Bioaccumulation of palladium, platinum and rhodium from urban particulates and sediments by the freshwater isopod Asellus aquaticus.

The three-way catalytic converters introduced to oxidize and reduce gaseous automobile emissions represent a source of platinum group elements (PGEs), in particular platinum, palladium and rhodium, to the urban environment. Abrasion of automobile exhausts leads to an increase of the concentration of PGEs in environmental matrices such as vegetation, soil and water bodies. The bioaccumulation of Pd, Pt and Rh by the freshwater isopod Asellus aquaticus was studied in natural ecosystems and under laboratory conditions. Owing to the low concentration level (ng g(-1)) of PGEs in the animals studied. analyses were performed with a quadrupole inductively coupled plasma mass spectrometry (ICP-MS) and hafnium, copper, yttrium, rubidium, strontium and lead were monitored for spectral interference correction. Asellus aquaticus collected in an urban river showed a content (mean +/- s) of 155.4 +/- 73.4, 38.0 +/- 34.6, and 17.9 +/- 12.2 ng g(-1) (dry weight) for Pd, Pt and Rh, respectively. The exposure of Asellus aquaticus to PGE standard solutions for a period of 24h give bioaccumulation factors of Bf: 150, 85, and 7 for Pd, Pt and Rh, respectively. Exposure of Asellus aquaticus to environmental samples for different exposure periods demonstrated that PGE bioaccumulation is time dependent. and shows a higher accumulation for the materials with a higher PGE content. While all three elements have the same uptake rate for exposure to catalyst materials, for exposure to environmental materials they havc a different uptake rate which can be attributed to transformations of the PGE species in the environment.     

Tolerance to lead in the freshwater isopod asellus aquaticus

Samples of the fresh-water crustacean Asellus aquaticus were taken from three sites in the River Trent basin, subjected to different amounts of lead pollution. The survival rate of large and small animals were compared experimentally in a series of different concentrations of lead. Differential survival was recorded between the size classes and the sites that could be explained in terms of genetic adaptation. The significance of the results is discussed in terms of adaptation to environmental pollution.     

Cadmium uptake by freshwater bacterial communities

Microcosm experiments in chemostat incubated at 20°C showed that cadmium contamination does not greatly affect bacterial communities in cultures contaminated with up to 1 mg Cd l⁻¹.Bacterial productivity remains unchanged and cadmium-resistant strains arise quickly and in great number. The cadmium accumulation by bacteria depends on the bacterial productivity. The free bacteria can accumulate up to 1200 ppm cadmium whereas the adhering bacteria concentrate up to 6100 ppm. At a steady state, 11–29% cadmium is removed from the water phase of cultures.     

A statistical approach for the assessment of the toxic influences on Gammarus pulex (Amphipoda) and Asellus aquaticus (Isopoda) exposed to urban aquatic discharges

A statistical procedure has been developed to quantify the mortality response of caged macroinvertebrates in terms of measured environmental parameters. Populations of Gammarus pulex and Asellus aquaticus were caged in urban receiving waters downstream of a combined sewer overflow (CSO) and a surface water outfall (SWO) for 36 d. During this period of exposure, the mortality and heavy metal bioaccumulation responses of populations of both species, as well as seventeen different chemical and hydrological characteristics of the receiving watercourse were monitored. Multivariate statistical techniques, comprising principal component analysis (with VARIMAX rotation) and multiple regression analysis were used to determine the measured variables that influenced mortality. Certain parameters (BOD₅, total aqueous copper concentration, flow rate and suspended solids) influenced the mortality responses of both species. Ammonia, total aqueous lead concentrations and dissolved aqueous concentrations of zinc and copper additionally affected the response of Gammarus pulex. Body concentrations of zinc, lead, cadmium and copper and dissolved aqueous concentrations of cadmium were found to be influential upon the mortality response of caged Asellus aquaticus. The relationships between the mortality responses of each species and the selected independent variables are expressed in the form of stable quantitative equations by regressing the dependent variable (ie mortality) against the principal components of the independent parameters. This statistical approach represents an important tool for interpreting large intercorrelated sets of environmental data obtained in situ.     

