Effects of different oxygen regimes on ecological performance and bioenergetics of a coastal marine bioturbator, the soft shell clam Mya arenaria.

Benthic species are exposed to oxygen fluctuations that can affect their performance and survival. Physiological effects and ecological consequences of fluctuating oxygen are not well understood in marine bioturbators such as the soft-shell clam Mya arenaria. We explored the effects of different oxygen regimes (21 days of exposure to constant hypoxia (~4.1 kPa PO2), cyclic hypoxia (~2.1-~10.4 kPa PO2) or normoxia (~21 kPa PO2)) on energy metabolism, oxidative stress and ecological behaviors (bioirrigation and bioturbation) of M. arenaria. Constant hypoxia and post-hypoxic recovery in cyclic hypoxia led to oxidative injury of proteins and lipids, respectively. Clams acclimated to constant hypoxia maintained aerobic capacity similar to the normoxic clams. In contrast, clams acclimated to cyclic hypoxia suppressed aerobic metabolism and activated anaerobiosis during hypoxia, and strongly upregulated aerobic metabolism during recovery. Constant hypoxia led to decreased lipid content, whereas in cyclic hypoxia proteins and glycogen accumulated during recovery and were broken down during the hypoxic phase. Digging of clams was impaired by constant and cyclic hypoxia, and bioirrigation was also suppressed under constant hypoxia. Overall, cyclic hypoxia appears less stressful for M. arenaria due to the metabolic flexibility that ensures recovery during reoxygenation and mitigates the negative effects of hypoxia, whereas constant hypoxia leads to depletion of energy reserves and impairs ecological functions of M. arenaria potentially leading to negative ecological consequences in benthic ecosystems.

Effects of variable oxygen regimes on mitochondrial bioenergetics and reactive oxygen species production in a marine bivalve, Mya arenaria.

Estuarine and coastal benthic organisms often experience fluctuations in oxygen levels that can negatively impact their mitochondrial function and aerobic metabolism. To study these impacts, we exposed a common sediment-dwelling bivalve, the soft-shell clam Mya arenaria, for 21 days to chronic hypoxia (PO2  âˆ¼4.1 kPa), cyclic hypoxia (PO2  âˆ¼12.7-1.9 kPa, mean 5.7 kPa) or normoxia (PO2  âˆ¼21.1 kPa). pH was manipulated to mimic the covariation in CO2/pH and oxygen levels in coastal hypoxic zones. Mitochondrial respiration, including proton leak, the capacity for oxidative phosphorylation (OXPHOS), the maximum activity of the electron transport system (ETS), reactive oxygen species (ROS) production, and activity and oxygen affinity of cytochrome c oxidase (CCO) were assessed. Acclimation to constant hypoxia did not affect the studied mitochondrial traits except for a modest decrease in the OXPHOS coupling efficiency. Cyclic hypoxia had no effect on OXPHOS or ETS capacity, but increased proton leak and lowered mitochondrial OXPHOS coupling efficiency. Furthermore, mitochondria of clams acclimated to cyclic hypoxia had higher rates of ROS generation compared with the clams acclimated to normoxia or chronic hypoxia. CCO activity was upregulated under cyclic hypoxia, but oxygen affinity of CCO did not change. These findings indicate that long-term cyclic hypoxia has a stronger impact on the mitochondria of M. arenaria than chronic hypoxia and might lead to impaired ATP synthesis, higher costs of mitochondrial maintenance and oxidative stress. These changes might negatively affect populations of M. arenaria in the coastal Baltic Sea under increasing hypoxia pressure.

Thirty-year monitoring of s-triazine herbicide contamination in the aquifer north of Vicenza (north-east Italy).

