Degradation studies of herbicides used in rice cultivation

Rice, like other important cereals, requires a great amount of chemicals, represented especially by fertilizers and pesticides. Nowadays, pesticides formulations are designed to offer a higher selectivity and a lower persistence in the environment than the formulations used in the past. But, unlikely, a lower persistence in the environment does not necessarily correspond to a lower toxicity. In fact, it has been demonstrated that many chemicals often undergo natural degradation reactions in the environment that may lead to the formation of new species potentially more toxic and stable than the precursors [1-3]. In the present study, Imazamox, Oxadiazon and Profoxydim that are the most important herbicides used in rice cultivation of Italy were undergone to degradation studies simulating natural environmental conditions. Aqueous solutions of the species both in mix and alone were exposed to sun light irradiation in a solarbox. Also hydrolysis processes were studied preserving the solutions at dark. At prefixed times, the solutions were analyzed by using a micro liquid chromatography system interfaced to a quadrupole-time of flight (QTOF) high resolution mass spectrometer. LC-MS analysis of the samples undergone to sunlight irradiation showed a decreased intensity of the herbicide signals, more evident than in the case of the hydrolysis processes. The kinetics of the degradation were evaluated and the degradation products were also investigated by LC-MS/MS analysis. This research has been supported by Fondazione Cariplo, grant n. 2014-1260

Non target approach for the identification of degradation products of herbicides used in rice cultivation

Nowadays pesticides of recent formulation are designed to offer higher selectivity and lower persistence in the environment than the formulations used in the past. However a lower persistence in the environment does not necessarily correspond to a lower toxicity since the pesticides undergo natural degradation reactions in the environment and new species potentially more toxic can be formed [1-4]. In this study some of the most important herbicides used in Italy in rice cultivation (imazamox, oxadiazon and profoxydim) were undergone to degradation studies simulating natural environmental conditions. To this aim: a) aqueous solutions of the species were exposed to simulated sun light irradiation in a solarbox; b) hydrolysis processes were studied preserving the solutions at dark. At prefixed times, the solutions were analyzed by using a micro liquid chromatography system interfaced to a quadrupole-time of flight (QTOF) high-resolution mass spectrometer. LC-MS/MS analyses of the samples undergone to sunlight irradiation showed a decreased intensity of the herbicide signals. Instead, no hydrolysis effect was evidenced in samples stored at the dark for three months. Moreover, solutions prepared in ultrapure water showed different degradation rates with respect to those prepared in paddy water. The LC-MS/MS analyses were carried out by using a non-target approach without any a priori knowledge of the possible species formed during the degradation process of the herbicides. All the MS/MS spectra were recorded without prefixed criteria with the help of the SWATHTM (Sequential Window Acquisition of all THeoretical Mass Spectra) acquisition method, and were used to elucidate the chemical structures of the predominant degradation products. This research has been supported by Fondazione Cariplo, grant n. 2014-1260

Monitoring of water quality inflow and outflow of a farm in Italian Padana plain for rice cultivation: a case study of two years

Rice cultivation requires a large use of pesticides and nutrients to control weed proliferation and improve production. The water quality of four neighboring rice fields located in the Lomellina area (Italian Padana plain) was monitored in this study along with the cultivation period (before, during, and after the period of planting), for two successive agricultural seasons (2015 and 2016). Two paddy fields were traditionally cultivated with wet-seeding and the other fields with dry-seeding. Eighteen sampling points were considered: eight points for surface water, two points for underground water, and eight points for porous cups with two different depths. In order to evaluate the goodness of the paddy field system to maintain unchanged the quality of the inflow with respect to the outflow water, three of the most used herbicides in Italian rice cultivation (imazamox, oxadiazon, and profoxydim) and other physical-chemical parameters were determined, namely biological oxygen demand after 5 days; chemical oxygen demand; total suspended solids; anionic surfactants; total hardness; total amount of phosphorus, nitrogen, and potassium; and heavy metal concentrations. In general, all the collected data confirmed that paddy fields did not contribute to worsen the environmental pollution. The different flooding techniques adopted in the fields did not highlight significant differences in concentrations of pesticides or metals. The pesticides reached their maximum concentration (of the magnitude order of few ng mL(-1)) on the day after the administration and on the day after the application in the adjacent field. A slight reduction of total As in grain was obtained adopting a dry period from steam elongation up to booting. From the collected data, it was possible to identify a general water flow direction in the paddy fields from north-west to south-east: this prevailing flow direction was useful to understand not only the diffusion of the pesticides and their degradation products in the fields but also that of the nutrients. Concerning nutrients, it was important not to activate a recirculation of the water in the field during the first 10 days from the administration, in order to avoid loss of nitrogen in the water vents or for percolation. Moreover, the monitoring of potassium concentration allowed to avoid the use of unnecessary potassic fertilization when there was already a high amount of this element in the paddy field derived from irrigation. However, all the investigated water quality parameters were under the limits fixed by the European regulation. In addition, the presence of seven unexpected compounds was identified by the nontarget approach in both campaigns in samples collected in the early summer period. Four of these emerging contaminants were identified as N, N-diethyl-meta-toluamide, tricyclazole, amidosulfuron, and one of the imazamox photodegradation products. Although the obtained low concentrations of oxadiazion, tricyclazole, and arsenic, in particular, justified a preexisting contamination of the water inflow or of the investigated paddy area, the obtained results supported the good quality of the paddy water outflow, confirming the rational use of the water resource and the correct use of agronomic practices

