Sediment cores were collected from ten eutrophic lakes in South Dakota to determine the lateral extent of sediment-bound mercury (Hg) concentrations and to assess the relationship between watershed and land use characteristics with lake Hg fish tissue consumption advisory (>1.0 mg Hg/kg fish tissue) status. Advisory lakes were characterized as having higher sediment Hg and organic matter and lower total sulfur content compared to non-advisory lakes, and results highlight the importance of sulfide and organic carbon availability associated with potential Hg methylation biogeochemical processes. Advisory lakes generally had higher percentage of areal development and grasslands, higher catchment to lake area, and lower percentage of wetlands compared to non-advisory lakes. These results signify the importance of minimizing watershed sediment transport and associated organic carbon loading as effective Hg fish tissue lake management strategies.

The performance of the Purolite A847 weak basic anion exchanger in the simultaneous removal of the azo dye Lanasyn Navy M-DNL (LNCr) and the phthalocyanine dye Acid Blue 249 (CuPc) from acidic aqueous solutions was studied under dynamic conditions. The comparison of FTIR spectra of unloaded and dye-loaded anion exchangers made it possible to consider suitable sorption mechanisms. The results of dynamic experiments revealed that anion exchanger had a greater dynamic sorption capacity with a longer breakthrough time and a shorter length of mass transfer zone when both dyes LNCr and CuPc were removed from the one-component solution as compared to those of their mixture. Models of Wolborska and Juang were found to be suitable to predict the character of breakthrough curves and to determine the characteristic parameters of the Purolite A847 column useful for process design: the mass transfer coefficient β (1/min) and time at the break point τ (minutes). The result would be useful in the design of wastewater treatment plants for removal of azo and phthalocyanine dyes from aqueous solutions and water recycling.

Tobacco (Nicotiana tabacum L.) stem ash (TSA) was evaluated as an adsorbent for removal of methylene blue (MB) from aqueous solution by batch adsorption method. MB adsorption increased with increase in contact time, initial solution pH, and adsorbent dose. Contact time for adsorption equilibrium was 180 min. The MB adsorption per unit mass of adsorbent (in milligram per gram) increased with the increasing initial dye concentration. Adsorption of MB onto TSA followed the pseudo-second-order kinetic model with a rate constant (k ₂) of 0.017 g mg⁻¹ min⁻¹. The mechanism of adsorption was described with intra-particle diffusion model. It was found that the intra-particle diffusion was not a sole rate-controlling step. Equilibrium adsorption was investigated by the Freundlich, Langmuir, Temkin, and Jovanoic isotherms. On the basis of coefficient of determination, the order of isotherm fit was Langmuir (R ² = 0.974) > Freundlich (R ² = 0.957) = Temkin (R ² = 0.957) > Jovanoic (R ² = 0.764) isotherm. The maximum monolayer adsorption capacity of TSA was 35.7 mg g⁻¹. The dimensionless separation factor (R L) was low (0.137), indicating favorable adsorption of MB onto TSA. The results clearly demonstrate the potential of TSA as a low-cost and an easily available adsorbent for sequestering MB from wastewater.

The effects of irrigation with meat processing factory effluent (MPE) in combination with additions of paunch to three arable sites and one pasture site on soil chemical and microbial properties were investigated in fields surrounding a beef meat processing factory. A pasture site that had only received MPE was also sampled along with adjoining arable and pasture control fields that had never received MPE or paunch. Additions of MPE/paunch caused increases in electrical conductivity, exchangeable Na and K, exchangeable sodium percentage (ESP), extractable P, organic C, total N, microbial biomass C, and metabolic quotient and decreases in exchangeable Ca and Mg, pH, and the proportion of organic C present as microbial biomass. The structure and diversity of bacterial and fungal communities was measured by polymerase chain reaction–denaturing gradient gel electrophoresis of 16S rDNA and internal transcribed spacer-RNA amplicons respectively and catabolic diversity by analysis of catabolic response profiles to 25 substrates. Principal component analysis of catabolic response profiles clearly separated control from MPE/paunch-treated sites, and this was associated with greater catabolic responses to the carboxylic acids α-ketoglutaric, α-ketobutyric, L-ascorbic, and citric acid in the control. At the arable sites, application of MPE and paunch caused increases in bacterial, fungal, and catabolic diversity. Canonical correspondence analysis of the relationship between catabolic, bacterial, and fungal fingerprints and soil properties indicated that the main soil variables separating MPE/paunch treatments from controls were the higher organic C, ESP, and extractable P and a lower pH, exchangeable Ca, and Mg. It was concluded that, although long-term MPE/paunch additions induce soil salinity, sodicity, and acidity, in general, they cause an increase in the size, activity, and structural and functional diversity of in the soil microbial community.

