, when used with logistic regression, produce an interpretable model. The main conclusion is that climate is the most relevant factor to explain land abandonment. Copyright © 2015 John Wiley & Sons, Ltd.     

The Spatial and Temporal Distributions of Spheroidal Carbonaceous Fly-Ash Particles (SCP) in the Sediment Records of European Mountain Lakes

Sediment cores were taken from 31 mountain lakes in 11 countries across Europe. For each core a full spheroidal carbonaceous particle (SCP) profile was produced. SCP are derived from the high temperature combustion of fossil-fuels and provide an unambiguous record of the atmospheric deposition of anthropogenic pollutants. The data from the sediment cores were therefore able to show both temporal and spatial trends in pollutant deposition across the continent from Svalbard to southern Spain and from Ireland to the Tatra mountains. In general, the temporal trends throughout Europe were remarkably consistent and were seen to be in good agreement with known historical emissions, combustion figures and modelled historical pollutant patterns for source countries. Spatial patterns showed that highest concentrations and accumulation rates were in central Europe, with clear decreases northwards and southwards from the region. An east to west decrease was also apparent. SCP profiles can be converted to full post-Industrial inventories and normalised against a ²¹⁰Pb inventory to create a ‘pollution index’ covering the whole of the SCP record. Such indices take into account sediment variability and some catchment influences and are therefore better for inter-site comparisons. These results were seen to show a clear latitudinal pattern, with a maximum at around 50°N and declining to the north and south. This agrees with European sulphur emissions data and are generally consistent with EMEP modelled distribution patterns. In many cases the SCP temporal profiles could only be explained by using emission and combustion statistics from more than one country emphasising the transboundary nature of particulate transport throughout Europe, in general, supporting EMEP modelled ‘blame matrices’.     

Metal Pollution by Old Lead-Zinc Mines in Urumea River Valley (Basque Country,Spain). Soil,Biota and Sediment

Soil, aquatic biota (moss: Brachythecium rivulare; aquatic macrophytes: Juncus effusus, Potamogeton crispus; fish: Salmo trutta fario, Anguilla anguilla, Phoxinus phoxinus, Chelon labrosus) and sediment samples from the Urumea river valley were analysed for metals by acid digestion and atomic absorption spectroscopy. The sediments show the presence of metal pollution (Cd: 2.5–24 mg kg^-1; Pb: 125–1,150 mg kg^-1; Zn: 125–2,500 mg kg^-1) because mining and industrial wastes. A selective retention of dense minerals in dam sediments contributes to the load of metal, but interstitial water analysis (Cd: <0.02–0.1 mg L^-1; Pb: 0.3–1.0 mg L^-1; Zn: <0.05–0.6 mg L^-1) shows that precipitation equilibrium controls their mobilisation. Biota samples show evidence of metal accumulation, moss reaching 1,100 mg kg^-1 in lead and 6,800 mg kg^-1 in zinc. Soil from the valley is polluted by both, river carried material and industrial sources (Cd: 1.0–4.0 mg kg^-1; Pb: 26–1,120 mg kg^-1; Zn: 105–1,390 mg kg^-1/math>), but they are used, indistinctly, for farming and pasture.     

Assessment of the Colonization and Primary Production of Microphytobenthos in the Littoral of Acidic Mining Lakes in Lusatia (Germany)

In 3 extremely acidic mining lakes (pH 2.6-3.1) in Lusatia (Brandenburg, Germany) microphytobenthos colonization was characterized by a very low species diversity, and partly high abundances of the dominant species. Eunotia exigua (Bacillariophyceae) was frequent in all lakes. The abundance of Nitzschia paleaeformis (Bacillariophyceae) clearly increased with increasing pH. Euglena mutabilis (Euglenophyceae) occured mainly in the littoral of Lake 108 with a strongly varying spatial and temporal distribution. Mean concentrations of microphytobenthic biomass, measured as chlorophyll a (Chl), showed marked variations between the lakes and ranged between 1.3 - 17.9 µg Chl g dw-1 or 5.1 - 120 mg Chl m-2. Primary production of microphytobenthos was measured using polyethylene foils as artificial substrates or by direct measurements of sediment surface samples. Primary production rates and specific production rates ranged between 0.99 - 5.1 mg C m-2h-1 and 0.04 - 0.33 mg C (mg Chl)-1h-1, respectively. The impact of the sediment chemistry (especially the available carbon) is discussed as determining factor for the species composition and activity of the microphytobenthic species. First insights can be given concerning the relevance of benthic algae for the carbon metabolism of the investigated acidic mining lakes.     

