A bentonite-based hydrogel was chemically modified to prepare a new effective adsorbent for the removal of phosphate from aqueous solutions using batch equilibrium experiments at the laboratory scale. The efficiency of the phosphate adsorption by the modified adsorbents followed the order: Al-Fe-hydrogel > Al-hydrogel > Fe-hydrogel > Rewoquate surfactant-hydrogel ≅ Irasoft surfactant-hydrogel > raw hydrogel. The amount of Fe and Al, as determined in proportion to the cation exchange capacity (CEC) of the hydrogel, was the most important parameter for optimizing the modification process by pillaring solutions. The results showed that the phosphate adsorption was rapid and pH independent. The removal of phosphate reached up to 99 % at the optimized conditions. The adsorption data were well fitted by Langmuir and Freundlich models. According to the Langmuir model, the maximum adsorption capacity of the phosphate on the Fe-Al-hydrogel was 14.29 mg L⁻¹. The removal of phosphate from an urban wastewater using the modified adsorbent was more than 99 %. The Fe-Al-hydrogel selectively adsorbed the phosphate from the solutions containing sulphate, bicarbonate, chloride, and nitrate. Based on the obtained results, the synthesized adsorbent could be used effectively to decontaminate the phosphate polluted water.

Ombrotrophic peatlands are highly sensitive to atmospheric heavy metal deposition. Previous attempts to quantify peatland lead pollution have been undertaken using the inventory approach. However, there can be significant within-site spatial heterogeneity in lead concentrations, highlighting the need for multiple samples to properly quantify lead storage. Field portable x-ray fluorescence (FPXRF) continues to gain acceptance in the study of contaminated soil, but has not thus far been used to assess peatland lead contamination. This study compares lead concentrations in surface peat samples from the South Pennines (UK) derived using (a) FPXRF in the field, (b) FPXRF in the lab on dried samples and (c) ICP-OES analysis. FPXRF field and lab data are directly comparable when field measurements are corrected for water content, both can be easily used to estimate acid extractable lead using regression equations. This study is a successful demonstration of FPXRF as a tool for a time- and cost-effective means of determining the lead content of contaminated peatlands, which will allow rapid landscape scale reconnaissance, core logging, surface surveys and sediment tracing.

With more and more emerging organic contaminants (EOCs) detected in the soil and groundwater, researches on interactions between these pollutants and soils or aquifer materials have attracted greater concerns. In this study, the removal of chlorpheniramine maleate (CP), an antihistamine drug used to treat rhinitis and urticaria, by birnessite, which is a common layered manganese oxide, in aqueous solution was investigated by batch studies, X-ray diffraction (XRD) and Fourier transform infrared (FTIR) analyses, and molecular simulations. The quantum mechanics simulation showed that the final energy of the interaction between CP and the (010) edge surfaces under a strong alkaline condition was much smaller than that under a neutral to slightly alkaline condition. A higher CP adsorption were achieved from neutral to weak alkaline solution, as the broken bond effect of birnessite was strongly influenced by solution pH by protonation and deprotonation of birnessite edges.

US National Ambient Air Quality Standards (NAAQS) are based on quantitative linkages between ambient air concentrations and an effects indicator. Critical loads (CLs) can provide quantitative information on safe levels of atmospheric deposition to aquatic systems, but CLs cannot be directly used in the NAAQS context because they are not expressed in terms of atmospheric concentrations. Here, we describe the aquatic acidification index (AAI) model that incorporates CL concepts and relates atmospheric nitrogen and sulfur concentrations to an acid neutralizing capacity (ANC) effects indicator (Fig. 1). The AAI estimates the potential surface water ANC associated with a set of atmospheric concentrations of nitrogen and sulfur and a region's biogeochemical and hydrological attributes by combining steady-state CL modeling with air quality modeling outputs. Initial applications of the AAI model yielded results consistent with well-recognized spatial patterns of acid-sensitive aquatic systems. Furthermore, the response of AAI predictions to future year changes in NO ₓ and SO ₓ emissions suggest that planned national emission reduction strategies designed to reduce ozone and particulate matter air pollution will produce increases in surface water ANC.

Polychlorinated dibenzo-p-dioxins and dibenzofurans (dioxins) are pollutants of significant global concern, and China is one of the main dioxin-emitting countries in the world. Facing increasing dioxin concentrations in the environment, the Chinese government set a mandatory goal of 10 % reduction in the rate of emission intensity by 2015 in an attempt to reduce dioxin emissions. In the study presented here, we estimated the outputs (or waste disposal capacities) of the four key dioxin-emitting industries in China in 2015. We then estimated that the total amount of dioxins released from these four industries was approximately 8.0 kg toxic equivalent (TEQ)/year. These results indicate that dioxin emissions in China have not decreased under the current plan, and the plan needs to be adjusted. A goal for a decrease in the total dioxin emissions in China is proposed, and several policies and measures aimed at allowing the target dioxin emission decrease to be achieved are recommended.

