Impacts of two biomanipulation fishes stocked in a large pen on the plankton abundance and water quality during a period of phytoplankton seasonal succession

Silver and bighead carp were stocked in a large pen to control the nuisance cyanobacterial blooms in Meiliang Bay of Lake Taihu. Plankton abundance and water quality were investigated about once a week from 9 May to 7 July in 2005. Biomass of both total crustacean zooplankton and cladocerans was significantly suppressed by the predation of pen-cultured fishes. There was a significant negative correlation between the N:P weight ratio and phytoplankton biomass. The size-selective predation by the two carps had no effect on the biomass of green alga Ulothrix sp. It may be attributed to the low fish stocking density (less than 40 g m(-3)) before June. When Microcystis dominated in the water of fish pen, the pen-cultured carps effectively suppressed the biomass of Microcystis, as indicated by the significant decline of chlorophyll a in the >38 mu m fractions of the fish pen. Based on the results of our experiment and previous other studies, we conclude that silver and bighead carp are two efficient biomanipulation tools to control cyanobacterial (Microcystis) blooms in the tropical/subtropical eutrophic waters. Moreover, we should maintain an enough stocking density for an effective control of phytoplankton biomass. (C) 2008 Elsevier B.V All rights reserved

Estimation of the natural purification rate of a eutrophic lake after pollutant removal

Pollution resulting from increased human activities is threatening Lake Donghu, its effects being characterized by serious eutrophication. A steady increase of phosphorus loading is the most important factor of the lake eutrophication. Pollution external control projects are being implemented and will be accomplished before the year 2010. In order to predict the restoration rate by the lake's self-purification after the projects of external control, a model of predicting the removal rate of total phosphorus (TP) from lake water is developed, and a brief method of estimating the release and export rate of sediment phosphorus is suggested. Results show that, on the premise of external loading fully controlled. The restoration needs about 55 years or more. Obviously, the great P pool in the sediment will be a limiting factor of preventing the improvement of water quality after the external loading is under control. Based on the estimation we conclude that after the external control projects before 2010, in order to restore the lake in a few years, although highly cost, the first step must be the sediment dredging to remove internal loading. The second step is diverting water of River Changjiang into the lake to accelerate the improvement of lake water. Otherwise, removal of pollutant sources will become meaningless. (c) 2006 Elsevier B.V. All rights reserved.

Roles of substrate microorganisms and urease activities in wastewater purification in a constructed wetland system

A vertical/reverse-vertical flow constructed wetland system was set up in Wuhan, China, to study its treatment efficiency of polluted lake water. The numbers of substrate microorganisms and urease activities in the substrate of the constructed wetland were determined by plate counts and colorimetric analysis, respectively. The removal efficiencies of biochemical oxygen demands (BOD5). chemical oxygen demands (COD), total phosphorus (TP), total Kjeldahl nitrogen (TKN), and total suspended solids (TSS) were measured by EPA approved methodology. The results showed there were significant positive correlations (P < 0.05) between numbers of microorganism in the substrate and removal rates of TKN and CODCr. Meanwhile, there was significant positive correlation (P < 0.05) between urease activities and removal efficiencies of TKN and negative correlation between urease activities and removal efficiencies of BOD5. Substrate microorganisms and urease activities played key factors during purification processes and they could be utilized as indicator of wastewater treatment performances in the constructed wetland system. (C) 2004 Elsevier B.V. All rights reserved.

Efficiency of constructed wetlands in decontamination of water polluted by heavy metals

A twin-shaped constructed wetland (CW) comprising a vertical flow (inflow) chamber with Cyperus alternifolius followed by a reverse-vertical flow (outflow) chamber with Villarsia exaltata was assessed for decontamination of artificial wastewater polluted by heavy metals. After application of Cd, Cu, Pb, Zn over 150 days, together with Al and Mn during the final 114 days, no heavy metals with the exception of Mn could be detected in either the drainage zone at the bottom, shared by both chambers, or in the effluent. The inflow chamber was, therefore, seen to be predominantly responsible for the decontamination process of more toxic metal species with final concentrations far below WHO drinking-water standards. About one-third of the applied Cu and Mn was absorbed, predominantly by lateral roots of C. alternifolius. Lower accumulation levels were observed for Zn (5%), Cd (6%), Al (13%). and Pb (14%). Contents of Cd, Cu, Mn, and Zn in soil were highest in top layer, while Al and Pb were evenly distributed through the whole soil column. Metal species accumulating mainly in the top layer can be removed mechanically. A vertical flow CW with C. alternifolius is an effective tool in phytoremediation for treatment of water polluted with heavy metals. (C) 2002 Elsevier Science B.V. All rights reserved.

