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.

An agricultural ammonia (NH3) emission inventory in the North China Plain (NCP) on a prefecture level for the year 2004, and a 5 × 5 km2 resolution spatial distribution map, has been calculated for the first time. The census database from China's statistics datasets, and emission factors re-calculated by the RAINS model supported total emissions of 3071 kt NH3–N yr−1 for the NCP, accounting for 27% of the total emissions in China. NH3 emission from mineral fertilizer application contributed 1620 kt NH3–N yr−1, 54% of the total emission, while livestock emissions accounted for the remaining 46% of the total emissions, including 7%, 27%, 7% and 5% from cattle, pigs, sheep and goats, and poultry, respectively. A high-resolution spatial NH3 emissions map was developed based on 1 × 1 km land use database and aggregated to a 5 × 5 km grid resolution. The highest emission density value was 198 kg N ha−1 yr−1. The first high-resolution spatial distribution of ammonia emissions for the North China Plain showed rates up to 200 kg NH3–N ha−1 yr−1.

Synthetic musks are ubiquitous contaminants in the environment. Compartmental distributions (dissolved, suspended particle associated and sedimentary) of the compounds throughout an axial estuarine transect and in coastal waters are reported. High concentrations of Galaxolide® (HHCB) and Tonalide® (AHTN) (987–2098 ng/L and 55–159 ng/L, respectively) were encountered in final effluent samples from sewage treatment plants (STPs) discharging into the Tamar and Plym Estuaries (UK), with lower concentrations of Celestolide® (ADBI) (4–13 ng/L), Phantolide® (AHMI) (6–9 ng/L), musk xylene (MX) (4–7 ng/L) and musk ketone (MK) (18–30 ng/L). Rapid dilution from the outfalls is demonstrated with resulting concentrations of HHCB spanning from 5 to 30 ng/L and those for AHTN from 3 to 15 ng/L. The other musks were generally not detected in the estuarine and coastal waters. The suspended particulate matter (SPM) and sedimentary profiles and compositions (HHCB:AHTN ratios) generally reflect the distribution in the water column with highest concentrations adjacent to sewage outfalls. Synthetic musks were determined in coastal environmental compartments along an estuarine transect indicating their ubiquitous occurrence in transitional waters.

Heavy metal contamination has been and continues to be a worldwide phenomenon that has attracted a great deal of attention from governments and regulatory bodies. In this context, our study proposes a regression-tree model to predict the concentration level of zinc in the soils of northern Lebanon (as a case study of Mediterranean landscapes) under a GIS environment. The developed tree-model explained 88% of variance in zinc concentration using pH (100% in relative importance), surroundings of waste areas (90%), proximity to roads (80%), nearness to cities (50%), distance to drainage line (25%), lithology (24%), land cover/use (14%), slope gradient (10%), conductivity (7%), soil type (7%), organic matter (5%), and soil depth (5%). The overall accuracy of the quantitative zinc map produced (at 1:50.000 scale) was estimated to be 78%. The proposed tree model is relatively simple and may also be applied to other areas. GIS regression-tree analysis explained 88% of the variability in field/laboratory Zinc concentrations.

Geography, population growth, and politics combine to make the Gaza Strip a worst-case scenario for water resource planners. Potable water sources are shrinking while at the same time, the proportion of potable water used for irrigation is increasing. To assess whether water from wastewater treatment plants could be safely used for irrigation, this study collected 51 treated wastewater, 51 sludge, 44 soil, 30 alfalfa, and 24 oranges and lemon samples and analyzed the samples for major and trace elements. Both Inductively Coupled Plasma - Optical Emission Spectroscopy (ICP/OES) and X-ray fluorescence (XRF) were used for the determination of Ag, Al, As, B, Ba, Br, Ca, Cd, Co, Cr, Cu, Fe, Hg, K, Mg, Mn, Na, Ni, P, Pb, Rb, Se, Sr, Zn, Zr, Th, and U in digested and solid samples, respectively. Treated wastewater characteristics showed a very good agreement with the guidelines of many developed countries. Moreover, none of the tested parameters in soil showed concentrations exceeding their corresponding background values. For alfalfa, both ICP/OES and XRF showed Zn concentrations in leaves (36-42 mg/kg, respectively) higher than in root (19-31 mg/kg, respectively). The Cu showed also the same trend as Zn. No significant variation was observed between the concentrations of Cr and Mn in plant parts; concentrations of Co and Pb were two times higher in roots than in leaves and stems. The findings confirm that treated wastewater is safe to use for irrigation in Gaza. Collecting and reclaiming this water can contribute to wise use of each drop of water available.

