摘要:

IntroductionPassive samplers, such as semi-permeable membrane devices (SPMDs), are rapidly being adopted for environmental monitoring of hydrophobic organic compounds. SPMDs can be deployed in aquatic environments for a number of different applications including determining the presence, source, and fate of contaminants; delineating contaminant fate in different environmental compartments; estimating time-weighted average contaminant concentrations; predicting organism exposure; and biomimetic extraction for toxicity assessment of aqueous contaminants.1Since the SPMD design was first introduced in 1990,2SPMDs have proven to be extremely efficient for monitoring hydrophobic contaminants in the environment, and over 300 studies have been published.3However, no studies are known to have been conducted in tropical regions or in tropical streams.Pesticide use in Central America is a concern, and several environmental and human poisonings have been documented.4–6However, few studies regarding environmental distribution, toxic effects on aquatic organisms, or general impact on ecosystems have been undertaken in tropical areas.5,6Similarly, no studies have examined the effect of biofouling on deployed SPMDs in tropical streams, even though SPMDs are known to experience heavy biofouling especially during extended exposures in warm or tropical surface waters.1This study was conducted to increase understanding of the interaction among biofouling, deployment time, and stream flow on pesticide sequestration in stream-deployed SPMDs. This first use of passive samplers, such as SPMDs, in Central America is part a larger study to detect and monitor pesticide presence, fate, and biological effects in the extensive agricultural region of the Sixaola River watershed in southeastern Costa Rica.7

ISSN:1464-0325    

DOI:10.1039/b904329b

出版商:RSC    

年代:2009

数据来源: RSC

摘要:

Environmental impactOur data make possible the chemometric evaluation of the accumulative abilities ofSaduria entomonas a candidate for biomonitoring of heavy metals in the southern Baltic Sea. The isopod is one of the sentinel organisms recommended by HELCOM for evaluating the state of the marine environment. Chemometric analysis indicates that several external environmental conditions, among others, the granulometric composition of the sediment, make an important contribution to the discrimination of isopod populations inhabiting two regions, namely open Baltic waters and the Gulf of Gdansk which is more exposed to anthropogenic factors. It appears that this is the first study concerning multivariate assessment of bioaccumulation of heavy metals inSaduria entomonwith respect to the concentration of their labile forms in the associated sediments as substrata.

ISSN:1464-0325    

DOI:10.1039/b900366e

出版商:RSC    

年代:2009

数据来源: RSC

摘要:

Environmental impactRecently, due to growing evidence of environmental impacts and the increased emphasis on artificial recharge using reclaimed water, endotoxins are under increasing interest. This research assesses the endotoxins in different treatment plant influents which are not designed to treat these chemicals. It generates data towards improvement of existing wastewater facilities to address endotoxin issues to maintain clean water environments, which is likely to create positive environmental impacts on sustainability of water and ecosystems. It considers the augmentation of drinking water supplies as a means of achieving a sustainable water supply and significant environmental benefits through protection against drought. Environmental sustainability is to be achieved once water resources are not lacking. Moreover, this study will enhance human trust to reuse practices.

ISSN:1464-0325    

DOI:10.1039/b911165d

出版商:RSC    

年代:2009

数据来源: RSC

摘要:

IntroductionUrban and suburban neighborhoods present challenges for the prediction of pollutant dispersion due to the heterogeneity of building configurations which sets up irregular, complex wind patterns. There is a need to identify and quantify the relative importance of the dominant factors that affect the dispersion. There have been many studies on regular arrays of buildings to develop an understanding of the phenomena involved in urban dispersion, focusing on such factors as street canyon width, building aspect ratio, traffic, and orientation of street canyons to prevailing winds.1–5These studies have produced a better understanding of the importance of near-field effects on the initial dispersion of a plume arising from an urban source (e.g., traffic) within the street canyon. Several recent studies6–10have highlighted the effect variations in building height can have on the airflow patterns in urban areas. These variations enhance the transfer of momentum from the winds aloft into the building canopy and provide for the rapid vertical mixing of the pollutant from the street canyons. In this paper, we examine the effect of a single building that towers above a neighborhood of buildings of uniform height.A wind tunnel study was undertaken to supplement a field study performed in Brooklyn, NY, USA, designed to study the dispersion of pollutants from a line source in an urban neighborhood. Preliminary computational fluid dynamics (CFD) simulations were also performed to visualize the flow with greater resolution. This paper is the first of two papers describing flow and pollutant dispersion for an idealized scale model of the site (see also Brixeyet al.11). The field study, the Brooklyn Traffic Real-Time Ambient Pollutant Penetration and Environmental Dispersion (B-TRAPPED) study, was performed in May 2005 with the goal of improving the understanding of airflow patterns through a complex area to be able to predict the dispersion patterns of pollution from traffic and hazardous releases along the roadway.12–16The section of the city chosen for the study has fairly regular city block shapes comprising row houses with uniform heights and common backyards that form a courtyard. Adjacent to the major thoroughfare passing through the study area was one tall building that dominated the area. Standing 12 stories tall, it was significantly higher than the neighborhood row houses which were typically three stories tall. Upwind of the city block containing the tall building was an industrial dock area and Upper New York Harbor.The wind tunnel study was designed to provide insight into the flow patterns throughout the study area, supplementing the information gathered from a limited number of field instruments deployed in typical field studies. Numerical simulations were also performed to visualize the flow and concentration fields since the resulting velocity and concentration fields are computed throughout the whole domain. The goal of this study was to identify important flow phenomena in urban and suburban areas shown by both techniques.

