Mycotoxins in the Environment: II. Occurrence and Origin in Swiss River Waters

Thirty-three different mycotoxins were surveyed over nearly two years in a typical Swiss wastewater treatment plant (WWTP), as well as in Swiss midland rivers. Out of these, 3-acetyl-deoxynivalenol, deoxynivalenol (DON), nivalenol (NIV), and beauvericin (BEA), were detected. DON was quantified in all WWTP effluent grab samples with a maximum concentration of 73.4 ng/L, while the lowest concentration was observed for BEA with 1.3 ng/L. NIV was detected in about 37%, the other three compounds in 9–36% of the weekly or fortnightly integrated flow proportional river water samples. Concentrations were river discharge dependent, with higher numbers in smaller rivers, but mostly in the very low ng/L-range, with a maximum of 24.1, and 19.0 ng/L for NIV and DON, respectively. While NIV and DON prevailed in summer and autumn, BEA occurred mostly during winter. Summer and autumn seasonal load fractions were, however, not correlating with other river basin parameters indicative of the probably most obvious seasonal input source, that is, <i>Fusarium graminearum</i> infected wheat crop areas. Nevertheless, together with WWTP effluents, these two sources largely explained the loads of mycotoxins quantified in river waters. The ecotoxicological relevance of mycotoxins as newly identified aquatic micropollutants has yet to be assessed

Nanomaterials in Plant Protection and Fertilization: Current State, Foreseen Applications, and Research Priorities

Scientific publications and patents on nanomaterials (NM) used in plant protection or fertilizer products have exponentially increased since the millennium shift. While the United States and Germany have published the highest number of patents, Asian countries released most scientific articles. About 40% of all contributions deal with carbon-based NM, followed by titanium dioxide, silver, silica, and alumina. Nanomaterials come in many diverse forms (surprisingly often ≫100 nm), from solid doped particles to (often nonpersistent) polymer and oil–water based structures. Nanomaterials serve equally as additives (mostly for controlled release) and active constituents. Product efficiencies possibly increased by NM should be balanced against enhanced environmental NM input fluxes. The dynamic development in research and its considerable public perception are in contrast with the currently still very small number of NM-containing products on the market. Nanorisk assessment and legislation are largely in their infancies

Critical Assessment of Models for Transport of Engineered Nanoparticles in Saturated Porous Media

To reliably assess the fate of engineered nanoparticles (ENP) in soil, it is important to understand the performance of models employed to predict vertical ENP transport. We assess the ability of seven routinely employed particle transport models (PTMs) to simulate hyperexponential (HE), nonmonotonic (NM), linearly decreasing (LD), and monotonically increasing (MI) retention profiles (RPs) and the corresponding breakthrough curves (BTCs) from soil column experiments with ENPs. Several important observations are noted. First, more complex PTMs do not necessarily perform better than simpler PTMs. To avoid applying overparameterized PTMs, multiple PTMs should be applied and the best model selected. Second, application of the selected models to simulate NM and MI profiles results in poor model performance. Third, the selected models can well-approximate LD profiles. However, because the models cannot explicitly generate LD retention, these models have low predictive power to simulate the behavior of ENPs that present LD profiles. Fourth, a term for blocking can often be accounted for by parameter variation in models that do not explicitly include a term for blocking. We recommend that model performance be analyzed for RPs and BTCs separately; simultaneous fitting to the RP and BTC should be performed only under conditions where sufficient parameter validation is possible to justify the selection of a particular model

Quantitative Determination of PAHs in Biochar: A Prerequisite To Ensure Its Quality and Safe Application

Biochar is increasingly promoted as a beneficial soil conditioner. However, it may contain residues of polycyclic aromatic hydrocarbons (PAHs) as a result of its production by pyrolysis. To date, analytical methods to analyze PAHs in biochar quantitatively are hardly available. This study presents an optimized and validated procedure to quantify the 16 U.S. EPA PAHs in biochar. PAHs were best extracted with Soxhlet for 36 h using 100% toluene. Average absolute recoveries of isotope labeled internal standards used for each analyte from three different biochars ranged from 42% to 72%, and relative recoveries were between 71% and 105%. The limits of detection were biochar-dependent, but on average a factor of >50 lower than quantified PAH concentrations (9–355 mg kg_dry weight^–1). The established method prepares the ground for a harmonized protocol for PAH analysis of biochars, a necessity for biochar quality control, registration, and legislation

Comprehensive Toxic Plants–Phytotoxins Database and Its Application in Assessing Aquatic Micropollution Potential

