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النتائج 1 - 10 من 36
Biogeochemical malfunctioning in sediments beneath a deep-water fish farm
2012
Valdemarsen, Thomas | Bannister, Raymond J. | Hansen, Pia K. | Holmer, Marianne | Ervik, Arne
We investigated the environmental impact of a deep water fish farm (190 m). Despite deep water and low water currents, sediments underneath the farm were heavily enriched with organic matter, resulting in stimulated biogeochemical cycling. During the first 7 months of the production cycle benthic fluxes were stimulated >29 times for CO₂ and O₂ and >2000 times for NH₄ ⁺, when compared to the reference site. During the final 11 months, however, benthic fluxes decreased despite increasing sedimentation. Investigations of microbial mineralization revealed that the sediment metabolic capacity was exceeded, which resulted in inhibited microbial mineralization due to negative feed-backs from accumulation of various solutes in pore water. Conclusions are that (1) deep water sediments at 8 °C can metabolize fish farm waste corresponding to 407 and 29 mmol m⁻² d⁻¹ POC and TN, respectively, and (2) siting fish farms at deep water sites is not a universal solution for reducing benthic impacts.
اظهر المزيد [+] اقل [-]Long-term biological monitoring of environmental quality around a solid waste landfill assessed with lichens
2012
Paoli, L. | Corsini, A. | Bigagli, V. | Vannini, J. | Bruscoli, C. | Loppi, S.
The diversity of epiphytic lichens and the accumulation of selected trace elements in the lichen Flavoparmelia caperata L. (Hale) were used as indicators of pollution around a landfill in central Italy along 14 years of waste management. Lichens revealed an increased deposition for some elements (i.e., Cd, Cr, Fe and Ni) and a decrease of the lichen diversity at sites facing the landfill after an enlargement of the dumping area. However, the results allowed to exclude a significant increase in heavy metal depositions in the surrounding area and suggested that successful waste management may be associated with environmental quality. It is concluded that lichen monitoring might provide essential information to enhance the implementation of ecological impact assessment, supporting industrial regulatory procedures, also when waste management is concerned.
اظهر المزيد [+] اقل [-]High nitrogen and elevated [CO₂] effects on the growth, defense and photosynthetic performance of two eucalypt species
2012
Novriyanti, Eka | Watanabe, Makoto | Kitao, Mitsutoshi | Utsugi, Hajime | Uemura, Akira | Koike, Takayoshi
Atmospheric nitrogen deposition and [CO₂] are increasing and represent environmental problems. Planting fast-growing species is prospering to moderate these environmental impacts by fixing CO₂. Therefore, we examined the responses of growth, photosynthesis, and defense chemical in leaves of Eucalyptus urophylla (U) and the hybrid of E. deglupta × E. camadulensis (H) to different CO₂ and nitrogen levels. High nitrogen load significantly increased plant growth, leaf N, net photosynthetic rate (Agᵣₒwₜₕ), and photosynthetic water use efficiency (WUE). High CO₂ significantly increased Agᵣₒwₜₕ, photosynthetic nitrogen use efficiency (PNUE) and WUE. Secondary metabolite (SM, i.e. total phenolics and condensed tannin) was specifically altered; as SM of U increased by high N load but not by elevated [CO₂], and vice versa for SM of H.
اظهر المزيد [+] اقل [-]Environmental contextualisation of potential toxic elements and polycyclic aromatic hydrocarbons in biochar
2012
Freddo, Alessia | Cai, Chao | Reid, Brian J.
Nine dissimilar biochars, produced from varying feedstock at different pyrolysis temperatures, are appraised with respect to concentrations of potentially toxic elements, specifically, metals, metalloids and polycyclic aromatic hydrocarbons (PAHs). Concentrations of the metals and metalloids varied with the following ranges (mg kg⁻¹): 0.02–0.94, Cd; 0.12–6.48, Cr; 0.04–13.2, Cu; 0.1–1.37, Ni; 0.06–3.87, Pb; 0.94–207, Zn and 0.03–0.27, As. Σ₁₆PAH concentrations (16 Environmental Protection Agency (EPA) PAHs) range between 0.08 mg kg⁻¹ to 8.7 mg kg⁻¹. Subsequent comparison with background soil concentrations, concentration applied to the regulation of composted materials (Publicly Available Specification (PAS 100)) and European Union (EU) regulations relating to the application of sewage sludge to agricultural land suggest low risk associated with the concentrations of PTEs observed in biochar. Collectively, results suggest that environmental impacts attributable to metals, metalloids and PAHs associated with biochar following its application to soil are likely to be minimal.
اظهر المزيد [+] اقل [-]Establishing indices for groundwater contamination risk assessment in the vicinity of hazardous waste landfills in China
2012
Li, Ying | Li, Jinhui | Chen, Shusheng | Diao, Weihua
Groundwater contamination by leachate is the most damaging environmental impact over the entire life of a hazardous waste landfill (HWL). With the number of HWL facilities in China rapidly increasing, and considering the poor status of environmental risk management, it is imperative that effective environmental risk management methods be implemented. A risk assessment indices system for HWL groundwater contamination is here proposed, which can simplify the risk assessment procedure and make it more user-friendly. The assessment framework and indices were drawn from five aspects: source term, underground media, leachate properties, risk receptors and landfill management quality, and a risk assessment indices system consisting of 38 cardinal indicators was established. Comparison with multimedia models revealed that the proposed indices system was integrated and quantitative, that input data for it could be easily collected, and that it could be widely used for environmental risk assessment (ERA) in China.
