Mulberry-silkworm food chain--a templet to assess heavy metal mobility in terrestrial ecosystems

Assessment of the food chain mobility of heavy metals inthe natural ecosystem receives more attention nowadays. Inthe present study, mulberry-silkworm food chain has beenfocused as a templet to assess the biomobility of heavymetals in soil-higher plant-insect hierarchy. Both in thecase of Cd and Cu treatments, higher mobility wasobserved in the level-1 (soil–root) followed by level-3(leaf–larva), level-4 (larvae–faecal) and level-2(root–leaf). Consequently, roots accumulated more amountsof Cd and Cu, with a limited transport to the leaves.Among the two metals (Cd and Cu) tested, in the plant,the transfer potential of Cd exceeds that of Cu. Whereasin the case of leaf–larval transfer, Cu precedes overCd. Accumulation of Cd and Cu in all the levels (1–4)tested showed a concentration dependent increase, except inthe level 4 (larva–faecal) of Cd treatment where adeclining trend was noticed.     

Collaborative study to improve the quality control of rare earth element determinations in environmental matrices

In order to control the quality of rare earth determinations in environmental matrices, the Standards, Measurements and Testing Programme (formerly Community Bureau of Reference, BCR) of the European Commission has started a project, the final aim of which is to certify four types of matrices (tuna muscle, mussel tissue, aquatic plant and estuarine sediment) for their contents of a range of rare earth elements (Sc, Y and the lanthanides: La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu). The elements U and Th were added to the study. The first part of this project consisted of an interlaboratory study which aimed to test the feasibility of preparation of environmental reference materials and to detect and remove most of the pitfalls observed in rare earth determinations. This paper presents the preparation of the four matrices for the intercomparison study and for the candidate reference material. The main results are presented of the interlaboratory study that was carried out prior to the certification campaign. This collaborative trial is the first attempt ever carried out at this scale to evaluate the state-of-the-art of rare earth determinations in the environment. Its impact on the improvement of chemical measurements will have positive effects on the comparability of data necessary for environmental monitoring.     

Modeling rhizofiltration: heavy-metal uptake by plant roots

The discovery of phytoaccumulation potential of plant species has led to its application for remediation of heavy-metal-contaminated soil and wastewater, which is termed as phytoextraction/rhizofiltration. For prediction, analysis, planning and cost-effective design of such systems, mathematical models not only are used as a screening tool but also provide optimal parameters like harvesting time, irrigation schedule, etc. Several laboratory and field scale studies have been carried out in the past, and mathematical expressions have been developed by various researchers for different phenomena like metal adsorption in soil, plant root growth with time, moisture and metal uptake by plant root, moisture movement in unsaturated zone, soil moisture relationship, etc. The complete design of any such phytoremediation program would require the knowledge of behavior of heavy-metal movement in soil, water and plant root system. In this paper, a model for simulating heavy-metal dynamics in soil, water and plant root system is developed and discussed. The governing non-linear partial differential equation is solved numerically by implicit finite difference method using Picard's iterative technique, and the formulation has been illustrated using a characteristic example. The source code is written in MATLAB.     

Integrating disciplinary research into an interdisciplinary framework: A case study in sustainability research

The complexity of today’s research problems increasingly demands that scientists move beyond the confines of their own discipline. In this special issue, the basics of a transdisciplinary framework are established and problems analyzed in a specific discipline are successfully integrated in this transdisciplinary network. The intent has been to go beyond only statements about the importance of enabling early stage researchers to work across disciplinary boundaries, and to show that important discoveries are being made at the intersection of disciplines. Embedding various research projects in a more global framework can meet the demands of an interdisciplinary or transdisciplinary approach (especially for early stage researchers) and contribute significantly to sustainable research.     

A study on the orbit of air temperature movement

In this paper, we describe an air temperature movement by mapping its time series to the polar coordinates: the value of the time series is plotted on the radial coordinate and the time on the angular coordinate. In this way, both the yearly and daily air temperature movements from five different locations of China are used to demonstrate that, in an intuitionistic view, air temperature movement is neither random nor chaotic, but has its own orbit. We then propose an elliptic orbit model for the air temperature movement. Our proposed model provides quite good results when it is applied to the evaluation of yearly air temperature movements in eight locations in various parts of the world, and the evaluation of daily air temperature movements in five locations in Hunan Province of China on December 17, 2005. Results show that our approach provides a concise and helpful model for air temperature analysis.     

