A systematic review of the methodology of trade-off analysis in agriculture.

Trade-off analysis (TOA) is central to policy and decision-making aimed at promoting sustainable agricultural landscapes. Yet, a generic methodological framework to assess trade-offs in agriculture is absent, largely due to the wide range of research disciplines and objectives for which TOA is used. In this study, we systematically reviewed 119 studies that have implemented TOAs in landscapes and regions dominated by agricultural systems around the world. Our results highlight that TOAs tend to be unbalanced, with a strong emphasis on productivity rather than environmental and socio-cultural services. TOAs have mostly been performed at farm or regional scales, rarely considering multiple spatial scales simultaneously. Mostly, TOAs fail to include stakeholders at study development stage, disregard recommendation uncertainty due to outcome variability and overlook risks associated with the TOA outcomes. Increased attention to these aspects is critical for TOAs to guide agricultural landscapes towards sustainability.

Simultaneous detection of pesticides and pharmaceuticals in three types of bio-based fertilizers by an improved QuEChERS method coupled with UHPLC-q-ToF-MS/MS.

Bio-based fertilizers (BBFs) have the potential to contain both pesticides and pharmaceutical residues, which may pose a threat to soils, crops, and human health. However, no analytical screening method is available currently to simultaneously analyze a wide range of contaminants in the complex origin-dependent matrices of BBFs. To fill this gap, our study tested and improved an original QuEChERS method (OQM) for simultaneously analyzing 78 pesticides and 18 pharmaceuticals in BBFs of animal, plant, and ashed sewage sludge origin. In spiked recovery experiments, 34-58 pharmaceuticals and pesticides were well recovered (recovery of 70-120%) via OQM at spiking concentrations levels of 10 ng/g and 50 ng/g in these three different types of BBFs. To improve the extraction efficiency further, ultrasonication and end-over-end rotation were added based on OQM, resulting in the improved QuEChERS method (IQM) that could recover 57-79 pesticides and pharmaceuticals, in the range of 70-120%. The detection limits of this method were of 0.16-4.32/0.48-12.97 ng/g, 0.03-11.02/0.10-33.06 ng/g, and 0.06-5.18/0.18-15.54 ng/g for animal, plant, and ash-based BBF, respectively. Finally, the IQM was employed to screen 15 BBF samples of various origins. 15 BBFs contained at least one pesticide or pharmaceutical with ibuprofen being frequently detected in at concentration levels of 4.1-181 ng/g. No compounds were detected in ash-based BBFs.

Organic contaminants in bio-based fertilizer treated soil: Target and suspect screening approaches.

Using bio-based fertilizer (BBF) in agricultural soil can reduce the dependency on chemical fertilizer and increase sustainability by recycling nutrient-rich side-streams. However, organic contaminants in BBFs may lead to residues in the treated soil. This study assessed the presence of organic contaminants in BBF treated soils, which is essential for evaluating sustainability/risks of BBF use. Soil samples from two field studies amended with 15 BBFs from various sources (agricultural, poultry, veterinary, and sludge) were analyzed. A combination of QuEChERS-based extraction, liquid chromatography quadrupole time of flight mass spectrometry-based (LC-QTOF-MS) quantitative analysis, and an advanced, automated data interpretation workflow was optimized to extract and analyze organic contaminants in BBF-treated agricultural soil. The comprehensive screening of organic contaminants was performed using target analysis and suspect screening. Of the 35 target contaminants, only three contaminants were detected in the BBF-treated soil with concentrations ranging from 0.4 ng g-1 to 28.7 ng g-1; out of these three detected contaminants, two were also present in the control soil sample. Suspect screening using patRoon (an R-based open-source software platform) workflows and the NORMAN Priority List resulted in tentative identification of 20 compounds (at level 2 and level 3 confidence level), primarily pharmaceuticals and industrial chemicals, with only one overlapping compound in two experimental sites. The contamination profiles of the soil treated with BBFs sourced from veterinary and sludge were similar, with common pharmaceutical features identified. The suspect screening results suggest that the contaminants found in BBF-treated soil might come from alternative sources other than BBFs.

Leaf wax n-alkane patterns of six tropical montane tree species show species-specific environmental response.

It remains poorly understood how the composition of leaf wax n-alkanes reflects the local environment. This knowledge gap inhibits the interpretation of plant responses to the environment at the community level and, by extension, inhibits the applicability of n-alkane patterns as a proxy for past environments. Here, we studied the n-alkane patterns of five Miconia species and one Guarea species, in the Ecuadorian Andes (653-3,507 m a.s.l.). We tested for species-specific responses in the average chain length (ACL), the C31/(C31 + C29) ratio (ratio), and individual odd n-alkane chain lengths across an altitudinally driven environmental gradient (mean annual temperature, mean annual relative air humidity, and mean annual precipitation). We found significant correlations between the environmental gradients and species-specific ACL and ratio, but with varying magnitude and direction. We found that the n-alkane patterns are species-specific at the individual chain length level, which could explain the high variance in metrics like ACL and ratio. Although we find species-specific sensitivity and responses in leaf n-alkanes, we also find a general decrease in "shorter" (C31) chain lengths with the environmental gradients, most strongly with temperature, suggesting n-alkanes are useful for reconstructing past environments.

