A comparison of the carbon balances of a natural lake (L. Orträsket) and a hydroelectric reservoir (L. Skinnmuddselet) in northern Sweden

Carbon balances were calculated for the summer stratification period of 2001 for the hydroelectric reservoir L. Skinnmuddselet (created in 1989) and the natural L. Ortr?sket, and estimated on annual basis for both lakes. The reservoir and the lake have similar chemical characteristics and are located in adjacent catchments in the northern part of Sweden. Our main hypothesis was that the CO(2) production and emissions from the reservoir, L. Skinnmuddselet, would be greater than in the natural L. Ortr?sket, due to the decomposition of flooded vegetation and peat. The carbon balances showed that the total production of CO(2) per unit lake surface area during the summer was very similar in the natural lake and the reservoir (31.3 g Cm(-2) in L. Ortr?sket and 25.3 g Cm(-2) in L. Skinnmuddselet). The sediments were the major CO(2) source in the reservoir, while most of the mineralization in the natural lake occurred in the water column. On annual basis the natural L. Ortr?sket produced and emitted more CO(2) per unit of lake surface area than the reservoir L. Skinnmuddselet since mineralization proceeded during winter when L. Skinnmuddselet was emptied for electricity production. Therefore, the potential for CO(2) emission was not greater in the reservoir than in the natural lake.     

Integral assessment of pollution in the Suquía River (Córdoba, Argentina) as a contribution to lotic ecosystem restoration programs

The Suquía River lower-middle basin (Córdoba, Argentina) is subject to a strong anthropic impact because it receives pollutants from different sources (industries, wastewaters, heavy traffic, agricultural land use, etc.) We have assessed the degree of watershed degradation of Suquía River lower-middle sections through the analysis of different ecosystem compartments (air, water, riparian soil, sediments and biota), in order to provide useful data to be considered in future river restoration programs. Four study sites were selected along the river (La Calera city, Córdoba city, Corazón de María village and Río Primero city) which were sampled during the low- and high-water flow periods. We analyzed: a) chemical and physical characteristics of water, sediments, and riparian soil; b) heavy metal content of water and sediments, and c) semi-volatile organic compounds in air. Besides, pollutant bioindicators such as fish assemblages, lichens (Usnea amblyoclada), vascular plants (Tradescantia pallida), and microorganisms (fecal coliform and Escherichia coli) were used to further assess the status of the river. All analyzed ecological compartments were affected by water pollution, particularly, fish assemblages, sediments and riparian soils by heavy metal and coliform bacteria. Moreover, we detected a possible contribution of sulfur and a high pollutant content in air that merit further research about other air-water exchanges. Accordingly, we strongly suggest that an action to restore or remediate the anthropic effect on the Suquía River be extended to all possible compartments along the river.     

Chlorinated pesticides and polychlorinated biphenyls in marine tucuxi dolphins (Sotalia fluviatilis) from the Cananéia estuary,southeastern Brazil

The Cananéia estuary is an important biological area on the southeast coast of Brazil. In the past, it was impacted by both chlorinated pesticides and polychlorinated biphenyls (PCBs) due to its natural location. The marine tucuxi dolphin (Sotalia fluviatilis) is a top predator in this ecosystem and can be found year round in Cananéia estuarine waters that represent an important nursing area for the species. This work investigated chlorinated compounds in the blubber of nine individuals from the Cananéia estuary. Residue levels of DDTs (0.541-125 microg g(-1) lipid wt.) were the highest, followed by PCBs (0.2-9.22 microg g(-1) lipid wt.), mirex (0.014-0.312 microg g(-1) lipid wt.), chlordanes (0.001-0.047 microg g(-1) lipid wt.), HCHs (<0.003-0.044 microg g(-1) lipid wt.), and HCB (n.d.-0.024 microg g(-1) lipid wt.). The mean p,p'-DDE/Sigma DDT ratio was approximately 0.8 and is indicative of the former DDT application in the study area. PCB contamination is suggested to be associated with atmospheric transport and relative proximity to the Cubat?o industrial complex-the most important along the Brazilian coast. Low levels of HCHs and HCB can be attributed to their high volatility in tropical environments. Concentrations of organochlorines in the blubber of marine tucuxis from the Cananéia estuary were lower than levels found in small cetacean species from developed countries, where the input of these compounds was considerably greater than in Brazil. At extremes, male dolphins can present DDT burden several orders of magnitude higher than females. Despite the high levels of total DDT found in males, the major detected compound was p,p'-DDE which is considered to be of low toxicity.     

