R. Jayasekera

Large scale air monitoring: lichen vs. air particulate matter analysis

Biological indicator organisms have been widely used for monitoring and banking purposes for many years. Although the complexity of the interactions between organisms and their environment is generally not easily comprehensible, environmental quality assessment using the bioindicator approach offers some convincing advantages compared to direct analysis of soil, water, or air. Measurement of air particulates is restricted to experienced laboratories with access to expensive sampling equipment. Additionally, the amount of material collected generally is just enough for one determination per sampling and no multidimensional characterization might be possible. Further, fluctuations in air masses have a pronounced effect on the results from air filter sampling. Combining the integrating property of bioindicators with the world wide availability and particular matrix characteristics of air particulate matter as a prerequisite for global monitoring of air pollution is discussed. A new approach for sampling urban dust using large volume filtering devices installed in air conditioners of large hotel buildings is assessed. A first experiment was initiated to collect air particulates (300-500 g each) from a number of hotels during a period of 3-4 months by successive vacuum cleaning of used inlet filters from high volume air conditioning installations reflecting average concentrations per 3 months in different large cities. This approach is expected to be upgraded and applied for global monitoring. Highly positive correlated elements were found in lichens such as K/S, Zn/P, the rare earth elements (REE) and a significant negative correlation between Hg and Cu was observed in these samples. The ratio of concentrations of elements in dust and Usnea spp. is highest for Cz, Zn and Fe (400-200) and lowest for elements such as Ca, Rb, and Sr (20-10).

Use of seaweeds for monitoring trace elements in coastal waters

Concentrations of a wide range of trace elements: arsenic, cadmium, cobalt, chromium, hafnium, nickel, thorium, uranium, zinc and the rare earth elements, cerium, europium, samarium, terbium and ytterbium were determined by instrumental neutron activation analysis in the brown alga,Fucus vesiculosus from Eckwarder Hörne, North Sea and from Rügen, Baltic Sea. Another brown alga,Sargassum filipendula from Sri Lanka, Indian ocean (representing an unpolluted control station) was similarly investigated. Cobalt, chromium and nickel concentrations were highest inF. vesiculosus from the North Sea while zinc was highest in samples from the Baltic Sea, reflecting high levels of these elements in coastal waters of the North and the Baltic sea. Cadmium, cobalt, nickel and zinc levels were lowest inS. filipendula from Sri Lanka, probably demonstrating lower levels of those elements in coastal waters. Concentration levels of hafnium, thorium, uranium, and the rare earth elements were highest inS. filipendula. Two years later in 1994,S. filipendula along withUlva sp. (green alga) was resampled from the same sampling site, and in addition to the above elements, six other trace elements (Ag, Ba, Br, Rb, Se and Sr) were determined.Sargassium filipendula showed a particular affinity for Ag, As, Br and Sr. For the other elements, marginal concentration differences were observed betweenS. filipendula andUlva sp., probably reflecting the regional background levels. Substantially higher concentrations of Hf, Th, U, and the rare earths were found again in the 1994Sargassum andUlva samples, reflecting the effect of a substrate rich in rare earth elements. The brown algae used in this study may be used to monitor trace elements in coastal waters.

Elemental composition of different plant species

Abstract Element concentrations in leaves and needles of different plant species (Rhizophora mangle, Aster tri‐polium, Vaccinium vitis—idaea and Pinus sylvestris) are presented in the form of element concentration cadasters with reference to their abundance. The concentration cadasters of the two halophytes (Rhizophora mangle and Aster tripolium) show that the elements Na, Cl, Br and Sr occur at high concentrations in halophytes. The changes in chemical abundances of halophytes can be attributed to the extreme habitat conditions, i. e. physiological drought, under which they grow. Certain elements are preferentially accumulated in specific plants, e. g. Mn in Vaccinium vitis‐idaea.

Chemical Composition of the Mangrove, Rhizophora mangle L.

Summary Enrichment and deposition of selected minerals in mangrove, Rhizophora mangle, plants grown under glasshouse conditions at near-constant salinity were investigated. The results show that R. mangle is capable of concentrating a variety of chemical elements by taking them up from salt water. Mean concentration factors for elements found in R. mangle lie in a higher range compared with those of a glycophyte, Brassica oleracea. Moreover, R. mangle plants seem to have higher affinities for elements such as sodium (Na), chlorine (CI), silicon (Si), cobalt (Co) and cerium (Ce), which may or may not be essential to them.