It was found that some of the medicinal plants accumulate increased amounts of toxic elements like Cd or Pb. Less is known about the accumulation of other hazardous elements like arsenic (As) and antimony (Sb) in these species. The present paper investigated selected medicinal plants naturally growing on old mining sites in Slovakia, Central Europe, contaminated by As and Sb. Both these elements are nonessential for plants and, in higher level, might be phytotoxic. The soil concentration of As and Sb at three different localities extensively used for mining of Sb ores in former times highly exceed values characteristic for noncontaminated substrates and ranged between 146 and 540 mg kg⁻¹ for As and 525 and 4,463 mg kg⁻¹ for Sb. Extraction experiments of soils show differences between As and Sb leaching, as the highest amount of mobile As was released in acetic acid while Sb was predominantly released in distilled water. In total, seven different plant species were investigated (Fragaria vesca, Taraxacum officinale, Tussilago farfara, Plantago major, Veronica officinalis, Plantago media, and Primula elatior), and the concentration of investigated elements in shoot ranged between 1 and 519 mg kg⁻¹ for As and 10 and 920 mg kg⁻¹ for Sb. Differences in the bioaccumulation of As and Sb as well as in the translocation of these elements from root to shoot within the same species growing on different localities have been found. This indicate that efficiency of As and Sb uptake might vary between individual plants of the same species on different sites. Increased bioaccumulation of As and Sb in biomass of investigated plants might be dangerous for human when used for traditional medicinal purposes.

The present study consisted of an in vitro experiment based on columns to restore a soil affected by the tsunami of 27 February 2010 that struck the Coliumo District, Bio-Bio region, Chile. The agricultural productivity of many coastal lands was severely affected, rendering them unfit for crop production. Composite soil samples were taken at 0 to 20 cm soil depth in Coliumo, Bio-Bio region. The initial physical and chemical analysis showed textural changes, low pH, high levels of electrical conductivity (EC), sodium (Na⁺), and sulfate (SO₄²⁻), whereas bioassay tests showed severe toxicity for lettuce (Lactuca sativa L.) seeds. Germination index (GI), length of hypocotyl (LH), and length of radicle (LR) were used as indicators in the bioassay tests. Two different treatments were used: T1 = soil amended with 7.7 t ha⁻¹ of limestone (CaCO₃) and T2 = soil amended with 7.7 t ha⁻¹ of gypsum (CaSO₄). A control treatment (T0) with unamended soil was included. Each treatment received a total of 1,100 mm of clean water (4 water loads, 275 mm each), which was equivalent to the mean annual precipitation of the area studied. The T2 treatment produced a significant decrease in the concentration of Na⁺ (8.27 to 0.16 meq L⁻¹), decreased EC (1.58 to 0.03 dS m⁻¹), and increased pH from 4.83 to 6.27 in the soil under study. Leaching of Na⁺ and SO₄²⁻ with successive water loads was effective in the soil. The bioindicators as GI, LH and LR revealed that T2 was more effective than T1 and control in removing Na and SO₄ analytes from the soil matrix. The CaSO₄ amendment showed good potential for seed development, but further research on plant growth to maturity is required to determine yield parameters in the affected area.