Distribution of Asellus aquaticus and microinvertebrates in a non-chlorinated drinking water supply system--effects of pipe material and sedimentation

Danish drinking water supplies based on ground water without chlorination were investigated for the presence of the water louse, Asellus aquaticus, microinvertebrates (<2 mm) and annelida. In total, 52 water samples were collected from fire hydrants at 31 locations, and two elevated tanks (6000 and 36,000 m³) as well as one clean water tank at a waterworks (700 m³) were inspected. Several types of invertebrates from the phyla: arthropoda, annelida (worms), plathyhelminthes (flatworms) and mollusca (snails) were found. Invertebrates were found at 94% of the sampling sites in the piped system with A. aquaticus present at 55% of the sampling sites. Populations of A. aquaticus were present in the two investigated elevated tanks but not in the clean water tank at a waterworks. Both adult and juvenile A. aquaticus (length of 2-10 mm) were found in tanks as well as in pipes. A. aquaticus was found only in samples collected from two of seven investigated distribution zones (zone 1 and 2), each supplied directly by one of the two investigated elevated tanks containing A. aquaticus. Microinvertebrates were distributed throughout all zones. The distribution pattern of A. aquaticus had not changed considerably over 20 years when compared to data from samples collected in 1988-89. Centrifugal pumps have separated the distribution zones during the whole period and may have functioned as physical barriers in the distribution systems, preventing large invertebrates such as A. aquaticus to pass alive. Another factor characterising zone 1 and 2 was the presence of cast iron pipes. The frequency of A. aquaticus was significantly higher in cast iron pipes than in plastic pipes. A. aquaticus caught from plastic pipes were mainly single living specimens or dead specimens, which may have been transported passively trough by the water flow, while cast iron pipes provided an environment suitable for relatively large populations of A. aquaticus. Sediment volume for each sample was measured and our study described for the first time a clear connection between sediment volume and living A. aquaticus since living A. aquaticus were nearly only found in samples with sediment contents higher than 100 ml/m³ sample. Presence of A. aquaticus was not correlated to turbidity of the water. Measurements by ATP, heterotrophic plate counting and Colilert^® showed that the microbial quality of the water was high at all locations with or without animals. Four other large Danish drinking water supplies were additionally sampled (nine pipe samples and one elevated tank), and invertebrates were found in all systems, three of four containing A. aquaticus, indicating a nationwide occurrence.     

Influence of Asellus aquaticus on Escherichia coli, Klebsiella pneumoniae, Campylobacter jejuni and naturally occurring heterotrophic bacteria in drinking water

Water lice, Asellus aquaticus (isopoda), frequently occur in drinking water distribution systems where they are a nuisance to consumers and water utilities. Whether they are solely an aesthetic problem or also affect the microbial water quality is a matter of interest. We studied the influence of A. aquaticus on microbial water quality in non-chlorinated drinking water in controlled laboratory experiments. Pure cultures of the indicator organisms Escherichia coli and Klebsiella pneumoniae and the pathogen Campylobacter jejuni as well as naturally occurring heterotrophic drinking water bacteria (measured as heterotrophic plate counts, HPC) were investigated in microcosms at 7 °C, containing non-sterilised drinking water, drinking water sediment and A. aquaticus collected from a non-chlorinated ground water based drinking water supply system. Concentrations of E. coli, K. pneumoniae and C. jejuni decreased over time, following a first order decay with half lives of 5.3, 18.4 and 1.3 days, respectively. A. aquaticus did not affect survival of indicators and pathogens substantially whereas HPC were influenced by presence of dead A. aquaticus. Growth rates increased with an average of 48% for bacteria grown on R-2A agar and an average of 83% for bacteria grown on yeast extract agar when dead A. aquaticus were present compared to no and living A. aquaticus present. A. aquaticus associated E. coli, K. pneumoniae and C. jejuni were measured (up to 25 per living and 500 per dead A. aquaticus) and so were A. aquaticus associated heterotrophic bacteria (>1.8*10⁴ CFU per living and >6*10⁴ CFU per dead A. aquaticus). A. aquaticus did not serve as an optimised habitat that increased survival of indicators and pathogens, since A. aquaticus associated E. coli, K. pneumoniae and C. jejuni were only measured as long as the bacteria were also present in the water and sediment.     