ISSN:1464-0325    

DOI:10.1039/b907135k

出版商:RSC    

年代:2009

数据来源: RSC

摘要:

Environmental impactThis study concerns a novel Plume Capture Device (PCD), which can temporarily store a plume sample so that comprehensive particle size distribution and gas and particle analysis measurements can be performed. The sampling technique is mobile making it very suitable for examining sources such as moving aircraft, motor vehicles and ships. The study examines particle losses in the PCD during size distribution measurements and the potential for these to affect measurement accuracy as well as steps for minimising and accounting for those losses. The sampling technique has been used in recently published studies of aircraft emissions where the plume was present for only 15 s. Further studies using the PCD are in progress.

ISSN:1464-0325    

DOI:10.1039/b907891f

出版商:RSC    

年代:2009

数据来源: RSC

摘要:

Environmental impactArsenic concentration in rice can be very high compared to other cereals due to the nature of the plant and its growth conditions as well as due to environmental pollution such as the use of arsenic containing pesticides and contaminated irrigation water. This study provides information about total arsenic and arsenic species in rice-based products such as miso, syrup and amazake to better understand their health impact. Consuming such products can provide up to 23% of the Provisional Tolerable Daily Intake of arsenic. This is of concern to certain population who already consume arsenic rich products (rice and seaweed). Similar products from barley or millet, which contain lower levels of inorganic arsenic, can be alternatives until low arsenic containing rice is available.

ISSN:1464-0325    

DOI:10.1039/b911615j

出版商:RSC    

年代:2009

数据来源: RSC

摘要:

1IntroductionThe relative abundance of the elements, the way that they speciate andthe properties of the resultant molecules have largely determined the courseof biological evolution. It is clear, however, that unlike the chemical speciationsthat occur in the inorganic environment those that occur in biological systemsare carefully controlled to facilitate some process. Living organisms survivebecause they direct the type and reactivity of the elements and moleculeswith which they associate.In order to appreciate this, imagine a mineral EL1that haspartly dissolved in an aqueous solution to release the element (E) and itsassociated ligand (L1). In this solution is a second ligand L2that is also capable of associating with element E. At equilibrium the systemwould exist as shown inFig. 1. Thefree dissociated ion of element E in the environment is shown as Ee.Possible interactionsof an element (E) with a variety of ligands (L1–L7). The element enters the aqueous environment by dissolution of the mineral(EL1) and dissociates to form a free metal ion (Ee)capable of speciating with other dissolved ligands (EL2). In thepresence of living organisms there may be other ligands released into thesystem (L3) that could form biofilms on the mineral, binding theelement (EL3) and potentially removing E from the system by sedimentation.A cell might also produce a membrane bound ligand (L5) capableof sensing the element E which may also enter the cell through a ion pump(L6) to be released in the cytoplasm (Ei) where it canspeciate onto intracellular ligands (L4). Alternatively anion transportingchannels (L7) may allow speciated forms of the element (EL1)direct access into the cell.Consider what would happen now if an organism that could act as a sourceof additional ligands (e.g., L3) resided within this system.Such ligands might be humic acids or bacterial exopolymers and they wouldraise at least two additional possibilities. First, the biological productsmight coat the surface of the mineral forming biofilms that interacted withelement E resulting in it becoming speciated onto this surface (EL3).Second, if this particle sedimented out of the aqueous environment there wouldalso be a loss of the surface-bound elements from the system. The systemwould now have progressed from an equilibrium situation to a kinetically drivenstate that determined the residence time of the element (E) in the aqueousphase.This example of the speciation of an element onto a surface and the sedimentationof such an organically coated particle has been used to explain both the compositionof the marine environment1and the occurrenceof geochemical cycling.2It is a powerful argumentthat when carried to its conclusion provides an explanation for the compositionof the extracellular fluids of many organisms since these are thought to reflectthe concentrations resulting from such biogeochemical processes.Let us, therefore, try to complete this model by considering the otherspeciation effects that a living cell could have on this system. Cells controlthe type and reactivity of the elements with which they associate. They dothis by isolating heterogeneous aqueous compartments within hydrophobic cellmembranes. This is achieved by trapping molecules with hydrophilic ligands(L4) and by synthesizing hydrophobic ligands that become trappedin the membrane itself. These form localised element-sensing molecules(L5) or vectorial channels containing elaborate structural ligands(L6,L7). Various elements become speciated with theseligands and thus segregated from the bulk phase to provide the organisationalbasis that defines living organisms.From this brief introduction it will be apparent that the definition ofspeciation as ‘the occurrence of an element in separate identifiableforms’ effectively requests a review of the whole of inorganic biochemistryand its relationship to biogeochemical cycling. This is an almost impossibleremit and in order to introduce some shape into this overview we pose threequestions.(1) Are the laws of inorganic chemistrydirectlyapplicable tobiological systems? If the operational answer to this question is ‘Yes’then we have a common starting ground for chemists and biologists. If theanswer is ‘No’ then we have to identify how living systems aremodified by factors such as nanoscale dimensions or localised energy inputs.(2) How diverse are the speciation processes that occur in biological systems?This, in effect, questions how many ‘identifiable ligands’ orspeciation pathways have to be considered either in the external environmentor within the cell. In order to control the types of speciation that haveto be discussed we have chosen to base our analysis on a few examples fromthe different aqueous, mineral and lipid environments that are involved inliving systems.(3) Does this provide a rational context for considering the toxicity ofsome speciation pathways that might otherwise appear to be disparate phenomena?

ISSN:1464-0325    

DOI:10.1039/b005563h

出版商:RSC    

年代:2000

数据来源: RSC