In freshwater environments direct biological effect of ultraviolet radiation (UVR) result from absorption of specific wavelengths by macromolecules and alteration of biochemical processes. Indirect effects are related to UVR interaction with water and dissolved organic carbon to form chemically reactive species (ROS: reactive oxygen species). Zooplankton photoprotection includes mycosporine-like amino acids, pigments, production of quenching agents and antioxidant enzymes. The relative importance of each mechanism would depend on the organisms. In this study, we determined the antioxidant enzyme activities Catalase (CAT) and Glutathione-S-transferase (GST) in the copepod Boeckella gracilipes and the cladoceran Ceriodaphnia dubia in three Andean lakes of the North-Patagonia region. There were differences in antioxidant enzymes expression between copepods and cladocerans. CAT was significantly higher in C. dubia than in B. gracilipes whereas GST was similar in both species. The comparison of B. gracilipes enzyme activity in the three lakes showed also differences in GST but not in CAT. DOC decreases the exposure by absorption of UVR but simultaneously acts as photosensitizer producing ROS and their successive toxic products in the surface waters. We discuss that comparisons among lakes of different DOC should be considered carefully because lake physico-chemicals parameters, as well as food web structure, will difficult any predictions on the net effect of DOC.

In order to gain insight into the community structure and the biodegradative potential of bacteria residing in a BTEX-contaminated field site, with benzene as main pollutant, an investigation strategy with a variety of cultivation-independent and -dependent approaches was undertaken. Based on 16S ribosomal DNA sequence analysis, sampling stations in the center of the pollution plume were found to be dominated by a bacterial consortium affiliated with various members of the class of Proteobacteria and Firmicutes, including different sporulating and non-sporulating sulfate-reducing bacteria and members of the genus Geobacter. Non-polluted samples retrieved from outside the plume revealed several phylotypes which were also observed in the centre of the plume. Bacterial sequences retrieved from the fringe of the plume were dominated by several genera of beta Proteobacteria subclass which were not associated with other phylotypes obtained in this study. All sampling stations were tested positive for catechol 2,3-dioxygenase genes, indicating the presence of microorganisms with the genetic potential degrading aromatic compounds via the meta-cleavage pathway. The groundwater system at the down-gradient edge of the plume was characterized, in contrast to all other sampling stations in the center and outside the plume, by high numbers of cultivable bacteria and cultivable aerobic benzene and toluene degraders. These findings are also in accordance with the investigations based on fluorescent in situ hybridization (FISH) with rRNA-targeted oligonucleotide probes, suggesting the presence of an actively benzene degrading bacterial community of beta Proteobacteria at the fringe of the pollution plume.

Fluxes of principal anions and cations with bulk and throughfall deposition during the growing period (April-September) were investigated for three years (2001-2003) at three sites differently exposed to the second biggest Lithuanian city - Kaunas. Fluxes of all investigated anions (SO₄ ²-, NO₃ - and Cl-) and most cations were found to be the highest in suburban area to compare with both - Rural and urban sites. The highest seasonal variability of monthly ion fluxes and the highest differences between throughfall and bulk fluxes (net throughfall) were recorded in suburban area. The highest throughfall enrichment by sulphur was detected in spring and the beginning of summer (April, May) in urban and especially in suburban sites. For nitrogen compounds (NO₃ -, NH₄ ⁺) positive net throughfall values were characteristic for urban and suburban sites and negative for rural site almost during the entire growing period. Uptake of NH₄ ⁺ ions was detected to be much higher of that for nitrates in rural area (46% vs. 22%). The most intensive enrichment of throughfall fluxes by K⁺ ions took place during the summer time (May, June, July), however, intensity of potassium leaching at the same amount of precipitation was the highest in suburban area.

Stormwater runoff from urban surfaces often contains elevated levels of toxic metals. When discharged directly into water bodies, these pollutants degrade water quality and impact aquatic life and human health. In this study, the composition of impervious surface runoff and associated rainfall was investigated for several storm events at an urban site in Orlando, Florida. Total mercury in runoff consisted of 58% particulate and 42% filtered forms. Concentration comparisons at the start and end of runoff events indicate that about 85% of particulate total mercury and 93% of particulate methylmercury were removed from the surface before runoff ended. Filtered mercury concentrations showed less than 50% reduction of both total and methylmercury from first flush to final flush. Direct comparison between rainfall and runoff at this urban site indicates dry deposition accounted for 22% of total inorganic mercury in runoff.

