Dissolution kinetics of copper oxide nanoparticles in presence of glyphosate.

Recently CuO nanoparticles (n-CuO) have been proposed as an alternative method to deliver a Cu-based pesticide for controlling fungal infestations. With the concomitant use of glyphosate as an herbicide, the interactions between n-CuO and this strong ligand need to be assessed. We investigated the dissolution kinetics of n-CuO and bulk-CuO (b-CuO) particles in the presence of a commercial glyphosate product and compared it to oxalate, a natural ligand present in soil water. We performed experiments at concentration levels representative of the conditions under which n-CuO and glyphosate would be used (∼0.9 mg/L n-CuO and 50 µM of glyphosate). As tenorite (CuO) dissolution kinetics are known to be surface controlled, we determined that at pH 6.5, T âˆ¼ 20 °C, using KNO3 as background electrolyte, the presence of glyphosate leads to a dissolution rate of 9.3 ± 0.7 ×10-3 h-1. In contrast, in absence of glyphosate, and under the same conditions, it is 2 orders of magnitude less: 8.9 ± 3.6 ×10-5 h-1. In a more complex multi-electrolyte aqueous solution the same effect is observed; glyphosate promotes the dissolution rates of n-CuO and b-CuO within the first 10 h of reaction by a factor of ∼2 to ∼15. In the simple KNO3 electrolyte, oxalate leads to dissolution rates of CuO about two times faster than glyphosate. However, the kinetic rates within the first 10 h of reaction are about the same for the two ligands when the reaction takes place in the multi-electrolyte solution as oxalate is mostly bound to Ca2+ and Mg2+.

Scalable and customizable parallel flow-through reactors to quantify biological processes related to contaminant attenuation by photosynthetic wetland microbial mats.

Shallow, unit process open water wetlands harbor a benthic microbial mat capable of removing nutrients, pathogens, and pharmaceuticals at rates that rival or exceed those of more traditional systems. A deeper understanding of the treatment capabilities of this non-vegetated, nature-based system is currently hampered by experimentation limited to demonstration-scale field systems and static lab-based microcosms that integrate field-derived materials. This limits fundamental mechanistic knowledge, extrapolation to contaminants and concentrations not present at current field sites, operational optimization, and integration into holistic water treatment trains. Hence, we have developed stable, scalable, and tunable laboratory reactor analogs that offer the capability to manipulate variables such as influent rates, aqueous geochemistry, light duration, and light intensity gradations within a controlled laboratory environment. The design is composed of an experimentally adaptable set of parallel flow-through reactors and controls that can contain field-harvested photosynthetic microbial mats ("biomat") and could be adapted for analogous photosynthetically active sediments or microbial mats. The reactor system is contained within a framed laboratory cart that integrates programable LED photosynthetic spectrum lights. Peristaltic pumps are used to introduce specified growth media, environmentally derived, or synthetic waters at a constant rate, while a gravity-fed drain on the opposite end allows steady-state or temporally variable effluent to be monitored, collected, and analyzed. The design allows for dynamic customization based on experimental needs without confounding environmental pressures and can be easily adapted to study analogous aquatic, photosynthetically driven systems, particularly where biological processes are contained within benthos. The diel cycles of pH and dissolved oxygen (DO) are used as geochemical benchmarks for the interplay of photosynthetic and heterotrophic respiration and likeness to field systems. Unlike static microcosms, this flow-through system remains viable (based on pH and DO fluctuations) and has at present been maintained for more than a year with original field-based materials.•Lab-scale flow-through reactors enable controlled and accessible exploration of shallow, open water constructed wetland function and applications.•The footprint and operating parameters minimize resources and hazardous waste while allowing for hypothesis-driven experiments.•A parallel negative control reactor quantifies and minimizes experimental artifacts.

Heavy metal removal by the photosynthetic microbial biomat found within shallow unit process open water constructed wetlands.

Nature-based solutions offer a sustainable alternative to labor and chemical intensive engineered treatment of metal-impaired waste streams. Shallow, unit process open water (UPOW) constructed wetlands represent a novel design where benthic photosynthetic microbial mats (biomat) coexist with sedimentary organic matter and inorganic (mineral) phases, creating an environment for multiple-phase interactions with soluble metals. To query the interplay of dissolved metals with inorganic and organic fractions, biomat was harvested from two distinct systems: the demonstration-scale UPOW within the Prado constructed wetlands complex ("Prado biomat", 88 % inorganic) and a smaller pilot-scale system ("Mines Park (MP) biomat", 48 % inorganic). Both biomats accumulated detectable background concentrations of metals of toxicological concern (Zn, Cu, Pb, and Ni) by assimilation from waters that did not exceed regulatory thresholds for these metals. Augmentation in laboratory microcosms with a mixture of these metals at ecotoxicologically relevant concentrations revealed a further capacity for metal removal (83-100 %). Experimental concentrations encapsulated the upper range of surface waters in the metal-impaired Tambo watershed in Peru, where a passive treatment technology such as this could be applied. Sequential extractions demonstrated that metal removal by mineral fractions is more important in Prado than MP biomat, possibly due to a higher proportion and mass of iron and other minerals from Prado-derived materials. Geochemical modeling using PHREEQC suggests that in addition to sorption/surface complexation of metals to mineral phases (modeled as iron (oxyhydr)oxides), diatom and bacterial functional groups (carboxyl, phosphoryl, and silanol) also play an important role in soluble metal removal. By comparing sequestered metal phases across these biomats with differing inorganic content, we propose that sorption/surface complexation and incorporation/assimilation of both inorganic and organic constituents of the biomat play a dominant role in metal removal potential by UPOW wetlands. This knowledge could be applied to passively treat metal impaired waters in analogous and remote regions.

[Volatile Organic Compounds(VOCs) Source Profiles of Industrial Processing and Solvent Use Emissions: A Review].

Industrial processing and solvent use are two most important industrial sources of volatile organic compounds (VOCs) in China, and the source profile study has attracted increasing attention recently. Studies of VOCs source profiles from industrial processing and solvent use since the year of 2000 were summarized in this study, focusing on the comparison among different studies and the potential impact of different research methods. In general, studies were very limited and focused on few sources. Specifically, only 8 of 32 sub-categories of the industrial processing (according to the source classification method of the National Guidelines for VOCs Inventories Preparation) have been reported, and in terms of the solvent use sources, 4 of 10 sub-categories have been reported. There were large differences among the VOCs patterns of different sub categories emissions of industrial processing or solvent use. In terms of studies of the similar emissions, significant differences of VOCs profiles were resulted from the different research methods, such as the different sampling methods and VOCs analysis techniques. In addition, the non-uniformity of VOC species in the source profile caused difficulty for the comparison of different research results. Oxygen-containing VOCs were important components of the above two types of pollution sources and needed to be included in the measurement. An opening and interactive database of VOCs from industrial processing and solvent use is critically essential in the future, and mechanisms of sharing and inputting relative research results should be formed to encourage researchers to join the database establishment. Correspondingly, detailed quality assurance and quality control procedures are also very important, which include the detailed information such as research objectives, sampling and analysis methods, research region and time, and test times, et al. Based on the community above, a better uncertainty analysis could be carried out for the VOCs emissions profiles, which is critically important to understand the VOCs emission characteristics of the industrial processing and solvent use.