Background, aim, and scope Experimental data on partition coefficients and environmental half-lives of sulfur analogs of polychlorinated organic compounds are scarce. Consequently, little is known about their overall persistence and long-range transport potential, which are the most vital measures in the environmental exposure assessment. We performed Multimedia Modeling of environmental fate and transport to complement this paucity of scientific data. The main aim of our study was to investigate whether the sulfur analogs of polychlorinated dibenzo-p-dioxins, -dibenzofurans, and -diphenylethers are as environmentally persistent and/or mobile as their oxygen counterparts and to propose the environmental exposure-related classification of the examined sulfur compounds. Materials and methods Our study included all possible congeners of the sulfur analogs generated in a combinatorial approach. We predicted (1) lacking data on partition coefficients (log K OW, log K OA and log K AW) for oxygen- and sulfur analogs using Quantitative Structure-Property Relationship (QSPR) modeling and (2) their half-lives in air, water, and soil using US EPA tool ‘The PBT Profiler, v. 1.203 2006'. Subsequently, we introduced these results into multimedia mass balance model ‘The OECD POV and LRTP Screening Tool, v. 2.2'. Results Our study revealed that log K OW and log K OA are increasing by constant values of 0.60 and 1.07, respectively, and the values of log K AW are decreasing by 0.90, whenever one oxygen atom in the carbon skeleton is replaced by sulfur. The persistence ranking performed by the PBT Profiler showed that PCDDs, PCDFs, PCDEs, and their sulfur analogs belong to one half-life class. Discussion The Multimedia Modeling by the means of ‘The OECD POV and LRTP Screening Tool, v. 2.2' suggested that the long-range transport potential depends on the presence/absence of oxygen/sulfur atoms in particular molecules, their substitution pattern and the parent carbon skeleton. Sulfur analogs are generally less mobile than their oxygen analogs, but have similar overall persistence and much higher bioaccumulation potential. Thus, according to the classification of chemicals proposed by Klasmeier et al. (Environ Sci Technol 40:53-60, 2006), some of them show POP-like POV and LRTP characteristics while the rest shows POP-like POV characteristics. Conclusions The sulfur analogs of PCDDs, PCDFs, or PCDEs bring environmental mobility comparable with the risk related to the oxygen ones; they belong to the pollutants of ‘highest' or ‘intermediate' priority. Recommendations and perspectives Further studies that would verify the necessity to include the studied sulfur molecules in the international lists of high-priority environmental pollutants are recommended.