The aquifer north of Vicenza, Italy, is one of the main and most studied drinking water reservoirs within the Veneto region. The area is an intensive cropland, and monitoring of s-triazine herbicides and metabolites has been carried out since the late eighties. This study analysed the trends of atrazine (ATR), terbuthylazine (TBZ), deethyl-atrazine (DEA), and deethyl-terbuthylazine (DET) concentrations from 1987 to 2016 and related the variations of agricultural land use, herbicide load, and pesticide regulations to the residence time of pollutants in the aquifer. In total, 785 water samples collected from 82 selected check wells were analysed with high-resolution gas chromatography combined with mass spectrometry. Non-detects were substituted by one-half the limit of detection. Over the 30 years of monitoring, concentrations of all of the pollutants decreased at all sampling sites. Since the beginning, TBZ and DET residues have been systematically lower than ATR and DEA, respectively, with more than 70% of the data below the limit of detection and never exceeding the European Maximum Acceptable Concentration (MAC) for a single pesticide (0.1 µg/L). The highest concentrations of ATR and DEA showed a spatial shift along the flow direction, suggesting an increase in groundwater residence time from the recharge zone to the accumulation zone of the aquifer. The last residues of ATR were found 27 years after its ban. Although all of the concentrations were lower than those found elsewhere in Europe, the sum of s-triazines overcame the MAC in 20% of the samples. Considering the structural and toxicological similarities of s-triazines, these findings confirm the necessity of better characterisation of the toxicological risk posed by mixtures.

Residual Monomer Content Affects the Interpretation of Plastic Degradation.

Plastic degradation rates in the marine environment are essential to understand. This study demonstrates that in plastic-microbial interaction experiments, residual monomeric and oligomeric content of PA6 significantly influences the development of dissolved organic carbon. While it is well recognized that additives in plastics should be considered during the inception of plastic-exposure experiments, residual monomers have yet to be prominently considered in the same light. As such, in degradation studies where residual contents of monomers and/or oligomers are not considered, degradation of synthetic polymers could be significantly overestimated. The substantial conversion of these monomeric and oligomeric leachates also has implications for plastic-biofilm development studies and microplastic-biota-based ingestion experiments.

Droplets deposition pattern from a prototype of a fixed spraying system in a sloping vineyard.

In Italy high-quality vines are sometimes grown in small fields with slope steeper than 5-10%, where an air-blast sprayer is impractical so spray-gun application of pesticides is used, a technique that is very costly and labour intensive, and that causes high pesticide exposure of the operators. A possible alternative is the use of a fixed spraying system, and the first researches are in progress in Italy. A fixed spraying system prototype was built in a vineyard at Laimburg Research Centre with an upper line with micro-sprinkler and a lower line with cooler-type nozzles, and a trial was performed with the aim of measuring the deposition pattern of droplets on the row and between rows with water sensitive papers, also in comparison with a precise low-drift air-blast sprayer. Results show that with the fixed spraying system the treated crop row accounts for 38-44% of total deposition, that about 85-88% of sprayed solution falls on the sprayed row and on the closest right and left adjacent inter-rows, and that at 4 m from the spraying line the spray drift was <0.1%. This highlights that a fixed spraying system has the potential to apply plant protection products without generating drift problems, with a field performance similar to a low-drift sprayer, becoming an opportunity for vineyards on very steep slopes.

Vegetated Ditches for the Mitigation of Pesticides Runoff in the Po Valley.

In intensive agricultural systems runoff is one of the major potential diffuse pollution pathways for pesticides and poses a risk to surface water. Ditches are common in the Po Valley and can potentially provide runoff mitigation for the protection of watercourses. The effectiveness depends on ditch characteristics, so there is an urgent need for site-specific field trials. The use of a fugacity model (multimedia model) can allows recognition of the mitigation main processes. A field experiment was conducted in order to evaluate the mitigation capacity of a typical vegetated ditch, and results were compared with predictions by a fugacity model. To evaluate herbicide mitigation after an extreme runoff, the ditch was flooded with water containing mesotrione, S-metolachlor and terbuthylazine. Two other subsequent floods with uncontaminated water were applied 27 and 82 days later to evaluate herbicides release. Results show that the ditch can immediately reduce runoff concentration of herbicides by at least 50% even in extreme flooding conditions. The half-distances were about 250 m. As a general rule, a runoff of 1 mm from 5 ha is mitigated by 99% in 100 m of vegetated ditch. Herbicides retention in the vegetated ditch was reversible, and the second flood mobilized 0.03-0.2% of the previous one, with a concentration below the drinking water limit of 0.1 µg L(-1). No herbicide was detected in the third flood, because the residual amount in the ditch was too low. Fugacity model results show that specific physical-chemical parameters may be used and a specific soil-sediment-plant compartment included for modelling herbicides behaviour in a vegetated ditch, and confirm that accumulation is low or negligible for herbicides with a half-life of 40 days or less. Shallow vegetated ditches can thus be included in a general agri-environment scheme for the mitigation of pesticides runoff together with wetlands and linear buffer strips. These structures are present in the landscape, and their environmental role can be exploited by proper management.