Imazamox loads in irrigation tailwaters and percolation fluxes from paddy fields in northern Italy

Italy is the Europe leading rice producer, with more than half of the total production and a high quality level. Although the main function of paddy areas is the production of rice, these complex agro-ecosystems are linked to issues of great concern such as the freshwater conservation in terms of both water consumption and water quality. An intensive experimental activity was started in 2015, in the framework of the WATPAD project (Fondazione Cariplo, Grant No 2014-1260), to investigate the water balance terms and the water quality impacts on surface water and groundwater of four paddy fields located in Lomellina (western part of the Po river plain). A different irrigation management was adopted for the four paddies: wet seeding and continuous flooding (WFL) was applied within two fields, while dry-seeding and delayed flooding was adopted for the other two paddies. The four fields were instrumented with devices measuring irrigation inflows and outflows, water level in the fields, soil moisture and groundwater depths. Additionally, in each field, three couples of porous cups were installed at depths of 25 and 60 cm. Water samples of irrigation inflows and outflows, water in porous cups, and groundwater were collected along the agricultural season (26 sampling dates in 2015). Water samples were analyzed for various compounds, including the herbicide Imazamox and its degradation products. The contemporaneous quantification of water fluxes and Imazamox concentrations allowed the determination of Imazamox loads released in surface waters and groundwater along the agricultural season for each field. The main findings, which will be discussed in the poster, are the following: i) most of the Imazamox loads leave the paddies through percolation; consequently, fields characterized by more permeable soils contribute more to Imazamox concentrations in groundwater; ii) Imazamox loads in surface outflows are modest, as the half-life of Imazamox in surface waters reached by solar radiation is very low; iii) from the data available to date (agricultural season 2015) Imazamox concentrations in porous cups may seem to be influenced from the concomitant use of fertilizer products. In particular, it is known from the literature that the degradation of Imazamox is pH and oxygen dependent; thus, the use of fertilizers having an effect on these water parameters could influence the Imazamox persistence in the field, favoring its transport to groundwater; iv) more research is needed to investigate the eventual field interaction between Imazamox and the use of fertilizers, as well as to monitor the environmental fate of Imazamox degradation products

Primary squamous cell carcinoma of the thyroid diagnosed as anaplastic carcinoma: failure in fine-needle aspiration cytology?

A case of primary squamous-cell carcinoma (SCC) of the thyroid which had been initially diagnosed as an anaplastic carcinoma (ATC) is described: female, 73 years old, with a fast-growing cervical nodule on the left side and hoarseness for 3 months. Ultrasonography showed a 4.5 cm solid nodule. FNA was compatible with poorly differentiated carcinoma with immunoreactivity for AE1/AE3, EMA. Thyroidectomy was performed. Histopathological examination showed a nonencapsulated tumor. Immunohistochemistry disclosed positivity for AE1/AE3, p53,p63, and Ki67. The diagnosis was ATC. A second opinion reported tumor consisting of squamous cells, with intense inflammatory infiltrate both in tumor and in the adjacent thyroid, with final diagnosis of SCC, associated with Hashimoto thyroiditis. No other primary focus of SCC was found. Patient has shown a 48-month survival period. Clinically, primary SCCs of the thyroid and ATCs are similar. The distinction is often difficult particularly when based on the cytological analysis of FNA material