Short- and medium-term effects of experimental nitrogen fertilization on arthropods associated with Calluna vulgaris heathlands in north-west Spain

We studied the short- and medium-term effects of experimental nitrogen fertilization (3 and 15 months after the treatment) on the arthropods of Calluna vulgaris heathlands in NW Spain. Three heathland sites were selected with two permanent plots per site: control and fertilized. Ammonium nitrate fertilizer (56 kg N ha(-1) yr(-1)) was applied monthly and insects were caught using pitfall traps. We found mainly species-level responses to nitrogen addition. Seven species (e.g. Lochmaea suturalis) showed a consistent trend (benefited or harmed) in both periods and were proposed as possible reliable indicators of the effects of nitrogen deposition in these ecosystems. We also found variable arthropod trophic-group responses: (a) herbivores (leaf beetles, true bugs) increased in abundance on a short-term scale; (b) predators (carabid beetles, true bugs) showed opposite and less clear responses in both periods. Further long-term studies are needed to determine the mechanisms underlying the observed arthropod responses.     

Prediction of Pb speciation in concentrated and dilute nutrient solutions

Despite the presence of numerous studies in the literature examining the phytotoxicity of Pb, there is a lack of precise quantitative data on limiting concentrations of Pb for plant growth. Using the PhreeqcI chemical equilibrium model, simulations were conducted to examine the speciation of Pb in concentrated and dilute nutrient solutions. Due to the higher P concentration of Hoagland's solution (1000microM), precipitation of chloropyromorphite (Pb5(PO4)3Cl) was predicted to occur at lower pH values, and at lower Pb concentrations, than for a dilute nutrient solution (2microM P). Although nutrient solutions prepared in the glasshouse were supersaturated (and Pb concentrations were substantially higher than predicted by modeling), they confirmed the importance of the P concentration in influencing the precipitation of Pb. Given the low solubility of Pb-phosphates, nutrient solutions with low P concentrations should be utilized, and plant growth should be related to measured Pb concentrations rather than to the quantity of Pb initially added.     

New metallothionein assay in Scrobicularia plana: heating effect and correlation with other biomarkers

Metallothionein (MT) and other biomarker levels were measured in Scrobicularia plana clams to assess pollution of the Guadalquivir Estuary possibly affected by metals released from Aznalcóllar pyrite mine in 1998. After optimizing reagent concentrations for monobromobimane derivatization, MT levels were quantified by reversed-phase high-performance liquid chromatography coupled to fluorescence detection (RP-HPLC-FD) in heated or unheated digestive gland extracts and compared to those obtained by differential pulse polarography (DPP). MT content assayed by RP-HPLC-FD in unheated samples was higher than that obtained by DPP and correlated better with metals and anti-oxidant activities. MT assay by RP-HPLC-FD in unheated extracts would be preferable for assessing metal pollution, due to its greater sensitivity and specificity. In addition to MT induction, glyoxalase II inhibition was well correlated with metal contents. Our results suggest that metals at the estuary do not originate from Aznalcóllar spill, but from those carried along by the river and deposited at its concave bank.     

Causes of change in nitrophytic and oligotrophic lichen species in a Mediterranean climate: impact of land cover and atmospheric pollutants

With the aim of determining the main drivers of changes in nitrophytic and oligotrophic macro-lichen communities in an industrial region with a Mediterranean climate, we considered both land-cover types and atmospheric pollutants. We determined the relation between the abundance of nitrophytic and oligotrophic species with environmental factors considering the distance of influence of land-cover types. The results showed that oligotrophic species decreased in the proximity of artificial areas, barren land and agricultural areas, associated with higher concentrations of NO₂ and Zn, and Ti, probably dust of industrial and agricultural origin. Nitrophytic species were positively related to all the mentioned land-cover types, and with higher concentrations of Fe and N. Magnesium, probably from ocean aerosols, was negatively related to oligotrophic species and positively to nitrophytic.     

A directional passive air sampler for monitoring polycyclic aromatic hydrocarbons (PAHs) in air mass

A passive air sampler was developed for collecting polycyclic aromatic hydrocarbons (PAHs) in air mass from various directions. The airflow velocity within the sampler was assessed for its responses to ambient wind speed and direction. The sampler was examined for trapped particles, evaluated quantitatively for influence of airflow velocity and temperature on PAH uptake, examined for PAH uptake kinetics, calibrated against active sampling, and finally tested in the field. The airflow volume passing the sampler was linearly proportional to ambient wind speed and sensitive to wind direction. The uptake rate for an individual PAH was a function of airflow velocity, temperature and the octanol-air partitioning coefficient of the PAH. For all PAHs with more than two rings, the passive sampler operated in a linear uptake phase for three weeks. Different PAH concentrations were obtained in air masses from different directions in the field test.     

