Eisenia fetida earthworms were exposed to phenanthrene for thirty days to compare hydroxypropyl-β-cyclodextrin (HPCD) extraction of soil and 1H NMR earthworm metabolomics as indicators of bioavailability. The phenanthrene 28-d LC50 value was 750 mg/kg (632–891, 95% confidence intervals) for the peat soil tested. The initial phenanthrene concentration was 319 mg/kg, which biodegraded to 16 mg/kg within 15 days, at which time HPCD extraction suggested that phenanthrene was no longer bioavailable. Multivariate statistical analysis of 1H NMR spectra for E. fetida tissue extracts indicated that phenanthrene exposed and control earthworms differed throughout the 30 day experiment despite the low phenanthrene concentrations present after 15 days. This metabolic response was better correlated to total phenanthrene concentrations (Q2 = 0.59) than HPCD-extractable phenanthrene concentrations (Q2 = 0.46) suggesting that 1H NMR metabolomics offers considerable promise as a novel, molecular-level method to directly monitor the bioavailability of contaminants to earthworms in the environment.

Federal agencies of several nations have or are currently developing guidelines for critical forest soil acid loads. These guidelines are used to establish regulations designed to maintain atmospheric acid inputs below levels shown to damage forests and streams. Traditionally, when the critical soil acid load exceeds the amount of acid that the ecosystem can absorb, it is believed to potentially impair forest health. The excess over the critical soil acid load is termed the exceedance, and the larger the exceedance, the greater the risk of ecosystem damage. This definition of critical soil acid load applies to exposure of the soil to a single, long-term pollutant (i.e., acidic deposition). However, ecosystems can be simultaneously under multiple ecosystem stresses and a single critical soil acid load level may not accurately reflect ecosystem health risk when subjected to multiple, episodic environmental stress. For example, the Appalachian Mountains of western North Carolina receive some of the highest rates of acidic deposition in the eastern United States, but these levels are considered to be below the critical acid load (CAL) that would cause forest damage. However, the area experienced a moderate three-year drought from 1999 to 2002, and in 2001 red spruce (Picea rubens Sarg.) trees in the area began to die in large numbers. The initial survey indicated that the affected trees were killed by the southern pine beetle (Dendroctonus frontalis Zimm.). This insect is not normally successful at colonizing these tree species because the trees produce large amounts of oleoresin that exclude the boring beetles. Subsequent investigations revealed that long-term acid deposition may have altered red spruce forest structure and function. There is some evidence that elevated acid deposition (particularly nitrogen) reduced tree water uptake potential, oleoresin production, and caused the trees to become more susceptible to insect colonization during the drought period. While the ecosystem was not in exceedance of the CAL, long-term nitrogen deposition pre-disposed the forest to other ecological stress. In combination, insects, drought, and nitrogen ultimately combined to cause the observed forest mortality. If any one of these factors were not present, the trees would likely not have died. This paper presents a conceptual framework of the ecosystem consequences of these interactions as well as limited plot level data to support this concept. Future assessments of the use of CAL studies need to account for multiple stress impacts to better understand ecosystem response.

The spatial distribution of organochlorine pesticides (OCs) in soils and their potential for soil–air exchange was examined. The most prominent OCs were the DDTs (Geometric Mean, GM = 1.6 ng g−1), endosulfans (0.16 ng g−1), and toxaphenes (0.64 ng g−1). DDTs in soils of southern Mexico showed fresher signatures with higher FDDTe = p,p′-DDT/(p,p′-DDT + p,p′-DDE) and more racemic o,p′-DDT, while the signatures in the central and northern part of Mexico were more indicative of aged residues. Soil–air fugacity fractions showed that some soils are net recipients of DDTs from the atmosphere, while other soils are net sources. Toxaphene profiles in soils and air showed depletion of Parlar 39 and 42 which suggests that soil is the source to the atmosphere. Endosulfan was undergoing net deposition at most sites as it is a currently used pesticide. Other OCs showed wide variability in fugacity, suggesting a mix of net deposition and volatilization. Chemical profiles of residues and soil–air fugacities are used to assess the potential of soil as a source of organochlorine pesticides to the air of Mexico.

Critical loads (CLs) define maximum atmospheric deposition levels apparently preventative of ecosystem harm. We present first nitrogen CLs for northwestern North America’s maritime forests. Using multiple linear regression, we related epiphytic-macrolichen community composition to: 1) wet deposition from the National Atmospheric Deposition Program, 2) wet, dry, and total N deposition from the Communities Multi-Scale Air Quality model, and 3) ambient particulate N from Interagency Monitoring of Protected Visual Environments (IMPROVE). Sensitive species declines of 20-40% were associated with CLs of 1-4 and 3-9 kg N ha-1 y-1 in wet and total deposition. CLs increased with precipitation across the landscape, presumably from dilution or leaching of depositional N. Tight linear correlation between lichen and IMPROVE data suggests a simple screening tool for CL exceedance in US Class I areas. The total N model replicated several US and European lichen CLs and may therefore be helpful in estimating other temperate-forest lichen CLs. Lichen-based critical loads for N deposition in western Oregon and Washington forests ranged from 3 to 9 kg ha-1 y-1, increasing with mean annual precipitation.