Spatial accuracy of hydrologic modeling inputs influences the output from hydrologic models. A pertinent question is to know the optimal level of soil sampling or how many soil samples are needed for model input, in order to improve model predictions. In this study, measured soil properties were clustered into five different configurations as inputs to the Soil and Water Assessment Tool (SWAT) simulation of the Castor River watershed (11-km² area) in southern Quebec, Canada. SWAT is a process-based model that predicts the impacts of climate and land use management on water yield, sediment, and nutrient fluxes. SWAT requires geographical information system inputs such as the digital elevation model as well as soil and land use maps. Mean values of soil properties are used in soil polygons (soil series); thus, the spatial variability of these properties is neglected. The primary objective of this study was to quantify the impacts of spatial variability of soil properties on the prediction of runoff, sediment, and total phosphorus using SWAT. The spatial clustering of the measured soil properties was undertaken using the regionalized with dynamically constrained agglomerative clustering and partitioning method. Measured soil data were clustered into 5, 10, 15, 20, and 24 heterogeneous regions. Soil data from the Castor watershed which have been used in previous studies was also set up and termed “Reference”. Overall, there was no significant difference in runoff simulation across the five configurations including the reference. This may be attributable to SWAT's use of the soil conservation service curve number method in flow simulation. Therefore having high spatial resolution inputs for soil data may not necessarily improve predictions when they are used in hydrologic modeling.

Adsorption of fluoroquinolone antibiotics using sludge-derived biochar made of various wastewater sludges was investigated. The sludge-derived biochar had relatively large Brunauer–Emmet–Teller specific surface areas that were beyond 110.0 m² g⁻¹ except the biochar made from the sludge collected from traditional sludge drying bed. The mesopore capacity was more than 57 % of the total pore capacity of all sludge-derived biochar except that made from the sludge dried through traditional sludge drying bed technique. High adsorption capacity of sludge-derived biochar was observed with a highest adsorption capacity of 19.80 ± 0.40 mg g⁻¹. High correlation between the adsorption capacity of sludge-derived biochar and the volatile content in the sludge source was observed. The Freundlich model (r ² values were in the range of 0.961–0.998) yielded the best fit with the experimental data of all the produced biochar. Fluoroquinolone antibiotics were readily adsorbed onto sludge-derived biochar. These findings suggest a new approach for the pollution control of fluoroquinolone antibiotics using low-cost sludge-derived biochar.

In this study, residues of passion fruit skin were examined as biosorbent materials, evaluating their capacity to adsorb lead(II) ions in in natura skin (SK-N) and two modified skins, with NaOH (SK-S) and with NaOH and citric acid (SK-SCA). The biomass characterization was done through Fourier transform infrared spectroscopy which confirmed the chemical modification by a peak at 1,730 cm⁻¹. Also, scanning electron microscopy analyses were done, where the increase of residue roughness was observed after the modification. And finally, the values of point of zero charge were determined and were lower than 5.5 for all residues. In the experiments of adsorption in function of pH, it was verified that after pH 4, the adsorbed amount was practically constant. Regarding the necessary time to reach equilibrium, the value that was found was approximately 170 min, and kinetics followed the behavior described by the pseudo-second-order equation. The maximum adsorption capacity was 204 mg g⁻¹ for the SK-SCA biomass. The residues followed Langmuir adsorption model. Through thermodynamic parameters, it was verified that adsorption occurs spontaneously due to the negative values of Gibbs' energy. Moreover, desorption studies showed that adsorbed ions may be recovered in two cycles. Thus, due to the high adsorption capacity of lead ions, passion fruit skin can be utilized in filters to retain this metal in the future.

We study the adsorption and desorption of chromium on two soils (a forest soil and a vineyard soil), both individually or after being combined with ground mussel shell, and on various materials (mussel shell, pyritic material from a dump site, and slate processing fines). The adsorption capacity depends mainly on the initial Cr concentration, on the pH, and on the abundance of noncrystalline Fe. The highest adsorption percentage (94 %) corresponds to the pyritic material, which also shows very low desorption rates (1.4 %), has the lowest pH, and has the highest concentration of noncrystalline Fe. The adsorption isotherms in most cases fit the Freundlich and Lineal models, rather than the Langmuir model, with no easily predictable maximum for chromium adsorption.