This study assessed the foliar uptake of 15N-labelled nitrogen (N) originating from wet deposition along with leaf surface conditions, measured by wettability and water storage capacity. Foliar 15N uptake was measured on saplings of silver birch, European beech, pedunculate oak and Scots pine and the effect of nitrogen form (NH4 + or NO3 −), NH4 + to NO3 − ratio and leaf phenology on this N uptake was assessed. Next to this, leaf wettability and water storage capacity were determined for each tree species and phenological stage, and the relationship with 15NH4 + and 15NO3 − uptake was examined. Uptake rates were on average five times higher (p < 0.05) for NH4 + than for NO3 − and four times higher for deciduous species than for Scots pine. Developing leaves showed lower uptake than fully developed and senescent leaves, but this effect was tree species dependent. The applied NH4 + to NO3 − ratio did only affect the amount of N uptake by senescent leaves. The negative correlation between measured leaf contact angles and foliar N uptake demonstrates that the observed effects of tree species and phenological stage are related to differences in leaf wettability and not to water storage capacity.

Aqueous natural organic matter (NOM) impacted by two contrasting human impacts was analyzed using by multiresponse fluorescence, decoupled with the resolution routine PARAFAC. The first site is Chalk River, Ontario, Canada, near a pit formerly used to dispose low-level wastes. The second site is the Grand River in Cambridge, south-central Ontario, which is impacted by urban activities and agriculture. Our analysis included raw water, plus fractions from ultrafiltration and solid-phase extraction (SPE). The fluorescence spectra of the NOM, resolved with PARAFAC, showed three common features: humic-like components, at excitation/emission wavelengths 325-350/450-475 nm, fulvic-like components at 325/380-420 nm and protein-like components, at 275/300 nm. Ultrafiltration revealed that most of the NOM comprised fine material below 5,000 Da cut-off (<4% of the total) in the urban-impacted sites and the clean site at Chalk River, but the colloidal fraction (larger than 5,000 Da) was substantially higher in the contaminated water, with ∼18-26% of the total. The protein-like components in the contaminated Chalk River water were affected by ultrafiltration, but less so in the clean Chalk River sample and the urban-impacted waters. SPE preferentially removed the protein-like component in the contaminated Chalk River water (typically 89-95% signal decrease), but had a limited effect on humic- and fulvic-like components elsewhere. In conclusion, multiresponse fluorescence provided new information on the NOM quality from two contrasting sites, aided by ultrafiltration and SPE. These results are consistent with the in situ production of NOM in the Chalk River contaminated site, and natural production at the other sites.

Biosorption has potential to be an economical colour removal technology. As such, the colour removal potential of inactivated Aspergillus niger biomass was investigated for the treatment of activated sludge-treated pulp mill effluent from a northern bleached softwood kraft mill. Biomass pretreatment methods, effects of initial pH of the effluent and preparative biomass washing methods were examined. The most effective pretreatment method was found to be simple autoclaving of the biomass and this approach was applied in subsequent kinetic and isotherm batch studies. It was also found that the pH of the wastewater prior to addition of the biomass affected the biosorption rate and the solubility of chromophores in pulp mill effluent. The results also indicated that biomass washing methods reduced the quantity of organic matter leached from the fungal biomass during application. The kinetic study revealed that colour removal by biosorption occurred most readily in the first 8 h and could be described adequately by both the Lagergren and Ho et al. models. The maximum colour removal was over 900 TCU, with a biomass dose of about 20 g/L. The isotherm study data were fitted with the BET isotherm model. The results indicated that adsorption occurred in a multi-layer fashion and that physical adsorption was the main mechanism contributing to the biosorption. Therefore, dead A. niger biomass was concluded to be a promising alternative for colour removal from pulp mill effluent.

The response to ozone (O3) of a range of Chinese leafy vegetables was investigated with respect to both inter- and intra-specific differences in sensitivity. In the interspecific experiment local Chinese cultivars of pak choi, rape, leaf mustard, leaf lettuce and coriander were fumigated with 90 ppb O3 for 9 h daily for 22–30 days. A similar fumigation was carried out using four different cultivars of pak choi. Sequential measurements were made of leaf injury, photosynthetic rate, stomatal conductance and chlorophyll fluorescence, together with dry weights at a final harvest. O3 injury appeared as white or yellow blemishes on the leaf surface of all species. The first signs of injury were seen following only 3-days’ O3 exposure (pak choi); the extent of injured leaf area increased over time for all species and cultivars, with 44.6% of the leaf area visibly injured for leaf mustard, the species with the greatest extent of injury, following 30-days’ exposure. Significant reductions in photosynthetic rate (22.7–40.7%) and stomatal conductance (19.1–33.1%) were found for all species and cultivars following O3 exposure. Plant productivity was also reduced in O3 compared to filtered air, with significant yield reductions for all species (11.1–50.8% above-ground dry weight) as well as for all cultivars of pak choi (15.8–28.1% above-ground dry weight). The mechanisms for observed impacts are discussed, together with the implications for current and future production of vegetables in the southern China province of Guangdong.