Is there a risk associated with the insect repellent DEET (N,N-diethyl-m-toluamide) commonly found in aquatic environments?

DEET (N,N-diethyl-m-toluamide) is the active ingredient of most commercial insect repellents. This compound has commonly been detected in aquatic water samples from around the world indicating that DEET is both mobile and persistent, despite earlier assumptions that DEET was unlikely to enter aquatic ecosystems. DEET's registration category does not require an ecological risk assessment, thus information on the ecological toxicity of DEET is sparse. This paper reviews the presence of DEET in aqueous samples from around the world (e.g. drinking water, streams, open seawater, groundwater and treated effluent) with reported DEET concentrations ranging from 40-3000 ng L(-1). In addition, new DEET data collected from 36 sites in coastal waterways from eastern Australia (detections ranging from 8 to 1500 ng L(-1)) are examined. A summary of new and existing toxicity data are discussed with an emphasis on preparing a preliminary risk assessment for DEET in the aquatic environment. Collated information on DEET in the aquatic environment suggests risk to aquatic biota at observed environmental concentrations is minimal. However, the information available was not sufficient to conduct a full risk assessment due to data deficiencies in source characterisation, transport mechanisms, fate, and ecotoxicity studies. These risks warrant further investigation due to the high frequency that this organic contaminant is detected in aquatic environments around the world.     

Mercury and flooding cycles in the Tapajós River basin, Brazilian Amazon: the role of periphyton of a floating macrophyte (Paspalum repens)

Methylmercury (MeHg) increases mercury (Hg) toxicity and is biomagnified in the trophic chain contaminating riverine Amazon populations. Freshwater macrophyte roots are a main site of Hg methylation in different Brazilian environments. Paspalum repens periphyton was sampled in four floodplain lakes during the dry, rainy and wet seasons for measurement of total Hg (THg), MeHg, Hg methylation potentials, %C, %N, δ¹³C, δ¹⁵N and bacterial heterotrophic production as ³H-leucine incorporation rate. THg concentration varied from 67 to 198 ng/g and the potential of Me²⁰³Hg formation was expressive (1-23%) showing that periphyton is an important matrix both in the accumulation of Hg and in MeHg production. The concentration of MeHg varied from 1 to 6 ng/g DW and was positively correlated with Me²⁰³Hg formation. Though methylmercury formation is mainly a bacterial process, no significant correlation was observed between the methylation potentials and bacterial production. The multiple regressions analyses suggested a negative correlation between THg and %C and %N and between methylation potential and δ¹³C. The discriminant analysis showed a significant difference in periphyton δ¹⁵N, δ¹³C and THg between seasons, where the rainy season presented higher δ¹⁵N and the wet period lighter δ¹³C, lower THg values and higher Me²⁰³Hg formation. This exploratory study indicates that the flooding cycle could influence the periphyton composition, mercury accumulation and methylmercury production.     

Isotopic identification of the sources of lead contamination for white storks (Ciconia ciconia) in a marshland ecosystem (Doñana,S.W. Spain)

White storks (Ciconia ciconia) fed in contaminated waters resulting from the Aznacollar acid mining-sludge spillage into the R. Guadiamar, which feeds the eastern flank of the Guadalquivir marshes (Do?ana), S.W. Spain. The sludge was rich in a range of toxic elements, and in organic pollutants such as the aromatic amines. Storks did not exhibit elevated metals in their blood immediately following the accident, but chick blood collected the year following the accident showed genotoxic damage compared to the controls. In this study lead isotope analysis was used to assess if the storks had ingested sludge-derived contaminants. The sludge lead isotope ratio was distinct from that of the Do?ana sediments. The stork blood lead isotope ratios exactly matched that of the sludge. It was concluded that the storks had ingested sludge-derived contaminants. A detailed study of the lead contamination along the R. Guadiamar and the R. Guadalquivir (of which the Guadiamar is a tributary) was also conducted to place the white stork colony lead exposure in the context of the spatial contamination of the storks' habitat.     