The transformative role of rivers in the evolution of urban landscapes: a case study from urban rivers of Chelmsford in Essex

ABSTRACT

Urban rivers across Europe have a long history of anthropogenic intervention and active use that make up a key part of our cultural landscapes. This article focuses on the morphological transformation processes of urban rivers in Europe. It approaches the topic through a review of the function, meaning and identity of rivers within the urban context. This is illustrated here using the case study of the urban sections of the rivers Chelmer and Can in Chelmsford, Essex, tracing the formation and transformation of their urban character and identifying the determinants of the development of Chelmsford’s urban form over time.     

论桂林山水间的城市文化

介绍了桂林独特的历史文化底蕴和文化气息,阐述了桂林在城市建设和发展过程中将古文化遗迹的保护与弘扬和现代化建设完美结合的成功经验,指出城市建设过程中不能盲目洋化,应结合自身特色和城市文化塑造个性。     

城市河道综合整治规划设计探索

针对城市河道综合整治问题,结合工程实例,阐述了城市滨水区规划的原则、景区性质及发展目标,探讨了城市空间布局、景点设计、植物配植规划、防洪规划、交通规划等规划构思,论述了河道整治和滨水地带规划建设可持续发展的途径.     

Methodology for the assessment of connectivity and comfort of urban rivers

Urban rivers differ from natural rivers because of the direct connection they have with human habitat. Furthermore, riverbanks are public spaces that contribute to the interaction between natural and urbanized areas and between people from different socioeconomic background. Due to this significance, the main objective of this research was to provide a methodology for the construction of a toolbox that evaluates connectivity and comfort of urban riverbanks, so as to allow comparative visual and numeric analysis between different zones of the same river, distinct rivers in the same city and rivers in various cities. The proposal was based on the disaggregation of the concepts of connectivity and comfort, through the analysis of four dimensions: (a) Spatial and visual accessibility, (b) Continuity of the green corridor, (c) Condition of public space, and (d) Condition of the first built line, expressed in thirteen quantitative condition indicators. For validation, the toolbox was applied to five zones of the Tomebamba River of the city of Cuenca in Ecuador and a series of maps were generated allowing spatial visualization of the results. In addition, an Urban River Sustainability Index (URSI) was developed to reinforce the decision-making processes in planning and urban design.     

A procedure for the routine biological evaluation of urban runoff in small rivers

A rationale and stepwise procedure for the biological evaluation of urban runoff in small rivers is described. The protocol is predicated on the application of the Brillouin diversity index to collections of benthic macroinvertebrates isolated from artificial substrates in the course of a year.     

Contamination of vinyl chloride in shallow urban rivers in Osaka, Japan

Vinyl chloride (VC) contamination had taken place in heavily polluted shallow rivers (Taishogawa and lower Hiranogawa Rivers) in Osaka, Japan. VC concentrations ranged from below detection limit to 55.6 micrograms l-1 (mean: 3.35 micrograms l-1, standard deviation: 5.96 micrograms l-1). Of 55 volatile organic compounds (VOCs) analyzed, concentrations of cis-1,2-dichloroethene (c-DCE), tetrachloroethene (PCE) and trichloroethene (TCE) were significantly correlated to VC concentrations in the rivers, indicating that they share common sources. The four VOCs were invariably present at approximate relative ratios of about 1:2.7:1.5:0.31 (VC: c-DCE: PCE: TCE). The similarity between sampling dates in the distribution pattern of the four VOCs concentrations were observed, but their concentrations were different between the dates. The concentrations of the four VOCs decreased with distance down the river. A sample from the upper Taishogawa River in July 1997 had 55.6 micrograms l-1 of VC, 152 micrograms l-1 of c-DCE, 86.2 micrograms l-1 of PCE and 18.4 micrograms l-1 of TCE, respectively. These values are about an order of magnitude higher than the other sites over the study period and are likely indicative of point source inputs.     

