Phosphorus recovery and recycling from waste: An appraisal based on a French case study

Phosphate rocks, used for phosphorus (P) fertilizer production, are a non-renewable resource at the human time scale. Their depletion at the global scale may threaten global food and feed security. To prevent this depletion, improved P resource recycling from food chain waste to agricultural soils and to the food and feed industry is often presented as a serious option. However, waste streams are often complex and their recycling efficiency is poorly characterized. The aim of this paper is to estimate the P recovery and recycling potential from waste, considering France as a case study. We assessed the P flows in food processing waste, household wastewater and municipal waste at the country scale using a substance flow analysis for the year 2006. We also quantified the P recycling efficiency as the fraction of P in waste that ultimately reached agricultural soils or was recycled in the food and feed industry. Efforts were made to limit data uncertainty by cross-checking multiple data sources concerning P content in waste materials. Results showed that, in general, P recovery in waste was high but that the overall P recycling efficiency was only 51% at the country scale. In particular, P recycling efficiency was 75% for industrial waste, 43% for household wastewater and 47% for municipal waste. The remaining P was discharged into water bodies or landfilled, causing P-induced environmental problems as well as losses of nutrient resources. Major P losses were through food waste (which amounted to 39% of P in available food) and treated wastewater, and the findings were confirmed through cross-checking with alternative data sources. Options for improving P resource recycling and, thereby, reducing P fertilizer use were quantified but appeared to be less promising than scenarios based on reduced food waste or redesigned agricultural systems.     

Country-scale phosphorus balancing as a base for resources conservation

In order to effectively conserve the non-renewable resource phosphorus (P), flows and stocks of P must be known at national, regional and global scales. P is a key non-renewable resource because its use as fertilizer cannot be substituted posing a constraint on the global food production in the long-term. This paper presents a methodology to establish country-wide P balances that emphasises resource use. We develop a material flow analysis (MFA) model that comprises all relevant flows and stocks of P in five subsystems, seven processes and 36 material flows. For quantification, statistical data from economic and agricultural sources as well as available information about P partitioning in natural and anthropogenic processes are used. Special attention is paid to data gaps and uncertainties. The model was tested in two case studies on P management in Turkey and Austria. MFA appears to be a tool well suited for establishing country-wide P balances, provided that national statistics are well-structured and accessible. If a common approach is used for modelling P-flows and stocks, regional and national balances can be compared and linked towards larger scale P balances for an improved management of the resource.     

铜陵市城市综合竞争力比较评价及战略对策

随着世界城市体系的形成、扩大和调整，城市在区域经济中的地位变得更加重要，城市成为国家和区域间竞争的主要载体和平台。重视和提升城市竞争力是有效推进城市化和提高区域经济水平的关键所在，它已成为各个国家和区域关注与研究的重点。运用定量方法，比较分析了铜陵市综合经济实力、产业、企业、开放、科技、基础设施、人力资源和城市环境等8个方面区域竞争力水平。结果表明，铜陵市具有良好的区位竞争优势，在皖江城镇带中具有较高的区域竞争力水平，产业优势是其核心竞争力的重要方面；但总量规模小、生态环境污染严重是阻碍其城市综合竞争力进一步提升的重要因素。     

Bioavailability of organic phosphorus in a submerged aquatic vegetation-dominated treatment wetland

Enzymatic hydrolysis and mineralization of organic phosphorus (P) were determined in surface water samples collected from inflow and outflow of a submerged aquatic vegetation (SAV)-dominated treatment wetland of the Florida Everglades. Water samples were fractionated into three size fractions (> 0.4 micron, < 0.4 to > 0.05 micron, and < 0.05 micron) with a sequential flow filtration technique. The fractionated water samples were incubated to hydrolyze with alkaline phosphatase (APase) and phosphodiesterase (PDEase), and to mineralize at different redox and pH. Unlike APase, which hydrolyzed < or = 10% of organic P, PDEase hydrolyzed > or = 71% of organic P in unfiltered water from both inflow and outflow waters, suggesting the domination of bioavailable diester P in the water. Phosphodiesterase completely hydrolyzed organic P in the < 0.4- to > 0.05-micron and < 0.05-micron fractions, as compared with < or = 35% in the > 0.4-micron fraction. However, the P mineralization in inflow and outflow waters at different redox and pH showed that P associated with particulate > 0.4 micron had been mineralized the most. Phosphorus-31 nuclear magnetic resonance (NMR) spectroscopy showed that surficial sediments from the inflow region contained a high proportion of polynucleotides, nucleoside monophosphates, and previously unreported glycerophosphoethanolamine and phosphoenolpyruvates. However, at the outflow, the relative proportion of polynucleotides and nucleoside monophosphates was reduced substantially. This suggests that the SAV wetland may sequester P via accretion of organic matter.     