Due to the inherent differences in bioavailability and transport properties of particulate and dissolved mercury (HgP and HgD), it is important to understand the processes by which each is mobilized from soil to stream. Currently, there is a paucity of HgP data in the literature despite the fact that it can be the dominant fraction in some systems. We analyzed HgP in conjunction with volatile solids (VS, an estimate of organic content) and total suspended solids (TSS) and investigated the viability of using turbidity as a surrogate measure of HgP. Samples were collected for flow conditions ranging from 72 to 8,223 L s−1 during October 2009 through March 2010 in a 10.5-km2 forested headwater catchment. Total Hg concentrations ranged from 0.28 to 49.60 ng L−1, with the relative amount of HgP increasing with discharge from approximately 40% to 97%. Storm dynamics of HgP and HgD were not consistent, indicating unique controls on the export of each fraction. During high-flow events, HgP was consistently higher on the rising limb of the hydrograph compared with the receding limb for a range of discharge events, with this hysteresis contributing to a degraded relationship between HgP and streamflow. Overall, HgP was strongly positively correlated with VS (r 2 = 0.97), confirming the known association with organic carbon. Due to a consistent organic fraction of the suspended solids (34 ± 6%), HgP was also well correlated with TSS (r 2 = 0.95), with an average of 0.10 ng of HgP per milligram of TSS in this system. Stream turbidity measured with an in situ sonde also had a strong correlation with TSS (r 2 = 0.91), enabling commutative association with VS (r 2 = 0.86) and HgP (r 2 = 0.76). Turbidity can explain more than twice the temporal variance in HgP concentrations (n = 50) compared with discharge (r 2 = 0.76 versus 0.36), which leads to improved monitoring of HgP dynamics and quantification of mass fluxes.

The present study was conducted in tropical Sal forest ecosystem of the Doon valley in the Indian Himalayas to assess the critical load of sulfur and nitrogen and their exceedances. The observed pattern of throughfall ionic composition in the study are Ca2+>K+>Mg2+>Cl−> HCO3−> Na+>NO3 −> SO3 2−≥ NH4 +>F−. The sum of cation studied is 412.29 μeq l−1 and that of anions is 196.98 μeq l−1, showing cation excess of 215.31 μeq l−1. The cations, namely Ca2+, Mg2+, K+, Na+, and NH4 +, made a contribution of about 67% of the total ion strength, where as anion comprising of SO4 2−, Cl−, NO3 −, and HCO3 − contributed 33%. The chief acidic components were Cl– (12%) and HCO3 − (8%), while the presence of SO4 2− (5%) and NO3 − (6%), respectively. Percentage contribution of bole to total aboveground biomass was ∼72.38% in comparison to 2.24–2.93% of leaf biomass, 10.34–10.96% of branch biomass and 13.21–17.07% of bark biomass. There was high and significant variation (P < 0.001) in the total aboveground biomass produced at different sites. The aboveground net primary productivity (ANPP) in these sites ranged between 2.09 and 9.22 t ha−1 year−1. The base cations and nitrogen immobilization was found to be maximum in bole. The net annual uptake of the base cations varied from 306.85 to 1,311.46 eq ha−1 year−1 and of nitrogen from 68.27 to 263.51 eq ha−1 year−1. The critical appraisal of soil showed that cation exchange capacity lied between 18.37 and 10.30 Cmol (p+) kg−1. The base saturation percentage of soil was as high as 82.43% in Senkot, whereas in Kalusidh it was just 44.28%. The local temperature corrected base cation weathering rates based on soil mineralogy, parent material class, and texture class varied from 484.15 to 627.25 eq ha−1 year−1, showing a weak potentiality of the system to buffer any incoming acidity and thus providing restricted acid neutralizing capacity to keep the ecosystem stable under increased future deposition scenarios in near future. The appreciable BS of the soil indicates the presence of intense nutrient phytorecycling forces within this climate and atmospheric deposition in replenishing base cations in the soil, which includes intrinsic soil-forming processes, i.e., weathering. The highest value of critical load for acidity was 2,896.50 eq ha−1 year−1 and the lowest was 2,792.45 eq ha−1 year−1. The calculated value of the minimum critical loads for nitrogen varied from 69.77 to 265.01 eq ha−1 year−1, whereas the maximum nitrogen critical load ranged between 2,992.63 and 4,394.45 eq ha−1 year−1. The minimum and the maximum critical loads of sulfur ranged between 2,130.49 and 3,261.64 eq ha−1 year−1 and 2,250.58 and 3,381.73 eq ha−1 year−1, respectively. The values of exceedance of sulfur and nitrogen were negative, implying that in the current scenario Sal forests of the Doon valley are well protected from acidification.