This study examines the seasonal variability in levels of nitrogen (N) leaching and acidity in four acid impacted upland regions of the UK: the South Pennines, Snowdonia, Galloway and the Mourne Mountains. All regions are acidified, with median pH values of <5.5. The South Pennines exhibit excess sulphate concentrations an order of magnitude higher than those for other regions and have the lowest pH values of all the regions. Nitrate concentrations are highest in the South Pennines (seasonal medians 20-26 μeq l-¹) and the Mourne Mountains (seasonal medians 9-26 μeq l-¹). Surface water in the Mourne Mountains is the most highly N impacted in terms of the proportional contribution of N to acidity. All N species exhibit seasonality, with greater retention by catchment soils and vegetation in August. This seasonality is most marked in Snowdonia and least marked in the South Pennines. This implies that the South Pennines have reached an advanced stage of N saturation. Despite the reductions in S deposition, xSO₄ is the dominant anion for all sites in the South Pennine and Snowdonia regions. A strong negative relationship between the contribution of NO₃ to total acidity and DON was observed for all regions except the South Pennines. It is hypothesized that catchments dominated by organic rich soils produced more DON and have an increased capacity to immobilise NO₃. Seasonal nitrogen budgets show that over 60% of the N inputs are retained within catchments, and no site retains all incoming N throughout the year.

Phenylalanine ammonia-lyase activity (PAL, EC 4.3.1.5), total phenolics, soluble proteins, malondialdehyde and metals accumulation in four-week old chamomile (Matricaria chamomilla) plants cultivated in nutrient solution and exposed to low (3 μM) and high (60 and 120 μM) levels of cadmium (Cd) or copper (Cu) for 7 days were studied. High Cd concentrations had a stimulatory effect on PAL activity and soluble phenolics accumulation while high Cu doses decreased soluble proteins in the leaf rosettes. In the roots, extreme stimulatory effects of 60 and 120 μM Cu were observed on PAL activity, phenolics and malondialdehyde accumulation, while protein content was reduced by these Cu doses. Cd accumulation was higher in the leaf rosettes compared to copper, but the opposite was recorded in the roots. Taken together, the stimulatory effect of Cu on phenolic metabolism was recorded, even though high malondialdehyde accumulation may be an indication that phenolics was not sufficient to counteract reactive oxygen species formation thus leading to damage of membrane integrity. In comparison to Cd, Cu had more noticeable effect on the parameters studied to support its strong redox-active properties. These facts in correlation to antioxidative properties of phenolic metabolites are also discussed.

The present study aimed to look at the fate of protozoan parasite Cryptosporidium parvum oocysts applied through surface drip irrigation on reclaimed water irrigation-history and non-history sandy-loam (Hamra) soil columns. A new and simple isolation method for recovery of oocysts from soil samples was developed and used along this study. The new soil isolation method of oocysts is based on the “two phase separation method” formerly used to recover Clostridium perfringens spores from sediments and soil samples with minor modifications. The range recovery achieved by this method was 64-95% (mean 61.2 ± 17.4). The objectives of the second part of this study were to investigate several physical and chemical factors governing transport and survival of C. parvum oocysts in sandy-loam soil columns by breakthrough curves. Comparison of fresh water and reclaimed water irrigation revealed that reclaimed water irrigated-history soil was more hydrophobic allowing water flow through channels with poor oocysts retention and fast flow. Examination of the organic matter effect (originating from reclaimed water irrigation) on oocysts breakthrough revealed that their soil infiltration increased. Calculations of oocysts concentration at different columns depths showed that most of the oocysts were retained in the first 5 cm of soil column. In the present study, comparing the two soil types (history and non-history of effluents irrigation) beside the surface electrostatic charge, one of the main elements found to affect oocysts infiltration and transport in soil columns was soil hydrophobicity caused by soluble organic matter originating from reclaimed water irrigation. Therefore, prior to application in soil irrigation, reclaimed water should be treated to high quality (i.e. membrane technology as the best option) to prevent enhanced transport of various pathogens through those irrigated soils.