Metal (i.e. Ag, As, Ca, Cd, Co, Cu, Mn, Pb and Zn) and metallothionein (MT) concentrations in the soft tissue of Littorina littorea were measured along the heavily polluted Western Scheldt (WS) and relatively clean Eastern Scheldt (ES) estuary. Along the WS metal and MT levels in periwinkles reflected the known downstream decreasing pollution gradient. Surprisingly in ES animals As, Mn and Zn concentrations decreased from east to west reflecting past pollution. Compared to the WS metal concentrations of ES periwinkles were significantly lower and both estuaries were maximally discriminated from each other based on their Cd soft tissue concentration using a canonical discriminant analysis. Furthermore, no overall difference was found in MT levels among animals from both estuaries. Using previously obtained condition data (i.e. dry/wet weight ratio and lipid content) the relation between soft tissue metal concentration (i.e. Cd, Cu and Zn) and fitness indicators (i.e. MT and condition data) was examined using a canonical correlation analysis. Periwinkles with a high metal load (i.e. Cd and Zn) also had high MT levels but were in a relatively poor condition.

Pools of Zn, Cu, Cd and Co in leaf, stem and root tissues of Sarcocornia fruticosa, Sarcocornia perennis, Halimione portulacoides and Spartina maritima were analyzed on a bimonthly basis, in a Tagus estuary salt marsh. All the major concentrations were found in the root tissues, being the concentrations in the aboveground organs neglectable for sediment budget proposes, as seen by the low root-aboveground translocation. Metal annual accumulation, root turnovers and cycling coefficients were also assessed. S. maritima showed the higher root turnovers and cycling coefficients for most of the analyzed metals, making this a phytostabilizer specie. By contrast the low root turnover, cycling coefficient and low root necromass generation makes S. perennis the most suitable specie for phytoremediation processes. Although the high amounts of metal return to the sediments, due to root senescence, salt marshes can still be considered sinks of heavy metals, cycling heavy metals mostly between sediment and root.

Effects of traffic-related nitrogenous emissions on purple moor grass (Molinia caerulea (L.) Moench) transplants, used here as a new biomonitoring species, were assessed along 500 m long transects orthogonal to roads located in two open areas in the Maurienne valley (French Alps). Leaves were sampled during summer 2004 and 2005 for total N-content and 15N-abundance determination while nitrogen oxides (NO and NO2) concentrations were determined using passive diffusion samplers. A significant and negative correlation was observed between plant total N-content, and 15N-abundance and the logarithm of the distance to the road axis. The strongest decreases in plant N parameters were observed between 15 and 100 m from road axis. They were equivalent to background levels at a distance of about 800 m from the roads. In addition, motor vehicle pollution significantly affected vegetation at road edge, as was established from the relationship between leaf 15N-abundance, total N-content and road traffic densities.

This experiment examined the effects of sulfate (S) and reduced glutathione (GSH) on arsenic uptake by arsenic hyperaccumulator Pteris vittata after exposing to arsenate (0, 15 or 30 mg As L-1) with sulfate (6.4, 12.8 or 25.6 mg S L=1) or GSH (0, 0.4 or 0.8 mM) for 2-wk. Total arsenic, S and GSH concentrations in plant biomass and arsenic speciation in the growth media and plant biomass were determined. While both S (18–85%) and GSH (77-89%) significantly increased arsenic uptake in P. vittata, GSH also increased arsenic translocation by 61-85% at 0.4 mM (p < 0.05). Sulfate and GSH did not impact plant biomass or arsenic speciation in the media and biomass. The S-induced arsenic accumulation by P. vittata was partially attributed to increased plant GSH (21-31%), an important non-enzymatic antioxidant countering oxidative stress. This experiment demonstrated that S and GSH can effectively enhance arsenic uptake and translocation by P. vittata.

Accumulation of cadmium in periphyton was investigated under field conditions while Cd concentration and speciation were dynamically varying in a small stream during rain events. Speciation in water was determined in situ by diffusion gradient in thin-films (DGT) and by modeling of complexation with fulvic acids. During the rain events, dissolved Cd concentrations increased from 0.17 nM to 0.27–0.36 nM, and 70–97% were DGT-labile. Cd content in periphyton closely followed Cd concentrations in water, despite higher concentrations of Zn and Mn, and may be controlled by either free or DGT-labile Cd concentrations. Decrease of Cd content in periphyton after the rain events was slower than the decrease of Cd concentration in water. Concentrations of Zn, Mn, Cu, Pb and Fe in periphyton also followed the dynamic variations of metal concentrations in water. Repeated exposure of periphyton to elevated dissolved Cd may lead to Cd accumulation. Cadmium accumulation in periphyton was examined in a small stream during rain events in relation to Cd speciation.

Both local adaptation and acclimation in tolerance mechanisms may allow populations to persist under metal pollution. However, both mechanisms are presumed to incur (energetic) costs and to trade-off with other life-history traits. To test this hypothesis, we exposed Pardosa saltans (Lycosidae) spiderlings originating from metal-polluted and unpolluted sites to a controlled cadmium (Cd) treatment, and compared contents of metal-binding metallothionein-like proteins (MTLPs), internal metal concentrations, and individual survival and growth rates with a reference treatment. While increased MTLP concentrations in offspring originating from both polluted and unpolluted populations upon exposure indicates a plastic tolerance mechanism, survival and growth rates remain largely unaffected, independent of the population of origin. However, MTLP and Cd concentrations were not significantly correlated. We suggest that MTLP production may be an important mechanism enabling P. saltans populations to persist in ecosystems polluted with heavy metals above a certain level.