اظهر المزيد [+] اقل [-]Ozone pollution affects flower numbers and timing in a simulated BAP priority calcareous grassland community
2012
Hayes, Felicity | Williamson, Jennifer | Mills, Gina
Mesocosms representing the BAP Priority habitat ‘Calcareous Grassland’ were exposed to eight ozone profiles for twelve-weeks in two consecutive years. Half of the mesocosms received a reduced watering regime during the exposure periods. Numbers and timing of flowering in the second exposure period were related to ozone concentration and phytotoxic ozone dose (accumulated stomatal flux). For Lotus corniculatus, ozone accelerated the timing of the maximum number of flowers. An increase in mean ozone concentration from 30ppb to 70ppb corresponded with an advance in the timing of maximum flowering by six days. A significant reduction in flower numbers with increasing ozone was found for Campanula rotundifolia and Scabiosa columbaria and the relationship with ozone was stronger for those that were well-watered than for those with reduced watering. These changes in flowering timing and numbers could have large ecological impacts, affecting plant pollination and the food supply of nectar feeding insects.
اظهر المزيد [+] اقل [-]Distribution of PCDD/Fs and organometallic compounds in sewage sludge of wastewater treatment plants in China
2012
Lu, Mang | Wu, Xue-Jiao | Zeng, De-Cai | Liao, Yong
Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), organotin and organolead compounds were measured in sewage sludge samples collected from 24 wastewater treatment plants from 18 cities of 13 provinces in China. Total international toxicity equivalent (I-TEQ) values were evaluated for PCDD/Fs. The total concentration of PCDD/Fs ranged from 104.0 to 1661 pg/g dry weight (d.w.) and 2.51–75.21 pg I-TEQ/g d.w., indicating that all I-TEQs were below Chinese legislation limit value regulated for land application. The concentrations ranged from 258 to 3886, 126 to 1129, and 84–2133 ng/g as Sn d.w., for tributyltin (TBT), dibutyltin (DBT), and diphenyltin (DPhT), respectively. On the other side, organolead concentrations ranged from 85 to 668 with an average of 279 ng/g as lead. High concentrations of organolead compounds in sewage sludge indicated that the environmental impact of organolead compounds remains in China.
اظهر المزيد [+] اقل [-]Caddisflies as biomonitors identifying thresholds of toxic metal bioavailability that affect the stream benthos
2012
Rainbow, P. S. | Hildrew, A. G. | Smith, Brian D. | Geatches, Tim | Luoma, Samuel N.
It has been proposed that bioaccumulated concentrations of toxic metals in tolerant biomonitors be used as indicators of metal bioavailability that could be calibrated against the ecological response to metals of sensitive biotic assemblages. Our hypothesis was that metal concentrations in caddisfly larvae Hydropsyche siltalai and Plectrocnemia conspersa, as tolerant biomonitors, indicate metal bioavailability in contaminated streams, and can be calibrated against metal-specific ecological responses of mayflies. Bioaccumulated concentrations of Cu, As, Zn and Pb in H. siltalai from SW English streams were related to the mayfly assemblage. Mayflies were always sparse where bioavailabilities were high and were abundant and diverse where bioavailabilities of all metals were low, a pattern particularly evident when the combined abundance of heptageniid and ephemerellid mayflies was the response variable. The results offer promise that bioaccumulated concentrations of metals in tolerant biomonitors can be used to diagnose ecological impacts on stream benthos from metal stressors.
اظهر المزيد [+] اقل [-]Impacts of human activities on coral reef ecosystems of southern Taiwan: A long-term study
2012
Liu, Pi-Jen | Meng, Pei-Jie | Liu, Li-Lian | Wang, Jih-Terng | Leu, Ming-Yih
In July 2001, the National Museum of Marine Biology and Aquarium, co-sponsored by the Kenting National Park Headquarters and Taiwan’s National Science Council, launched a Long-Term Ecological Research (LTER) program to monitor anthropogenic impacts on the ecosystems of southern Taiwan, specifically the coral reefs of Kenting National Park (KNP), which are facing an increasing amount of anthropogenic pressure. We found that the seawater of the reef flats along Nanwan Bay, Taiwan’s southernmost embayment, was polluted by sewage discharge at certain monitoring stations. Furthermore, the consequently higher nutrient and suspended sediment levels had led to algal blooms and sediment smothering of shallow water corals at some sampling sites. Finally, our results show that, in addition to this influx of anthropogenically-derived sewage, increasing tourist numbers are correlated with decreasing shallow water coral cover, highlighting the urgency of a more proactive management plan for KNP’s coral reefs.
اظهر المزيد [+] اقل [-]A comparative study on the effects of barite, ilmenite and bentonite on four suspension feeding bivalves
2012
F. Strachan, Maia | F. Kingston, Paul
The impact of drilling mud components on the filtration activity and survival of bivalve molluscs was investigated by exposing them to suspensions of ‘standard’ barite, finely milled barite, ilmenite and bentonite in sea water. Introduction of the components stimulated filtration activity in all four bivalves. In addition, the introduction of standard barite and ilmenite both had lethal effects, with none of the bivalves surviving the full duration of the experiments. In-vivo observations of the gill surfaces provided direct evidence of physical damage caused by the administration of barite and ilmenite. A marked difference between filtration activity and survival of animals dosed with ‘standard’ barite and ‘fine’ barite suggests that the observed effects were primarily caused by physical interference with gill function. The results also suggest that the use of fine barite in offshore drilling may provide a more favourable environmental impact profile than the use of ilmenite.
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