The restoration of aquatic macrophytes for improving water quality in a hypertrophic shallow lake in Hubei Province, China

This paper deals with a case study of the restoration of submerged macrophytes for improving water quality in a hypertrophic shallow lake, Lake Donghu of Wuhan, Hubei Province, China. Macrophyte restoration experiments were conducted in large-scale enclosures established in three sublakes of different trophic status, and the effectiveness for water quality improvement was tested by using the enclosure experiment in the hypertrophic sublake. Water quality was remarkably improved after the reestablishment of aquatic macrophytes. It is suggested that the submerged vegetation of less polluted sublakes could be capable of recovering spontaneously once the stocking of herbivorous fishes has been ceased, and the K-selected plants such as Potamogeton maackianus should be introduced into these sublakes to enhance the stability of aquatic vegetation. However, it may not be possible and economical to restore the submerged macrophytes in severely polluted basins unless external pollution has been cut off and internal nutrient loadings considerably reduced. In this case, the r-selected submerged plants should be used as the pioneer species for macrophyte recovery. (C) 2001 Elsevier Science B.V. All rights reserved.

浑太流域洪涝灾害及其治理方略

Hunhe, Taizihe rivers originating from the east mountain areas of Liaoning Province are the biggest tributaries of the left bank of Liaohe River. From the initial stage of New China to the early 1990s, the frequency of flood damage had decreased, but recently the disasters have upgraded and changed from trunk stream to tributary basins. In July 1995, Dongzhouhe, a tributary of Hunhe River, suffered from a heaviest flood since establishing the document of floods in Hunhe basin. Meanwhile, a peak discharge, almost beyond double defending ability, occurred at Dadongshanpu Station of Beishahe River, a tributary of Taizihe River. Besides the continued heavy rainstorm, no controllable water conservancy projects and ecological damages caused by quickly decreasing forest cover and water and soil loss are the two main causes of flood damage. In addition, the low flood protection standard is also one of causes. According to the above analyses, some strategies of synthetic controlling for flood damages were put forward: 1) Establishing the system of ecological engineering to defend floods and reduce disasters; 2)Setting up storage and detention areas; 3) Establishing flood controlling information system; 4) Improving the accuracy of media short period and short period rainstorm forecast and flood forecast; 5) Insurance of flood protection.

Novel comparison of kinetic models for the adsorption-coupled reduction of Cr(VI) using untreated date pit biomaterial

Biosorption of Cr(VI) onto date pit biomass has been investigated via kinetic studies as functions of initial Cr(VI) concentration, solution temperature and date pit particle size. Kinetic experiments indicated that chromate ions accumulate onto the date pits and then reduce to less toxic Cr(III) compounds. The López-García, Escudero and Park Cr(VI) biosorption kinetic models, which take into consideration the direct reduction, the passivation process and the follow-on decrease of the active surface area of reaction, were applied to the kinetic data. The models represented the experimental data accurately at low Cr(VI) concentration (0.480 mM) and small particle size (0.11–0.22 mm) at which the Cr(VI) was completely removed from the aqueous solution and completely reduced to Cr(III) after 420 min. Date pit biomass thus offers a green chemical process for the remediation of chromium from wastewater. This investigation will help researchers employ the adsorption-coupled reduction of Cr(VI) models and simplify their application to kinetic experimental data.

Using recycled aggregates in green roof substrates for plant diversity

Extensive green roofs are becoming a popular tool for restoring green infrastructure in urban areas, particularly biodiverse habitats such as post-industrial/brownfield sites. This study investigated the use of six recycled lightweight aggregates and combinations of them in green roof growing substrate, to determine their effectiveness for enhancing plant abundance and species diversity. In two separate experiments, we examined the roles of substrate type and depth on the establishment of a perennial wildflower mix over a 15-month period. We found that some of the alternative substrates are comparable to the widely used crushed red brick aggregate (predominantly found in commercial green roof growing substrate) for supporting plant establishment. For some materials such as clay pellets, there was increased plant coverage and a higher number of plant species than in any other substrate. Substrates that were produced from a blend of two or three aggregate types also supported higher plant abundance and diversity. Generally, increasing substrate depth improved plant establishment, however this effect was not consistent across substrates. We conclude that recycled materials may be viable constituents of growing substrate for green roofs and they may improve green roof resilience, through increased plant cover and diversity. The results could provide evidence to support the construction of mosaic habitat types on single roofs using various substrate blends.

