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1.
ABSTRACT This study investigated the impact of pastoral land use and nutrient and fine sediment inputs on Microcoleus autumnalis and filamentous algae-dominated mats, and benthic chlorophyll-a in streams (lower North Island, New Zealand). Surveying and sampling was undertaken monthly at 61 sites spanning a wide gradient in catchment cover and environmental conditions. Two boosted regression tree models were built. The first models included pastoral land cover and five environmental variables as predictors. In the second model pastoral land cover was replaced by nutrient/sediment data. The abundance of the two mat types and chlorophyll-a increased when pastoral land cover was between 20% and 70% (model 1). Replacement of pastoral land cover by nutrient/sediment data (model 2) slightly improved the model fit for all three periphyton variables. Microcoleus autumnalis-dominant mats increased with dissolved inorganic nitrogen concentrations up to ca. 0.6?mg?L?1, and in streams with more frequent flushes. In contrast, filamentous algal-dominated mats increased with turbidity, and in streams with less frequent flushes. Chlorophyll-a generally followed the response of the dominant periphyton type. Increased knowledge on responses of specific periphyton types, rather than total biomass, to environmental variables is essential to guide effective management strategies. 相似文献
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Pollani Annika Triantafyllou George Petihakis George Nittis Konstantinos Dounas Costas Christoforos Koutitas 《Marine pollution bulletin》2001,43(7-12):270-278
In this work the development and the application of an operational management tool for the Greek Seas is described. This tool consists of a three-dimensional floating pollutant prediction model coupled with a weather, a hydrodynamic and a wave model in order to track the movements and the spreading of the pollutants and indicate those coastal areas which might be affected. The tool is part of the Poseidon system which has been designed to provide real time data and forecasts for marine environmental conditions in the Greek Seas. In this paper, we present four case studies based on realistic scenarios that show the value of the application for long-term strategic planning and short-term decision making in oil spill accidents. 相似文献
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Edmundo Placencia-Gómez Annika Parviainen Tero Hokkanen Kirsti Loukola-Ruskeeniemi 《Environmental Earth Sciences》2010,61(7):1435-1447
The Haveri tailings area contains 1.5 Mt of sulfide-bearing waste from the Au–Cu mine that operated during 1942–1961. Geophysical
and geochemical methods were used to evaluate and characterize the generation of acid mine drainage (AMD). Correlations were
examined among the electrical resistivity tomography (ERT) data, the total sulfide content and concentrations of sulfide-bound
metals (Cu, Co, Fe, Mn, Ni, Pb and Zn) of tailings samples, and the resistivity and geochemistry of surface water. The resulting
geophysical–geochemical model defines an area in the vadose tailings, where a low resistivity anomaly (<10 Ohm m) is correlated
with the highest sulfide content, extensive sulfide oxidation and low pH (average 3.1). The physical and geochemical conditions,
resulting from the oxidation of the sulfide minerals, suggest that the low resistivity anomaly is associated with acidic and
metal-rich porewater (i.e., AMD). The lower resistivity values in the saturated zone of the central impoundment suggest the
formation of a plume of AMD. The natural subsoil layer (silt and clay) and the bedrock surface below the tailings area were
well mapped from the ERT data. The detected fracture zones of the bedrock that could work as leakage pathways for AMD were
consistent with previous geological studies. The integrated methodology of the study offers a promising approach to fast and
reliable monitoring of areas of potential AMD generation and its subsurface movement over large areas (ca. 9 ha). This methodology
could be helpful in planning drill core sampling locations for geochemical and mineralogical analysis, groundwater sampling,
and choosing and monitoring remedial programs. 相似文献
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Janina Konarska Fredrik Lindberg Annika Larsson Sofia Thorsson Björn Holmer 《Theoretical and Applied Climatology》2014,117(3-4):363-376
