Many management strategies to improve the health of Chesapeake Bay focus on reducing losses of sediments and nutrients from agricultural land. Plot-scale studies have suggested that Best Management Practices (BMPs) reduce these losses, and natural resource managers have since supported implementation of a variety of BMPs on farms in the Chesapeake Bay watershed over the last two decades. As a test of the efficiency of these BMPs at the watershed scale, all farms within German Branch watershed had BMPs implemented in the early 1990s. Using water quality from two past monitoring programs (i.e., in 1986 and 1991-1995) and current water quality monitoring (i.e., collected 2003-2006), we detected a 28% decrease in baseflow P concentrations a decade after BMP implementation. There were no significant changes in nitrate or total nitrogen concentrations between BMP implementation and the most recent sampling. However, the significant rate of increase (~0.08 mg N L⁻¹ year⁻¹) from 1986 to the 1990s did not continue to 2003-2006 baseflow conditions, which suggests that BMPs may have suppressed the rate of increase in nitrogen observed earlier in German. These data suggest that other management practices that increase agricultural N losses and natural processes that attenuate N losses at the watershed scale may obscure significant N reductions by current BMPs in the watershed.

Air pollution associated with particulate matters is a serious problem in the mineral products industrial area (MPIA) in Saraburi, central Thailand. PM₁₀ concentrations monitored at Nah Phra Laan station located in the MPIA show that PM₁₀ levels exhibit strong seasonal variations; the number of days in 2005 that PM₁₀ concentrations exceeded the daily National Ambient Air Quality Standard of 120 μg/m³ were 58%, 29%, and 12% in the winter, rainy, and summer seasons, respectively. In this paper, the Hybrid Particle And Concentration Transport (HYPACT) model with meteorological fields from the Regional Atmospheric Modeling System (RAMS) was applied to Saraburi to investigate the impacts of meteorological parameters upon seasonal variations in PM₁₀ concentration. Analysis of model results shows that daily average PM₁₀ concentrations exceeding 200 μg/m³ are found in the downwind direction of emission sources and their horizontal gradients are strong. Hourly PM₁₀ concentrations exhibit obvious diurnal variation with maximum values in wintertime at around 2000-2100 local standard time in association with low ventilation with light wind speed and weak vertical mixing, while in the rainy season, they are generally higher in the daytime than in the nighttime, as that mixing height in cloudy days is low in daytime whereas emission rates are high during working time.

Individuals of Hexaplex trunculus, Tapes decussatus, and associated sediments were collected from 16 coastal sampling plots of the Mar Menor lagoon (SE Spain), and the metal and As concentrations were determined. The sediments had maximum values (in milligrams per kilogram dry weight [d.w.]) of 7,132 for Zn; 6,975 for Pb; 5,039 for Mn; 501 for As; 74 for Cu; and 9.1 for Cd. Specimens of H. trunculus could be collected from all the sampling plots, and it was found that concentrations of Zn (between 883 and 3,130 mg kg⁻¹ d.w.), Pb (between 0.09 and 222 mg kg⁻¹ d.w.), Mn (between 7.6 and 17.7 mg kg⁻¹ d.w.), As (between 144 and 418 mg kg⁻¹ d.w.), and Cd (between undetectable and 8.4 mg kg⁻¹ d.w.) in soft tissues significantly increased when concentrations in sediments increased. H. trunculus apparently regulated Cu assimilation (concentrations between 17.7 and 47.2 mg kg⁻¹ d.w.) in its soft tissues. T. decussatus was very scarce or even absent from sites with higher metal and As contents in the sediments. Hence, H. trunculus could be used as a bioindicator of metals and As pollution, but not T. decussatus. Based on our results, a human health risk exists because the species analyzed are collected from the studied zone and so are consumed by the population.

