The theoretical basis for estimating phytoplankton production and specific growth rate from chlorophyll, light and temperature data

Phytoplankton maximum specific growth rate, μ_max, and maximum photosynthetic quantum yield, Φ_max, can be related mathematically via the photosynthetic light curve, P(I). A model is presented in which maximum quantum yield defines the initial slope of the light curve and is assumed to be a known constant, while maximum specific growth rate defines the light-saturated region of the curve and is assumed to be a known function of temperature. The effect of introducing μ_max(T) into P(I, Φ_max) is to replace the unknown, temperature-dependent light saturation parameter with a term involving the ratio μ_max/Φ_max. The advantage of writing P(I) in terms of both μ_max and Φ_max is that those parameters are particularly well documented in the literature. Consequently, estimates of nutrient-unlimited phytoplankton growth and production rates can be based solely on the constants μ_max, Φ_max and k_c (light absorption per unit of chlorophyll) and the free variables light, temperature and chlorophyll concentration. Rate estimates appear to be accurate to within a factor of two for an extremely wide range of conditions.One particularly significant result of introducing μ_max into P(I, Φ_max) is that the carbon : chlorophyll ration, θ, appears explicitly. It is possible to derive an expression for optimum θ based on the assumption that adaptive changes in carbon/chlorophyll occur so as to maximize the specific growth rate for given conditions of light and temperature. Laboratory and field data are compiled from the literature to test the formulae presented here.     

An evaluation of adaptation options for climate change impacts on agriculture in Kazakhstan

Agriculture in Kazakhstan is sensitive to climate, and wheat yields could be reduced up to 70% under climate change. With the transition from a socialist economy to a free market economy, decisions are being made now that will affect Kazakhstan's ability to cope with climate change. A team of Kazakh and American researchers examined the cost-effectiveness and barriers to implementations of adaptation options for climate change. Twelve adaptation options that increase flexibility to respond to climate change were identified using a screening matrix. Four options, forecasting pest outbreaks, developing regional centers for preserving genetic diversity of seeds, supporting a transition to a free market, and reducing soil erosion through the use of changed farming practices, were examined. The Adaptation Decision Matrix (ADM) was then applied to estimate benefits using expert judgment (using an arbitrary numerical scale, not monetary values) and benefits estimates were compared to costs to determine cost-effectiveness. The ADM uses subjective measures of how well adaptation options meet policy objectives. Controlling soil erosion was estimated to have the highest benefits, but the high costs of implementation appears to make it relatively cost-ineffective. Supporting a transition to a free market was ranked as the most cost-effective measure, with regional centers second. However, use of different scales to quantify benefits or different weights can result in regional centers being more cost-effective than the transition to a free market. Regional centers was also judged to have fewer barriers to implementation than a transition to a free market. These results will be incorporated in Kazakhstan's National Action Plan. The ADM and other tools are relatively easy to apply, but are quite subjective and difficult to evaluate. The tools can be quite useful by decision makers to analyze advantages and disadvantages between different adaptation options, but should be supplemented with additional, particularly quantitative analysis.     

The Monitoring,Evaluation, Reporting and Verification of Climate Change Projects

Because of concerns with the growing threat of global climate change from increasing emissions of greenhouse gases, the United States and other countries are implementing, by themselves or in cooperation with one or more other nations, climate change projects. These projects will reduce greenhouse gas (GHG) emissions or sequester carbon, and will also result in non-GHG benefits (i.e., environmental, economic, and social benefits). Monitoring, evaluating, reporting, and verifying (MERV) guidelines are needed for these projects to accurately determine their net GHG, and other, benefits. Implementation of MERV guidelines is also intended to: (1) increase the reliability of data for estimating GHG benefits; (2) provide real-time data so that mid-course corrections can be made; (3) introduce consistency and transparency across project types and reporters; and (4) enhance the credibility of the projects with stakeholders. In this paper, we review the issues involved in MERV activities. We identify several topics that future protocols and guidelines need to address, such as: (1) establishing a credible baseline; (2) accounting for impacts outside project boundaries through leakage; (3) net GHG reductions and other benefits; (4) precision of measurement; (5) MERV frequency and the persistence (sustainability) of savings, emissions reduction, and carbon sequestration; (6) reporting by multiple project participants; (7) verification of GHG reduction credits; (8) uncertainty and risk; (9) institutional capacity in conducting MERV; and (10) the cost of MERV.     