Effects of clay minerals, hydroxides, and timing of dissolved organic matter addition on the competitive sorption of copper, nickel, and zinc: A column experiment.

Infiltration of heavy metal (HM) polluted wastewater can seriously compromise soil and groundwater quality. Interactions between mineral soil components (e.g. clay minerals) and dissolved organic matter (DOM) play a crucial role in determining HM mobility in soils. In this study, the influence of the timing of addition of DOM, i.e. concurrent with or prior to HMs, on HM mobility was explored in a set of continuous flow column experiments using well defined natural soil samples amended with goethite, birnessite and/or smectite. The soils were subjected to concurrent and sequential additions of solutions of DOM, and Cu, Ni and Zn. The resulting breakthrough curves were fitted with a modified dose-response model to obtain the adsorption capacity (q0). Addition of DOM prior to HMs moderately enhanced q0 of Cu (8-25%) compared to a control without DOM, except for the goethite amended soil that exhibited a 10% reduction due to the blocking of binding sites. Meanwhile, for both Zn and Ni sequential addition of DOM reduced q0 by 1-36% for all tested soils due to preferential binding of Zn and Ni to mineral phases. In contrast, concurrent addition of DOM and HMs resulted in a strong increase of q0 for all tested metals and all tested soil compositions compared to the control: 141-299% for Cu, 29-102% for Zn and 32-144% for Ni. Our study shows that when assessing the impact of soil pollution through HM containing wastewater it is crucial to take into account the presence of DOM.

Robust analysis of underivatized free amino acids in soil by hydrophilic interaction liquid chromatography coupled with electrospray tandem mass spectrometry.

Amino acids are an important and highly dynamic fraction of organic N in soils and their determination in soil without derivatization is challenging due to the difficulties in separation and detection of trace amounts of these polar analytes. In the present work, we developed an analytical method to quantify 20 free amino acids in aqueous soil extracts without derivatization. The method employed hydrophilic interaction liquid chromatography-tandem mass spectrometry (HILIC-MS/MS) technique combined with a cation exchange solid phase extraction (SPE). Four stable isotope labelled amino acids were used as internal standards to improve the method performance. Good separation of 20 underivatized amino acids was achieved within 12min. The limit of detection (LODs) and limit of quantification (LOQs) were in the range of 13-384ngg(-1) and 43-1267ngg(-1) (dry soil basis), respectively. The results showed that overall recoveries with high precision were obtained for the extracted free amino acids from ten different soils. The overall recoveries of 18 amino acids were similar for the ten soils used, which differed substantially in organic C content and in other properties as soil texture and pH. For most of the amino acids, the average recoveries from soil extracts were between 74% and 117%, with the exception of Met (31%), Pro (52%) and Arg (68%). Variability was within acceptable limits (relative standard deviations were between 4% and 13%), with the exception of Met (relative standard deviation=90%) and Arg (relative standard deviation=53%). Thus the proposed method with high throughout and high analyte specificity shows great promise for consistent analysis of free amino acids extracted from soils and offers new horizons for the analysis of amino acids in terrestrial and aquatic ecosystem.

Rare Moss-Built Microterraces in a High-Altitude, Acid Mine Drainage-Polluted Stream (Cordillera Negra, Peru).

The Rio Santiago in the Cordillera Negra of Peru is severely contaminated by acid mine drainage in its headwaters. In a strongly acid stream, at about 3800 m above sea level (masl), microterraces were found with terrace walls built up of dead moss, with encrustations and interstitial fine, creamy sediment. The stream water was turbid due to the presence of similar suspended sediment, which also occurred as a thin basal layer in inter-rim basins. The moss was identified as the rare bryophyte Anomobryum prostratum (Müll. Hal.) Besch. Chemical and mineralogical analyses show that green, living parts of the moss are gradually coated by Al/Fe (hydr)oxides, inducing their senescence and death. The necromass is covered by creamy crusts through precipitation of schwertmannite-type material from the stream water and simultaneous 'capture' of fine sediment. The latter consists of a mixture of precipitate and fine detrital primary minerals. These processes are held responsible for the formation of the microterraces, which regarding their composition and environment seem to be unique. Remarkable is the high As content of the creamy crusts and sediment, attributed to strong sorption of As, whereas its solute concentration is relatively low. This calls for more attention to suspended fine sediment in the assessment of environmental risks of stream water use. Lastly, the results raise serious doubts about the use of aquatic bryophytes as bioindicator for chemical pollution in acid mine drainage-polluted streams.