Phosphorus Fractionation and Short-term Mobility in the Surface Sediment of a Polymictic Shallow Lake Treated with a Low Dose of Alum (Courtille Lake,France)

Lake Courtille was a polymictic eutrophic lake prone to large pH variations and sediment resuspension. Short term P release (96 hr) under laboratory resuspension conditions for two sedimentsample types, surface sediments which represent sediment accumulated over several years and trap sediments which representcurrent year sediment, was studied. The experiments were carriedout in oxic conditions at different pH values. According to phosphorus fractionation, Fe-bound-P, Al-bound-P and Organic-bound-P comprised the largest phosphorus pool (80% of Total Phosphorus). Phosphorus release was from the Fe-P, Al-P and organic fractions. These represent 35% of the total phosphorus content at pH 10. At circumneutral pH, in oxic conditions, a lower quantity of P was released (roughly 4% of total P sediment content) than at pH 10. The organic matter mineralization occurring at the end of summer can also influenceP release as illustrated by the difference in total phosphoruscontent between sediment samples of 2000 and of the last five years. This type of P release was observed in Lake Courtille. High soluble reactive phosphorus content was measured in the water column at the end of summer. Aluminium treatment was thus not efficient in preventing P release. Moreover, a higher alum dose was needed to reduce P content in the water column in order to decrease primary productivity and subsequent organic matter sedimentation.     

Impact of Nitrate Addition on Phosphorus Availability in Sediment and Water Column and on Plankton Biomass-Experimental Field Study in the Shallow Brackish Schlei Fjord (Western Baltic, Germany)

The Schlei is a hypertrophic brackish fjord of the Baltic. In order to assess the optimal method for restorative sediment treatment, an in-situ-experiment was carried out to oxidize the uppermost sediment strata by direct nitrate injection. An area of 3,5 ha, covered with sapropelic sediment, was treated with 50 t of commercial calcium-salpetre. Half of this area was treated once with a dose of 140 g NO3-N m-2, whereas the other half was treated twice receiving a dose of 280 g NO3-N m-2. Two enclosures were installed on these treated areas. The reaction in the interstitial water of the sediment (nitrate, phosphate, sulphate, iron) and in the water bulk (tot-N, tot-P) are documented and compared with an untreated reference area. Moreover, the impact of the sediment treatment on the phyto- and zooplankton biomass is discussed.     

云南省两种地貌类型下河流悬沙浓度变化状况与治理对策

分析了云南省大理白族自治州漾濞江流域和文山壮族苗族自治州盘龙河流域的河流悬沙浓度的持续变化状况，结果表明：漾濞江流域河流悬沙浓度逐年减少，而盘龙河流域却一直在攀升。结合区内的自然与经济状况，探讨了相应的治理对策。     

Closed basins and Vertisol formation in the rincon lagoon (Andalusia,Spain)

A study was made of the genetic relationship between the geomorphological phenomenon of closed basins and Vertisol formation in an area of Southern Spain.The lithology of the area, the low erosive power of the drainage system and the semi-arid climate are factors which favour the seasonal hydromorphism responsible for the evolution of original material into Vertisols.Depth dissolution of Keuper saline materials gives rise to the creation of basins, where water accumulates, forming laggons.Although El Rincón lagoon is now a closed basin, in the past it formed part of a larger lacustrine area which to a great extent gave rise to the blackening of the soils.     

Plant succession and soil degradation in desertified areas (Fuerteventura,Canary Islands,Spain)

The eastern Canary Islands constitute a region that is vulnerable to desertification processes, mainly due to its intensely arid climate and the action of man. Vegetation in the island of Fuerteventura has been profoundly transformed over the last few hundred years, and the greater part of the insular territory is presently covered by substitution brush.In this work, a study of soil degradation processes relating to plant cover transformation is presented. To this end, soils that characterize the present-day countryside of the island and those associated with enclaves of original vegetation are studied, and the sequential variation of soil properties along the plant succession is established by means of multivariant analysis of environmental gradients.The results indicate that the original vegetation was established on soils with a low natural quality, severely limited by natural aridity, salinity and sodicity as well as the water and wind erosion processes dominant in the island. These same ecological factors condition the quality of the island's present soils, although the degradation of the plant cover has increased the severity of several soil degradation processes, particularly those of a physical and biological nature.     

