Chemical Partitioning to Foliage: The Contribution and Legacy of Davide Calamari

- DOI: http://dx.doi.org/10.1065/espr2006.01.002 Background Davide Calamari and his colleagues were among the first to appreciate that vegetation could play a key role in determining the fate and effects of organic contaminants. They conducted pioneering experiments to investigate the uptake of contaminants by plants from the atmosphere and they sought to model the observed phenomena. In the nearly two decades since there has been a marked increase in understanding of these phenomena as a result of both experimental and modelling studies. - Goal. In this study we briefly review our current understanding of chemical partitioning between foliage and air. A model in both fugacity and concentration format is described, based on that of Tolls and McLachlan (1994), in which the leaf is treated as consisting of two layers, a waxy cuticle with an underlying 'reservoir' layer, the cuticle being surrounded by an air boundary layer and containing stomata that provide direct access from the air to the 'reservoir'. The model quantifies the dynamic penetration of a defined chemical into a defined leaf as a function of time. Main Features The model is applied for illustrative purposes to a hypothetical but typical leaf for a set of illustrative chemicals to demonstrate the effect of changes in physical-chemical properties and leaf characteristics. Discussion The results are compared qualitatively with a variety of field and laboratory studies of foliage uptake and clearance of chemicals. Conclusion It is concluded that the model yields results that are generally consistent with observations. It is suggested that with appropriate parameterisation and validation, the model can contribute to an improved understanding of the process of foliage uptake from the atmosphere and to the development of an improved predictive capability.     

Use of Small Forage Fish for Regional Streams Wildlife Risk Assessment: Relative Bioaccumulation of Contaminants

Selection of fish species for sampling to assess extent and potential effects of fish tissue contaminants is a criticalconsideration in the design of regional probability-designsurveys. The ideal species would be ubiquitous, bioaccumulatetoxic chemicals, and be prey of consumers of concern(piscivorous wildlife, humans). In first to third order streams,small short-lived forage fish (minnows (F. Cyprinidae), darters (F. Percidae), and sculpins (F. Cottidae), are more frequently found and therefore likely to be prey to more species ofwildlife than those of sportfish whose adults grow to a largesize (suckers (F. Catostomidae), trout (F. Salmonidae), bass, andsunfish (F. Centrarchidae), and carp). Targeting smaller foragefish should also produce a larger number of individuals persample on average than may be achieved with the larger species.An analysis of fish collected in 1993 and 1994 as part of theMid-Atlantic Highlands Assessment (MAHA) showed that, asexpected, forage fish were more ubiquitous than sportfishspecies. Analysis also revealed that, on a regional basis, forage fish bioaccumulated comparable levels to sportfish, ofsome widely occurring contaminants such as DDT, MeHg, and PCBs.Results indicated that smaller forage fish can be used asindicator species for a regional assessment for mostcontaminants (Zn being the one clear exception), that was notsignificantly different from one based on the larger species.Forage fish may therefore be an excellent choice as indicatorspecies for regional streams ecological risk assessment studies.     

Assessment of contamination and biomarker responses in two species of herons on the St. Lawrence river

This study was undertaken to validate potential biomarkers of exposure and effects due to chemical contaminants in breedingcolonies of the Great Blue Heron and the Black-crowned Night-Heron on the St. Lawrence River. Eggs and fledglings from both species were collected from many colonies along theRiver. The fledglings from colonies in freshwater and brackishwater were more contaminated by mercury and PCBs than those from estuarine and gulf colonies. With respect to fledglings ofthe two heron species, some morphometric and blood biochemicalmeasurements, including plasma thyroid hormones and retinol, were significantly different among colonies. Significant differences were also observed in liver retinoids, EROD and porphyrins among colonies. The results of this study suggestthat plasma retinoids and thyroid hormones are good biomarkersof exposure and effects, and are sufficiently sensitive to reflect local and regional variations in contamination. Along with the measure of contaminants in egg and plasma, they constitute non-invasive biomarkers which represent an importantcriteria for long term monitoring of wildlife species. It is concluded that the Great Blue Heron is an appropriate sentinelspecies in the surveillance network for the St. Lawrence River.     

Incidence of stress in benthic communities along the U.S. Atlantic and Gulf of Mexico coasts within different ranges of sediment contamination from chemical mixtures

Synoptic data on concentrations of sediment-associated chemical contaminants and benthic macroinfaunal community structure were collected from 1,389 stations in estuaries along the U.S. Atlantic and Gulf of Mexico coasts as part of the nationwide Environmental Monitoring and Assessment Program (EMAP). These data were used to develop an empirical framework for evaluating risks of benthic community-level effects within different ranges of sediment contamination from mixtures of multiple chemicals present at varying concentrations. Sediment contamination was expressed as the mean ratio of individual chemical concentrations relative to corresponding sediment quality guidelines (SQGs), including Effects Range-Median (ERM) and Probable Effects Level (PEL) values. Benthic condition was assessed using diagnostic, multi-metric indices developed for each of three EMAP provinces (Virginian, Carolinian, and Louisianian). Cumulative percentages of stations with a degraded benthic community were plotted against ascending values of the mean ERM and PEL quotients. Based on the observed relationships, mean SQG quotients were divided into four ranges corresponding to either a low, moderate, high, or very high incidence of degraded benthic condition. Results showed that condition of the ambient benthic community provides a reliable and sensitive indicator for evaluating the biological significance of sediment-associated stressors. Mean SQG quotients marking the beginning of the contaminant range associated with the highest incidence of benthic impacts (73–100% of samples, depending on the province and type of SQG) were well below those linked to high risks of sediment toxicity as determined by short-term toxicity tests with single species. Measures of the ambient benthic community reflect the sensitivities of multiple species and life stages to persistent exposures under actual field conditions. Similar results were obtained with preliminary data from the west coast (Puget Sound).     