Investigating urban migrants' sense of place through a multi-scalar perspective

This paper investigates the interconnections between sense-of-place dimensions across different geographical scales. While existing knowledge on sense of place has demonstrated that place meanings rest at various scales, little attention has been devoted to exploring how sense-of-place dimensions at different geographical scales can be interconnected in forming a multi-scalar construction of place meanings. In this paper, we approach this under-theorization of multi-scalarity of sense of place by looking at urban migrants’ sense of place at two geographical scales - a community culture center and the city of Guangzhou, China. In so doing, we also contribute to the scholarship on Chinese urban migrant, particularly in terms of how urban migrants reestablish their psychological connections with place of destination through specific place experiences. Our research methodology combines both quantitative (structural equation modeling analysis with 104 questionnaires) and qualitative (12 in-depth interviews) approaches. Quantitative study reaches a structural model that has not been observed by existing research, while qualitative data provide strong empirical evidence in support of the statistical relations in the structural model. Major findings in this research include: 1. at the scale of culture center, place dependence contributes strongly to both place identity and place attachment, while the latter two dimensions can be seen as parallel constructs; 2. at the scale of Guangzhou, place dependence is a dimension independent of both place identity and place attachment, and on the other hand, it is place identity that has a strong impact on place attachment; 3. migrants’ place dependence on the culture center significantly influences their place identity to Guangzhou, which further contributes to the migrants’ place attachment to the city. Although the scope of this research is limited in its sampling and research location, the empirical evidence in this paper provides a basis to argue that the construction of sense of place involves the working of sense-of-place constructs at various geographical scales. Particularly, we also argue that connecting different places across geographical scales requires a delicate network that involves various sense-of-place constructs that work both within and across scales.     

SUBALPINE,COLD CLIMATE,STORMWATER TREATMENT WITH A CONSTRUCTED SURFACE FLOW WETLAND1

The Tahoe City Wetland Treatment System (TCWTS) was constructed in 1997 to treat stormwater runoff from 23 ha of commercial, highway, and residential land use in the Lake Tahoe Basin. This subalpine, constructed, surface flow wetland treatment system consists of two cells in series, with a design water surface area of about 0.6 ha. Water quality monitoring from October 2002 through September 2003 was conducted with autosamplers at the inflow and outflow sites during 24 sampling events, with a median duration of 53 hours, representing 42 percent of total inflow to this wetland during the year. Monitoring data indicate an improvement of 49 percent or greater in effluent concentrations of dissolved phosphorus, nitrate, orthophosphorus, and total suspended solids. On average, event mean concentrations of total phosphorus were reduced from a median 279 μg/l at the inflow to 94 μg/l at the outflow. Event mean concentrations of total nitrogen were reduced from a median 1,599 μg/l at the inflow to 810 μg/l at the outflow. Net nutrient retention for the sampling period was estimated at 3 g phosphorus (P)/m²/y and 13 g nitrogen (N)/m²/y. Almost 4,000 kg of suspended sediment was captured by this wetland system during the year.     

Nitrogen and Phosphorus Removal in a Rain Garden Flooded with Wastewater and Simulated Stormwater

Rain gardens, also known as bioretention cells, are low‐impact developments designed to mitigate several problems associated with urban stormwater. This four‐month field study involved a rain garden at a wastewater treatment plant in north‐central Texas in the United States of America. Partially treated wastewater from an anaerobic digester spilled into the rain garden at the beginning of the study. Subsequently, inflow and outflow concentrations of nitrogen and phosphorus were measured for nine simulated floods, preceded by dry‐spell intervals of 5, 8, or 12 days. Despite large inputs from the wastewater spill, the rain garden gradually processed and flushed the nitrogen. Longer dry spells tended to produce relatively higher outflow nitrate concentrations. A large pool of phosphorus in the soil restricted the rain garden's ability to reduce outflow orthophosphate concentrations, which were stable and lower than inflow concentrations throughout the study; however, adsorptive processes attenuated a relatively high inflow concentration by the end of the study.     