Trees play an important role in mitigating heat stress on hot summer days, mainly due to their ability to provide shade. However, an important issue is also the reduction of solar radiation caused by trees in winter, in particular at high latitudes. In this study, we examine the transmissivity of total and direct solar radiation through crowns of single street trees in Göteborg, Sweden. One coniferous and four deciduous trees of species common in northern European cities were selected for case study. Radiation measurements were conducted on nine clear days in 2011–2012 in foliated and leafless tree conditions using two sunshine pyranometers—one located in shade of a tree and the other one on the roof of an adjacent building. The measurements showed a significant reduction of total and direct shortwave radiation in the shade of the studied trees, both foliated and leafless. Average transmissivity of direct solar radiation through the foliated and defoliated tree crowns ranged from 1.3 to 5.3 % and from 40.2 to 51.9 %, respectively. The results confirm the potential of a single urban tree to reduce heat stress in urban environment. However, the relatively low transmissivity through defoliated trees should be considered while planning street trees in high latitude cities, where the solar access in winter is limited. The results were used for parameterisation of SOLWEIG model for a better estimation of the mean radiant temperature (Tmrt). Measured values of transmissivity of solar radiation through both foliated and leafless trees were found to improve the model performance. 相似文献
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Anne Klöppel Martin Pfannkuchen Annika Putz Peter Proksch & Franz Brümmer 《Marine Ecology》2008,29(2):259-272
Sponges provide the largest number of biologically active natural products known from the marine environment and continue to be a very well studied phylum of marine fauna. The Mediterranean sponge Aplysina aerophoba accumulates brominated isoxazoline alkaloids such as Aplysinamisin-1, Aerophobin-2, Isofistularin-3 and the biotransformation product Aeroplysinin-1, which possesses, for example, antibiotic and cytotoxic properties. Until now, it is still being discussed which organisms – the sponge itself or associated microorganisms – are responsible for metabolite production. For cultivating Aplysina individuals under ex situ conditions, we surveyed relevant ecological factors in situ and controlled them in our aquarium system. We maintained A. aerophoba for more than 9 months and analysed changes of metabolite content and composition, microbial association as well as morphology in situ and ex situ under different light exposure. Although sponges showed slight reduction during maintenance, ex situ cultivation similar to in situ conditions provides a promising method to keep sponges and obtain their bioactive metabolites. 相似文献
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Due to the climate change, vegetation of tundra ecosystems is predicted to shift toward shrub and tree dominance, and this change may influence bryophytes. To estimate how changes in growing environment and the dominance of vascular plants influence bryophyte abundance, we compared the relationship of occurrence of bryophytes among other plant types in a five-year experiment of warming (T), fertilization (F) and T + F in two vegetation types, heath and meadow, in a subarctic–alpine ecosystem. We compared individual leaf area among shrub species to confirm that deciduous shrubs might cause severe shading effect. Effects of neighboring functional types on the performance of Hylocomium splendens was also analyzed.Results show that F and T + F treatments significantly influenced bryophyte abundance negatively. Under natural conditions, bryophytes in the heath site were negatively related to the abundance of shrubs and lichens and the relationship between lichens and bryophytes strengthened after the experimental period. After five years of experimental treatments in the meadow, a positive abundance relationship emerged between bryophytes and deciduous shrubs, evergreen shrubs and forbs. This relationship was not found in the heath site. Our study therefore shows that the abundance relationships between bryophytes and plants in two vegetation types within the same area can be different. Deciduous shrubs had larger leaf area than evergreen shrubs but did not show any shading effect on H. splendens. 相似文献
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Annika Nolte Malte Eley Matthias Schöniger David Gwapedza Jane Tanner Sukhmani Kaur Mantel Konstantin Scheihing 《水文研究》2021,35(6):e14264