Pyrolysis-gas chromatography-mass spectrometry with electron-ionization or resonance-enhanced-multi-photon-ionization for characterization of polycyclic aromatic hydrocarbons in the Baltic Sea.

Polycyclic aromatic hydrocarbons (PAH), as a part of dissolved organic matter (DOM), are environmental pollutants of the marine compartment. This study investigates the origin of PAH, which is supposed to derive mainly from anthropogenic activities, and their alteration along the salinity gradient of the Baltic Sea. Pyrolysis in combination with gas chromatography and two mass selective detectors in one measurement cycle are utilized as a tool for an efficient trace analysis of such complex samples, by which it is possible to detect degradation products of high molecular structures. Along the north-south transect of the Baltic Sea a slightly rising trend for PAH is visible. Their concentration profiles correspond to the ship traffic as a known anthropogenic source, underlined by the value of special isomer ratios such as phenanthrene and anthracene (0.31-0.45) or pyrene and fluoranthene (0.44-0.53). The detection of naphthalene and the distribution of its alkylated representatives support this statement.

Application of pyrolysis-mass spectrometry and pyrolysis-gas chromatography-mass spectrometry with electron-ionization or resonance-enhanced-multi-photon ionization for characterization of crude oils.

A novel analytical system for gas-chromatographic investigation of complex samples has been developed, that combines the advantages of several analytical principles to enhance the analytical information. Decomposition of high molecular weight structures is achieved by pyrolysis and a high separation capacity due to the chromatographic step provides both an universal as well as a selective and sensitive substance detection. The latter is achieved by simultaneously applying electron ionization quadrupole mass spectrometry (EI-QMS) for structural elucidation and [1+1]-resonance-enhanced-multi-photon ionization (REMPI) combined with time-of-flight mass spectrometry (ToFMS). The system has been evaluated and tested with polycyclic aromatic hydrocarbon (PAH) standards. It was applied to crude oil samples for the first time. In such highly complex samples several thousands of compounds are present and the identification especially of low concentrated chemical species such as PAH or their polycyclic aromatic sulfur containing heterocyclic (PASH) derivatives is often difficult. Detection of unalkylated and alkylated PAH together with PASH is considerably enhanced by REMPI-ToFMS, at times revealing aromatic structures which are not observable by EI-QMS due to their low abundance. On the other hand, the databased structure proposals of the EI-QMS analysis are needed to confirm structural information and isomers distinction. The technique allows a complex structure analysis as well as selective assessment of aromatic substances in one measurement. Information about the content of sulfur containing compounds plays a significant role for the increase of efficiency in the processing of petroleum.

Investigating the need for complex vs. simple scenarios to improve predictions of aquatic ecosystem exposure with the SoilPlus model.

A spatially-explicit version of the recent multimedia fate model SoilPlus was developed and applied to predict the runoff of three pesticides in a small agricultural watershed in north-eastern Italy. In order to evaluate model response to increasing spatial resolution, a tiered simulation approach was adopted, also using a dynamic model for surface water (DynA model), to predict the fate of pesticides in runoff water and sediment, and concentrations in river water. Simulation outputs were compared to water concentrations measured in the basin. Results showed that a high spatial resolution and scenario complexity improved model predictions of metolachlor and terbuthylazine in runoff to an acceptable performance (R(2) = 0.64-0.70). The importance was also shown of a field-based database of properties (i.e. soil texture and organic carbon, rainfall and water flow, pesticides half-life in soil) in reducing the distance between predicted and measured surface water concentrations and its relevance for risk assessment.

