In this study, natural calcium-rich attapulgite (NCAP) was used to develop a low-cost adsorbent for removing fluoride (F⁻) from contaminated water. The results showed that calcination can dramatically increase the F⁻ sorption capacity of NCAP and that the maximum F⁻ sorption capacity occurred at 700 °C. The sorption of F⁻ on NCAP heated at 700 °C (NCAP700) followed pseudo-second-order kinetics and was described by the Langmuir equilibrium model. The estimated F⁻ sorption capacity was approximately 140.0 mg/g at pH 8.0, which was comparable with the sorption capacities of some nanomaterials. The sorption of F⁻ on NCAP700 performed well at pH values of 7 to 10. In addition, anions such as NO₃ ⁻ and SO₄ ²⁻ did not affect fluoride removal, but PO₄ ³⁻ and HCO₃ ⁻ moderately influenced fluoride removal. A column study conducted using NCAP700 with a particle size of 0.2–0.5 mm indicated that the adsorbent could effectively purify nearly 200 bed volumes (BV) of water containing 3.0 mg F/l at pH 8.5. The removal of F⁻ from water mainly resulted from the formation of calcium fluoride precipitates and the complexation of fluoride with the –OH group of NCAP700, which was further confirmed by scanning electron microscopy–energy dispersive spectrometry (SEM-EDS) and X-ray photoelectron spectroscopy (XPS).

The epibenthic amphipod Melita plumulosa shows unique gene expression profiles when exposed to different contaminants. We hypothesized that specific changes in transcript abundance could be used in a battery of quantitative polymerase chain reaction (qPCR) assays as a toxicity identification evaluation (TIE)-like approach to identify the most relevant stressor in field-contaminated sediments. To test this hypothesis, seven candidate transcriptomic markers were selected, and their specificity following metal exposure was confirmed. The performance of these markers across different levels of added metals was verified. The ability of these transcripts to act as markers was tested by exposing amphipods to metal-contaminated field-collected sediments and measuring changes in transcript abundance via qPCR. For two of the three sediments tested, at least some of the transcriptomic patterns matched our predictions, suggesting that they would be effective in helping to identify metal exposure in field sediments. However, following exposure to the third sediment, transcriptomic patterns were unlike our predictions. These results suggest that the seven transcripts may be insufficient to discern individual contaminants from complex mixtures and that microarray or RNA-Seq global gene expression profiles may be more effective for TIE. Changes in transcriptomics based on laboratory exposures to single compounds should be carefully validated before the results are used to analyze mixtures.

The phenolics and high organic content present in palm oil mill effluent are the major contributors to its dark brown color, toxicity, and antimicrobial properties. In this study, ten white rot fungi were screened for their potential in the dephenolization and decolorization of treated palm oil mill effluent (TPOME) in solid and liquid state cultures. Among them, Trametes hirsuta strain AK 04 was found to be more tolerant to high TPOME concentrations and showed the highest phenolics and color removal activities. This strain was immobilized onto oil palm fibers (OPFs) and appeared more resistant to inhibitory compounds such as phenolics in TPOME than the free cell culture. The OPF-immobilized fungus was able to effectively remove phenolics and color of TPOME without effluent dilution and addition of nutrients. The activities of laccase and manganese peroxidase were found during dephenolization and decolorization processes. Moreover, the degradation rate of immobilized fungus could be accelerated by pretreatment of phenolics with phenol-degrading bacteria. This method improved the fungal dephenolization and decolorization simultaneously up to 82.2 ± 3.8 % and 87.1 ± 1.1 % after 8 days of incubation. Therefore, a two-stage biological process containing phenol-degrading bacteria and OPF-immobilized fungus could be a feasible and economical method for simultaneous improvement of dephenolization and decolorization of TPOME.

Peatlands are often regarded as metal repositories, but under drought conditions may switch from sinks to sources of metals and contaminate downstream ecosystems. To evaluate whether the release of metals into soil solution in peatlands is predictable using simple, widely available soil parameters, six peatlands, with varying levels of metal contamination, including a previously limed peatland, were sampled around the Sudbury, Ontario, region, and were subjected to simulated drought. The simulated drought lowered soil water pH and dissolved organic carbon (DOC) concentrations, which is consistent with field observations. Metal partitioning (K d) values for Co, Mn, Ni, and Zn, with just one exception at one peatland, could be significantly predicted by just the pH of the soil water, although the strength of the relationship varied considerably among sites. The metal speciation model WHAM VII predicted that the free metal ion concentration of all metals tested, including Cu and Al, increased significantly with decreasing pH. At the same time, DOC-bound metal concentrations were predicted to decrease as DOC levels were lower, which for metals with strong organic matter affinities (Cu and Al) offset the increase in free metal ion concentration in soil solution following summer drought. Climate change forecasts for more frequent and sustained droughts may promote metal release from peatlands and increased mobilization to surface waters, and importantly, for some metals, the potential toxicity of the metals released from peatlands may increase to a greater extent than expected from increases in total metal concentrations because of decreased DOC following drought.

Disposing of nitrate-containing effluents from seawater-fed intensive aquacultural applications is a major environmental problem. A possible solution is to mix nitrate-rich effluents from marine recirculating aquaculture systems (RASs) with citrate-rich liquid wastes (CLW), a common by-product of the food industry. Where possible, such strategy can alleviate two environmental problems simultaneously, in a cost-effective fashion. However, concerns are often raised regarding secondary pollution stemming from the use of CLW, particularly related to phosphorus and heavy metals. This work showed that both phosphorus and heavy metal were completely absorbed by the bacterial sludge generated in the process, indicating low environmental risk associated with the disposal of the treated effluent to the environment. Operation of continuous stirred-tank reactor (CSTR) single-sludge denitrification reactor with CLW as electron and carbon donor resulted in high nitrate removal efficiency (>95 %) and denitrification rate of up to 1.6 g NO₃-N L⁻¹reactor day⁻¹along with low bacterial biomass yield [0.23 g chemical oxygen demand (COD) new cells g⁻¹COD citrate]. Moreover, the use of CLW was found to be environmentally safe and equally efficient to the use of traditional, costly carbon sources such as methanol and acetic acid, rendering this alternative attractive for treatment of nitrate-rich saline effluents.

