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.

Industries on the island of Mauritius are under increasing pressure from the regulatory authority and from the general public to control the air pollution from their boilers and particularly that of sulfur dioxide emissions from fuel oil combustion. The measures taken by industry are usually “ad hoc” in nature, and there has been yet no proper scientific methodology to justify the nature of the pollution control interventions. Air modeling as a planning tool provides a scientific methodology to industries and to the regulatory authority to select the optimum option(s) among various scenarios such as raising stack heights, changing fuels, implementing cleaner production opportunities or installation of wet scrubbers. The aim of this project was to use an air dispersion model for the selection of air pollution control systems for industrial boilers in an industrial estate. Given a number of constraints on small island developing states like Mauritius, it is recommended to start using established and simple modeling methods, as the complexity of the more refined models requires a relatively long learning curve to be able to use the model correctly. The Industrial Source Complex Short Term (ISCST3) is recommended for that purpose. The application of the ISCST3 model to the multiple-source case study helped in the identification of the most cost-effective options.

Retardation of tritium migration in the Chinese loess media was studied through column experiments by comparison of the migration velocity with other three “non-adsorptive” tracers of Br−, 99Tc, and 131I. Results showed that the transport peak of Br− was 1.25 times earlier than that of tritium when the tracers were simultaneously injected into the column, and the migration of 99Tc was even 1.60 times faster than 3H when the tracers were simultaneously injected. For iodine, it was only 1.02 times faster than that of tritium, but it should not be ignored. It reflected that the transport of 3H, compared to that of Br−, 99Tc, or 131I in the loess media, was retarded. In order to validate the adsorption behavior of tritium on loess, batch tests were carried out using Chinese loess soil. The experimental results indicated that the adsorption of tritium was actual existence, and the distribution coefficient of tritium is influenced by initial activity of tritium, pH, water/solid ratio, and the content of humic and fulvic acids.

Total topsoil 50th percentile Cu, Pb and Zn concentrations (n = 491) in the Sydney estuary catchment were 23 μg g−1, 60 μg g−1 and 108 μg g−1, respectively. Nine percent, 6% and 25% of samples were above soil quality guidelines, respectively and mean enrichment was 14, 35 and 29 times above background, respectively. Soils in the south-eastern region of the catchment exhibited highest metal concentrations. The close relationship between soil metal and road network distributions and outcomes of vehicular emissions modelling, strongly suggested vehicular traffic was the primary source of metals to catchment soils. Catchment soil and road dust probably make an important contribution to contamination of the adjacent estuary. The concentration of soil metals followed the land use trend: industrial > urban > undeveloped areas. A high proportion (mean 45%, 62% and 42%, for Cu, Pb and Zn, respectively) of metals in the soils may be bioavailable.

Identifying the factors responsible for the diversity of responses of biota to industrial pollution is crucial for predicting the fates of polluted ecosystems. A meta-analysis based on 49 field studies conducted around 47 point polluters demonstrated that the individual (growth and reproduction) and community (abundance and species richness) characteristics of bryophytes in polluted habitats are reduced to about a half of the values observed in unpolluted sites. Non-ferrous smelters cause a stronger reduction in species richness and larger changes in species composition than other types of polluters. The magnitudes of the effects of pollution on the abundances of individual bryophyte species are not linked with their taxonomic position, life form or Ellenberg indicator values for light, moisture and nitrogen. The variation in species’ responses to pollution is mostly explained by differences in their reproductive characteristics; bryophyte species that possess special forms of vegetative reproduction and those that produce abundant sporophytes are more successful in polluted habitats. Ranking of bryophyte species according to their sensitivity to pollution is independent of the type of the polluter. Changes in bryophyte cover follow changes in tree cover, but not changes in the cover of the vascular field layer in the same pollution gradients. Pollution impacts cause stronger adverse effects on bryophytes in warmer climates.