Influence of tidal regime on the distribution of trace metals in a contaminated tidal freshwater marsh soil colonized with common reed (Phragmites australis)

A historical input of trace metals into tidal marshes fringing the river Scheldt may be a cause for concern. Nevertheless, the specific physicochemical form, rather than the total concentration, determines the ecotoxicological risk of metals in the soil. In this study the effect of tidal regime on the distribution of trace metals in different compartments of the soil was investigated. As, Cd, Cu and Zn concentrations in sediment, pore water and in roots were determined along a depth profile. Total sediment metal concentrations were similar at different sites, reflecting pollution history. Pore water metal concentrations were generally higher under less flooded conditions (mean is (2.32 ± 0.08) × 10⁻³ mg Cd L⁻¹ and (1.53 ± 0.03) × 10⁻³ mg Cd L⁻¹). Metal concentrations associated with roots (mean is 202.47 ± 2.83 mg Cd kg⁻¹ and 69.39 ± 0.99 mg Cd kg⁻¹) were up to 10 times higher than sediment (mean is 20.48 ± 0.19 mg Cd kg⁻¹ and 20.42 ± 0.21 mg Cd kg⁻¹) metal concentrations and higher under dryer conditions. Despite high metal concentrations associated with roots, the major part of the metals in the marsh soil is still associated with the sediment as the overall biomass of roots is small compared to the sediment.     

Mercury biomethylation assessment in the estuary of Bilbao (North of Spain)

The relationship between the microbial methylation of mercury and the microbial activities in sediments and water collected from the estuary of Bilbao (North of Spain) was studied in three different sampling points and in two different seasons. Three different cultures were prepared with a sediment slurry to distinguish between biotic and abiotic methylation pathways and the variations of the methylmercury concentration and the variations of the population of total number of bacteria (TDC), anaerobic heterotrophic bacteria (AHB), sulphate-reducing bacteria (SRB) and Desulfovibrio were measured. From this work, it can be concluded that the variation of MeHg concentrations is a result of the methylation/demethylation processes in the sediments, and that the abiotic processes have a negligible contribution to those processes. According to the statistical analysis of the results (partial least squares analysis) a significant statistical correlation was established between methylmercury and the SRB counts.     

Hepatic monooxygenase (CYP1A and CYP3A) and UDPGT enzymatic activities as biomarkers for long-term carbofuran exposure in tench (Tinca tinca L)

The effect of a long-term exposure of tenchs to different concentrations (10 and 100 micro g/L) of the pesticide carbofuran has been evaluated. Microsomal hepatic cytochrome P450 subfamily 1A (CYP1A) and 3A (CYP3A) activities, as well as the phase II enzyme uridine diphospho-glucuronosyltransferase (UDPGT) activity were evaluated as adequate biomarkers of fish exposure to environmentally relevant concentrations of the pesticide carbofuran in freshwater ecosystems. A clear time-dependent inhibition of both CYP1A and UDPGT activities was observed in fish exposed to the highest dose of carbofuran with respect to controls, whereas in the case of CYP3A activity, values of exposed animals did not show a clear pattern of alteration during the experiment. The results of the present study demonstrated that hepatic CYP1A and UDPGT activities from tench could be considered as sensitive biomarkers for carbamate pesticides in polluted water, thus allowing future and ecologically relevant biomonitoring studies with this species.     

Hans-Joachim Schallna? (1957–2007)

Ohne Zusammenfassung     

Adsorption of chloridazon from aqueous solution on modified kerolite-rich materials

The adsorption of chloridazon (5-amine-4-chloro-2-phenylpyridazin-3(2H)-one) on kerolite samples heated at 110 degrees C (K-110), 200 degrees C (K-200), 400 degrees C (K-400), 600 degrees C (K-600) and acid-treated with H(2)SO(4) solutions of two different concentrations (0.25 and 0.5 M) (K-0.25 and K-0.5, respectively) from pure water at 25 degrees C has been studied by using batch and column experiments. The adsorption experimental data points were fitted to the Freundlich equation in order to calculate the adsorption capacities (K(f)) of the samples; K(f) values ranged from 184.7 mg kg(-1) (K-0.5) up to 2253 mg kg(-1) (K-600). This indicated that the heat treatment given to the kerolite greatly increases its adsorption capacity for the herbicide whereas the acid treatment produces a clear decrease in the amount of chloridazon adsorbed. The removal efficiency (R) was also calculated; R values ranging from 52.8% (K-0.5) up to 88.3% (K-600). Thus, the results showed that the 600 degrees C heat-treated kerolite was more effective in relation to adsorption of chloridazon and it might be reasonably used in removing this herbicide from water.