Economic Modelling in Sustainability Science: Issues,Methodology, and Implications

Sustainability science is a new branch of human knowledge. It is necessary to model sustainability science based on a framework consisting of the interactions of society, ecology, the environment and the economy. This paper develops such a model, the SEEOSG model, containing the essential structural relationships that incorporate the environmental and economic conditions required for sustainability. The model is solved as a dynamic optimisation problem. This optimal growth model of ecology and economic growth enables us also to analyse the issues which are specific to sustainability science such as the ecologically sustainability and inter-generational equity implications of economic activities and policies. In the model results growth maximisation goals appear to be fraught with difficulties such as infeasibility and non-sustainability. The results also suggest also that an equilibrium ecological and economic system does not sustain over a very long period of time unless appropriate actions are taken. Readers should send thier comments on this paper to: BhaskarNath@aol.com within 3 months of publication of this issue.     

Evaluation of zeolite-sand mixtures as reactive materials protecting groundwater at waste disposal sites

To recognize properties of a mixture of Vistula sand (medium sand acc. to USCS) with Slovak zeolite as reactive materials suitable for permeable reactive barriers proposed for protection of groundwater environment in vicinity of old landfills comprehensive laboratory investigations were performed. The present study investigates the removal of contaminants specific for landfill leachates onto zeolite-sand mixtures containing 20%, 50% and 80% of zeolite (ZS20, ZS50 and ZS80). Taking into account the results of batch tests it was concluded that the Langmuir isotherm best fitted the data. It was observed that the presence of ammonium, calcium and magnesium decreases the removal efficiency of copper by 32%. Column tests of contaminant migration through the attenuation zone of the reactive materials were interpreted using the software package CXTFIT, which solves a one-dimensional advection-dispersion equation. Column test results also indicate the strong influence of the presence of interfering substances on copper immobilisation; dynamic sorption capacities decrees twofold. Throughout the landfill leachate flow through ZS80 sample, a constant reduction of NH+4 (at 100%), K+ (at 93%) and Fe total (at an average of 86%) were observed. There was no reduction in chemical oxygen demand and biochemical oxygen demand.     

新型污染物卤代咔唑的环境行为及生态毒理效应

卤代咔唑(PHCs)是一类与多氯二苯并呋喃结构相类似的新型环境有机污染物.单种卤素取代的PHCs具有135个同系物.绝大多数PHCs不是人类合成化学品或工业品.虽然20世纪80年代即首次在环境中发现PHCs,但直到本世纪这类化合物才逐渐引起人们的关注.近年来,20余种PHCs在河流湖泊沉积物和土壤中被陆续检出.另外,PHCs具有类二噁英毒性、持久性和生物累积性.作为一类新型污染物,PHCs的环境行为研究目前相对较少.因此,了解PHCs的环境分布、来源和生态毒理效应对正确认识这类化合物的环境风险具有重要意义.本文综述了PHCs的环境分布、来源、分析方法和生态毒理效应,并对其未来的研究发展方向作了展望.     

九龙江下游水源水中新发病原微生物和抗生素抗性基因的定量PCR检测

新发水传病原微生物和抗生素抗性基因对于饮用水的生物安全性有重要意义.以7种典型的水传病原微生物和4种抗生素抗性基因作为检测指标,对闽西南地区的重要水源九龙江下游水源水进行了检测.从九龙江下游4个采样点和附近某水厂进出水采集水样,用0.22μm的滤膜过滤后,进行DNA提取及荧光定量PCR检测.结果表明,九龙江下游水源水中Salmonella enterica(Salmonella spp.)、Legionella pneumophila(L.pneumophila)和Pseudomonas aeruginosa(P.aeruginosa)等个别指标可达到103、104、105copies.mL-1的水平.有机物浓度可能对病原微生物和抗生素抗性基因的水平有较大影响.水厂常规工艺对于大多数病原微生物和抗生素抗性基因可以实现有效去除,但对Salmonella spp.的去除效果不理想.因此为保证饮用水安全,需要在清理污染源、提高处理工艺水平以及末端控制方面加强管理.     

A critical review on the application of biochar in environmental pollution remediation: Role of persistent free radicals (PFRs)

Biochar as an emerging carbonaceous material has exhibited a great potential in environmental application for its perfect adsorption ability. However, there are abundant persistent free radicals (PFRs) in biochar, so the direct and indirect PFRs-mediated removal of organic and inorganic contaminants by biochar was widely reported. In order to comprehend deeply the formation of PFRs in biochar and their interactions with contaminants, this paper reviews the formation mechanisms of PFRs in biochar and the PFRs-mediated environmental applications of biochar in recent years. Finally, future challenges in this field are also proposed. This review provides a more comprehensive understanding on the emerging applications of biochar from the viewpoint of the catalytic role of PFRs.