This research evaluated the efficiency of a mesocosm scale bioreactor to remove Mn from a synthetic mine drainage in the presence of selected organic and inorganic substrate combinations that could enhance sulfate reduction and induce Mn sulfide precipitation. The mine drainage tested was slightly acidic (pH 6.2) and had average Mn and SO₄ concentrations of 90 and 1,500 mg/L, respectively. The substrates used were creek sediment amended with either wood mulch or a wood mulch and biosolid mixture. Greater than 90% of Mn and 70% of sulfate was removed over a 65-day test period. The results suggested multiple Mn removal mechanisms including sorption, complexation, and Mn sulfide, Mn oxide, and/or Mn carbonate precipitation.

Two-year (June 2003-May 2005) precipitation samples were collected from three monitoring sites with similar economy development level in the Yangtze River Delta Region of China to investigate the spatial-temporal variation of inorganic N wet deposition. The results showed that the Yangtze River Delta Region had higher inorganic N wet deposition than the northwestern, northern, or southern China. There was spatial variation of inorganic N wet deposition. The positive relationship between inorganic N deposition and precipitation suggested that rainfall amount might be an important factor influencing the wet deposition of inorganic N. Deposition of inorganic N occurred mainly in the spring and summer season (March-August; 70% of the annual total), which was in accord with seasonal distribution of precipitation. However, a negative logarithmic relation between rainfall and inorganic N concentration in rainwater indicated the dilution effect of rainwater on inorganic N concentration. Distinguished variation of NH₄ ⁺/NO₃ ⁻ ratio in wet deposition existed in the different time scale. NH₄ ⁺/NO₃ ⁻ ratio evidently decreased from 6 in 1980s to 1.2 in 2003/2005 and greatly varied between 0.3 and 9.9 within a year. NH₄ ⁺/NO₃ ⁻ ratio peaked in accordance with nitrogen-fertilizing time during crop growing season. Annual alternate appearance of the ¹⁵N-enriched and ¹⁵N-depleted periods coincided with the temporal variation of NH₄ ⁺/NO₃ ⁻ ratio, which was closely related to the timing of fertilization and seasonal climate changes, suggesting the effect of NH₄ ⁺ sources in the wet deposition.

This paper presents the development of a filtered stepwise clustering (FSC) method for facilitating the pump-and-treat (PAT) designs in groundwater remediation programs. To investigate the performances of different remediation strategies, a subsurface model is employed to simulate contaminant transport. Multivariate relationships between decision variables and selected modeling outputs are developed through the FSC method. Based on the developed statistical relationships, a set of possible outcomes for the remediation design can be presented; the solution space has been confined to a narrowed range. The proposed method can aid the PAT design by (a) quickly providing predicted outcomes given different remediation strategies and (b) directly locating the optimum remediation strategy for any outcome. The FSC method is examined through its application to a real-world aquifer remediation case in western Canada. The prediction results can help decision makers to evaluate the remediation design in an explicit way.

To test the possible use of tree ring chemical properties as proxies for precipitation acidity ([H⁺]), we investigated the relationships between tree ring chemistry (δ¹³C, δ¹⁵N, Ca-to-Al ratio, and N concentration) of Pinus densiflora and precipitation [H⁺] between 1992 and 2005 in an industrial area in the southwest region of South Korea. Statistical analyses showed that all tree ring chemistry parameters were significantly correlated with precipitation [H⁺]. Tree ring δ¹³C was negatively correlated with precipitation acidity (r = -0.67, P < 0.01), reflecting the photosynthetic fixation of ¹³C-depleted CO₂ from fossil fuel combustion that would be the primary source of precipitation acidity. A positive correlation of N concentration (r = 0.89, P < 0.001) and a negative correlation of δ¹⁵N (r = -0.63, P < 0.05) in tree rings with precipitation acidity most likely reflected the influence of ¹⁵N-depleted N compounds deposited via precipitation. The Ca-to-Al ratio was negatively (r = -0.58, P < 0.05) correlated with precipitation acidity, indicating that soil acidification caused the loss of Ca from the soil and solubilization of Al resulting from acid precipitation. Such relationships suggest that δ¹³C, δ¹⁵N, N concentration, and Ca-to-Al ratio in tree rings can be reliably used to evaluate the impact of acid precipitation on the studied P. densiflora stands.