Adsorption and desorption of heavy metals in bottom mud of urban rivers

An adsorption experiment has been carried out to determine the factors affecting the uptake of heavy metals by bottom mud in urban rivers. The adsorption of Cu, Zn, Cd, and Pb was described using the Freundlich adsorption equation. The Freundlich constant (K) was related to the grain size and organic matter content of bottom mud. It was found that the main factor controlling the adsorption of metal was organic matter, since the adsorbed metals decreased remarkably due to the destruction of organic matter from the fine bottom mud. The desorption experiment proved that the metals adsorbed by mud were extracted approx. 100% with dilute HCI. Therefore, the amount of heavy metal adsorbed per 1 g of TOC can be calculated from the acid soluble metal content of bottom mud. Moreover, the method of extraction by 2 N CH₃COONH₄ can be used to distinguish between an ion exchangeable form by minerals and a chemical form by organic matter.The adsorption and desorption experiments indicated that fine bottom mud with a high organic matter content contributes to the uptake of metals in urban rivers and that such metals can be extracted with 0.5 N HCI.     

北京市城市河道生态治理存在的问题及对策

针对北京市城市河道治理中存在的问题,提出在明确生态河道建设目标的基础上,以生态治河理念为指导,恢复自然河道的生态系统,对边坡进行生态防护和绿化,恢复和营造良好的都市型河道景观,改善河道水体水质,以期满足水安全和人们对水的各种需求,恢复水域生态系统的完整性,实现人水和谐。     

树立城市森林建设理念 构建山水宜居城市

通过张家口市城市森林的建设,探讨了城市森林建设的意义,针对森林建设的紧迫性,确立了城市森林建设的思路,阐述了张家口城市森林建设的实践与成果,以积累城市森林建设经验,创造城市森林建设新的行之有效的发展模式.     

Cadmium uptake by floating macrophytes.

Cd uptake capacity of a group of floating macrophytes (Salvinia herzogii, Pistia stratiotes, Hydromistia stolonifera and Eichhornia crassipes) was determined in outdoors experiments during the lowest temperature period of the year. Although all studied species were highly efficient in the Cd uptake, Pistia stratiotes was selected for further research because of its superior performance and its higher average relative growth rate. Cadmium% removal by Pistia stratiotes was greater in the first 24 h of the experiments (63, 65, 72 and 74% of the added Cd for 1, 2, 4 and 6 mg Cd 1(-1), respectively). After 31 days of growth, Pistia statiotes efficiently removed Cd at the studied concentrations. The macrophyte was able to keep its capacity for Cd removal even though some toxicity symptoms appeared at 4 and 6 mg Cd 1(-1). The greater the initial concentration, the greater Cd bioaccumulation rates. The increase of Cd concentration in plant tissues occurred especially in roots and was linearly related to the quantity of Cd added. Cd sorption by roots is faster than translocation to the plant aerial part and it occurs mainly during the first 24h.     

A decision support system for identifying the habitat quality and rehabilitation potential of urban rivers

Few habitat survey, classification or assessment methodologies have been developed specifically for urban or heavily engineered rivers, and yet these rivers need careful assessment if management options are to be considered and prioritised in an economically and environmentally effective way. This paper presents a refinement of a previously proposed urban river survey (URS), which is a modification of the Environment Agency's River Habitat Survey. It then describes indices and classifications that have been developed from URS data and that provide a link between the type of engineering applied to a stretch of urban river and its habitat characteristics. Finally, some simple decision trees and scenario‐modelling tools are presented that allow (i) newly surveyed urban stretches to be classified and (ii) some simple scenarios of channel management change to be assessed in order to prioritise management options for stretches of urban river across urban catchments.     