Polycyclic aromatic hydrocarbons (PAH) have been identified and quantified in dated layers of freshwater and marine sediments in Norway. Furthermore, profiles of the individual PAH (22 different) have been used to evaluate possible PAH sources. There is a significant increase in total PAH levels (sum of the 22 PAH) in freshwater sediments from the south-western part of Norway representing the 1800–1950 period, whereas the concentrations have decreased with a factor of approximately four since the 1950s. This pronounced trend was observed in two independent surveys. In northern Norway, the PAH levels in lake sediments have increased slightly during the past decades. In spite of this, the levels are considerably lower than in lake sediments from the south-western part of Norway. In fact, the PAH levels are decreasing northwards on the Norwegian mainland for both freshwater and marine surface sediments. Generally, the regional total PAH levels are higher (three to four times) in freshwater sites compared to the corresponding marine sites. Results of PAH source allocation indicate that pyrogenic sources are important in almost all sediment samples studied. Sediment samples were also collected at Svalbard where the local coal reserve is the major contributor to PAH.

Lipophilic anthropogenic contaminants enter the environment from different kinds of human activities and corresponding emission sources. In the hydrosphere, they accumulate frequently in specific sedimentary zones, among others, and at coastal areas, forming reservoirs of pollutants. Marine and freshwater sediment samples as well as soil samples from a highly industrialized coastal area in Northern Greece have been analyzed in order to have a detailed view on the state of the particle-associated pollution. Noteworthy, based on extended GC/MS non-target screening analyses, interesting, so far unknown, or rarely documented contaminants have been identified and quantified comprising, e.g., mono- and dichlorocarbazoles, bromocarbazole, 2,6-di-tert-butyl-4-nitrophenol, etc. However, all relevant contaminants are discussed with respect to their spatial concentration profiles, their emission sources, and their pathway. In addition, numerous pollutants are suggested to become selected for environmental monitoring programs. Hence, this study can act as an example for adapting individual monitoring programs to the individual contamination in coastal areas.

This paper investigates the changes in bioavailable phosphorus (P) within the hyporheic zone of a groundwater-dominated chalk stream. In this study, tangential flow fractionation is used to investigate P associations with different size fractions in the hyporheic zone, groundwater and surface water. P speciation is similar for the river and the chalk aquifer beneath the hyporheic zone, with ‘dissolved’ P (<10 kDa) accounting for ~90% of the P in the river and >90% in the deep groundwaters. Within the hyporheic zone, the proportion of ‘colloidal’ (<0.45 μm and >10 kDa) and ‘particulate’ (>0.45 μm) P is higher than in either the groundwater or the surface water, accounting for ~30% of total P. Our results suggest that zones of interaction within the sand and gravel deposits directly beneath and adjacent to river systems generate colloidal and particulate forms of fulvic-like organic material and regulate bioavailable forms of P, perhaps through co-precipitation with CaCO3. While chalk aquifers provide some degree of protection to surface water ecosystems through physiochemical processes of P removal, where flow is maintained by groundwater, ecologically significant P concentrations (20–30 μg/L) are still present in the groundwater and are an important source of bioavailable P during baseflow conditions. The nutrient storage capacity of the hyporheic zone and the water residence times of this dynamic system are largely unknown and warrant further investigation.

Land use and its relation to nutrient concentrations and loading via streams is an important issue in coastal lagoons and embayments worldwide including the Maryland coastal bays system, USA. As in many coastal areas around the globe, declining water quality in the bays is the result of nutrient inputs from the surrounding watershed. In this study, the sources of the nutrient inputs were examined. Monthly concentrations of total nitrogen (TN), ammonium (NH4 +), nitrate (NO3 -), phosphate (PO4 -3), and total phosphorus (TP) were measured in six streams in the St. Martin River basin from July 2006 to January 2008. Current land use information for the basins of each stream was also compiled. Several significant correlations between nutrients and land use type were found. The most significant correlation was with the land area of feeding operations, which demonstrated a significant positive relationship with mean baseflow TN concentrations. A similar relationship was also found with anthropogenic land area (cropland + urban + feeding operations), and wetland area was also positively associated with hydric soils. Using local water yields from a US Geological Survey station, annual stream watershed export was calculated using the concentration data, which indicated that the watershed with the most crop agriculture had the highest N export coefficient (20.4 kg N ha-1 year-1), while the highest P export (0.47 kg P ha-1 year-1) was in a watershed containing a nonoperational chicken hatchery and a subsequently modified channel. This suggests that agricultural development, especially animal feeding operations, and landscape characteristics are important factors to understand nutrient loading in St. Martin River and Maryland coastal bays. The methods used and the results determined in this study have implications for determining nutrient loading in lagoons and embayments, in relation to land use in coastal regions globally.