Heavy metal concentrations in particle size fractions from street dust of Murcia (Spain) as the basis for risk assessment.

Street dust has been sampled from six different types of land use of the city of Murcia (Spain). The samples were fractionated into eleven particle size fractions (<2, 2-10, 10-20, 20-50, 50-75, 75-106, 106-150, 150-180, 180-425, 425-850 µm and 850-2000 µm) and analyzed for Pb, Cu, Zn and Cd. The concentrations of these four potentially toxic metals were assessed, as well as the effect of particle size on their distribution. A severe enrichment of all metals was observed for all land-uses (industrial, suburban, urban and highways), with the concentration of all metals affected by the type of land-use. Coarse and fine particles in all cases showed concentrations of metals higher than those found in undisturbed areas. However, the results indicated a preferential partitioning of metals in fine particle size fractions in all cases, following a logarithmic distribution. The accumulation in the fine fractions was higher when the metals had an anthropogenic origin. The strong overrepresentation of metals in particles <10 µm indicates that if the finest fractions are removed by a vacuum-assisted dry sweeper or a regenerative-air sweeper the risk of metal dispersion and its consequent risk for humans will be highly reduced. Therefore, we recommend that risk assessment programs include monitoring of metal concentrations in dust where each land-use is separately evaluated. The finest particle fractions should be examined explicitly in order to apply the most efficient measures for reducing the risk of inhalation and ingestion of dust for humans and risk for the environment.

Copper complexation by tannic acid in aqueous solution.

The speciation of titrated copper in a dissolved tannic acid (TA) solution with an initial concentration of 4 mmol organic carbon (OC)/l was investigated in a nine-step titration experiment (Cu/OC molar ratio=0.0030-0.0567). We differentiated between soluble and insoluble Cu species by 0.45 microm filtration. Measurements with a copper ion selective electrode (ISE) and diffusive gradients in thin films (DGT) were conducted to quantify unbound Cu(II) cations ("free" Cu) and labile soluble Cu complexes. For the DGT measurements, we used an APA hydrogel and a Chelex 100 chelating resin (Na form). Insoluble organic Cu complexes (>0.45 microm) was the dominant Cu species for Cu/OC=0.0030-0.0567 with a maximum fraction of 0.96 of total Cu. At Cu/OC>0.0100, Cu-catalysed degradation of aggregate structures resulted in a strong increase of free Cu and (labile) soluble Cu complexes with a maximum fraction of 0.28 and 0.32 of total Cu, respectively. Labile (i.e. DGT-detectable) soluble Cu complexes had a relatively high averaged diffusion coefficient (D) in the APA hydrogel (3.50 x 10(-6)- 5.58 x 10(-6)cm(2)s(-1)).

(Un)certainty of overall binding constants of Al with dissolved organic matter determined by the Scatchard approach.

One of the best approaches to date to obtain overall binding constants (Ko) for Al and dissolved organic matter (DOM) from acidic soil solutions is to collect 'free' Al data with diffusive gradients in thin films (DGT) and to infer the Ko values by fitting a continuous distribution model based on Scatchard plots. Although there is clear established literature demonstrating the usefulness of the Scatchard approach, relatively little attention has been given to a realistic assessment of the uncertainties associated with the final fitted Ko values. In this study we present an uncertainty analysis of the fitted Ko values using a synthetic dataset with different levels of random noise and a real data set using DGT data from an acidic soil solution. The parameters in the continuous distribution model and their corresponding upper and lower 95% uncertainty bounds were determined using the Shuffled Complex Evolution Metropolis (SCEM) algorithm. Although reasonable fits of the distribution model to the experimental data were obtained in all cases, an appreciable uncertainty in the resulting Ko values was found due to three main reasons. Firstly, obtaining 'free' Al data even with the DGT method is relatively difficult, leading to uncertainty in the data. Secondly, before Scatchard plots can be constructed, the maximum binding capacity (MBC) must be estimated. Any uncertainty in this MBC propagates into uncertainty associated with the final plots. Thirdly, as the final fitted Ko values are largely based on extrapolation, a small uncertainty in the fit of the binding data results in an appreciable uncertainty in the obtained Ko. Therefore, while trends in Ko for Al and DOM could easily be discerned and compared, the uncertainty in the Ko values hinders the application in quantitative speciation calculation. More comprehensive speciation models that avoid the use of Ko seem to fit better for this purpose.

Thermodynamic and kinetic models for the extraction of essential oil from savory and polycyclic aromatic hydrocarbons from soil with hot (subcritical) water and supercritical CO2.