Elemental concentrations in a tropical montane rain forest in Sri Lanka

As a preliminary to studies on biogeochemistry of a tropical montane rain forest at about 1800 m altitude in Sri Lanka, the concentrations of 17 chemical elements in different forest compartments, i.e. in leaves of six floristically dominant tree species, undergrowth, litter, and soil at 0–10 cm and 11–60 cm depth were determined. Foliar chemical differences between species were large. Mean leaf water content, mean leaf area per leaf, and specific leaf weight of each species were also determined. Calcium seems to be used in relatively large quantities by these plants. Phosphorus concentration in all compartments was consistently low. A few species investigated appeared to concentrate aluminium and silicon at high amounts. Concentration differences between compartments were significant only for certain elements. Location effect on the concentrations in soil was considerable for most of the elements studied. When studying plant-soil chemical interactions in these forests, species-level concentrations must be taken into account as the species-specific chemical differences are obscured when treated as canopy leaves.

Seasonal Changes in Potential Net Photosynthesis of Sun and Shade Leaves of Fagus Sylvatica L.

Summary Sun and shade leaves of the deciduous tree, Fagus sylvatica , were investigated for their potential photosynthetic activity during the course of one growing season. During the initial period of leaf development and expansion, sun leaves exhibited relatively higher photosynthetic rates. After full expansion of leaves, shade leaves had a higher activity in potential net photosynthesis until about the end of August. Low diffusion resistance for CO 2 /O 2 and higher activities of photosystems in shade leaves seem to be the main causes of their higher photosynthetic potential.

Bulk and trace element analysis of spices: the applicability of k0-standardization and energy dispersive X-ray fluorescence.

Methodology has been developed for the bulk and trace element analysis of spices such as curry powder and turmeric powder originated from Sri Lanka by the k0-standardization method (INAA-k0) and by energy dispersive X-ray fluorescence (EDXRF). SRM 1572 citrus leaves was used to check the accuracy of the results obtained by the two nuclear techniques. The elements determined quantitatively in these matrices by the EDXRF analysis were bromine, calcium, copper, iron, potassium, magnesium, manganese, phosphorus, rubidium, sulphur, strontium and zinc. The results obtained by the two techniques are comparable, although a few inconsistencies were detected, requiring adequate attention for their correction, whenever possible, in future studies.

Background levels of heavy metals in plants of different taxonomic groups from a montane rain forest in Sri Lanka

An undisturbed natural reserve area iocated in a tropical montane rain forest at about 1800 m altitude in Sri Lanka served as a study site to investigate and assess the natural background concentration levels of As, Cd, Co, Cu, Ni, Pb and Zn in plants representing different taxonomic groups (divisions) in the plant kingdom. The plants selected were: the lichen,Usnea barbata (old mans beard);Pogonatum sp. (a moss);Lycopodium selago (epiphytic lycopod);Polypodium lanceolatum (epiphytic fern);Bulbophyllum elliae (epiphytic orchid) andActinodaphne ambigua (dicotyledonous large tree). Degree of homogeneity with respect to Cd, Cu, Pb and Zn in homogenised materials of all samples were within acceptable limits, whereasPogonatum sp. showed the highest degree of homogeneity for Pb. In addition to confirming extremely low levels of heavy metals in all plant species, the survey also found that generally the primitive plants,Usnea andPogonatum appear to have a greater tendency to accumulate As, Cd, Co and Pb; in particular,U. barbata appears to be an efficient accumulator for those heavy metals, suggesting its potential use in environmental studies.Actinodaphne ambigua was found to have a specific accumulating ability for nickel. Surface cleaning of theA. ambigua leaves resulted in a substantial decrease in the foliar contents of Cd, Ni, Pb and Zn. Variations in heavy metal contents observed in different plant genera are discussed in terms of their habits and place of growth in the forest. It is anticipated that the background levels presented in this paper from a remote, unpolluted tropical ecosystem will provide useful reference data for comparative environmental studies.

Multi-laboratory chemical characterization of ecological samples

SummaryThe influence of high concentrations of sodium (Na), chlorine (Cl) and bromine (Br) on the analytical results obtained by means of several modern analytical methods by different laboratories was investigated. The results obtained for the halophytic plants, Aster tripolium and Rhizophora mangle, were compared with that of NBS-Citrus leaves (NBS 1572). With a few outliers no considerable “interference effects” from Na, Cl and Br on the results of other elements were found.

Interelement relationships in leaves of tropical montane trees

Chemical concentrations in leaves are reported for 14 elements in 6 tree species of a montane rain forest in Sri Lanka. The plant taxa varied greatly in chemistry and a few taxa appeared to concentrate several elements in high amounts. The chemical variability among taxonomic units was examined by comparing element-by-element concentration ratios in leaves. Several species seemed to have typical patterns of concentration ratios for certain elements and the interelement relationships of different species seemed to be repeated across varying habitat conditions.