Background, aim and scope The paper presents concentrations of trace elements in blood of homebred animals (cows and sheep) from Southern Serbia (Bujanovac) and the contents of natural and anthropogenic radionuclides and some heavy metals in feed. The region of Southern Serbia was exposed to contamination by depleted uranium ammunition during NATO attacks in 1999 and therefore, is of great concern to environmental pollution and human and animal health. Materials and methods Conventional instrumental and epithermal neutron activation analyses are used to measure trace elements in cow and sheep blood samples collected randomly at six locations in the region of Bujanovac (village of Borovac) in the spring of 2005. Samples of feed (grass and crops: corn, wheat and oats), collected on the same locations (households), are analysed for the contents of radionuclides on an HPGe detector (Ortec, relative efficiency 23%) by standard gamma spectrometry. The content of Hg, Pb and Cd in feed is determined by standard atomic absorption spectrometry on the VarianSpectra220/ThermoSolar GFS97 spectrometer. Results Concentrations of 29 elements (Na, Al (P), Cl, K, Sc, Cr, Mn, Ni, Fe, Co, Zn, Se, As, Br, Sr, Rb, Sb, In, I, Ba, Cs, La, Nd, Eu, Sm, Tb, Hf, Ta and Th) are determined in blood of the examined animals. In feeds, natural ⁴⁰K is found in all of the samples, cosmogenic ⁷Be and fission product ¹³⁷Cs are detected only in the grass samples, while heavy metals Hg, Cd and Pb are found in the range of 0.01-0.02, 0.84-1.15 and 0.74-7.34 mg/kg, respectively. Calculated soil-to-blood transfer factors are in a wide range of 8·10⁻⁶ to 64, as a result of varying significance of the elements in animal metabolism and feeding habits. Discussion The results of trace elements' concentrations in animal blood are in good agreement with available data for K, Ni, Zn, Se and Rb. Higher Br concentrations in animal blood are most probably caused by large biomass burning events during blood sampling. Very low concentration of Fe in cows and sheep confirms the results of previous biochemical studies on animal anaemia in the region. High concentration of As correlates with geochemical peculiarities of the Balkans and is also likely influenced by the use of pesticides in the agricultural production. For some of the elements (La, Nd, Eu, Sm, Tb, Sb, Hf, Ta, Th, In, Ba, Sr, Sc and Cs), there are few or no literature data. Therefore, some of the presented data are significant not only for the country and the region, but on a wider scale. Activities of natural radionuclides in feeds are within the average values reported for the region, while the activities of ²¹⁰Pb and ²³⁵/²³⁸U are below the limit of detection. This is in accordance with previous investigations showing no widespread contamination by depleted uranium in the area. Contents of Hg and Pb in feeds are below the nationally permissible levels, unlike the content of Cd which exceeds it, probably caused by the use of phosphate fertilisers and fossil fuel combustion in the area. Conclusions In general, the concentrations of trace elements in blood of homebred cows and sheep are in good agreement with reference materials, available literature data and the results of previous studies in the area. The exceptions are Fe, As and Br. The contents of natural and anthropogenic radionuclides in feeds are within the expected levels, and there are no signs of contamination by depleted uranium or other fission products. Apart from Cd, there are no signs of pollution by heavy metals in feeds. The highly sensitive method of instrumental neutron activation analysis provides data on the concentration of some elements in animal blood not previously reported for the region and elsewhere. Recommendations and perspectives The presented study is a part of the long term ongoing project on the health risk assessment on animals and humans in the region. The collected data is intended to provide a base for the animal and human risk assessment as well as an estimate of the general pollution status of the environment in the region. Since some of the investigated elements are classified as important trace elements for livestock, the results could also be used to balance and improve the animal diet and thus, improve the growth and reproduction rate.

Background, aim and scope A new method using sedimentary metals and geographic information system as indicators for assessing temporal and spatial anthropogenic change in estuaries has been applied to a large coastal lake (Lake Macquarie) in New South Wales, Australia. Materials, methods and results Two vintages of data (1975 and 2003) on surficial sediment metal (Cd, Cu, Pb and Zn) concentrations combined with ²¹⁰Pb core profiles were used to determine past changes in sediment quality and to predict possible future relaxation rates for the entire lake area in response to change in anthropogenic pressure. Sediment cores showed distinct vertical profiles; sedimentation rates in the northern part of the lake were consistent (14 mm year⁻¹) over the 55-year period investigated. Discussion and conclusions Surficial metal concentrations were highest in the 1975 sediment than in the 2003 samples, with the northern part of Lake Macquarie having much greater metal concentrations than the rest of the lake. Past and future declining sedimentary metal concentrations in the northern part of the lake were expected due to the closure of a nearby Pb-Zn smelter; however, possible increases in Cu in the south of the lake to the year 2020 were surprising. The new method presented in this study can assist estuary managers by providing data on past, present and future conditions, which are essential in making informed decisions for the improvement of estuarine systems.

