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201.
202.
Maurizio Pettine Silvio Capri Maria Giuseppina Farrace Maura Manganelli Luisa Patrolecco Alberto Puddu 《Chemistry and Ecology》2013,29(1-2):13-25
The results obtained in the four seasonal cruises planned in the PRISMA II project are reported. These concern dissolved and colloidal organic carbon, free amino acids and total dissolved carbohydrates and heterotrophic activity. Main factors controlling organic matter degradation, resulting from laboratory tests not planned in the above project, are also discussed. Dissolved organic matter shows seasonal accumulation, which may be markedly different from year to year, and large contributions by colloidal and saccharide components. Heterotrophic activities play an important role in the carbon cycle, although laboratory runs highlight limitations caused by aging of organic matter and phosphorus deficiency. 相似文献
203.
Zhengchi Yang Lihua Liu Lu Zhao Gang Su Zuoxiao Wei Anping Tang Jianrong Xue 《环境科学学报(英文版)》2019,31(12):24-37
Problems associated with water eutrophication due to high phosphorus concentrations and related environmentally safe solutions have attracted wide attention. A novel bis(diallyl alkyl tertiary ammonium salt) polymer, particularly poly(N~1,N~1,N~6,N~6-tetraallylhexane-1,6-diammonium dichloride)(PTAHDADC), was synthesized and characterized by Fourier transform infrared spectroscopy, nuclear magnetic resonance, scanning electron microscopy, mercury intrusion method, and thermogravimetric analysis. The adsorption characteristics in phosphorus were evaluated in dilute solution, and the recycling properties of PTAHDADC were investigated. Results showed that PTAHDADC possessed macropores with a size distribution ranging from 30 to 130 μm concentrating at 63 μm in diameter and had 46.52% of porosity, excellent thermal stability below 530 K, and insolubility. PTAHDADC could effectively remove phosphorus at p H = 7–11 and had a removal efficiency exceeding 98.4% at pH = 10–11. The adsorption equilibrium data of PTAHDADC for phosphorus accorded well with the Langmuir and pseudo-second-order kinetic models. Maximum adsorption capacity was 52.82 mg/g at 293 K. PTAHDADC adsorbed phosphorus rapidly and reached equilibrium within 90 min. Calculated activation energy Eawas 15.18 k J/mol. PTAHDADC presented an excellent recyclability with only 8.23% loss of removal efficiency after five adsorption–desorption cycles. The morphology and structure of PTAHDADC slightly changed as evidenced by the pre-and post-adsorption of phosphorus, but the process was accompanied by the partial deprotonation of the(–CH_2)_3-NH~+ group of PTAHDADC. The adsorption was a spontaneous exothermic process driven by entropy through physisorption, electrostatic attraction, and ion exchange. Survey results showed that PTAHDADC was a highly efficient and fast-adsorbing phosphorus-removal material prospective in treating wastewater. 相似文献
204.
Maurizio Pettine Silvio Capri Maria Giuseppina Farrace Maura Manganelli Luisa Patrolecco Alberto Puddu Annamaria Zoppini 《Chemistry and Ecology》2002,18(1):13-25
The results obtained in the four seasonal cruises planned in the PRISMA II project are reported. These concern dissolved and colloidal organic carbon, free amino acids and total dissolved carbohydrates and heterotrophic activity. Main factors controlling organic matter degradation, resulting from laboratory tests not planned in the above project, are also discussed. Dissolved organic matter shows seasonal accumulation, which may be markedly different from year to year, and large contributions by colloidal and saccharide components. Heterotrophic activities play an important role in the carbon cycle, although laboratory runs highlight limitations caused by aging of organic matter and phosphorus deficiency. 相似文献
205.
Sabine Braun Vera F.D. Thomas Rebecca Quiring Walter Flückiger 《Environmental pollution (Barking, Essex : 1987)》2010,158(6):2043-2052
Effects of elevated N deposition on forest aboveground biomass were evaluated using long-term data from N addition experiments and from forest observation plots in Switzerland. N addition experiments with saplings were established both on calcareous and on acidic soils, in 3 plots with Fagus sylvatica and in 4 plots with Picea abies. The treatments were conducted during 15 years and consisted of additions of dry NH4NO3 at rates of 0, 10, 20, 40, 80, and 160 kg N ha−1 yr−1. The same tree species were observed in permanent forest observation plots covering the time span between 1984 and 2007, at modeled N deposition rates of 12-46 kg N ha−1 yr−1. Experimental N addition resulted in either no change or in a decreased shoot growth and in a reduced phosphorus concentration in the foliage in all experimental plots. In the forest, a decrease of foliar P concentration was observed between 1984 and 2007, resulting in insufficient concentrations in 71% and 67% of the Fagus and Picea plots, respectively, and in an increasing N:P ratio in Fagus. Stem increment decreased during the observation period even if corrected for age. Forest observations suggest an increasing P limitation in Swiss forests especially in Fagus which is accompanied by a growth decrease whereas the N addition experiments support the hypothesis that elevated N deposition is an important cause for this development. 相似文献
206.