Marine tar residues originate from natural and anthropogenic oil releases into the ocean environment and are formed after liquid petroleum is transformed by weathering, sedimentation, and other processes. Tar balls, tar mats, and tar patties are common examples of marine tar residues and can range in size from millimeters in diameter (tar balls) to several meters in length and width (tar mats). These residues can remain in the ocean environment indefinitely, decomposing or becoming buried in the sea floor. However, in many cases, they are transported ashore via currents and waves where they pose a concern to coastal recreation activities, the seafood industry and may have negative effects on wildlife. This review summarizes the current state of knowledge on marine tar residue formation, transport, degradation, and distribution. Methods of detection and removal of marine tar residues and their possible ecological effects are discussed, in addition to topics of marine tar research that warrant further investigation. Emphasis is placed on benthic tar residues, with a focus on the remnants of the Deepwater Horizon oil spill in particular, which are still affecting the northern Gulf of Mexico shores years after the leaking submarine well was capped.

In the European registration procedure for pesticides, microcosm and mesocosm studies are the highest aquatic experimental tier to assess their environmental effects. Evaluations of microcosm/mesocosm studies rely heavily on no observed effect concentrations (NOECs) calculated for different population-level endpoints. Ideally, a power analysis should be reported for the concentration–response relationships underlying these NOECs, as well as for measurement endpoints for which significant effects cannot be demonstrated. An indication of this statistical power can be provided a posteriori by calculated minimum detectable differences (MDDs). The MDD defines the difference between the means of a treatment and the control that must exist to detect a statistically significant effect. The aim of this paper is to expand on the Aquatic Guidance Document recently published by the European Food Safety Authority (EFSA) and to propose a procedure to report and evaluate NOECs and related MDDs in a harmonised way. In addition, decision schemes are provided on how MDDs can be used to assess the reliability of microcosm/mesocosm studies and for the derivation of effect classes used to derive regulatory acceptable concentrations. Furthermore, examples are presented to show how MDDs can be reduced by optimising experimental design and sampling techniques.

The soils found in urban remnant patches may be considered anthropogenic inner urban soils—soils within the administrative boundaries of a municipalities influenced by activities adding artefacts into the soils. Such activities include housing, trading, traffic, production, and disposing. The objective of this study is to determine the scope to which field spectroscopy methods can be used to extend the knowledge of urban soils features and components. The spectroscopy techniques are used broadly for determining specific components or for differentiating between known ones. Moreover, this technique is able to determine low concentration in various phases and to trace hazardous material, and most studies are keen on quantification of those hazardous. In this paper, a top–down analysis for detecting the presence of minerals, organic matter, and pollutants in mixed soil samples is developed and presented. The developed method applies spectral activity (SA) detection in a structured hierarchical approach to quickly and, more importantly, accurately identify dominant spectral features. The developed method is adopted by multiple in-production tools including continuum removal normalization, guided by polynomial generalization, and spectral-likelihood algorithms: orthogonal subspace projection (OSP) and iterative spectral mixture analysis (ISMA).

Biosolids are a source of recycled organic matter and nutrients. To evaluate the impact of biosolids application (1984–2008) on soil quality, composite soils (Genesee silt loam, fine loamy, mixed, nonacid, and mesic typic udifluvent) were randomly sampled at geo-referenced sites from 0 (control), 2, 5, and 25 years of lime-stabilized anaerobically digested biosolid-applied fields. Results showed that microbial biomass C (Cₘᵢc), N (Nₘᵢc), and P (Pₘᵢc) contents were significantly higher at both depths of the 5 and 25 years of biosolid-applied fields compared to the control. Biosolid application significantly enlarged the biologically labile C (Cₘᵢc over total organic C, Cₘᵢc:Cₒᵣg) and N (Nₘᵢc over total N, Nₘᵢc:TN) pools with an associated decrease in metabolic C loss (20–53 %) by specific maintenance respiration (qCO₂) relative to the control. The Cₒᵣg, active (AC) and soluble C (SC), TN and reactive N (RN), and reactive P (RP) contents were significantly higher in the long-term biosolid-applied fields than in the control. However, there was an indication of leaching of SC, RN, and RP between depths. Years of biosolid application significantly increased soil moisture content (θ ᵥ at −0.03 MPa) by 20–40 %, macroaggregate stability (MaA) by 2–44 %, and mean weight diameter (MWD) of aggregates by 7–51 %, respectively. Consequently, there was a decrease in soil bulk density (ρ b) and microaggregate stability (MiA) at both depths. Results confirmed that biosolids application at rates recommended is a viable management option to improve soil quality for crop production. However, long-term and repeated biosolid applications above the recommended agronomic N and P rates may be responsible for accumulation and consequent leaching and runoff of SC, RN, and RP to cause groundwater and surface water pollution with environmental consequences.

Benzotriazoles (BTs) are an emerging class of environmental pollutants used in a wide range of industrial applications. Benzotriazole (BTri) and 5-methylbenzotriazole (5-MeBT) have recently been detected in water supplies around the world, and are thus attracting the attention of many environmental researchers. The focus of this review is on assessing contemporary methods to detect BTs using high-performance liquid chromatography (HPLC), and providing information regarding their occurrence, degradation and toxicity within the environment.