Atmospheric Deposition and Ionic Input in Adirondack Forests

Major mechanisms for input of ions to forest ecosystems in the central Adirondack Mountains of New York State were studied. Precipitation and throughfall in adjacent northern hardwood and lake margin coniferous forests were continuously sampled from May 2, 1979 to May 7, 1980. Important mechanisms for transport of ions from atmosphere to forest floor were identified using regression analyses and the assumption that deciduous and coniferous forests capture particulates and aerosols with differing efficiencies. Sodium was delivered in precipitation and dry-fall and interacted little with the forest canopies. Hydrogen, potassium, and magnesium were also deposited primarily by bulk precipitation but hydrogen was retained by foliage while additional quantities of potassium and magnesium were leached from tree canopies. Impaction of suspended particulates and/or aerosols on forest vegetation was an important source of additional sulfate and nitrate, and these ions contributed to the leaching of calcium from foliage.     

Dioxins and furans in emissions from medical waste incinerators

Dioxins and furans were detected in emissions from eight medical waste incinerators tested in California. Total uncontrolled emissions ranged from 363 to 11, 811 nanograms per dry standard cubic meter. The most effective of three wet scrubbers achieved an emissions control efficiency of 95 percent for total PCDD and PCDF. A baghouse was less than 30 percent efficient in removing PCDD and PCDF from the incinerator emissions.     

Monitoring the impact of sulphur with the Austrian Bioindicator Grid

In Austria, the impact of sulphur has been assessed since 1985 with the help of the Austrian Bioindicator Grid on 760 sample plots with Picea abies as the main tree species (90%). The annual sampling allows a precise evaluation of the temporal and regional development of the impact of sulphur on the basis of legal standards. Despite the reduction of SO2 emissions in Austria, the legal standard is still exceeded on 8% of the plots. These plots are mainly located near large Austrian emittors, but also in areas affected by transboundary sulphur emissions from neighbouring countries. The present paper describes how the Bioindicator Grid can be applied for the control of legal requirements to enact effective clean air measures in Austria and take supportive measures that reduce the impact of sulphur from emittors in neighbouring countries.     

Changes of AhR-mediated activity of humic substances after irradiation

Humic substances (HS) and natural organic matter (NOM) are natural organic compounds ubiquitous in the environment. However, some studies indicate that both HS and NOM can act as xenobiotics, e.g. induce hormone-like effects in fish, amphibians and invertebrates. Molecules of these substances contain a number of aromatic rings and conjugated double bonds--the so called chromophores. Irradiation of dissolved HS and NOM can lead to a series of photochemical reactions which can act on these substances itself, or on other substances present in aquatic environment along with HS and NOM such as e.g. xenobiotics. In our previous study, we have found significant interactions of five humic acids (HA) with cytosolic aryl hydrocarbon receptor (AhR) in an in vitro bioassay based on H4IIE-luc cells. In the present study, we have studied the changes in AhR-mediated activities both of HS and NOM after irradiation that simulated natural solar light. Nine different HS and two NOM samples were irradiated in Pyrex tubes with a medium-pressure mercury lamp for a duration of 0 to 52 h (which corresponds to 0-52 d natural solar radiation). Original concentrations of the samples were 50 mg L(-1), and the greatest concentration of HS and NOM photoproducts subsequently tested in the bioassay was 17 mg L(-1), which is an environmentally relevant concentration. After irradiation the absorbances of all the samples were less than the original materials. The AhR-mediated activity of the HA-Fluka and HA Sodium Salt were partially decreased by irradiation. The activities of other HS and NOM, that were either AhR-active or -inactive were not changed by irradiation. The results of the study demonstrate that AhR-mediated activities of two active HA is caused by both photo-stable and photo-labile AhR activators, while the other three active HA contain only photo-stable AhR activators. Potential mechanisms of the observed irradiation-induced changes in AhR-mediated activities are discussed.     

Arsenic geochemistry and health

Arsenic occurs naturally in the earth's crust and is widely distributed in the environment. Natural mineralization and activities of microorganisms enhance arsenic mobilization in the environment but human intervention has exacerbated arsenic contamination. Although arsenic is useful for industrial, agricultural, medicinal and other purposes, it exerts a toxic effect in a variety of organisms, including humans. Arsenic exposure may not only affect and disable organs of the body, especially the skin, but may also interfere with the proper functioning of the immune system. This paper, therefore, generally highlights the toxic effects of arsenic as well as its mobilization in the natural environment and possible controls. It also briefly attempts to outline the impact of arsenic on the immune system, whose alteration could lead to viral/bacterial infections.     