Dry Deposition to the Forest Canopy and Surrogate Surfaces in Two Mediterranean Holm Oak Forests in Montseny (NE Spain)

The fluxes recovered from washing branches and surrogatesurfaces were compared for two holm oak (Quercus ilex L.)forests in the Montseny mountains (NE Spain) differentiallyexposed to pollution. For 5 periods in May and June 1996 afterexposures ranging between 68–189 hr, 6 metacrylate plates and 8branches were extracted with distilled water. Also, a sequentialwashing of branches was undertaken, with 5 min separationsbetween the 3 initial washes, one hour between the 3rd and the4th, and 6 hr between the 4th and the last one. The compositionwas analysed for PO₄ ^3-, SO₄ ^2-,NO₃ ^-, Cl, F, NH₄ ⁺,Ca²⁺, Mg²⁺, Na⁺, K⁺, Cu, Pb, Mn, Co, Ni and Zn. The applied techniques were consistent in that dry deposition would accountfor the throughfall fluxes of NO₃ ^-, Cl^-,Cu and Zn. Potassium and Mn would derive mostly from leaching and their fluxes were strongly related with the holm oak flower growth. ForMg²⁺ and SO₄ ^2- either leaching or impaction of small particles or gases (for SO₄ ^2-) could account forthe recovered fluxes. Also for Na⁺ and Ca²⁺ the experiments did not produce conclusive results. Ammonium, F, Pb,Co, and Na were under the detection limit of analyticaltechniques in the plate-wash. The exposed site presented higherleaf-wash and plate-wash fluxes for all elements. This wasattributed to its higher exposure to pollutants, and forleaching-derived elements, to its higher site fertility.     

Flood events in Mediterranean ephemeral streams (ramblas) in Valencia region,Spain

This article deals with flood events in Mediterranean ephemeral streams typical of the Valencia region. The combination of the basin physical characteristics (steep slopes, sparse vegetation, thin soils and permeable rock) and intense, heavy and irregularly distributed rain, generates flash floods. Runoff generation is sudden, giving rise to flash floods with sharp, narrow hydrographs with short time lags. The high amount of runoff is, nevertheless, only a small fraction of the total rainfall, since the characteristics of the river basins are such that infiltration of large amounts of water occurs. Using daily hydrological data from the Rambla de la Viuda basin and 5-min data from both the Barranc del Carraixet and the Rambla de Poyo basins, the rainfall–runoff processes have been analysed during flood events in these ephemeral streams.     

Sediment Accumulation of Nutrients (N, P) in the Eastern Gulf of Finland (Baltic Sea)

Dry weight (DW), ignition loss (IL) and concentrations of total nitrogen (TN) and total phosphorus (TP) of the sediment surface layer (0 to 10 cm, 1 cm slices) were analyzed from 20 sites in the eastern Gulf of Finland. The distance of the sampling sites from the mouth of the River Neva explained the nutrient concentrations of the sediments well, while the effect of water depth was negligible. The increase of TN and the decrease of TP along the transect from the river mouth towards the open Gulf were caused by the diminishing share of allochthonous material supplied from the River Neva. The mean TN concentration of the different accumulation areas was about 40 % higher in the sediment surface than in the deeper layer (9 to 10 cm). The corresponding difference for TP varied from 53 to 56 %. The results suggest considerable netflux of nutrients from sediment to water. The net sediment accumulation of nutrients were estimated as 6.0 g m-2 a-1 of N and 1.7 g m-2 a-1 of P corresponding 22 000 t a-1 of N and 6 100 t a-1 of P for the whole eastern Gulf.     

Nitrogen Fractions and Release in the Sediments from the Shallow Lakes in the Middle and Lower Reaches of the Yangtze River Area, China

Different nitrogen (N) fractions from 14 sediments from the shallow lakes in the middle and lower reaches of Yangtze River area before and after N release experiments were investigated, and the content of different N fractions, and contribution of different N fractions to the N released from sediments were also studied. Ion-exchangeable form (IEF–N), carbonate form (CF–N), iron-manganese oxide form (IMOF–N) and organic matter-sulfide form (OSF–N) accounted for 2.72～17.67%, 0.47～4.43%, 1.18～3.49% and 31.05 to 71.61% to total N, respectively. The N released was higher than 50% from IEF–N, approximately 35% from OSF–N, 6 and 8% from CF–N and IMOF–N on the average. Approximately 27.32～70.02% of IEF–N, 10.37～32.11% of CF–N, 11.37～33.43% IMOF–N and 2.02～8.19% OSF–N were released. For the sediments that were slightly polluted, IEF–N was the main N fraction that may be released and its contribution to total N released was more than 63.07%, for the sediments that TN was higher than 3,540.27 mg·kg^?1, OSF–N would become the main N fraction that can be released and its contribution to total N released was more than 45%.