Algal plating as a tool for investigating allelopathy among marine microalgae

Chemical interactions among marine microalgae were studied in cultures of pennate diatoms on agar plates. Nine marine and freshwater pennate diatoms were surveyed as potential bioassay organisms; Cylindrotheca fusiformis was most favourable for assays because of its rapid and even growth on agar. Diatom and bacterial bioassays were used to screen cell and filtrate extracts of 14 microalgal cultures. A number of these algal species, which were grown axenically, produced extractable, intracellular and/or extracellular substances that inhibited the growth of C. fusiformis. Our results suggest that the culturing of pennate diatoms on a solid medium can provide a simple bioassay for screening algal extracts which potentially contain growth inhibitors involved in microalgal allelopathy.     

Conserving biodiversity that matters: practitioners' perspectives on brownfield development and urban nature conservation in London

Policies designed to conserve sites of nature conservation importance are an important aspect of city planning in the UK. London has led the way in putting in place a spatial hierarchy of sites of nature conservation importance designed to protect wildlife habitats from development. Some wasteland habitats associated with derelict and vacant land receive protection in this way but development pressure on these so-called 'brownfield sites' is high and is likely to continue. This paper examines how conservation professionals in the private, public and voluntary sectors are responding to the threats of biodiversity loss and opportunities for habitat creation posed by re-development of brownfield sites. The study draws on in-depth interviews conducted with conservation professionals and the practices employed by ecological advisers employed by developers seeking to re-develop wasteland sites. It finds that practitioners are negotiating their role in the re-development process in different ways. Key issues relate to the role of ecological science in codifying wasteland habitats, uncertainties about how best to evaluate the conservation importance of such sites and the strategies and tactics employed by different practitioners as they seek to mobilise a range of knowledges and practices to secure ecologically sensitive proposals. Scientific knowledge about wasteland habitats has not stabilised in ways that can consistently inform conservation policy and practice. As a result biodiversity issues of wasteland sites are often discounted in the re-development process. Investment in studies of the basic ecology of urban wastelands could provide a firmer scientific foundation on which conservation policies could build. At the same time, many conservation professionals involved in urban re-development are struggling to promote a pro-active approach to secure environmentally sensitive development. The knowledge and co-operation networks being mobilised to support this approach are fluid and unstable, and favourable development outcomes as yet are few. Formalising these networks to achieve more effective engagements with developers and the construction industry could consolidate ecological practices designed to conserve and re-create the biodiversity of wasteland habitats.     

SEPTAGE QUALITY AND ITS EFFECT ON FIELD LIFE FOR LAND APPLICATIONS1

ABSTRACT: Maintenance of the more than 24 million septic tanks in the U.S. requires removal and disposal of septage. Disposal options include application to agricultural lands where the nutrients and organic matter can provide soil benefits. However, pathogens and contaminants are also contained in septage. An extensive search turned up very few data on septage quality, and those reveal high variability. The data used by the U.S. Environmental Protection Agency (EPA) in developing regulations had the lowest metal concentrations among the nine data sets that could be compared. Based on these data, EPA assumed that septage could be applied to agricultural land for more than 100 applications before reaching unacceptable cumulative loading of metals. They thus did not establish federal standards for metals in septage, and no monitoring is required under federal rules governing septage disposal. Analysis of the nine data sets we found showed that field site life would be reached in less than 100 applications for most septage and cumulative loading limits established by EPA for sewage sludges will be exceeded in 16 applications for some septage as opposed to the 100 application estimate used by EPA. Determination of acceptable cumulative loading depends on numerous technical and policy considerations. All septage sources reached the more restrictive loading limits such as those established by the New York State Department of Environmental Conservation (NYSDEC) and the recommendations in Cornell publications in less than 100 applications. In one case the cumulative limit for copper was exceeded in a single application. These findings suggest additional data are needed on septage quality and that the federal and state agencies responsible for regulating application of septage to agricultural land should reassess their standards.     

Ecological effects of endocrine disruption: current evidence and research priorities.

An overview is presented of the main evidence for endocrine disruption in wildlife, focusing on reproductive effects. While there are a few clear examples of endocrine disruptive effects resulting from environmental chemical exposure, in most cases a causal link between the observed abnormalities and chemical exposure has not been established. In other cases there appears to be a link but the specific chemicals responsible for the observed effects, and the mechanisms involved, remain to be elucidated. Also it is largely unknown whether or not observed changes in individual animals lead to population-level effects. Priority research projects for the UK, ultimately aimed at determining the population-level significance of endocrine disruption, are described.     