Assessing soil biodiversity across Great Britain: national trends in the occurrence of heterotrophic bacteria and invertebrates in soil

An assessment of the biodiversity of soils was a component of the Countryside Survey 2000 (CS2000). This was the first integrated survey of soil biota and chemical properties at a national scale. A total of 1052 soil samples were collected across Great Britain during CS2000 and analysed for a range of soil microbial and invertebrate characteristics resulting in the production of a series of robust datasets. A principal objective was to use these datasets to investigate relationships between soil biota and environmental factors such as geographical location, vegetation, land use, land cover, soil type and pollutant levels as first stages in characterising the inherent biodiversity of British soils and investigating the potential of soil biodiversity as indicators of soil health at a regional or national scale. Preliminary results for culturable heterotrophic, invertebrate taxa, Acari, Collembola and Oribatid mites are presented here to illustrate the nature of the data collected and the patterns of soil biodiversity in relation to large-scale regional, vegetation and soil characteristics across the British countryside.     

Effect of manure application timing, crop, and soil type on phosphorus leaching

Phosphorus (P) leaching losses from manure applications may be of concern when artificial drainage systems allow for hydrologic short-cuts to surface waters. This study quantified P leaching losses from liquid manure applications on two soil textural extremes, a clay loam and loamy sand soil, as affected by cropping system and timing of application. For each soil type, manure was applied at an annual rate of 93 800 L ha(-1) on replicated drained plots under maize (Zea mays L.) in early fall, late fall, early spring, and as a split application in early and late spring. Manure was applied on orchardgrass (Dactylis glomerata L.) in split applications in early fall and late spring, and early and late spring. Drain water was sampled at least weekly when lines were flowing, and outflow rate and total P content were determined. High P leaching losses were measured in the clay loam as soon as drain lines initiated flow after manure application. Flow-weighted mean P leaching losses on clay loam plots averaged 39 times higher (0.504 mg L(-1)) than those on loamy sand plots (0.013 mg L(-1)), and were above the USEPA level of concern of 0.1 mg L(-1). Phosphorus losses varied among application seasons on the clay loam soil, with highest losses generally measured for early fall applications. Phosphorus leaching patterns in clay loam showed short-term spikes and high losses were associated with high drain outflow rates, suggesting preferential flow as the main transport mechanism. Phosphorus leaching from manure applications on loamy sand soils does not pose environmental concerns as long as soil P levels remain below the saturation level.     

Spatial extrapolation of soil characteristics using whole-soil particle size distributions

Soils support ecosystem functions such as plant growth and water quality because of certain physical, chemical, and biological properties. These properties have been studied at different spatial scales, including point scales to satisfy basic research needs, and regional scales to satisfy monitoring needs. Recently, soil property data for the entire USA have become available in the State Soil Geographic Data Base (STATSGO), which is appropriate for regional-scale research. We analyzed and created models of STATSGO data in this study to serve as a research tool, for example, for linking the soil to regional water quality monitoring data in our companion paper. Map units in STATSGO define geographic land areas by soil characteristics (SCs) of similar soil series. We selected 27 SCs that influenced water properties (in varying degrees), aggregated the layer and component SCs to map unit SCs, and used SCs to calculate relationships among map units. The relationships were defined by equations of conditional mean for the qth SC (SCq), while using the remaining 26 SCs as predictors. The relative standard errors for 22 of the 27 SCs were less than 10%, and less than 22% for the remaining five. We conclude that spatial extrapolation of SCs is feasible and the procedures are a first step toward extrapolating information across a region using SC-water property relationships. Although our procedure is for regional scale monitoring, it is also applicable to finer spatial scales commensurate with available soil data.     