Effect of vegetative filter strips on herbicide runoff under various types of rainfall.

Narrow vegetative filter strips proved to effectively reduce herbicide runoff from cultivated fields mainly due to the ability of vegetation to delay surface runoff, promote infiltration and adsorb herbicides. A field trial was conducted from 2007 to 2009 in north-east Italy in order to evaluate the effectiveness of various types of vegetative filter strips to reduce spring-summer runoff of the herbicides mesotrione, metolachlor and terbuthylazine, widely used in maize, and to evaluate the effect of the rainfall characteristics on the runoff volume and concentration. Results show that without vegetative filter strip the herbicide load that reaches the surface water is about 5-6 g ha(-1)year(-1) for metolachlor and terbuthylazine (i.e. 0.5-0.9% of the applied rate), confirming that runoff from flat fields as in the Po Valley can have a minor effect on the water quality, and that most of the risk is posed by a few, or even just one extreme rainfall event with a return period of about 25-27 years, causing runoff with a maximum concentration of 64-77 µg L(-1). Mesotrione instead showed rapid soil disappearance and was observed at a concentration of 1.0-3.8 µg L(-1) only after one extreme (artificial) rainfall. Vegetative filter strips of any type are generally effective and can reduce herbicide runoff by 80-88%. Their effectiveness is steady even under severe rainfall conditions, and this supports their implementation in an environmental regulatory scheme at a catchment or regional scale.

Accumulation and distribution pattern of macro- and microelements and trace elements in Vitis vinifera L. cv. Chardonnay berries.

This paper describes the accumulation pattern of 42 mineral elements in Vitis vinifera L. berries during development and ripening and their distribution in berry skin, seeds, and flesh around harvest time. Grape berries were sampled in two different vineyards with alkaline soil and analyzed using a ICP-MS. Although elemental amounts were significantly different in the grapes from the two vineyards, the accumulation pattern and percentage distribution in different parts of the berries were generally quite similar. Ba, Eu, Sr, Ca, Mg, Mn, and Zn accumulate prior to veraison. Al, Ce, Dy, Er, Ga, Gd, Ho, La, Nd, Pr, Sm, Sn, Zr, Th, Tm, U, Y, and Yb accumulate mainly prior to veraison but also during ripening. Ag, As, B, Cd, Cs, Cu, Fe, Ge, Hg, K, Li, Na, P, Rb, Sb, Se, and Tl accumulate progressively during growth and ripening. With regard to distribution, Ba, Ca, Eu, Fe, Mn, P, Sr, and Zn accumulate mainly in the seeds, Al, B, Ga, Sn, and the rare earths analyzed, except for Eu, accumulate mainly in the skin, and Ag, As, Cd, Cs, Cu, Ge, Hg, K, Li, Mg, Na, Rb, Sb, Se, Th, Tl, U, and Zr accumulate mainly in the flesh. A joint representation of the accumulation and distribution patterns for the elements in the berry is also given.

Chemical elemental distribution and soil DNA fingerprints provide the critical evidence in murder case investigation.