Humic substances

GOAL, SCOPE AND BACKGROUND: Freshwater bodies which chemistry is dominated by dissolved humic substances (HS) seem to be the major type on Earth, due to huge non-calcareous geological formations in the Northern Hemisphere and in the tropics. Based on the paradigm of the inertness of being organic, direct interactions of dissolved HS with freshwater organisms are mostly neglected. However, dissolved organic carbon, the majority of which being HS, are natural environmental chemicals and should therefore directly interact with organisms. Major results that widened our perspective on humic substance ecology come from experiments with the compost nematode, Caenorhabditis elegans, which behaved contradictorily to textbook knowledge and provoked an in-depth re-consideration of some paradigms. APPROACH: To overcome old paradigms on HS and their potential interactions with organisms, we reviewed recent international literature, as well as 'grey' literature. We also include results from own ongoing studies. RESULTS: This review focuses on direct interactions of dissolved HS with freshwater organisms and disregards indirect effects, such as under-water light quenching. Instead we show with some macrophyte and algal species that HS adversely interfere with photosynthesis and growth, whereby closely related algal species show different response patterns. In addition to this, HS suppress cyanobacteria more than eukaryotic algae. Quinones in the HS appear to be the effective structure. Furthermore, HS can modulate the offspring numbers in the nematode C. elegans and cause feminization of fish and amphibians--they possess hormone-like properties. The ecological consequences of this potential remain obscure at present. HS also have the potential to act as chemical attractants as shown with C. elegans and exert a mild chemical stress upon aquatic organisms in many ways: induction of molecular chaperons (stress proteins), induction and modulation of biotransformation and anti-oxidant enzymes. Furthermore, they produce an oxidative stress with lipidperoxidation as one clear symptom or even stress defense strategy. Stronger chemical stresses by HS may even lead to teratogenic effects as shown with fish embryos; all physiological responses to HS-mediated stress require energy, which were compensated on the expense of yolk as shown with zebra fish embryos. One Finnish field survey supports the view of a strong chemical stress, as the weight yield in fish species decreases with increasing HS content in the lakes. DISCUSSION: HS exert a variety of stress symptoms in aquatic and compost organisms. According to current paradigms of ecotoxicology, these symptoms have to be considered adverse, because their compensation consumes energy which is deducted from the main metabolism. However, the nematode C. elegans looks actively for such stressful environments, and this behavior is only understandable in the light of new paradigms of aging mechanisms, particularly the Green Theory of Aging. In this respect, we discuss the mild HS-mediated stress to aquatic and compost organisms. New empirical findings with HS themselves and HS building blocks appear to be consistent with this emerging paradigm and show that the individual lifespan may be expanded. At present the ecological consequences of these findings remain obscure. However, a multiple-stress resistance may be acquired which improves the individual fitness in a fluctuating environment. CONCLUSIONS: It appears that dissolved HS have to be considered abiotic ecological driving forces, somewhat less obvious than temperature, nutrients, or light. PERSPECTIVES: The understanding of the ecological control by dissolved humic substances is still fragmentary and needs to be studied in more details.     

Analysis of perfluorooctanoate (PFOA) and other perfluorinated compounds (PFCs) in the River Po watershed in N-Italy

C7-C11 perfluorinated carboxylates (PFACs) and perfluorooctansulfonate (PFOS) were analysed in selected stretches of the River Po and its major tributaries. Analyses were performed by solid-phase extraction (SPE) with Oasis HLB cartridges and methanol elution followed by LC-MS-MS detection using 13C-labelled internal standards. High concentration levels ( approximately 1.3 microg l(-1)) of perfluorooctanoate (PFOA) were detected in the Tánaro River close to the city Alessandria. After this tributary, levels between 60 and 337 ng l(-1) were measured in the Po River on several occasions. The PFOA concentration close to the river mouth in Ferrara was between 60 and 174 ng l(-1). Using the river discharge flow data in m3 s(-1) at this point (average approximately 920 m3 s(-1) for the year 2006), a mass load of approximately 0.3 kg PFOA per hour or approximately 2.6 tons per year discharged in the Adriatic Sea has been calculated. PFOS concentration levels in the Po River at Ferrara were approximately 10 ng l(-1).