Phosphorus flux from wetland soils affected by long-term nutrient loading

Wetland soils play a key role in the cycling of nutrients within an ecosystem. Since soils are potentially a source or a sink for inorganic nutrients, it is important to quantify their influence on overlying water quality in order to understand their importance in overall ecosystem nutrient budgets. Laboratory and field studies were performed in the northern Everglades (WCA-2A) to determine the magnitude of phosphorus (P) flux between the soil and the overlying water column, under various redox conditions. The P flux was estimated using three techniques: intact soil cores, in situ benthic chambers, and porewater equilibrators. There was reasonable agreement between the P flux estimated using intact soil cores and benthic chambers; however, P flux estimates using the porewater equilibrators were considerably lower than the other two techniques. Models of solute flux, based solely on soil physico-chemical characteristics, may substantially underestimate soil-water nutrient exchange processes. Phosphorus flux measured with the intact soil cores varied from 6.5 mg m(-2) d(-1) near nutrient inflow areas to undetectable flux 4 km away from the inflow. Oxygen consumption varied from 4 mg m(-2) d(-1) near the inflow to a constant 1 to 2 mg m(-2) d(-1) at a distance of 4 km from the inflow. Rate of consumption of NO3- -N and SO4(2-) showed no significant trend with respect to distance from inflow. Nitrate N and SO4 consumption rates averaged 120 and 130 mg m(-1) d(-1), respectively. Consumption of O2 was correlated with P flux, whereas NO3- -N and SO4(2-) consumption were not.     

Timing of phosphorus fertilizer application within an irrigation cycle for perennial pasture

Irrigated pastures are significant contributors of phosphorus (P) to inland watercourses, with much of the P coming from applied fertilizer. It was hypothesized that the timing of P fertilizer application relative to irrigation regulates P concentrations in runoff and infiltrating water. To test this hypothesis, a two-by-two factorial experiment was conducted on twelve 8- x 30-m border-irrigated bays growing perennial pasture. Phosphorus fertilizer in the form of single superphosphate (44 kg P ha(-1)) was surface-broadcast onto the bays when the nominal change in soil water deficit reached 0 or 50 mm (U.S. Class A pan evaporation minus rainfall). Following fertilizer application, the bays were again irrigated when the nominal soil water deficit between fertilizing and the subsequent irrigation reached either 0 or 50 mm. The volume of water applied, runoff volume, and changes in soil water content were recorded for the three irrigations following fertilizer application. Total phosphorus (TP) and filtrable reactive phosphorus (FRP, <0.45 microm) concentrations in runoff and at depths of 0.1, 0.3, and 0.6 m in the soil were also measured. Soil water content at fertilizer application had less effect on P concentrations in runoff and soil water than the additional time between fertilizing and irrigating. By allowing a deficit of 50 mm between fertilizer application and irrigation, the average concentration of P in runoff and moving below a soil depth of 0.1 m was approximately halved. To maximize fertilizer use efficiency and minimize environmental effects, a delay should occur between applying P fertilizer and irrigating perennial pasture.     

Modelling the Ecological Vulnerability to Forest Fires in Mediterranean Ecosystems Using Geographic Information Technologies

Forest fires represent a major driver of change at the ecosystem and landscape levels in the Mediterranean region. Environmental features and vegetation are key factors to estimate the ecological vulnerability to fire; defined as the degree to which an ecosystem is susceptible to, and unable to cope with, adverse effects of fire (provided a fire occurs). Given the predicted climatic changes for the region, it is urgent to validate spatially explicit tools for assessing this vulnerability in order to support the design of new fire prevention and restoration strategies. This work presents an innovative GIS-based modelling approach to evaluate the ecological vulnerability to fire of an ecosystem, considering its main components (soil and vegetation) and different time scales. The evaluation was structured in three stages: short-term (focussed on soil degradation risk), medium-term (focussed on changes in vegetation), and coupling of the short- and medium-term vulnerabilities. The model was implemented in two regions: Aragón (inland North-eastern Spain) and Valencia (eastern Spain). Maps of the ecological vulnerability to fire were produced at a regional scale. We partially validated the model in a study site combining two complementary approaches that focused on testing the adequacy of model’s predictions in three ecosystems, all very common in fire-prone landscapes of eastern Spain: two shrublands and a pine forest. Both approaches were based on the comparison of model’s predictions with values of NDVI (Normalized Difference Vegetation Index), which is considered a good proxy for green biomass. Both methods showed that the model’s performance is satisfactory when applied to the three selected vegetation types.     