Investigations of vegetation stress along non-paved roads treated with a range of magnesium chloride (MgCl₂) application rates utilized 60 roadside and 79 drainage plots on 15 and 18 roads, respectively. Evaluations were completed of foliar damage, plant health, biotic and abiotic damage incidence and severity, soil and foliar chemistry and other common site and stand characteristics of Pinus contorta, Populus tremuloides, Picea engelmannii, Abies lasiocarpa, and lower elevation plots dominated by shrubs and grasses. High concentrations of soil magnesium and chloride (400-500 ppm), high foliar chloride (2,000-16,000 ppm depending on species) and high incidence of foliar damage were measured in roadside plots along straight road segments in the first 3 to 6.1 m adjacent to treated roads. In drainage plots, where water is channeled off roads, high concentrations of both magnesium and chloride ions and associated foliar damage were measured between 3 and 98 m from the road. High incidence of foliar damage and elevated ion concentrations were not apparent in control plots along non-treated roads. Lodgepole pine appeared to be the most sensitive species, while aspen accumulated the most chloride and exhibited the least amount of damage. Foliar chloride concentrations strongly correlated with percent foliar damage for all species (r = 0.53 to 0.74, p < 0.0001) while the incidence of biotic damages did not correlate well. Positive relationships between foliar chloride and magnesium chloride application rates were strong and can be used to predict foliar concentrations and subsequent damage to roadside trees.

Frame and daughters directives for evaluating the ambient air quality have been adopted by the EU as a part of the new strategies for pollution prevention and control and environmental management. Therefore, the prediction of ozone concentration and the identification of episodes by modeling are fundamental for protecting and preventing the population and environment against the harmful effects of this species. Under this approach, ambient air quality (immission) data in three zones: A Guarda, Corrubedo and Verín (two coastal and one interior) of Galicia (NW Spain), were collected and evaluated using statistical tools. Punctual and functional background and standard levels of ozone and NOx in the three zones have been determined for detecting abnormal situations and identifying possible emission sources. With this aim, threshold values were established by defining confidence levels. Finally, ozone concentration has been forecasted by time series modeling. Descriptive and predictive models of ozone involving different parameters depending of the area considered have been developed. Satisfactory estimation of ozone concentration was obtained in the three cases with proved efficiency, since predictive values did not exceed the 95% confidence level.

Storm water detention devices collect runoff from impermeable catchments. They provide flow attenuation as well as storage capacity, and rely on natural self-purification processes such as sedimentation, filtration and microbial degradation. The aim was to assess the performance of an experimental combined planted gravel filter, storm water detention and infiltration tank system treating runoff from a car park and its access road. Flows were modeled with the US EPA Storm Water Management Model. An overall water balance of the system was compiled, demonstrating that 50% of the rainfall volume escaped the system as evaporation, whereas, of the remaining 50%, approximately two thirds were infiltrated and one third was discharged into the sewer system. These findings illustrated the importance of evaporation in source control, and showed that infiltration can be applied successfully even on man-made urban soils with low permeability. The assessment of the system's hydrological efficiency indicated mean lag times of 1.84 and 10.6 h for the gravel filter and the entire system, respectively. Mean flow volume reductions of 70% and mean peak flow reductions of 90% were achieved compared to conventional drainage. The assessment of the pollutant removal efficiency resulted in promising removal efficiencies for biochemical oxygen demand (77%), suspended solids (83%), nitrate-nitrogen (32%) and ortho-phosphate-phosphorus (47%). The most important removal processes were identified as biological degradation (predominantly within the gravel ditch), sedimentation and infiltration.