Fu-Liu Xu

POLYCYCLIC AROMATIC HYDROCARBONS (PAHS) IN AGRICULTURAL SOIL AND VEGETABLES FROM TIANJIN

Several types of vegetables were collected from two contaminated sites in Tianjin, China. The bulk soil and the rhizosphere soil samples were also collected from the same plots. Sixteen PAHs in the samples were measured. The total concentrations of PAH16 in the bulk soil from the two sites were 1.08 and 6.25 microg/g, respectively, with similar pattern. The concentrations of PAH16 and individual compounds in the rhizosphere were significantly higher than those in the bulk soil with mean values of 2.25 and 7.82 microg/g for the two sites, respectively. The contents of both total and dissolved organic matter in the rhizosphere were also higher than those in the bulk soil. Almost all PAH compounds studied were detected in both roots and aerial parts of the vegetables studied. Abundance of higher molecular weight PAHs in vegetable, however, was lower than that in soil. Concentrations of PAH16 in vegetable were higher than those reported in the literature for other areas. It appears that agricultural soils and vegetables in Tianjin, especially those from the site located immediately next to an urban district and irrigated with wastewater for several decades, are severely contaminated by PAHs. Among the eight types of vegetable studied, the highest concentration of PAHs was found in cauliflower. By average, the concentration of PAH16 in the aerial part of vegetables was 6.5 times higher as that in vegetable root, suggesting that foliar uptake is the primary transfer pathway of PAHs from environment to vegetables.

Handbook of Ecological Indicators for Assessment of Ecosystem Health

Ecological Indicators Introduction S. E. Jorgensen Application of Indicators for the Assessment of Ecosystem Health S. E. Jorgensen, Fu-Liu Xu, Joao C. Marques, and Fuensanta Salas Eco-Exergy as Ecological Indicator S. E. Jorgensen Emergy Indices of Biodiversity and Ecosystem Dynamics Mark T. Brown and Sergio Ulgiati Eco-Exergy to Emergy Flow Ratio for the Assessment of Ecosystem Health F. M. Pulselli, C. Gaggi, and S. Bastianoni Natural Capital Security/Vulnerability Related to Disturbance in a Panarchy of Social-Ecological Landscapes Nicola Zaccarelli, Irene Petrosillo, and Giovanni Zurlini Species Richness in Space and Time as an Indicator of Human Activity and Ecological Change Erich Tasser, Georg Niedrist, Patrick Zimmermann, and Ulrike Tappeiner Landscape Development Intensity and Pollutant Emergy/Empower Density Indices as Indicators of Ecosystem Health Mark T. Brown and Kelly Chinners Reiss Ecosystem Services and Ecological Indicators Robert Costanza Assessment of Ecosystem Health Application of Ecological Indicators for the Assessment of Wetland Ecosystem Health S. E. Jorgensen Application of Ecological Indicators for the Assessment of Ecosystem Health in Estuaries and Coastal Zones Joao C. Marques, Fuensanta Salas, J. Patricio, J. Neto, H. Teixeira, and R. Pinto Application of Ecological and Thermodynamic Indicators for the Assessment of Ecosystem Health of Lakes Fu-Liu Xu Application of Ecological Indicators in Forest Management in Africa Kouami Kokou, Adzo Dzifa Kokutse, and Kossi Adjonou Using Ecological Indicators to Assess the Health of Marine Ecosystems: The North Atlantic Villy Christensen and Philippe Cury Indicators for the Management of Coastal Lagoons: Sacca di Goro Case Study J. M. Zaldivar, M. Austoni, M. Plus, G. A. De Leo, G. Giordani and P. Viaroli Ecosystem Indicators for the Integrated Management of Landscape Health and Integrity Felix Muller and Benjamin Burkhard Integrated Indicators for Evaluating Ecosystem Health: An Application to Agricultural Systems V. Niccolucci, R. M. Pulselli, S. Focardi, and S. Bastianoni Ecological Indicators to Assess the Health of River Ecosystems Carles Ibanez, Nuno Caiola, Peter Sharpe, and Rosa Trobajo Appendix Index