Nitrogen fertilizer recommendations for corn grown on soils amended with oily food waste

Soil and plant indices of soil fertility status have traditionally been developed using conventional soil and crop management practices. Data on managing N fertilizer for corn (Zea mays L.) produced on soils amended with C-rich organic materials, such as oily food waste (OFW) is scarce. Identification of a reliable method for making N fertilizer recommendations under these conditions is imperative. The objective of this research was to evaluate soil NO(3)-N (0- to 30-cm depth) at preplant and presidedress (PSNT) times of sampling for predicting N requirements for corn grown on fields receiving OFW. Experiments were conducted at two locations in Ontario, Canada over 3 yr (1995-1997) where OFW was applied at different rates (0, 10, and 20 Mg ha(-1)), times (fall and spring), and slope positions (upper, mid, and lower) within the same field. Presidedress soil NO(3)-N contents were higher compared with preplant time of sampling under all OFW management conditions. Corn grain yields were significantly affected by OFW management and N fertilizer application rates. Maximum economic rate of N application (MERN) varied depending on OFW management conditions. Presidedress soil NO(3)-N contents had a higher inverse relationship with MERN (r = -0.88) compared with soil NO(3)-N at preplant (r = -0.74) time of sampling. A linear regression model (Y = 180.1 - 8.22 NO(3)-N at PSNT) is proposed for making N fertilizer recommendations to corn grown on soils amended with OFW in this geographical region.     

Biological Connectivity of Seasonally Ponded Wetlands across Spatial and Temporal Scales

Many species that inhabit seasonally ponded wetlands also rely on surrounding upland habitats and nearby aquatic ecosystems for resources to support life stages and to maintain viable populations. Understanding biological connectivity among these habitats is critical to ensure that landscapes are protected at appropriate scales to conserve species and ecosystem function. Biological connectivity occurs across a range of spatial and temporal scales. For example, at annual time scales many organisms move between seasonal wetlands and adjacent terrestrial habitats as they undergo life‐stage transitions; at generational time scales, individuals may disperse among nearby wetlands; and at multigenerational scales, there can be gene flow across large portions of a species’ range. The scale of biological connectivity may also vary among species. Larger bodied or more vagile species can connect a matrix of seasonally ponded wetlands, streams, lakes, and surrounding terrestrial habitats on a seasonal or annual basis. Measuring biological connectivity at different spatial and temporal scales remains a challenge. Here we review environmental and biological factors that drive biological connectivity, discuss implications of biological connectivity for animal populations and ecosystem processes, and provide examples illustrating the range of spatial and temporal scales across which biological connectivity occurs in seasonal wetlands.     

Spatial Calibration and Temporal Validation of Flow for Regional Scale Hydrologic Modeling1

Abstract: Physically based regional scale hydrologic modeling is gaining importance for planning and management of water resources. Calibration and validation of such regional scale model is necessary before applying it for scenario assessment. However, in most regional scale hydrologic modeling, flow validation is performed at the river basin outlet without accounting for spatial variations in hydrological parameters within the subunits. In this study, we calibrated the model to capture the spatial variations in runoff at subwatershed level to assure local water balance, and validated the streamflow at key gaging stations along the river to assure temporal variability. Ohio and Arkansas‐White‐Red River Basins of the United States were modeled using Soil and Water Assessment Tool (SWAT) for the period from 1961 to 1990. R² values of average annual runoff at subwatersheds were 0.78 and 0.99 for the Ohio and Arkansas Basins. Observed and simulated annual and monthly streamflow from 1961 to 1990 is used for temporal validation at the gages. R² values estimated were greater than 0.6. In summary, spatially distributed calibration at subwatersheds and temporal validation at the stream gages accounted for the spatial and temporal hydrological patterns reasonably well in the two river basins. This study highlights the importance of spatially distributed calibration and validation in large river basins.     