Mechanisms that control the extraction rates of essential oil from savory (Satureja hortensis) and polycyclic aromatic hydrocarbons (PAHs) from historically-contaminated soil with hot water and supercritical carbon dioxide were studied. The extraction curves at different solvent flow-rates were used to determine whether the extractions were limited primarily by the near equilibrium partitioning of the analyte between the matrix and solvent (i.e. partitioning thermodynamics, or the "elution" step) or by the rate of analyte desorption from the matrix (i.e. kinetics, or the "initial desorption" step). Two simple models were applied to describe the extraction profiles obtained with hot water and with supercritical CO2: (1) a model based solely on the thermodynamic distribution coefficient KD, which assumes that analyte desorption from the matrix is rapid compared to elution. and (2) a two-site kinetic model which assumes that the extraction rate is limited by the analyte desorption rate from the matrix, and is not limited by the thermodynamic (KD) partitioning that occurs during elution. For hot water extraction, the thermodynamic elution of analytes from the matrix was the prevailing mechanism as evidenced by the fact that extraction rates increased proportionally with the hot water flow-rate. This was also confirmed by the fact that simple removal calculations based on a single KD (for each essential oil compound) gave good fits to experimental data for flow-rates from 0.25 to 4 ml/min. In contrast, supercritical CO2 extraction showed only minimal dependence on flow-rate, and the simple KD model could only describe the initial 20-50% of the extraction. However, a simple two-site kinetic model gave a good fit for all CO2 flow-rates tested. The results of these investigations demonstrated that very simple models can be used to determine and describe extractions which are limited primarily by partitioning thermodynamics, or primarily by desorption kinetics. Furthermore, these results show that the time required for the recovery of essential oil from savory with hot water can be minimized by increasing flow-rate, with little change in the total volume of water required. In contrast, raising the flow-rate of supercritical CO2 has little effect on the mass of essential oils recovered per unit of time, indicating that optimal recovery of these compounds with supercritical CO2 (amount recovered for the lowest amount of CO2) requires longer extraction times rather than faster flow-rates.

Copper complexation by dissolved organic matter and uncertainty assessment of their stability constants.

The interaction of Cu with dissolved organic matter (DOM, extracted from an organic forest floor) was investigated and the resulting data was evaluated in terms of their uncertainty. The speciation of Cu over 'free' Cu (as analysed by diffusive gradients in thin films (DGT)), dissolved Cu-DOM complexes and precipitated Cu-DOM was determined as a function of pH (3.5, 4.0 and 4.5) and Cu/C ratio. The dissolved organically bound fraction was highest at pH 4.5, but this fraction decreased with increasing Cu/C ratio, which was observed for all pH levels. In the range of Cu/C = 7 x 10(-5) -2.3 x 10(-2) (mol/mol) the precipitated fraction was very small. The speciation of both Al and Fe was not affected by increasing Cu concentrations. From a continuous distribution model using the Scatchard approach, we calculated the optimal fit and corresponding upper and lower 95% uncertainty bounds of the overall stability constants (K(o)) with the shuffled complex evolution Metropolis (SCEM) algorithm. Although the optimal equation fitted the data very well, the uncertainty of the, according to literature, most reliable approach to establish stability constants, was still large. Accordingly, the usually reported intrinsic stability constants exhibited large uncertainty ranging from log K(i) = 6.0-7.1 (optimal 6.7) for pH 3.5, log K(i) = 6.5-7.1 (optimal 6.8) for pH 4.0, and log K(i) = 6.4-7.2 (optimal 6.8) for pH 4.5 and showed only little effect of pH.

Dissolved organic matter, aluminium and iron interactions: precipitation induced by metal/carbon ratio, pH and competition.

To better understand the precipitation behaviour of dissolved organic matter induced by interactions with metals, a systematic titration experiment was conducted mimicking the soil solution conditions in an acidic, sandy soil. The variables of interest included the type of metal species (Al, Fe), the redox state [Fe(II), Fe(III)], the pH (3.5, 4.0, 4.5), the metal to organic carbon (M/C) ratio and the competition between Al and Fe. Precipitation of DOM-Al appeared to be strongly correlated with M/C ratio and the pH. For Fe(II) only little precipitation occurred, while the strongest flocculation degree was found after addition of Fe(III). In contrast to Al, hardly any correlation between DOM-Fe precipitation and pH was observed. Both reduction and oxidation of Fe was found and exhibited a strong effect on the precipitated amounts of DOM and Fe. In competition, Al determined the precipitation behaviour at lower M/C ratios (<0.10), while at higher M/C ratios Fe determined the flocculation. Below a M/C ratio of 0.06 Al was the dominant metal in the precipitates, especially at lower pH levels, while the opposite trend was found at M/C ratios above 0.06. Overall, Fe(III) gave the strongest flocculation, although Al influenced the impact of Fe(III) interactions with DOM in relation to pH and M/C ratio.