Medium-Sulfur Coal and Fly Ash Resistivity

Electric generating plants burning medium-sulfur coal need a way to predict when ESP performance will be limited by high electrical resistivity of the collected fly ash. The main uncertainty in mathematical predictions of fly ash resistivity lies in the marginal effect of naturally occurring SO₃ vapor in the flue gas. This paper results from a project to expand the data base of SO₃/SO₂ concentrations and fly ash resistivities measured in utility fly ash precipitators. Complete data sets are presented from three plants in the Southern Company electric system. In situ resistivity data are compared with laboratory measurements and with two different mathematical predictions of resistivity based on coal and ash analyses. The revised version of the resistivity predictor gives results in good agreement with resistivity values measured both in situ and in the laboratory.     

Estimating net changes in life-cycle emissions from adoption of emerging civil infrastructure technologies

There is a net emissions change when adopting new materials for use in civil infrastructure design. To evaluate the total net emissions change, one must consider changes in manufacture and associated life-cycle emissions, as well as changes in the quantity of material required. In addition, in principle one should also consider any differences in costs of the two designs because cost savings can be applied to other economic activities with associated environmental impacts. In this paper, a method is presented that combines these considerations to permit an evaluation of the net change in emissions when considering the adoption of emerging technologies/materials for civil infrastructure. The method factors in data on differences between a standard and new material for civil infrastructure, material requirements as specified in designs using both materials, and price information. The life-cycle assessment approach known as economic input-output life-cycle assessment (EIO-LCA) is utilized. A brief background on EIO-LCA is provided because its use is central to the method. The methodology is demonstrated with analysis of a switch from carbon steel to high-performance steel in military bridge design. The results are compared with a simplistic analysis that accounts for the weight reduction afforded by use of the high-performance steel but assuming no differences in manufacture.     

Metallurgy,environmental pollution and the decline of Etruscan civilisation

Background, aim and scope  

The Etruscans were justifiably famous in antiquity for their advanced metallurgy and for the rich mineral resources of their region (including La Tolfa, the Colline Metallifere, Mont’Amiata and Elba). We offer a new perspective on certain Iron Age and Archaic (ca. 1,000–480 bc) Etruscan industrial and habitation sites, and on the problem of heavy metal poisoning, still being investigated today, coincidentally in some of the same areas that originally saw Etruscan mines and workshops.     

Variation of the mixing state of Saharan dust particles with atmospheric transport

Mineral dust is an important aerosol species in the Earth’s atmosphere and has a major source within North Africa, of which the Sahara forms the major part. Aerosol Time of Flight Mass Spectrometry (ATOFMS) is first used to determine the mixing state of dust particles collected from the land surface in the Saharan region, showing low abundance of species such as nitrate and sulphate internally mixed with the dust mineral matrix. These data are then compared with the ATOFMS single particle mass spectra of Saharan dust particles detected in the marine atmosphere in the vicinity of the Cape Verde islands, which are further compared with those from particles with longer atmospheric residence sampled at a coastal station at Mace Head, Ireland. Saharan dust particles collected near the Cape Verde Islands showed increased internally mixed nitrate but no sulphate, whilst Saharan dust particles collected on the coast of Ireland showed a very high degree of internally mixed secondary species including nitrate, sulphate and methanesulphonate. This uptake of secondary species will change the pH and hygroscopic properties of the aerosol dust and thus can influence the budgets of other reactive gases, as well as influencing the radiative properties of the particles and the availability of metals for dissolution.     

Source apportionment of fine particles at urban background and rural sites in the UK atmosphere

Airborne fine particulate matter (PM_2.5) has been collected at two sites in the West Midlands conurbation, UK, representing urban background and rural locations. Chemical analyses have been carried out for major anions, trace metals, total OC and EC, and for individual organic marker species including n-alkanes, hopanes, PAHs, organic acids and sterols. Source apportionment has been conducted using both a pragmatic mass closure model and the US EPA chemical mass balance (CMB) model. The pragmatic mass closure model is well able to account for the measured PM_2.5 mass in terms of chemical/source components, and the chemical mass balance model has been used to apportion the carbonaceous component of the aerosol. The dominant components of PM_2.5 at both sites are secondary inorganic (sulphate and nitrate) and carbonaceous particles. The CMB model shows the latter to arise mainly from road traffic sources, with smaller contributions from vegetative detritus, wood smoke, natural gas, coal, and dust/soil. The CMB model also identifies an important component of the organic aerosol not associated with these primary sources, which correlates very strongly with secondary organic aerosol estimated from the OC/EC ratio. The split between different automotive source types does not relate well to UK emission inventories, and may indicate that CMB source profiles from North American studies and different carbon analysis protocols may lead to erroneous conclusions.