Therapeutic modulation of microbiota-host metabolic interactions

The complex metabolic relationships between the host and its microbiota change throughout life and vary extensively between individuals, affecting disease risk factors and therapeutic responses through drug metabolism. Elucidating the biochemical mechanisms underlying this human supraorganism symbiosis is yielding new therapeutic insights to improve human health, treat disease, and potentially modify human disease risk factors. Therapeutic options include targeting drugs to microbial genes or co-regulated host pathways and modifying the gut microbiota through diet, probiotic and prebiotic interventions, bariatric surgery, fecal transplants, or ecological engineering. The age-associated co-development of the host and its microbiota provides a series of windows for therapeutic intervention from early life through old age

The influence of plant species number on productivity, ground coverage and floral performance in grass-free lawns

The grass-free lawn is a novel development in modern ornamental horticulture where the traditional monoculture of grass is replaced by a variety of mowing-tolerant clonal forbs. It brings floral aesthetics and a diverse species approach to the use of lawn space. How the number of constituent forb species affects the aesthetic and structural performance of grass-free lawns was investigated using grass-free lawns composed of four, six and twelve British native clonal perennial forb species. Lawn productivity was seen to increase with increasing species number but the relationship was not linear. Plant cover was dynamic in all lawn types, varied between years and was not representative of individual species' floral performance. The behaviour of component species common to all lawns suggested that lawns with 12 species show greater structural stability than the lawns with a lower species number. Visual performance in lawns with the greatest species number was lower than in lawns with fewer species, with increasing variety in floral size and individual species floral productivity leading to a trade-off between diversity and floral performance. Individual species were seen to have different aesthetic functions in grass-free lawns either by providing flowers, ground coverage or both.

Emergy-based sustainability assessment of different energy options for green buildings

It is necessary to minimize the environmental impact and utilize natural resources in a sustainable and efficient manner in the early design stage of developing an environmentally-conscious design for a heating, ventilating and air-conditioning system. Energy supply options play a significant role in the total environmental load of heating, ventilating and air-conditioning systems. To assess the environmental impact of different energy options, a new method based on Emergy Analysis is proposed. Emergy Accounting, was first developed and widely used in the area of ecological engineering, but this is the first time it has been used in building service engineering. The environmental impacts due to the energy options are divided into four categories under the Emergy Framework: the depletion of natural resources, the greenhouse effect (carbon dioxide equivalents), the chemical rain effect (sulphur dioxide equivalents), and anthropogenic heat release. The depletion of non-renewable natural resources is indicated by the Environmental Load Ratio, and the environmental carrying capacity is developed to represent the environmental service to dilute the pollutants and anthropogenic heat released. This Emergy evaluation method provides a new way to integrate different environmental impacts under the same framework and thus facilitates better system choices. A case study of six different kinds of energy options consisting of renewable and non-renewable energy was performed by using Emergy Theory, and thus their relative environmental impacts were compared. The results show that the method of electricity generation in energy sources, especially for electricity-powered systems, is the most important factor to determine their overall environmental performance. The direct-fired lithium-bromide absorption type consumes more non-renewable energy, and contributes more to the urban heat island effect compared with other options having the same electricity supply. Using Emergy Analysis, designers and clients can make better-informed, environmentally-conscious selections of heating, ventilating and air-conditioning systems.

Preliminary results of a floating subirrigation system (Aquaforest system) as an alternative to conventional tree nurseries

A new methodology for tree seedling production (Aquaforest system) based on a continuous floating subirrigation system was developed and tested using creeks with different nutrient levels. Eucalyptus grandis seedlings were produced in water from polluted and clean creeks, and compared to conventional tree nursery production. The growth variables analyzed in the seedling phase were: survival, height, diameter, shoot and root dry weight, leaf area, and root/shoot ratio. Water and substrate were analyzed, as well as leaf nutritional status. Plant survival was 100% in all treatments. Height and diameter were greater in the higher nutrient water treatment. Leaf area and dry weight of plants produced in the higher nutrient water treatment were similar to those of the control. The results showed that polluted water can represent a good nutrient source. The preliminary results show that the Aquaforest system can be a viable alternative for tree seedling production. (C) 2004 Elsevier B.V. All rights reserved.

Tendency towards homogenization in fish assemblages in the cascade reservoir system of the Tiete river basin, Brazil

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Soil seed banks in tropical forest fragments with different disturbance histories in southeastern Brazil

Soil seed banks are considered an important mechanism for natural regeneration in tropical forest ecosystems. This paper investigated the soil seed bank in two semideciduous seasonal tropical forest fragments with different disturbance histories in Botucatu, southeastern Brazil. In each study site, 40 superficial soil samples (30 cm × 30 cm × 5 cm) were taken at the end of both the dry and rainy seasons. The seeds were estimated by the germination method. Average soil seed density was 588.6 and 800.3 seeds m-2, respectively, for site 1 (less disturbed) and site 2 (more disturbed). Seed density and diversity (H′) were significantly higher in site 2 in both seasons. Non-woody taxa predominated in both fragments, but pioneer tree species were better represented in the less disturbed forest. Both ecosystems have a potential for regeneration from soil seed banks, but this potential is higher in the less disturbed site. Low richness and density of pioneer tree species in the seed bank indicate that the ecosystem has lost its resilience. The seed bank is not as important in these ecosystems as in other forests. Results indicate that management strategies to restore these forests should take into account the possibility of recovering soil seed bank processes and dynamics. © 2007 Elsevier B.V. All rights reserved.