Samples of surface sediment were collected off the north Shandong Peninsula for grain size and element analyses. Based on the grain size analysis, the surface sediments were dominated by silt and sand, with a small portion of clay, and were probably from the coastal erosion of the Shandong Peninsula. The spatial distribution patterns of the heavy metals were primarily controlled by the sediment types. The geo-accumulation indexes suggest that there was no Cu, Zn and Cr pollution in the study area; Pb and Cd contaminations appeared only at a few stations, while As pollution was distributed widely. The enrichment factors indicated that Cu, Zn and Cr were primarily from terrigenous materials. By contrast, Cd, Pb and As, and especially Cd and As, were probably largely provided by anthropogenic sources. Due to the dilution of coarse-grained matters, there was no contamination at some of the stations at which the influence of human activities was obvious.

The aim of this study was to assess the levels of heavy metal pollution in the clay/silt fraction (<63μm fraction) of marine sediments from Quintero Bay, Chile. For this, sediment samples were collected from 14 sites from the bay and analyzed for major and minor element determination. The metal concentrations found suggest an anthropogenic origin related with Cu, Se, Mo, As, Sb and Pb. The mineralogical characteristics of the samples were determined by XRD and selected samples were examined by SEM to determine morphological differences. The results showed heavy metal-bearing particles such as Cu, Zn, As and Pb, which are most likely associated with by the copper smelter.

Silicate clay materials are promising natural adsorbents with abundant, low cost, stable, and eco-friendly advantages, but the limited adsorption capacity restricts their applications in many fields. Herein, palygorskite (PAL) was facilely activated with alkali to enhance its adsorptive removal capability for methylene blue (MB). The effects of alkali activation on the microstructure, physicochemical, and adsorption properties of PAL for MB were intensively investigated. It was found that the moderate alkali activation can partially remove the metal cations (i.e., Al³⁺, Mg²⁺) and Si in the crystal backbone of PAL by which new “adsorption sites” were created and the surface negative charges increased. The adsorption capacity and rate of PAL for MB were evidently enhanced due to the effective activation. The adsorption isotherms were described by Freundlich isotherm model very well, and the adsorption kinetics can be accurately presented by a pseudo-second-order model. It can be inferred from the fitting results that the overall adsorption process was controlled by external mass transfer and intra-particle diffusion (the dominant role). The multiple adsorption interactions (hydrogen bonding, electrostatic interactions, mesopore filling, and complexing) were turned out to be the dominant factors to improve the adsorption properties. It was revealed that the activated PAL could be used as a potential adsorption candidate for environmental applications.

A sensitive, high-throughput, and cost-effective method for screening bacterial pathogens in the environment was developed. A variety of environmental samples, including aerosols, soil of various types (sand, sand/clay mix, and clay), wastewater, and vegetable surface (modeled by tomato), were concomitantly spiked with Salmonella enterica and/or Pseudomonas aeruginosa to determine recovery rates and limits of detection. The various matrices were first enriched with a general pre-enrichment broth in a dilution series and then enumerated by most probable number (MPN) estimation using quantitative PCR for rapid screening of amplicon presence. Soil and aerosols were then tested in non-spiked environmental samples, as these matrices are prone to large experimental variation. Limit of detection in the various soil types was 1–3 colony-forming units (CFU) g⁻¹; on vegetable surface, 5 CFU per tomato; in treated wastewater, 5 CFU L⁻¹; and in aerosols, >300 CFU mL⁻¹. Our method accurately identified S. enterica in non-spiked environmental soil samples within a day, while traditional methods took 4 to 5 days and required sorting through biochemically and morphologically similar species. Likewise, our method successfully identified P. aeruginosa in non-spiked aerosols generated by a domestic wastewater treatment system. The obtained results suggest that the developed method presents a broad approach for the rapid, efficient, and reliable detection of relatively low densities of pathogenic organisms in challenging environmental samples.

Soil is a primary resource used by mankind to ensure its needs mainly through agriculture. Its sustainability is regulated by the indigenous organisms it contains such as microorganisms. Current agricultural practices employ mixtures of pesticides to ensure the crops yield and can potentially impair these non-target organisms. However despite this environmental reality, studies dealing the susceptibility of microorganisms to pesticide mixtures are scarce. In this context, we designed a 3-month microcosm study to assess the ecotoxicity of realistic herbicide mixtures of formulated S-metolachlor (Dual Gold Safeneur®), mesotrione (Callisto®), and nicosulfuron (Milagro®) on the abundance, the diversity, and the activities of microorganisms from a “clay/organic matter-rich” soil, with a particular attention given to N-cycle communities. These communities appeared to be quite resistant to realistic mixtures even if transient effects occurred on the N-cycle-related communities with an increase of ammonification and an inhibition of nitrification as a short-term effect, followed by an increase of denitrification and an accumulation of nitrates. As nitrates are known to be highly leachable with a strong pollution potential, intensive studies should be carried out at field level to conclude on this potential accumulation and its consequences. Moreover, these data now need to be compared with other agricultural soils receiving these herbicide mixtures in order to bring general conclusion on such practices.