Ecotoxicological impacts (survivorship, growth) of two detergents, the linear alkylbenzene sulfonates (LAS) and the nonionic surfactants, nonylphenol ethoxylate (NPE), were examined on two branching coral species (Stylophora pistillata and Pocillopora damicornis). Nubbins assays (n = 1,890, 24-h exposures, 203-day monitoring) revealed high mortality in 1 and 5 mg/l detergents concentrations (for both species combined, LAS LC₅₀ = 1.99 mg/l; NPE LC₅₀ = 2.16 mg/l). Assays further showed detergent as species-specific mortalities (Stylophora LAS LC₅₀ = 1.00 mg/l; NPE = 3.03 mg/l; Pocillopora LAS LC₅₀ = 2.21 mg/l; NPE = 2.26 mg/l), also influenced by genotype-specific mortalities, phenomena which could downgrade genetic diversity of corals in the field, leaving frequently or chronically affected areas with detergent-resistant genotypes. Results revealed that LAS detergents were significantly more detrimental to coral nubbins than NPE detergents, resulting in high mortality and reduced tissue growth on substrates. Surprisingly, nubbins exposed to second and third LAS treatments exhibited significant higher survivorship levels than after the first exposure, whereas in all NPE treatments, nubbins’ survivorship did not significantly differ in the repeated exposures as compared to the first set of assays. This outcome, while adding to our knowledge for the toxicity of various detergents, highlights the need to reduce repeated sewage spills. Furthermore, it is recommended that reef managers should emphasize disparate detergents’ ecotoxicity on corals when establishing environmental policies.

The potential use of the arsenic-tolerant woody leguminous species Anadenanthera peregrina (L) Spegazzini for rehabilitating arsenic (As)-contaminated areas was studied. In an As (539.33 mg/kg)-contaminated soil experiment, plants were able to accumulate arsenic in their roots with a low transfer index to the shoot. Inoculation with arbuscular mycorrhizal fungi (AMF) amplified this behavior and improved both biomass production and the phosphorus concentration in the shoot. AMF inoculation not only improved A. peregrina plant growth but also protected the shoot against As toxicity. Aside from the AMF inoculation, the addition of organic matter reduced the soil pH, thus improving the ability of the roots to accumulate arsenic. The majority (81 %) of the variations in As accumulation in A. peregrina roots were explained by the effects of the organic matter and soil pH as well as AMF treatments, as found by a principal component analysis. A. peregrina promoted phytostabilization through As root sequestration. Therefore, A. peregrina plants inoculated with AMF in the presence of organic matter are recommended to rehabilitate degraded areas of soil contaminated with arsenic.

The outstanding biological performance and non-food utilization of bioenergy grass possibly make it to be the best candidate for phytoremediation of heavy metal-contaminated soil, but evidence is limited. In this study, we conducted pot experiments to quantify the performance of two promising energy grasses, Arundo donax and Miscanthus sacchariflorus, in the phytoremediation of Zn- and Cr-contaminated soil. The results showed that (1) the biomass and root length of the two grasses were firstly increased and then kept stable or slightly decreased with increasing soil Zn/Cr concentration, implying that the two grasses had strong tolerance to Zn/Cr contamination; (2) the Zn/Cr concentration in the grass roots was two to seven times of that in the shoots, while both of them were positively correlated with the Zn/Cr concentration in soil; (3) the total accumulation of Zn/Cr in the grass (shoots + roots) was firstly determined by their concentration in the shoots and secondly determined by the shoots’ biomass, indicating that most of the Zn/Cr could be removed from contaminated soil by harvesting the aboveground parts; (4) the accumulating amount of the two grasses for Zn were 17.5 and 12.1 mg plant⁻¹, respectively; while the accumulating amount for Cr were 3.9 and 2.9 mg plant⁻¹, respectively. Taken together, the two energy grasses had strong tolerance and high accumulating ability for Zn/Cr, and therefore, they are promising candidates for the phytoremediation of Zn-/Cr-contaminated soil.

Poultry feed is often supplemented with low dosages of antibiotic to promote growth, making farms and animal processing facilities potential point sources of antibiotic-resistant fecal bacteria to aquatic ecosystems. In 2010 and 2011, we detected high concentrations of fecal indicator bacteria (FIB) in effluent released from a poultry processing plant into a headwater stream in Greenville, South Carolina. The FIB pollution became undetectable in 2012 with the plant under new management. To determine the plant’s impacts on the stream, we compared the genetic variations of Escherichia coli populations from upstream and downstream of the plant and from reference streams in the same watershed by classifying each isolate into an E. coli reference collection (ECOR) phylogenetic group. For tetracycline-resistant E. coli isolates, we analyzed the resistance genes, minimum inhibitory concentrations (MICs), gene transferability, and plasmid incompatibility groups (Inc). Distributions of ECOR groups upstream and downstream of the plant differed significantly in 2011 but not in 2012. The resistance genes tet(A) and tet(B) were prevalent, with tet(A) more likely to be found on the promiscuous IncP plasmid. A higher percentage of isolates having both tet(A) and tet(B) was found downstream in 2011 than in 2012. Dual-gene isolates did not have higher MICs than single-gene isolates but were more likely to transfer tet(A) on IncP. We propose that the processing plant acted not only as a point source of FIB but also as a factor influencing gene transferability. Additionally, given the results from 2012, the FIB impacts of the processing plant appeared to be reversible.