Zinc and lead sequestration in an impacted wetland system

The fate and bioavailability of pollutant metals is important to the long-term health of freshwater wetland systems, particularly in areas with elevated background levels of trace metals. Precipitation of some authigenic mineral phases in wetland sediments can potentially limit metal bioavailability through sequestration in low-solubility compounds, such as metal sulfides. Zinc and Pb concentrations were analyzed in water, plant and sediment samples taken from a metal-contaminated wetland in Chicago, IL, USA in order to assess metal fate and bioavailability, while X-ray absorption spectroscopy (XAS) studies were conducted to determine zinc speciation in the wetland sediments. The results showed sequestration of metal into the pond sediments, most likely in iron precipitate phases. In surface sediments, re-release of Zn and Pb into pore waters was correlated with microbial iron reduction, while the presence of sulfide in anoxic pore waters corresponded to decreased dissolved concentrations of both elements. Analysis of extended X-ray absorption fine structure (EXAFS) data confirmed that sulfide compounds dominated zinc speciation throughout the sediment. Uptake of trace metals in Phragmites plants was limited primarily to plant roots, while concentrations of both Pb and Zn in aquatic vegetation were significantly elevated, representing a potential bioaccumulation hazard.     

Four-marker serum screening for Down's syndrome

The value of measuring the separate sub-units of human chorionic gonadotrophin (free α-hCG and free β-hCG) instead of total hCG together with alpha-fetoprotein (AFP) and unconjugated oestriol (uE₃) was examined to determine the effect on the performance of serum screening for Down's syndrome between 15 and 22 weeks of pregnancy. The study was based on stored serum samples relating to 75 singleton pregnancies with fetal Down's syndrome and 367 unaffected singleton pregnancies, matched for maternal age, gestational age, and duration of storage of the serum sample, supplemented by data from 970 white women with unaffected pregnancies. Using the four serum markers AFP, uE₃, free β-hCG, and free α-hCG, in addition to maternal age, 65 per cent of Down's syndrome pregnancies were detected for a 5 per cent false-positive rate compared with 59 per cent with the conventional triple test (AFP, uE₃, total hCG with maternal age). If gestation was based on an ultrasound scan examination, the detection rate was 72 per cent using the four serum markers compared with 67 per cent with the triple test. As an alternative illustration, if the detection rate was kept at 60 per cent and gestation was estimated by an ultrasound scan examination the four-marker test reduced the false-positive rate by one-third from 3 per cent using the triple test to 2 per cent with the four-marker test. Screening performance was hardly affected by adjusting marker levels for maternal weight. The four-marker test is, both from a medical and from a financial perspective, the most effective method of prenatal screening for Down's syndrome suitable for routine use.     

Oral teratoma (epignathus) with intracranial extension: A report of two cases

Epignathi are unusual congenital tumours presenting as oropharyngeal masses, often resulting in rapid asphyxia following birth. Occasionally, intracranial extension of the tumour is present, and two such cases are described. The presence of this complication, diagnosable by ultrasound examination, indicates that aggressive surgical treatment is inappropriate.     

Does Soil Carbon Loss in Biomass Production Systems Negate the Greenhouse Benefits of Bioenergy?

Interest in bioenergy is growing across the Western world in response to mounting concerns about climate change. There is a risk of depletion of soil carbon stocks in biomass production systems, because a higher proportion of the organic matter and nutrients are removed from the site, compared with conventional agricultural and forestry systems. This paper reviews the factors that influence soil carbon dynamics in bioenergy systems, and utilises the model FullCAM to investigate the likely magnitude of soil carbon change where bioenergy systems replace conventional land uses. Environmental and management factors govern the magnitude and direction of change. Soil C losses are most likely where soil C is initially high, such as where improved pasture is converted to biomass production. Bioenergy systems are likely to enhance soil C where these replace conventional cropping, as intensively cropped soils are generally depleted in soil C. Measures that enhance soil C include maintenance of productivity through application of fertilisers, inclusion of legumes, and retention of nutrient-rich foliage on-site. Modelling results demonstrate that loss of soil carbon in bioenergy systems is associated with declines in the resistant plant matter and humified soil C pools. However, published experimental data and modelling results indicate that total soil C loss in bioenergy systems is generally small. Thus, although there may be some decline in soil carbon associated with biomass production, this is negligible in comparison with the contribution of bioenergy systems towards greenhouse mitigation through avoided fossil fuel emissions.     

Urban flooding in Australia: Policy development and implementation

This paper presents a review of Australian urban riverine flooding. By world standards the Australian flood problem is relatively small, though there are pockets of development subject to regular severe inundation. In the past, government response to flooding was ad hoc and characterized by structural adjustments. The 1970s and 1980s, however, have seen a major shift in approach. The new approach emphasizes resource management rather than construction, and consists of the announcement of policies, enactment of enabling legislation, and the introduction of procedures to help ensure that the widest range of flood damage reduction measures are considered. The changes are evident at both the federal and state levels of government.
Though problems remain, particularly at the local government level, where ultimate responsibility for policy implementation generally rests, the authors feel there are good grounds for optimism. Some suggestions for future policy are offered and the importance of public safety is stressed.