To increase the resilience of regional water supply systems in South Africa in the face of anticipated climatic changes and a constant increase in water demand, water supply sources require diversification. Many water-stressed metropolitan regions in South Africa depend largely on surface water to cover their water demand. While climatic and river discharge data is widely available in these regions, information on groundwater resources – which could support supply source diversification – is scarce. Groundwater recharge is a key parameter that is used to estimate groundwater amounts that can be sustainably exploited at a sub-watershed level. Therefore, the objective of this study was to develop a reliable hydrological modelling routine that enables the assessment of regional spatio-temporal variations of groundwater recharge to discern the most promising areas for groundwater development. Accordingly, we present a semi-distributed hydrological modelling approach that incorporates water balance routines coupled with baseflow modelling techniques to yield spatio-temporal variations of groundwater recharge on a regional level. The approach is demonstrated for the actively managed catchment areas of the Amathole Water Supply System situated in a semi-arid part of the Eastern Cape of South Africa. In the investigated study area, annual groundwater recharge exhibits a high spatio-temporal heterogeneity and is estimated to vary between ~0.5% and 8% of annual rainfall. Despite some uncertainties induced by limited data availability, calibration and validation of the model were found to be satisfactory and yielded model results similar to (point) data of annual groundwater recharge reported in earlier studies. Our approach is therefore found to derive crucial information for efficiently targeting more detailed groundwater exploration studies and could work as a blueprint for orientating groundwater potential exploration in similar environments. 相似文献
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Annika Parviainen Matthew B.J. Lindsay Rafael Pérez-López Blair D. Gibson Carol J. Ptacek David W. Blowes Kirsti Loukola-Ruskeeniemi 《Applied Geochemistry》2012
Nearly half a century after mine closure, release of As from the Ylöjärvi Cu–W–As mine tailings in groundwater and surface water run-off was observed. Investigations by scanning electron microscopy (SEM), electron microprobe analysis (EMPA), synchrotron-based micro-X-ray diffraction (μ-XRD), micro-X-ray absorption near edge structure (μ-XANES) and micro-extended X-ray absorption fine structure (μ-EXAFS) spectroscopy, and a sequential extraction procedure were performed to assess As attenuation mechanisms in the vadose zone of this tailings deposit. Results of SEM, EMPA, and sequential extractions indicated that the precipitation of As bearing Fe(III) (oxy)hydroxides (up to 18.4 wt.% As2O5) and Fe(III) arsenates were important secondary controls on As mobility. The μ-XRD, μ-XANES and μ-EXAFS analyses suggested that these phases correspond to poorly crystalline and disordered As-bearing precipitates, including arsenical ferrihydrite, scorodite, kaňkite, and hydrous ferric arsenate (HFA). The pH within 200 cm of the tailings surface averaged 5.7, conditions which favor the precipitation of ferrihydrite. Poorly crystalline Fe(III) arsenates are potentially unstable over time, and their transformation to ferrihydrite, which contributes to As uptake, has potential to increase the As adsorption capacity of the tailings. Arsenic mobility in tailings pore water at the Ylöjärvi mine will depend on continued arsenopyrite oxidation, dissolution or transformation of secondary Fe(III) arsenates, and the As adsorption capacity of Fe(III) (oxy)hydroxides within this tailings deposit. 相似文献
10.
Many individual-level behaviors are associated with greenhouse gas (GHG) emissions. Reliable and valid assessment instruments are needed to (1) identify behaviors and populations to target with emissions-reduction programs and policies, (2) evaluate the effectiveness of such programs, (3) link self-reported and objective measures of GHG emissions to establish the impact of specific behaviors, and (4) estimate frequencies of behaviors and their changes over time to aid policy makers in understanding energy consumption trends. The self-administered Stanford Climate Change Behavior Survey (SCCBS) is shown to be a reliable and valid instrument that can be used for these purposes in college students, and we anticipate that it will also be useful for assessing these behaviors in other adolescent or adult populations in developed countries. Questions included behaviors likely to be within the control of most individuals and did not include behaviors specific to home owners (e.g. appliance purchases). Ten indices were identified: Energy Use, No-, Low-, and High-GHG Transportation, Waste, Food Packaging, High- and Low-GHG Food, Food Purchasing, and GHG Credits use. A Total GHG Behavior score was calculated. Test–retest reliabilities of individual items ranged from .64 to .91. Internal consistency reliabilities for each of the indices ranged from .51 to .89. Most indices were statistically significantly correlated with one another. Correlational validity of the SCCBS was demonstrated with statistically significant associations between behavior scores and perceived importance of environmental sustainability and membership in an environmental organization. The use of the SCCBS to identify potential target sub-populations and behaviors was demonstrated. 相似文献