The large spatial heterogeneity in soil physico-chemical and microbial parameters challenges our ability to predict and model pesticide leaching from agricultural land. Microbial mineralization of pesticides is an important process with respect to pesticide leaching since mineralization is the major process for the complete degradation of pesticides without generation of metabolites. The aim of our study was to determine field-scale variation in the potential for mineralization of the herbicides glyphosate, bromoxyniloctanoate, diflufenican, and bentazone and to investigate whether this variation can be predicted by variations in basic soil parameters. Sixty-five soil samples were sampled from an agricultural, loamy field in Silstrup, Denmark, from a 60 × 165 m rectangular grid. The mineralization potential of the four pesticides was determined using a 96-well microplate ¹⁴C-radiorespirometric method. Initial mineralization rates were determined using first-order kinetics for glyphosate and bromoxyniloctanoate and zero-order kinetics for diflufenican and bentazone. The mineralization rates of the four pesticides varied between the different pesticides and the different soil samples, but we could not establish correlations between the pesticide mineralization rates and the measured soil parameters. Only the glyphosate mineralization rates showed slightly increasing mineralization potentials towards the northern area of the field, with increasing clay and decreasing OC contents. The mineralization potentials for glyphosate and bentazone were compared with 9-years leaching data from two horizontal wells 3.5 m below the field. The field-scale leaching patterns, however, could not be explained by the pesticide mineralization data. Instead, field-scale pesticide leaching may have been governed by soil structure and preferential flow events.

Various geochemical studies have yielded conflicting data on whether humic coatings decrease or increase adsorption of heavy metals by soil minerals. The objective of the present study is to determine how humate pre-adsorption affects subsequent retention of Cd and Pb by palygorskite and sepiolite, as special silicate clay minerals of soil in many arid regions. For this purpose, a series of equilibrium batch experiments were conducted on the interactions of Pb and Cd with Ca–palygorskite and Ca–sepiolite before and after humate adsorption. The results showed that the Langmuir (L), Freundlich (F), Langmuir–Freundlich (LF), and Toth (T) equations satisfactorily described metal sorption data on the minerals. In the presence of humate as the pre-adsorbate, the values for sorption capacities of palygorskite and sepiolite for Cd and Pb slightly decreased. This can be attributed to the competition between humates and metal ions for mineral active sites and steric hindrance of the adsorbed humates, which reduces the access of metal ions to the mineral surface and internal channels. Humate coatings decreased the adsorption equilibrium constants of Cd, suggesting that the affinity of the organo-clays for Cd sorption is lower than those of Ca–clays. The values for the heterogeneity factor (β) generally showed an increasing trend with increasing humate coverage on palygorskite and sepiolite, which can be explained by the increased diversity of adsorption centers on humate–clay complexes. It may be concluded that the presence of humate bound on fibrous clay surfaces can influence the sorption, and hence the bioavailability and mobility of heavy metals in fibrous clay-containing arid and semiarid soils.

Surface water bodies can be impaired by turbidity and excessive sediment loading due to urban development, construction activities, and agricultural practices. Turbidity has been considered as a proxy for evaluating water quality, aquatic habitat, and aesthetic impairments in surface waters. The US Environment Protection Agency (USEPA) has listed turbidity and sediment as major pollutants for construction site effluent. Recently proposed USEPA regulations for construction site runoff led to increased interest in methods to predict turbidity in runoff based on parameters that are more commonly predicted in runoff–erosion models. In this study, a turbidity prediction methodology that can be easily incorporated into existing runoff–erosion models has been developed using fractions of sand, silt, and clay plus suspended sediment concentration of eight parent soils from locations in Oklahoma and South Carolina, USA.

A pure clay ball and surface-modified clay ball were investigated to remove phosphate from synthetic wastewater; phosphate causes eutrophication in hydro-ecological systems. Adsorption tests of phosphate from aqueous solutions onto two types of adsorbents were conducted. The maximum phosphate adsorption capacities of the pure and surface-modified clay ball were found to be 0.084 and 8.869 mg/g, respectively. In a fixed-bed column packed with surface-modified clay balls, the first breakthrough of phosphate appeared after approximately 4000 min. In addition, the phosphate adsorbed on the surface-modified clay ball was effectively desorbed using a 1 M zirconium sulfate solution, and the adsorbent was regenerated for four adsorption and three desorption cycles by maintaining the adsorption capacity at the value before regeneration. X-ray diffraction (XRD), scanning electron microscopy (SEM)/energy-dispersive X-ray spectroscopy (EDX), and Brunauer-Emmett-Teller (BET) analysis method were performed to reveal the characteristics of the surface-modified clay ball. Cytotoxicity experiment was conducted on the developed adsorbents, and as a result, these showed low cytotoxic effect on the human cells. These results indicated that the surface-modified clay ball, due to the low cost, high adsorption capacity, and non-toxicity, has the potential to be utilized in the cost-effective removal of phosphate from aqueous solutions.