Trends in motor-vehicle related air pollutants in central London

Results of intermittent monitoring of six aromatic hydrocarbons (benzene, toluene, ethyl-benzene, m-xylene, p-xylene and o-xylene), carbon monoxide and oxides of nitrogen over a thirteen year period at a site in central London (Exhibition Road) are presented. Four monitoring regimes were undertaken; namely, 1979, 1982/83, 1986/87 and 1991/92. The summertime daytime mean ambient concentrations of the measured parameters at this site are presented. The reported concentrations show a reduction from 1979 to 1992 by approximately a factor of two, despite national increases in motor fuel consumption and the volume of traffic. Relevant European Community legislation covering emissions from motor-vehicles are outlined and comparisons are made with emissions from motor vehicles predicted from the UK national inventory. The importance of the frequency of measurements was also noted.     

Overstory mortality as an indicator of forest health in California

The interagency Forest Health Monitoring Program involves a network of about 4200 forest plots on a triangular grid across the United States. We present data on recent mortality of trees 27.9 cm diameter from the first three years of measurements in California (1992–1994). Three plot designs were used to collect data representative of a 1-ha stand at each site; the designs differed primarily in total area sampled (0.067, 0.4 and 1.0 ha). Approximately 50 sites were visited each year yielding a total of about 150. Field tallies showed few cases of recent mortality in the smallest plot size. Cumulative distribution functions of recent dead tree densities in the 0.067-ha plots differed significantly from those generated by tallies from entire 1-ha stands. We conclude that an area of 0.067 ha is unsuitable to assess and monitor overstory mortality in Pacific Coast forests.The U.S. government right to retain a non-exclusive, royalty free licence in and to any copyright is acknowledged.     

Estimating Trophic State Proportions of a Regional Lake Population: Are Larger Samples Always Better?

During the summers of 1991–1994, the Environmental Monitoringand Assessment Program (EMAP) sampled 344 lakes throughout thenortheastern United States using a proportional stratified sampling design based on lake size. Approximately one-quarter ofthe 344 lakes were sampled each year (4 years) for totalphosphorus to determine the proportion (and associated95% confidence intervals) of the northeast lake population 1ha (11,076 ± 1,699 lakes) that was in oligotrophic,mesotrophic, eutrophic, or heupereutropic (4 classes) conditionaccording to the total phosphorus criteria of the North AmericaLake Manegement Society. Estimates for the second, third, andfourth yr were developed as cumulative of the previous yrsamples and the current yr samples for the northeast as a wholeand for each of its three ecoregions (4 regions). New confidence intervals were computed for each cumulative yrcondition estimate. This produced a total (4 years × 4classes × 4 regions) of 64 cumulative yr tropic conditionestimates. Confidence intervals for 21% of these estimates didnot shorten with increased sample size. This phenomena raisedquestions about the accuracy of estimates based on cumulativesampling procedures. We explain why and how the phenomenon comesabout with both straight random and proportional randomsampling. Further, we present an example of the effects thisphenomenon has on lake tropic state condition estimates in thenortheastern United States.     

Temporal variation in a coral reef community at Pattaya Bay,Gulf of Thailand

Changes in the fringing coral reef community of a small island (Ko Nok) at Pattaya Bay, Gulf of Thailand, were examined at the beginning and at the end of a 3-year period using 7m×7m permanent quadrats for benthic organisms, and visual census along 100m transects for fish. The coral community was dominated by Porites lutea in terms of colony number and areal cover throughout the period. Variations in the community structure parameters on opposite sides of the island indicated increasing dissimilarity with time. Little variation in live coral cover was noted, but colony number and species diversity declined on both sides. The abundance of edible fish species dropped while that of non-edible species increased over the 3-year period, indicating selective removal of the former category through fishing. Impacts from both human and natural influences are implicated in these changes.