In this paper, Taguchi method was applied to determine the optimum condition for Pb (II) removal from aqueous solution by spent Agaricus bisporus. An orthogonal array experiment design (L₉(3⁴) which is of four control factors (pH, t (contact time), m (sorbent mass), and C ₀ (initial Pb (II) concentration)) having three levels was employed. Biosorption capacity (mg metal/g biosorbent) and percent removal (%) were investigated as the quality characteristics to be optimized. In order to determine the optimum levels of the control factors precisely, range analysis and analysis of variance were performed. The optimum condition for biosorption capacity was found to be pH = 5.00, t = 5.0 h, m = 0.010 g, and C ₀ = 50 mg/L. And for percent removal, the optimum condition was found to be pH = 4.00, t = 4.0 h, m = 0.100 g, and C ₀ = 50 mg/L. Under these optimum conditions, biosorption capacity and percent removal can reach 60.76 mg/g and 80.50%, respectively.

The effects of heavy metal contamination (Cr, Cu, Pb, Cd) in the lower basin of the Salado River (Argentina) were studied on the zooplanktonic community. The determination of heavy metals in water and sediments was carried out in a previous study. Zooplankton was analyzed quali- and quantitatively. Total density, by-group density (Copepoda, Cladocera and Rotifera), micro and mesozooplankton density, biomass, species richness (S), and species diversity (H) were studied. The results showed that total density of zooplankton was significantly higher in the river than in the channels and streams (p < 0.001), with dominance of rotifers but a higher copepod biomass. Calanoida dominated over Ciclopoidea and Harpacticoida. Total species richness was 74, showing the highest values (59 and 56) at the points corresponding to the Salado River at localities Manucho and San Justo (MSR, SJSR) and the lowest ones in North and South channels (NCH, SCH), with 16 and 17 species, respectively), and in the two sampling stations of Las Prusianas stream (LP1, LP2), between 13 and 38 species. The species diversity showed low values (1.8 to 2.3) in channels and streams, and higher values (3.0) in the Salado River, at Manucho and San Justo. Absolute biomass varied in the order SJSR > MSR > LP1 > NCH > SCH > LP2, similarly to absolute density, which varied in the order SJSR > MSR > LP1 > NCH > SCH > LP2. The comparison of the content of heavy metals in water between the control site (SJSR) and the most contaminated sites showed significant differences with the North and Las Prusianas 1 and 2 channels (ANOVA p = 0.001; 0.012 and 0.011, respectively) and non-significant differences, although close to the significance level, with the South Channel and Manucho (p = 0.08; p = 0.059). The following positive correlations were found: depth with mesozooplankton density, H and S (p < 0.001); temperature with microzooplankton density, H and S (p < 0.004), and dissolved oxygen with mesozooplankton density, H and S (p < 0.01), but not with microzooplankton, indicating a higher tolerance of the organisms belonging to this fraction. A negative correlation was found between biomass of copepods and concentration of Pb and Cu (p < 0.05 and p = 0.01, respectively). Rotifers were the most tolerant to heavy metal contamination, followed by copepods and cladocerans. Diversity (H) and richness (S) were good indicators of stress of contaminated systems. The clustering of biological variables and the concentration of heavy metals in water and sediments showed three groups of environments: the first one was the main course of the river, with lower contamination by heavy metals and higher density, biomass, H and S, which separated clearly from the other two groups of the tributaries, composed by channels and streams. In the tributaries, r strategists and a few tolerant species, such as Eucyclops neumani, proliferated. The results of this study show that zooplankton responds as good descriptor of water quality, constituting an efficient tool to assess heavy metal contamination.

Methane oxidation within a passive methane oxidation barrier (PMOB) and the downward migration of molecular O₂, whose presence is necessary for the oxidation reaction to occur, were simulated using the finite element simulator TOUGH2-LGM. The goals of the study were to validate the use of TOUGH2-LGM by reproducing real field profiles obtained under different conditions and to evaluate the depth of O₂ penetration under several conditions. TOUGH2-LGM handles both advective and diffusive gas fluxes. The oxidation reaction was simulated by imposing a Neumann condition, i.e. CH₄ was extracted from pre-determined elements. The main variables of concern were the degree of water saturation of the PMOB, the pressure differential between its base and the surface, the position and thickness of the oxidation front and, finally, the oxidation rate, i.e. the rate at which CH₄ was removed from the system. Other important variables, such as the gas permeability and diffusion coefficient were obtained in the laboratory. Inspection of the results shows that TOUGH2-LGM was able to quite accurately reproduce the field profiles. The simulator also makes it possible to predict the depth of O₂ penetration as a function of pressure differential and humidity within the PMOB. This type of information is fundamental for the design of effective biocovers.

The paper presents the first comprehensive account of congener profiles of polycyclic aromatic hydrocarbons (PAHs) in intertidal bivalve mollusks [Meretrix meretrix, Macoma birmanica, and Sanguilonaria (Soletellina) acuminata] of Sunderban mangrove wetland (India). The main aim of this work was to use the bivalves as bioindicators of the contamination of the 16 USEPA PAH. The PAH profile in bivalves is largely dominated by a petrogenic fingerprint, with over-imposition of pyrolytic PAH sources, as evidenced by diagnostic molecular ratios. Bioaccumulation factors (BAF) of individual compounds from the sediments were calculated, and it reveals overall higher values in the visceral mass of the bivalves. S acuminata showed significantly higher levels of PAHs, especially the high molecular weight (HMW) PAHs, compared to the other two species as a sensitive indicator of trace organic stress in future monitoring programs.

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.

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.

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.

The present study aimed to elucidate the atmosphere-forest exchange of ammoniacal nitrogen (NHX-N) at a young larch ecosystem. NHX-N exchanges were measured at a remote site in northernmost Japan where 4-year-old larches were growing after a pristine forest had been clear-cut and subsequent dense dwarf bamboo (Sasa) had been strip-cut. The site was a clean area for atmospheric ammonia with mean concentrations of 0.38 and 0.11 μg N m⁻³ in snowless and snow seasons, respectively. However, there was a general net emission of NHX-N. The annual estimated emission of NHX-N of 4.8 kg N ha⁻¹ year⁻¹ exceeded the annual wet deposition of 2.4 kg N ha⁻¹ year⁻¹, but the weekly exchange fluxes may have been underestimated by 28-60%. The main cause of the ammonia loss from the young larch ecosystem was probably enhanced nitrogen supply stimulated by the cutting of the pristine forest and Sasa, in particular, the Sasa.

The goal of this study is to clarify the surface-chemical and microphysical variables that influence bacterial spore transport through soil, thereby defining the factors that may affect spore transport velocity. Bacillus cereus spores were continuously monitored in a soil column under saturated conditions with experimental variations in soil grain size (0.359 and 0.718 mm), pH (7.2 and 8.5), and water flow rate (1.3 and 3.0 mL/min). Increasing soil grain size, flow rate, and pH resulted in enhanced spore movement. Spore transport increased 82% when soil grain size was doubled. An increase in effluent flow rate from 1.3 to 3.0 mL/min increased spore movement by 71%. An increase in pH increased spore transport by 53%. The increase in hydrodynamic forces resulting from the larger grain size soil and higher flow rate functioned to overcome the hydrophobic nature of the spore's coat, and the interparticle bonding forces between the spore and soil particles.

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.