The production of toxic plant secondary metabolites (phytotoxins) for defense is a widespread phenomenon in the plant kingdom and is even present in agricultural crops. These phytotoxins may have similar characteristics to anthropogenic micropollutants in terms of persistence and toxicity. However, they are only rarely included in environmental risk assessments, partly because a systematic overview of phytotoxins is missing. Here, we present a newly developed, freely available database, Toxic Plants–PhytoToxins (TPPT), containing 1586 phytotoxins of potential ecotoxicological relevance in Central Europe linked to 844 plant species. Our database summarizes phytotoxin patterns in plant species and provides detailed biological and chemical information as well as in silico estimated properties. Using the database, we evaluated phytotoxins regarding occurrence, approximated from the frequencies of Swiss plant species; environmental behavior based on aquatic persistence and mobility; and toxicity. The assessment showed that over 34% of all phytotoxins are potential aquatic micropollutants and should be included in environmental investigations

Mycotoxins in the Environment: I. Production and Emission from an Agricultural Test Field

Mycotoxins are secondary metabolites that are naturally produced by fungi which infest and contaminate agricultural crops and commodities (e.g., small grain cereals, fruits, vegetables, and organic soil material). Although these compounds have extensively been studied in food and feed, only little is known about their environmental fate. Therefore, we investigated over nearly two years the occurrence of various mycotoxins in a field cropped with winter wheat of the variety Levis, which was artificially inoculated with <i>Fusarium</i> spp., as well as their emission via drainage water. Mycotoxins were regularly quantified in whole wheat plants (0.1–133 mg/kg_dry weight, for deoxynivalenol), and drainage water samples (0.8 ng/L to 1.14 μg/L, for deoxynivalenol). From the mycotoxins quantified in wheat (3-acetyl-deoxynivalenol, deoxynivalenol, fusarenone-X, nivalenol, HT-2 toxin, T-2 toxin, beauvericin, and zearalenone), only the more hydrophilic ones or those prevailing at high concentrations were detected in drainage water. Of the total amounts produced in wheat plants (min: 2.3; max: 292 g/ha/y), 0.5–354 mg/ha/y, i.e. 0.002–0.12%, were emitted via drainage water. Hence, these compounds add to the complex mixture of natural and anthropogenic micropollutants particularly in small rural water bodies, receiving mainly runoff from agricultural areas

What Factors Determine the Retention Behavior of Engineered Nanomaterials in Saturated Porous Media?

A fundamental problem associated with the vertical transport of engineered nanomaterials (ENMs) in saturated porous media is the occurrence of nonexponential, for example, nonmonotonic or linearly increasing, retention profiles. To investigate this problem, we compiled an extensive database of ENMs transport experiments in saturated porous media. Using this database we trained a decision tree that shows the order of importance, and range of influence, of the physicochemical factors that control the retention profile shape. Our results help identify domains where current particle-transport models can be used, but also highlight, for the first time, large domains where nonexponential retention profiles dominate and new approaches are needed to understand ENM transport. Importantly, highly advective flow and high ENM influent mass can mask the influence of other physicochemical factors on the retention profile shape; notably, this occurs in 50% of the experiments investigated. Where the relationship between physicochemical factors and retention profile shape can be investigated in detail, our results agree with, and provide validation for, the current understanding of how these factors influence ENM transport

Diuron Sorbed to Carbon Nanotubes Exhibits Enhanced Toxicity to Chlorella vulgaris

Carbon nanotubes (CNT) are more and more likely to be present in the environment, where they will associate with organic micropollutants due to strong sorption. The toxic effects of these CNT-micropollutant mixtures on aquatic organisms are poorly characterized. Here, we systematically quantified the effects of the herbicide diuron on the photosynthetic activity of the green alga Chlorella vulgaris in presence of different multiwalled CNT (industrial, purified, pristine, and oxidized) or soot. The presence of carbonaceous nanoparticles reduced the adverse effect of diuron maximally by <78% (industrial CNT) and <34% (soot) at 10.0 mg CNT/L, 5.0 mg soot/L, and diuron concentrations in the range 0.73–2990 μg/L. However, taking into account the measured dissolved instead of the nominal diuron concentration, the toxic effect of diuron was equal to or stronger in the presence of CNT by a factor of up to 5. Sorbed diuron consequently remained partially bioavailable. The most pronounced increase in toxicity occurred after a 24 h exposure of algae and CNT. All results point to locally elevated exposure concentration (LEEC) in the proximity of algal cells associated with CNT as the cause for the increase in diuron toxicity

Total TiO₂ suspended or sedimented in the hydroponic system.

<p>Red clover was exposed (n = 3) over 162 h to the two nanoparticles P25 and E171. TiO₂ amounts of the pooled stock suspension is shown at t = 0 in black. TiO₂ amounts of the top (white, 17 ml, in contact with roots) and bottom part (grey, 3 ml, including precipitate) are shown. Differences of the total TiO₂ NP amount (bottom and top part together) to the total Ti amount at t = 0 are indicated with asterisks (p<0.05). Error bars indicate standard deviations (n = 3).</p

Number of root tips and number of secondary roots of red clover in hydroponic system.

<p>Roots were assessed at the harvest (n = 6, mean ± standard deviation). Exposure concentrations (1<2) are described in detail in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0155111#pone.0155111.t002" target="_blank">Table 2</a>.</p