Lake Ecosystem Health Assessment: Indicators and Methods

A set of ecological indicators including structural, functional, and system-level aspects were proposed for a lake ecosystem health assessment, according to the structural, functional, and system-level responses of lake ecosystems to chemical stresses including acidification, eutrophication and copper, oil and pesticide contamination. The structural indicators included phytoplankton cell size and biomass, zooplankton body size and biomass, species diversity, macro- and micro-zooplankton biomass, the zooplankton phytoplankton ratio, and the macrozooplankton microzooplankton ratio. The functional indicators encompassed the algal C assimilation ratio, resource use efficiency, community production, gross production/respiration (i.e. P/R) ratio, gross production standing crop biomass (i.e. P/B) ratio, and standing crop biomass unit energy flow (i.e. B/E) ratio. The ecosystem-level indicators conisisted of ecological buffer capacities, energy, and structural energy. Based on these indicators, a direct measurement method (DMM) and an ecological modeling method (EMM) for lake ecosystem health assessment were developed. The DMM procedures were designed to: (1) identify key indicators; (2) measure directly or calculate indirectly the selected indicators; and, (3) assess ecosystem health on the basis of the indicator values. The EMM procedures were designed to: (1) determine the structure and complexity of the ecological model according to the lakes ecosystem structure; (2) establish an ecological model by designing a conceptual diagram, establishing model equations, and estimating model pararmeters; (3) compare the simulated values of important state variables and process rates with actual observations; (4) calculate ecosystem health indicators using the ecological model; and, (5) assess lake ecosystem health according to the values of the ecological indicators. The results of a case study demonstrated that both methods provided similar results which corresponded with the lakes actual trophic state.

Ecological indicators for assessing freshwater ecosystem health

The paper presents the structural, functional and system-level symptoms of four chemical stresses, acidification, copper, oil and pesticide contamination in freshwater ecosystems. Exergy, structural exergy and zooplankton buffer capacity were used as ecological indicators for the measurement of ecosystem-level responses to the four chemical stresses. The results showed that the changes in ecosystem level were highly related to the changes in structure and function of the studied ecosystems and these changes indicated the effects of chemical stress on freshwater ecosystem health. Exergy, structural exergy and zooplankton buffer capacity followed the significant decline of zooplankton biomass, Bz/Bp ratio, species richness or diversity and resource use efficiency, caused by chemical stress. A slight change in structure and function of local ecosystems, was accompanied by unchanged or slightly changed exergy, structural exergy and zooplankton buffer capacity. The results lead to a set of comprehensive ecological indicators for assessing the impacts of chemical stress on freshwater ecosystem health, including structural, functional and system-level indicators. These indicators were successfully applied to assess the health of a lake ecosystem.

Modeling the effects of ecological engineering on ecosystem health of a shallow eutrophic Chinese lake (Lake Chao)

Two ecological models that describe phosphorus-food web dynamics with and without macrophytes in Lake Chao ecosystems are developed in this paper. Ecosystem health indicators used in the two models include exergy (Ex), structural exergy (Exst), the ratio of zooplankton to phytoplankton biomass (RBZBA), and transparency in Secchi Disc depth (SD). The calculated values of important state variables and process rates from model 1 are compared with the measured data. Model 2 uses the same parameters and rate coefficients as model 1 for phytoplankton, zooplankton, fish, detritus, sediment, and soluble inorganic phosphorus submodels. The macrophyte submodel in model 2 is given realistic parameters taken from the literature. The lake ecosystem health indicators are calculated and compared by means of models 1 and 2. The changes of ecosystem health indicators and lake biological structure following macrophyte restoration are predicted using model 2. The results from model 1 show that there are good agreements between observed and simulated values of important variables and process rates. The results from model 2 reveal that macrophyte restoration in the Lake Chao ecosystem can decrease phytoplankton biomass, and increase Ex, Exst, SD, RBZBA, and fish biomass. With the increase of initial macrophyte biomass, phytoplankton biomass is declined, and Ex, Exst, SD, RBZBA, and fish biomass are increased. These findings mean that macrophyte restoration can regulate lake biological structure and improve lake ecosystem health.

Changes of copper speciation in maize rhizosphere soil.

Chemical forms of copper in the rhizosphere and bulk soil of maize were investigated using rhizobox cultivation and sequential extraction techniques. The copper accumulations were also determined. The results demonstrated that there were continuous changes in copper fractionation within the maize rhizosphere. Initially, the amount of exchangeable copper increased before dropping below the initial level after 40 days or so. Carbonate associated copper followed a similar trend of change, but with a slower pace than the exchangeable copper. The increase in carbonate associated copper only become evident after 30 days, with the net loss occurring after 60 days. There were also initial increases in oxide bound copper as well as decreases in the organic matter associated copper, both followed by a turnover after 40-50 days. The accumulation of copper in the maize plant was found to be biomass dependent. The amount of accumulated copper absorbed in the plant material exceeded the initial quantity of the exchangeable copper in the soil, revealing a transformation from less bioavailable to more bioavailable fractions. During cultivation, decreases in redox potential and increases in pH, dissolved organic carbon (DOC), and microbial activity in the maize rhizosphere were observed. The change in copper speciation may result from root-induced changes in DOC, redox potential, and microbial activity in the rhizosphere.