Increase in phosphorus losses from grassland in response to Olsen-P accumulation

The Olsen-P status of grazed grassland (Lolium perenne L.) swards in Northern Ireland was increased over a 5-yr period (March 2000 to February 2005) by applying different rates of P fertilizer (0, 10, 20, 40, or 80 kg P ha(-1) yr(-1)) to assess the relationship between soil P status and P losses in land drainage water and overland flow. Plots (0.2 ha) were hydrologically isolated and artificially drained to v-notch weirs, with flow proportional monitoring of drainage water and overland flow. Annually, the collectors for overland flow intercepted between 11 and 35% of the surplus rainfall. Single flow events accounted for up to 52% of the annual dissolved reactive phosphorus (DRP) load. The Olsen-P status of the soil influenced DRP and total phosphorus (TP) concentrations in land drainage water and overland flow. Annual TP loss was highly variable and ranged from 0.19 to 1.55 kg P ha(-1) yr(-1) for the plot receiving no P fertilizer and from 0.35 to 2.94 kg P ha(-1) yr(-1) for the plot receiving 80 kg P ha(-1) yr(-1). Despite the Olsen-P status in the soils ranging from 22 to 99 mg P kg(-1), after 5 yr of fertilizer P applications it was difficult to identify a clear Olsen-P concentration at which P losses increased. Any relationship was confounded by annual variability of hydrologic events and flows and by hydrologic differences between plots. Withholding P fertilizer for over 5 yr was not long enough to lower P losses or to have an adverse effect on herbage P concentrations.     

Risk-based targeting of diffuse contaminant sources at variable spatial scales in a New Zealand high country catchment.

Management of agricultural diffuse pollution requires targeting or prioritising critical source areas at various spatial scales within watersheds. This study develops, evaluates and illustrates a risk-based approach for assessment and targeting of source areas at catchment, subarea and individual farm scales. Catchment water quality data are used in conjunction with information on watershed characteristics from the New Zealand Land Resources Inventory at the subarea scale and land use information at the farm scale to assess risk and target source areas. Total phosphorus in the Lake Hayes Catchment, a high country pastoral catchment in the South Island of New Zealand, is used as a case study. Use, comparison and evaluation of several different methodologies for subareas and individual properties showed that a subarea in the upper catchment and one immediately upstream from the lake were the worst source areas. Targeting of other subareas varied dependent on the method used. The worst individual properties were targeted based on the combination of intensity of cattle and sheep grazing, fertilizer usage, bank erosion and location in the worst subareas. Water quality results are critical to successful targeting, particularly for convincing landowners that streams will benefit from best management practices on their properties. In addition to concentrations, average and extreme loadings are important. Data on catchment characteristics, particularly land use, are needed for targeting, but are not always readily available at small scales. This study demonstrated simple but useful methods for application of assessment information for quantitative targeting of contaminant source areas at different spatial scales.     

简析绿色产业在威海的振兴及其发展的启示

通过剖析绿色产业的概念及科学内涵，系统地阐述了国内外绿色产业体系构建的特点及进展，详细描述了威海市以绿色能源、节能减排、农村环保、循环经济和生态农业为主导的绿色产业体系，总结了威海市利用区位优势及地理条件，将发展绿色产业与环保模范城市、生态市创建等活动相结合，把绿色产业体系建设纳入国民经济与社会发展规划，采取加大关键技术研究推广力度，加速绿色产业工业园创建等一系列举措推进绿色产业发展，为利用绿色产业发展机遇振兴地区经济提供有益借鉴。     

Assessing the Risk of Phosphorus Loss and Identifying Critical Source Areas in the Chaohu Lake Watershed,China

Agricultural nonpoint phosphorus (P) pollution is a primary cause of eutrophication in many freshwater systems. Identifying areas that are at high risk for P loss in a watershed and concentrating management efforts on these smaller sections is a more effective method for limiting P loss than implementing general strategies over a broad area. A modified P index scheme was used to assess the risk of P loss and identify critical source areas in the Chaohu Lake watershed on a regional scale. In the new P ranking scheme, soil P sorption index (PSI) and degree of P saturation (DPS) were introduced as source factors to represent the inherent ability of P transport in the soil-water interface. Distance from P sources to Chaohu Lake was also considered as a transport factor to take into account P degradation from source to the final receiving water. The ranking scheme was modified to use available data on the regional scale. P index calculation results showed high spatial variation of P loss risk in the Chaohu Lake watershed. The highest risk areas focused on the downstream parts of the main rivers that discharge into Chaohu Lake. The induction of new components into the P index calculation makes it possible to identify critical source areas of nonpoint P loss on a regional scale, thus allowing decision makers to implement best management practices (BMPs) in such a manner as to minimize P loss to sensitive watercourses.