Pattern recognition techniques for the evaluation of spatial and temporal variations in water quality. A case study: Suquía River Basin (Cordoba-Argentina)

We report a comparative study using three different chemometric techniques to evaluate both spatial and temporal changes in Suquía River water quality, with a special emphasis on the improvement obtained using discriminant analysis for such evaluation. We have monitored 22 parameters at different stations from the upper, middle, and beginning of the lower river basin during at least two years including 232 different samples. We obtained a complex data matrix, which was treated using the pattern recognition techniques of cluster analysis (CA), factor analysis/principal components (FA/PCA). and discriminant analysis (DA). CA renders good results as a first exploratory method to evaluate both spatial and temporal differences, however it fails to show details of these differences. FA/PCA needs 13 parameters to point out 71% of both temporal and spatial changes, consequently data reduction from FA/PCA in this case is not as considerable as expected. However, FA/PCA allows to group the selected parameters according to common features as well as to evaluate the incidence of each group on the overall change in water quality, specially during the analysis of temporal changes. DA technique shows the best results for data reduction and pattern recognition during both temporal and spatial analysis. DA renders an important data reduction using 6 parameters to afford 87% right assignations during temporal analysis. Besides, it uses only 5 parameters to yield 75% right assignations during the spatial analysis of four different basin areas. DA allowed us to greatly reduce the dimensionality of the starting data matrix, pointing out to a few parameters that indicate the biggest changes in water quality as well as variation patterns associated with seasonal variations, urban run-off, and pollution sources, presenting a novel approach for water quality assessments.     

建筑的意义就在于建筑本身——a+a、S.Y.C、A+E(奥意)、北方工业大学与黄星元大师的对话

<正>a+a:今天,我们邀请了黄星元建筑大师就建筑设计有兴趣的话题进行讨论,对大家来说是一个非常难得的机会。黄大师的建筑设计经历已有50多年,在设计一线岗位工作从未停止,完成了许多国家重点工程项目,平时喜欢与年轻建筑师讨论一些问题,直到现在仍参加许多建筑交流活动,不知黄大师最近忙些什么?今天的交流就从以年轻建筑师如何发展作为话题开始吧!黄星元:最近主要忙着编写一本书,书中只介绍一个项目,总结建筑创作从开始构思和     

Landscape dynamics of Mediterranean montane grasslands over 60 years and implications for habitats conservation. A case study in the northern Apennines (Italy)

Widespread trends of abandonment have strongly affected Mediterranean mountains after the Second World War, triggering spontaneous recolonisation of forests. A diachronic analysis of the landscape in a Natura 2000 site (Tuscany, Italy) was carried out using digital aerial photographs (1954, 2013) and a GIS-based methodology, focusing on territories above 1300 m a.s.l. The detected variations of total areas, patch shape, patch dimensions and selected metrics showed a notable shift of the vegetation towards woody types and a drastic reduction of open grasslands, some with high conservation value, accompanied by a strong increase in patch number, surface and edge. A decrease of SDI and SEI diversity indices was also observed. Considering that fragmentation is one of the main causes threatening habitats and species, our results point out a clear necessity for a monitoring programme and suitable actions aimed at improving the status of biodiversity-rich montane grasslands.     