Characterizing and comparing risks of polycyclic aromatic hydrocarbons in a Tianjin wastewater-irrigated area.

A probability risk assessment was conducted to characterize the ecotoxicity of three polycyclic aromatic hydrocarbons (PAHs), including benzo[a]pyrene, fluoranthene, and phenanthrene, to various species in a wastewater-irrigated area of Tianjin, China. The relative risk of these chemicals was investigated using joint risk probability distribution curves, which were generated based on the distributions of exposure and acute toxicity data. Risk at various exposure levels was discussed. The results indicated that among the three PAHs studied, the overall risk of phenanthrene was the highest, with that of benzo[a]pyrene the lowest, due mainly to their exposure concentrations. For lower exposure levels at which the percentage of species affected was less than 20%, the risk associated with benzo[a]pyrene was clearly higher than that of the other two chemicals.

A GIS-based method of lake eutrophication assessment

Abstract A geographical information system (GIS)-based method of lake eutrophication assessment was undertaken to study the spatial distribution of eutrophication conditions in lake environments. A trophic state index (TSI) consisting of six physical, chemical and biological indicators including total phosphorus (TP), total nitrogen (TN), chemical oxygen demand (COD), Secchi disk depth (SD), chlorophyll-a concentration (Chl-a) and phytoplankton biomass (CA) was constructed to describe the eutrophication state of the lake environment. A 0–100 eutrophication scale was also developed to indicate seven different trophic levels within the lake environment: oligotrophic, lower-mesotrophic, mesotrophic, upper-mesotrophic, eutrophic, hypereutrophic and extremely hypereutrophic. A representation of the spatial distribution of TSI TP , TSI TN , TSI COD , TSI SD , TSI Chl-a and TSI CA was developed using the inverse distance weighted (IDW) interpolation method. By categorizing the interpolated values, a clear illustration of the different trophic levels was developed on six thematic maps. A GIS overlay technique was applied to synthesize the information from the six thematic maps into a final map illustrating the spatial distribution of eutrophication conditions within the study area. The different periods or levels associated with lake eutrophication assessment using GIS were then discussed.

Spatio-temporal distributions and the ecological and health risks of phthalate esters (PAEs) in the surface water of a large, shallow Chinese lake.

The spatio-temporal distributions and the ecological and health risks of PAEs in surface water of Lake Chaohu, the fifth largest lake in China, were studied based on the monthly monitoring of six PAE congeners from May 2010 to April 2011. The annual total concentration of the six PAE congeners (Σ6PAE) in the surface water ranged from 0.467 to 17.953 μg L(-1), with the average value of 4.042±3.929 μg L(-1). The di-n-butyl phthalate (DnBP) that dominated the Σ6PAE at 65.8% was found at its highest and lowest levels in the western lake (TX) and eastern drinking water source area (JC), respectively. The temporal distributions of Σ6PAE showed that the highest and lowest levels were observed in September 2010 and June 2010, respectively. The different relationships between the runoff and the PAEs with low and high levels of carbon might suggest their different sources. The DnBP had much greater ecological risks than the other studied PAE congeners as indicated by its potential affected fractions (PAFs) and the margin of safety (MOS10). The PAE congeners studied posed little health risk to the nearby male and female citizens.

The restoration of riparian wetlands and macrophytes in Lake Chao, an eutrophic Chinese lake: possibilities and effects

Experiments with replanting macrophytes in Lake Chao showed that the water quality inside an Alternathera philoxeroides Griseb.and a Phragmites australis community were better than outside. Transparency was significantly higher and the content of N and P decreased inside the communities, as did the rate of sedimentation of organic suspended matter in the Phragmites australis community. Modeling revealed that macrophyte restoration could decrease phytoplaniton biomass, increase fish biomass, exergy, structural exergy, zooplankton/phytoplankton ratio and transparency (Xu et al., 1999b). It is concluded that macrophyte restoration can purify lake water, regulate lake biological structure and control eutrophication.