BACKGROUND: The scientific contribution to the solution of crime cases, or throughout the consequent forensic trials, is a crucial aspect of the justice system. The possibility to extract meaningful information from trace amounts of samples, and to match and validate evidences with robust and unambiguous statistical tests, are the key points of such process. The present report is the authorized disclosure of an investigation, carried out by Attorney General appointment, on a murder case in northern Italy, which yielded the critical supporting evidence for the judicial trial. METHODOLOGY/PRINCIPAL FINDINGS: The proportional distribution of 54 chemical elements and the bacterial community DNA fingerprints were used as signature markers to prove the similarity of two soil samples. The first soil was collected on the crime scene, along a corn field, while the second was found in trace amounts on the carpet of a car impounded from the main suspect in a distant location. The matching similarity of the two soils was proven by crossing the results of two independent techniques: a) elemental analysis via inductively coupled plasma mass spectrometry (ICP-MS) and optical emission spectrometry (ICP-OES) approaches, and b) amplified ribosomal DNA restriction analysis by gel electrophoresis (ARDRA). CONCLUSIONS: Besides introducing the novel application of these methods to forensic disciplines, the highly accurate level of resolution observed, opens new possibilities also in the fields of soil typing and tracking, historical analyses, geochemical surveys and global land mapping.

Effect of pesticide inoculation, duration of composting, and degradation time on the content of compost fatty acids, quantified using two methods.

Compost biobeds can promote biodegradation of pesticides. The microbial community structure changes during the composting process, and simple methods can potentially be used to follow these changes. In this study the microbial identification (MIDI) and ester-linked (EL) procedures were used to determine the composition of fatty acid methyl esters (FAMEs) in composts aged 3 and 12 months, inoculated with 3 recalcitrant pesticides (azoxystrobin, chlorotoluron, and epoxyconazole and a coapplication of all three) after 0, 56, and 125 days of degradation. Pesticide persistence was high, and after 125 days the residue was 22 to 70% of the applied amount depending mostly on the composting age. Seventy-one FAMEs belonging to nine groups were detected. The EL method provided three times as many detections as did the MIDI method and was more sensitive for all FAME groups except alcohol. Thirty-six and five FAMEs were unique to the EL and MIDI methods, respectively. The extraction method was of importance. The EL method provided a higher number of detections for 57 FAMEs, and the MIDI method provided a higher number for 9 FAMEs, while the two methods were equal for 5 FAMEs; thus, the EL method provided a more uniform overall FAME profile. Effects of the other factors were not always clear. Inoculation with pesticide did not influence the FAME profile with the MIDI method, while it influenced cyclopropane and monounsaturated content with the EL method. Composting age and degradation time had an effect on some groups of FAMEs, and this effect was greater with the EL method. The use of some FAMEs as biomarkers to follow microbial community succession was likely influenced by the type of compost and other factors.

Estimating ecotoxicological effects of pesticide drift on nontarget arthropods in field hedgerows.

When hedgerows grow in orchards where pesticides are applied, they can play a double role: Providing a barrier for chemical spray drift and as a refuge for beneficial arthropods such as pollinators and predators. Effectiveness of hedgerows as barriers to drift depends mainly on canopy density (that can be estimated through optical porosity) and wind speed. When optical porosity is low, the hedgerow can intercept a significant amount of spray drift and act as an effective barrier, but the intercepted pesticide can negatively affect the beneficial arthropods living there. A drift model was used to simulate drift in a hedgerow- vineyard system, and a deposition distribution model was used to calculate the pesticide spatial pattern distribution on a hedgerow with different optical porosity and wind speed conditions. The possible ecotoxicological effects were estimated for 28 active ingredients with different median lethal rates for two nontarget arthropods, Aphidius rhopalosiphi and Typhlodromus pyri. A spatialized risk assessment for a hedgerow is suggested to improve procedures based on application rate, standard drift, and vegetation distribution values, as in the hazard quotient approach. An alternative method for calculation of the exposure is also proposed, with a step-by-step example of a toxicity/exposure ratio calculation. The results highlighted the importance of the spatial pattern of drift and proved that a hedgerow can be an effective barrier against spray drift. Analysis of the toxicity/exposure ratio values showed that a hedgerow can continue its shelter and feeding function for nontarget arthropods when low-toxicity pesticides are used, there is no significant wind interference, or both.

Predicting pesticide environmental risk in intensive agricultural areas. I: Screening level risk assessment of individual chemicals in surface waters.