Platinum levels in natural and urban soils from Rome and Latium (Italy): significance for pollution by automobile catalytic converter

Platinum concentrations in topsoil samples collected in 1992 (48) and in 2001 (16) from the urban area of Rome have been determined by ICP-MS. Concentrations in 47 soil samples collected in 1992 from natural sites of Latium (an area around Rome) have been determined for a first assessment of natural background levels. The Pt concentrations in Rome urban soils collected in 1992 range from 0.8 to 6.3 ng/g (mean = 3.8 +/- 1.0) overlapping the concentration range of natural soils from Latium (mean = 3.1 +/- 2.1 ng/g). No significant correlation has generally been found between Pt contents in the 'natural' soils and related bedrock or major pedogenetic parameters. These results suggest that there is no evidence of Pt pollution in Rome urban soils at that time, because the massive use of the automobile catalytic converter has only just started. Higher (up to six times more) Pt concentrations, than those measured in the 1992 samples, have been measured, in some cases, in Rome urban soils collected in 2001, suggesting a possible start of Pt accumulation because of the large-scale use in the last decade of automobile catalytic converters. At the same time, a clear decrease of lead levels in Rome urban soils with respect to the levels measured in 1992 has been observed, paralleling the decreasing number of lead gasoline-fuelled cars. Here we present one of the first systematic studies for defining background levels of Pt in Italian natural soils, thus allowing for monitoring, in the future, should any possible Pt pollution caused by the use of automobile catalytic converter, especially in urban soils, occur.     

电感耦合等离子体原子发射光谱(ICP-AES)法测定铂金材料中杂质元素

建立了微波消解-电感耦合等离子体原子发射光谱(ICP-AES)法同时测定铂饰品国家标准物质中金、铜、铱、钴、钯、铑、钌7种杂质元素含量的方法。方法中7种元素的检出限为:钯与钌<0.0001%,其它元素<0.000 62%。经与国家标准物质认定值比对,结果满意。稀释系数95.5%~104.7%。方法测定结果与标准样品认定值一致,可满足铂金材料中杂质元素检测。     

Platinum and palladium variations through the urban environment: evidence from 11 sample types from Sheffield, UK

Platinum (Pt) and Palladium (Pd) concentrations have been analysed in 194 samples from within the city of Sheffield in the UK. The samples were taken from road dust, gully pots (also known as drains), soils, a motorway drainage pipe, rivers, lakes, sewage sludge, incinerator ash, incinerator ash in landfill, street cleansers and gully cleansers. The introduction of Pt- and Pd-bearing automobile catalysts, has been cited as the cause of a rise in the concentration of urban Pt and Pd accumulations. Geochemical analyses for the different sample types are used here to show how the Pt and Pd accumulate in different urban environments as they are transported from their catalytic source. Initially Pt and Pd collect in road dust and gully pots at values of up to 450 ppb although most analyses for both elements are around 100 ppb. The four roadside soils analysed, have a great range in values, the highest with a value of over 600 ppb Pt and 1000 ppb Pd. Then the fate of the Pt and Pd is either to be removed by gully flushers and road sweepers (which contain around half the concentration of that in road dust) or to be washed from the roads, through the gully pots, into either the river or urban drainage systems. Due to the addition of terrestrial sediments, river samples contain much reduced values of Pt and Pd, at approximately an order of magnitude lower than in road dust. Similarly, sewage sludge contains Pt and Pd values which are lower than road dust. However, the Pt and Pd analyses are much higher in incinerated sewage (with many samples over 150 ppb for both metals), probably due to the loss of the mass of other material during the incineration process. Weathered incinerator ash in landfill has lower values of Pt and Pd than fresh ash from the incinerator. Although the range in values of Pt and Pd is similar for road dust and gully pot sediments their modal values tell a different story. The mode for Pt is very similar for both road dust and gully pot sediments, at around 100 ppb, whereas there is a drop of 50 ppb in the mode for Pd in the gully pots (from 80 ppb to around 40 ppb). Given that gully pot sediment is derived from road dust, it is suggested that in gully pots, Pd is preferentially mobilized over Pt. Furthermore, a comparison of the modal values of Pt and Pd in river sediments suggests that this process continues into the natural drainage system of the city.