The characteristics of transport and transformation of SO₂, NOx and O₃ in northeast Asia have been investigated by using a comprehensive regional air quality model (RAQM) driven by a meteorological model MM5. A study period of 1-15 March 2002 has been selected due to the availability of intense observation of chemical species for both ground and upper levels. Model results have been compared against observational data to provide insights into the strength and weakness of the model's ability and the evolutionary features of chemical species. Validation shows a good skill of this model system in reproducing most of the key features in long-range transport, but apparent bias still remains due to a series of uncertainties from either emission estimates, prescribed parameters, or inherent model limitations. In general, this model shows a better skill for SO₂ and O₃ than for NOx. Large discrepancy occurs between the observed and calculated NOx concentration at higher levels, with the model results being much lower. A series of sensitivity tests have been conducted to investigate the potential affecting factors and it is found that the inaccuracy or incompleteness in currently used emission inventories could be a most likely cause for such discrepancy. Long-range transport from Asian continent to the western Pacific is pronounced in springtime. Substantially high concentrations of SO₂ and NOx in or above the boundary layer (0.5~3.0 km) over the Yellow Sea suggest an important pathway for long-range transport in northeast Asia.

To evaluate the acid deposition reduction negotiated for 2010 within the UNECE LRTAP Gothenburg Protocol, sulphur and nitrogen deposition time-series (1880-2100) were compared to critical loads of acidity on five French ecosystems: Massif Central basalt (site 1) and granite (2); Paris Bassin tertiary sands (3); Vosges mountains sandstone (4) and Landes eolian sands (5). The SAFE model was used to estimate the response of soil solution pH and [graphic removed] ratio to the deposition scenario. Among the five sites, critical loads were exceeded in the past at sites 3, 4 and 5. Sites 3 and 4 were still expected to exceed in 2010, the Protocol year. Further reduction of atmospheric deposition, mainly nitrogen, would be needed to achieve recovery on these ecosystems. At sites 3, 4 and 5, the delay between the critical load exceedance and the violation of the critical chemical criterion was estimated to be 10 to 30 years in the top soil and 50 to 90 years in the deeper soil. At site 5, a recovery was expected in the top soil in 2010 with a time lag of 10 years. Unexpectedly, soil pH continued to decrease after 1980 in the deeper soil at sites 2 and 5. This time lag indicated that acidification moved down the soil profile as a consequence of slow base cation depletion by ion exchange. This delayed response of the soil solution was the result of the combination of weathering rates and vegetation uptake but also of the relative ratio between base cation deposition and acid compounds.

Regular additions of NH₄NO₃ (35-140 kg N ha-¹ yr-¹) and (NH₄)₂SO₄ (140 kg N ha-¹ yr-¹) to a calcareous grassland in northern England over a period of 12 years have resulted in a decline in the frequency of the indigenous bryophyte species and the establishment of non-indigenous calcifuge species, with implications for the structure and composition of this calcareous bryophyte community. The lowest NH₄NO₃ additions of 35 kg N ha-¹ yr-¹ produced significant declines in frequency of Hypnum cupressiforme, Campylium chrysophyllum, and Calliergon cuspidatum. Significant reductions in frequency at higher NH₄NO₃ application rates were recorded for Pseudoscleropodium purum, Ctenidum molluscum, and Dicranum scoparium. The highest NH₄NO₃ and (NH₄)₂SO₄ additions provided conditions conducive for the establishment of two typical calcifuges - Polytrichum spp. and Campylopus introflexus, respectively. Substrate-surface pH measurements showed a dose-related reduction in pH with increasing NH₄NO₃ deposition rates of 1.6 pH units between the control and highest deposition rate, and a further significant fall in pH, of >1 pH unit, between the NH₄NO₃ and (NH₄)₂SO₄ treatments. These results suggest that indigenous bryophyte composition may be at risk from nitrogen deposition rates of 35 kg N ha-¹ yr-¹ or less. These effects are of particular concern for rare or endangered species of low frequency.