Can fluorescence spectrometry be used as a surrogate for the Biochemical Oxygen Demand (BOD) test in water quality assessment? An example from South West England

The fluorescence intensities of tryptophan-like, tyrosine-like and humic-like materials were determined using excitation-emission-matrices (EEMs) for a wide range of samples including natural surface waters, sewage and industrial effluents and waters that have experienced known pollution events from the South West of England (n=469). Fluorescence intensities reported in arbitrary fluorescence units (AFU) were correlated with standard five day Biochemical Oxygen Demand (BOD(5)) values which were used as an indicator of the amount of biodegradable organic material present. Tryptophan-like fluorescence, which has been found to relate to the activity of the biological community, showed the strongest correlation with BOD(5). Fluorescence analysis of the tryptophan-like peak (excitation/emission wavelength region 275/340 nm) is found to provide an accurate indication of the presence, and relative proportions of bioavailable organic material present (natural or anthropogenic). It therefore provides an insight relating to its oxygen depleting potential. Thus fluorescence spectroscopy is recommended as a portable or laboratory tool for the determination of the presence of biodegradable organic matter with intrinsic oxidising potential in natural waters. The novel application of Geographically Weighted Regression (GWR) to the data illustrates that strong local relationships exist between the two parameters and that site specific character may be a strong factor in the strength of the tryptophan-like fluorescence/BOD(5) relationship.     

Anthropogenic CO2-flux into cave atmosphere and its environmental impact: A case study in the Císarská Cave (Moravian Karst, Czech Republic)

The evolution of CO2 levels was studied in the ventilated and unventilated Nagel Dome chamber (the Císarská Cave) with- and without human presence. Based on a simplified dynamic model and CO2/Rn data (222Rn considered as a conservative tracer), two types of CO2-fluxes into the chamber were distinguished: (1) the natural input of (2-4) x 10(-6) m3 s(-1), corresponding to a flux of (8.5-17) x 10(-10) m3 m(-2) s(-1) and (2) an anthropogenic input of (0.6-2.5) x 10(-4) m3 s(-1), corresponding to an average partial flux of (4.8-7.7) x 10(-6) m3 s(-1) person(-1). The chamber ventilation rates were calculated in the range from 0.033 to 0.155 h(-1). Comparison of the chamber CO2-levels with chamber dripwater chemistry indicates that the peak CO2-concentrations during stay of persons (log p(CO2) approximately -2.97, -2.89, and -2.83) do not reach the theoretical values at which dripwater carbonate species and air CO2 are at equilibrium (log p(CO2[DW]) approximately -2.76 to -2.79). This means that CO2-degassing of the dripwaters will continue, increasing supersaturation with respect to calcite (dripwater saturation index defined as SI(calcite) = a(Ca2+)a(CO3(2-))/10(-8.4) varied in the range from 0.76 to 0.86). The p(CO2[DW]) values, however, would easily be exceeded if the period of person stay in the chamber had been slightly extended (from 2.85 to 4 h under given conditions). In such case, the dripwater CO2-degassing would be inverted into CO2-dissolution and dripwater supersaturation would decrease. Achieving the threshold values at which water become aggressive to calcite (log p(CO2[EK]) approximately -1.99, -2.02, and -1.84) would require extreme conditions, e.g., simultaneous presence of 100 persons in the cave chamber for 14 h. The study should contribute to a better preservation of cave environment.     

Do time‐averaged,whole‐building,effective volatile organic compound (VOC) emissions depend on the air exchange rate? A statistical analysis of trends for 46 VOCs in U.S. offices

We used existing data to develop distributions of time‐averaged air exchange rates (AER), whole‐building ‘effective’ emission rates of volatile organic compounds (VOC), and other variables for use in Monte Carlo analyses of U.S. offices. With these, we explored whether long‐term VOC emission rates were related to the AER over the sector, as has been observed in the short term for some VOCs in single buildings. We fit and compared two statistical models to the data. In the independent emissions model (IEM), emissions were unaffected by other variables, while in the dependent emissions model (DEM), emissions responded to the AER via coupling through a conceptual boundary layer between the air and a lumped emission source. For 20 of 46 VOCs, the DEM was preferable to the IEM and emission rates, though variable, were higher in buildings with higher AERs. Most oxygenated VOCs and some alkanes were well fit by the DEM, while nearly all aromatics and halocarbons were independent. Trends by vapor pressure suggested multiple mechanisms could be involved. The factors of temperature, relative humidity, and building age were almost never associated with effective emission rates. Our findings suggest that effective emissions in real commercial buildings will be difficult to predict from deterministic experiments or models.