Background, aim, and scope The Lower Mississippi River is a major transportation route for commercial goods and petroleum products produced and refined locally. Oil spills caused by vessel accidents and equipment failure at refineries are a serious threat to the drinking water supply of Southern Louisiana, as well as to the many natural, economic, and social resources supported by the river. Providing accurate trajectory modeling to contingency planners is critical to protecting the local environment. The majority of trajectory model results, assuming a uniform shoreline, show 60-70% of spilled oil can be retained. This study examines the impact of detailed shoreline mapping that captures spatial and temporal changes in shoreline type on oil spill trajectory modeling. Materials and methods Detailed shoreline maps based on recent remote sensing imagery were generated to identify spatial changes in shoreline. A hydrodynamic model of the 78 mile reach from Convent, Louisiana to West Pointe a la Hache was developed to obtain the stage levels and velocity fields of four river discharges. Based on river stage level, another layer was added to the shoreline maps, so that shoreline type was accurately represented at each river discharge, a feature not included in previous mapping. An oil spill trajectory model was then used to investigate the effect of implementing different re-floatation half-lives that correlate to the shoreline maps developed for this study at four river discharges. Results Detailed shoreline mapping showed the Lower Mississippi River has four major shoreline types each with different oil re-floatation half-lives: muddy clay, sand, low vegetation, and high vegetation. As flow rate changed, the shoreline spatial variability also changed, from 84% mud/sand and 16% vegetation at low flow rates to 4% mud and 96% vegetation at higher flow rates. At flow rates with large variability in shoreline type, the distribution of oil attached to the shore was significantly different from results of simulations that used a constant shoreline type and re-floatation half-life. Discussion At low flow rates, simulations with the detailed delineation of shoreline type predicted that ~30% of the oil would be beached/retained because the oil was able to travel further down the reach and interact with the shoreline in multiple locations. Simulations at the low flow rates with the existing shoreline mapping predicted approximately 65% of the oil would be retained as did all the simulations at the highest flow rates. At high flow rates, the oil interacted mostly with vegetation and results were very similar to those obtained with a single re-floatation half-life of 1 year. In addition to shoreline type, river geometry and the hydrodynamics were major factors influencing the distribution of oil along the river reach. Conclusions Shoreline re-floatation half-lives have a major impact on simulating the distribution of oil along the shore after a spill, especially in areas with a high variability of shoreline type as in the lower Mississippi River. Assigning the correct re-floatation half-life and retention capacity is only possible when shoreline types have been correctly identified. The maps developed for this study provided an important level of detail and incorporated the change in shoreline type with flow rate, resulting in more detailed trajectory modeling of the study reach. Recommendations and perspectives Shoreline maps should include as much detail about shoreline type as possible. When developing shoreline maps or environmental sensitivity assessments, the focus should include specific characteristics of the study area; using standardized maps or methods of assessment may leave out detail that could negatively impact modeling efforts. Finally, shoreline sensitivity to oiling is an important area of research that will benefit from an improved understanding of oil retention by vegetation.

Background, aim, and scope Riverine retention decreases loads of nitrogen (N) and phosphorus (P) in running water. It is an important process in nutrient cycling in watersheds. However, temporal riverine nutrient retention capacity varies due to changes in hydrological, ecological, and nutrient inputs into the watershed. Quantitative information of seasonal riverine N and P retention is critical for developing strategies to combat diffuse source pollution and eutrophication in riverine and coastal systems. This study examined seasonal variation of riverine total N (TN) and total P (TP) retention in the ChangLe River, an agricultural drainage river in east China. Methods Water quality, hydrological parameters, and hydrophyte coverage were monitored along the ChangLe River monthly during 2004-2006. Nutrient export loads (including chemical fertilizer, livestock, and domestic sources) entering the river from the catchment area were computed using an export coefficient model based on estimated nutrient sources. Riverine TN and TP retention loads (RNRL and RPRL) were estimated using mass balance calculations. Temporal variations in riverine nutrient retention were analyzed statistically. Results and discussion Estimated annual riverine retention loads ranged from 1,538 to 2,127 t year⁻¹ for RNRL and from 79.4 to 90.4 t year⁻¹ for RPRL. Monthly retention loads varied from 6.4 to 300.8 t month⁻¹ for RNRL and from 1.4 to 15.3 t month⁻¹ for RPRL. Both RNRL and RPRL increased with river flow, water temperature, hydrophyte coverage, monthly sunshine hours, and total TN and TP inputs. Dissolved oxygen concentration and the pH level of the river water decreased with RNRL and RPRL. Riverine nutrient retention ratios (retention as a percentage of total input) were only related to hydrophyte coverage and monthly sunshine hours. Monthly variations in RNRL and RPRL were functions of TN and TP loads. Conclusions Riverine nutrient retention capacity varied with environmental conditions. Annual RNRL and RPRL accounted for 30.3-48.3% and 52.5-71.2%, respectively, of total input TN and TP loads in the ChangLe River. Monthly riverine retention ratios were 3.5-88.7% for TN and 20.5-92.6% for TP. Hydrophyte growth and coverage on the river bed is the main cause for seasonal variation in riverine nutrient retention capacity. The total input TN and TP loads were the best indicators of RNRL and RPRL, respectively. Recommendations and perspectives High riverine nutrient retention capacity during summer due to hydrophytic growth is favorable to the avoidance of algal bloom in both river systems and coastal water in southeast China. Policies should be developed to strictly control nutrient applications on agricultural lands. Strategies for promoting hydrophyte growth in rivers are desirable for water quality management.