The diversity and community composition of phosphorus accumulating organisms (PAOs) in the sediments of the Sanshiliujiao Lake reservoir in Pingtan island, Fujian Province, were investigated by terminal restriction fragment length polymorphism (T-RFLP) methods combined with the construction of clone libraries. The diversity of PAOs in summer samples was significantly higher than that in winter. The dominant terminal restriction fragments (T-RFs) of PAOs were in the range of 200 to 300 bp in summer, while they were in the range of 150 to 200 bp in winter. Cloning sequencing and phylogenetic analysis showed that the main phyla of PAOs in the sediment of the Sanshiliujiao Lake reservoir were Proteobacteria, Actinobacteria, and Acidobacteria. Anaeromyxobacter, Azospirillum, Microlunatus phosphovorus, and Burkholderia were the dominant genera in the summer samples. Anaeromyxobacter, Methylobacterium, Solibacter, Azospirillum, and Microlunatus phosphovorus were the dominant genera in sediment samples in winter. The results of this study demonstrated that the diversity and community composition of PAOs in the sediments of the Sanshiliujiao Lake reservoir had specific seasonal characteristics. Various forms of phosphorus also showed their influence on the diversity of PAOs, especially Fe/Al-P. Our findings lays a scientific foundation for the future disclosure of microbial mechanisms involved in the phosphorus metabolic cycle in the sediments of reservoirs. © 2018 Science Press. All rights reserved. 相似文献
207.
A. Chapelle 《Ecological modelling》1995,80(2-3)
A model of nitrogen and phosphorus cycles in the sediment of a lagoon has been developed. This model was applied to the Thau lagoon (southern France). Sediment was sliced in three layers to reproduce the oxygen profile, which is simulated within the model. Following an equilibrium hypothesis, the model was calibrated against field data. State variables and fluxes were estimated in the sediment and across the sediment-water interface. A Monte Carlo sensitivity analysis was performed to determine the most sensitive parameters and sediment state variables. A dynamic simulation with varying oxygen concentrations then showed the influence of anoxia on the phosphorus and nitrogen fluxes between water and sediment. 相似文献
208.
209.
A newly installed combined detention/wetland stormwater treatment facility upstream from Lake McCarrons, Roseville, Minnesota,
was monitored for 21 months to evaluate its effectiveness and the response of the lake to decreased phosphorus loads. The
treatment facility consists of a 1.0-ha detention pond that discharges into a series of six constructed wetland “chambers.”
Data from snowmelt and rainfall events are presented for several pollutants. Results show good reductions for most pollutants.
Discussion on the facets of the system's operation are presented. Data from the lake show very little change in its water
quality from three years prior to restoration (1984–1986) to three years following restoration (1987–1989): the lake's phosphorus
and chlorophyll has actually increased. 相似文献
210.
Edgar F. Lowe Lawrence E. Battoe David L. Stites Michael F. Coveney 《Environmental management》1992,16(1):67-74
Lake Apopka in Florida, USA, is a large (area=124 km2), hypertrophic (mean total phosphorus=0.220 g/m3; mean chlorophylla=60 mg/m3) lake, with a large sedimentary store of available P (1635 × 106 g P). Phosphorus loading from floodplain farms (132 × 106 g P/yr) has been the primary cause of eutrophication. Assuming elimination of farm P loading, the Vollenweider model predicts
a decline in equilibrium P concentration from 0.270 to 0.024 g/m3, if the P sedimentation coefficient (σ) remains constant. It is likely, however, that the value for σ will fall with the
elimination of farm loading due to unabated internal P loading from the sediments. Under a worst-case scenario (σ=0), the
model predicts that exportation of P from the lake via wetland filtration will greatly accelerate the lake's recovery. Recirculation
of lake water through a 21-km2, created wetland and elimination of farm P loading is projected to result in a negative P balance for the lake (−23 × 106 g P/yr) leading to depletion of P stores in the lake in about 60 yr. The estimated cost of the project, $20 million, is less
than 3% of the estimated cost of dredging. A 3.65-km2 demonstration project is underway to test and refine the wetland filtration technique. We believe the technique could be
cost-effective for other hypertrophic lakes. 相似文献