A GIS-based procedure for assessing and mapping pesticide ecotoxicological risk for surface waters was applied to all active ingredients used in a catchment characterized by intensive agriculture. Chemical concentrations in riverwaterwere calculated for 54 chemicals in 25 drift and 21 runoff events that occurred during the growing season, from March to September. Screening level risk for the aquatic community was estimated using a risk index. The different role of drift and runoff processes, as well as the temporal trends of exposure and risk, were compared for the three classes of pesticides (herbicides, fungicides, and insecticides). High levels of risk are usually associated with runoff events for herbicides and to drift events for insecticides and fungicides. The described approach may serve as a powerful tool for a comparative evaluation of site-specific pesticide risk for surface water. However, for large-scale risk mapping, getting information on pesticide use with sufficient detail would be the major problem.

Predicting pesticide environmental risk in intensive agricultural areas. II: Screening level risk assessment of complex mixtures in surface waters.

In a previous article, a procedure for assessing pesticide ecotoxicological risk for surface water was applied to all active ingredients in a pilot basin. This data set has been used to assess the composition of pesticide mixtures that are likely to be present in surface waters as a consequence of pesticide emissions from the crops grown within the basin (maize, soybean, sugar beet, and vineyard). Temporal evolution of the mixture composition has been evaluated as a function of the different contamination patterns (drift and runoff). Ecotoxicological risk has been assessed for the mixtures released by individual crops and from all the relevant crops cultivated in the basin. The different role of drift and runoff, as well as the temporal trends of exposure and risk are compared. Daphnia is the most affected among the three indicator organisms considered, particularly from drift mixtures after insecticide application on vineyard. The highest risk for algae occurs during runoff events in spring. In most risk events, one or a few chemicals are usually responsible for more than 80% of the toxic potency of the mixture. The CA model for predicting mixture response is assumed to be a reliable approach for assessing risk for ecologically relevant pesticide mixtures.

Terbuthylazine contamination of the aquifer north of Vicenza (north-east Italy).

BACKGROUND AND GOAL: Agricultural practices can affect the quality of aquifers given that they are often located in cropped areas, so significant amounts of pesticides can be found in the water. In particular, triazine herbicides are always carefully checked by the official monitoring systems. The goal of this study was to find the mean concentration of terbuthylazine in an Italian aquifer and to set up a mass balance of this compound. METHODS: Terbuthylazine concentrations in the aquifer were measured in various check-wells during 1998-2004, and the value of censored data were estimated using a Gompertz inverse in order to evaluate the overall mean concentration. The total terbuthylazine load in the recharge area was calculated on the basis of surveys of cropped land and the main weed control techniques applied in the area. Data on aquifer water balance were obtained from previous studies. RESULTS AND DISCUSSION: The herbicide terbuthylazine applied in the recharge zone can be transported by surface water and enter the aquifer. Detected concentrations were always well below the EU drinking water limit and the fraction that can reach the groundwater under normal cropping practices is small, very likely less than 0.2%. RECOMMENDATIONS AND OUTLOOK: The use and application rates of pesticides should be strictly regulated in recharge areas. Vegetated buffer strips can mitigate the impact of herbicides on surface water through reducing drift and early-spring runoff. Attention should also be paid to the fate of the main metabolites from soil biochemical processes.

Experimental validation of a geographical information systems-based procedure for predicting pesticide exposure in surface water.

A GIS-based procedure for predicting pesticide exposure in surface waters has been applied on a pilot river basin characterized by intensive agricultural activity. The predictive approach has been validated through experimental monitoring, performed by collecting manual and automatic water samples during the productive season. Five active ingredients (terbuthylazine, metolachlor, alachlor, linuron, fenitrothion) were selected for analysis to validate the predictive approach. Comparison between predicted and experimental values showed good agreement for terbuthylazine and metolachlor (used in large volumes within the basin), demonstrating the reliability of the approach. However, some anomalous results were obtained for some of the other chemicals, which serve to highlight the difficulties in getting reliable input data, in particular on application patterns (rate and time). Furthermore, the value of mapping pesticide exposure on the medium-large scale is described, and the limitations of the reported predictive approach are discussed.