Georgios Zalidis

Use of liquid chromatography/electrospray ionization tandem mass spectrometry to study the degradation pathways of terbuthylazine (TER) by Typha latifolia in constructed wetlands: identification of a new TER metabolite.

S-Triazines are used worldwide as herbicides for agricultural and non-agricultural purposes. Although terbuthylazine (TER) is the second most frequently used S-triazine, there is limited information on its metabolism. For this reason, an analytical method based on liquid chromatography/electrospray ionization tandem mass spectrometry (LC-ESI MS/MS) has been developed aiming at the identification of TER and its five major metabolites (desisopropyl-hydroxy-atrazine, desethyl-hydroxy-terbuthylazine, desisopropyl-atrazine, hydroxy-terbuthylazine and desethyl-terbuthylazine) in constructed wetland water samples. The separation of TER and its major metabolites was performed by reversed-phase high-performance liquid chromatography (HPLC) on a C(8) column using a gradient elution of aqueous acetic acid 1% (solvent A) and acetonitrile (solvent B), followed by MS/MS analysis on a triple quadrupole mass spectrometer. The data-depended analysis (DDA) scan approach has been employed and the main degradation pathways of both hydroxyl and chloro (dealkylated and alkylated) metabolites are elucidated through the tandem mass spectral (MS/MS) interpretation of triazine fragments under CID conditions. In addition, another major metabolite of TER, namely N2-tert-butyl-N4-ethyl-6-methoxy-1,3,5-triazine-2,4-diamine, has been identified. This methodology can be further employed in biodegradation studies of TER, thus assisting the assessment of its environmental impact.

Wetland Rehabilitation in the Mediterranean Basin

The wetlands of the Mediterranean basin are predominantly at low altitudes and many of them are coastal (Hollis and Jones 1991) (Figure 1). There are about 1,200,000 ha of natural lakes and marshes, 600,000-650,000 ha of coastal lagoons, and up to 1,000,000 ha of artificial wetlands, mostly inland reservoirs-a total of about 2,850,000 ha (Pearce and Crivelli 1994).

Determination of herbicide terbuthylazine and its major hydroxy and dealkylated metabolites in constructed wetland sediments using solid phase extraction and high performance liquid chromatography-diode array detection

This paper describes the development of a new analytical method for the analysis of the herbicide TER and its degradation products in sediment samples. This method, based on high-performance liquid chromatography with diode-array detection, was validated for the simultaneous determination of TER and its major metabolites, desethylterbuthylazine, desisopropyatrazine, hydroxyterbuthylazine, desethylhydroxyatrazine and desethylhydroxyterbuthylazine. This method includes a cleanup and a solid-phase extraction step, using ultra-pure water and MCX cartridges respectively, with an overall recovery efficiency ranging from 89.3 to 97.9%. The statistical evaluation demonstrates good linearity with correlation coefficients >0.999 and adequate accuracy and precision for all analytes, with% Er and RSD values up to 10.5% and 8.3% respectively. The limit of detection for all substances was found to be 3.3 ng g−1. This method can be employed in remediation studies of TER and its major metabolites in sediments of constructed wetlands leading to useful results for the degradation and dispersion of TER in the vertical profile of wetland sediment substrates.

Simultaneous Determination of Herbicide Terbuthylazine and Its Major Hydroxy and Dealkylated Metabolites in Typha latifolia L. Wetland Plant Using SPE and HPLC-DAD

Abstract The worldwide application of s-Triazines as herbicides for agricultural and nonagricultural purposes, results in a significant environmental pollution. It is necessary to develop sustainable and environmental friendly techniques in order to remediate surface water from the aforementioned organic substances. Phytoremediation with the wetland plant Typha latifolia L. is a technique that could potentially aid the restoration of polluted surface water. However, there is no analytical method for the determination of terbuthylazine (TER) and its metabolites in Typha latifolia L. and the assessment of the effectiveness of such a procedure. For this reason a method based on high performance liquid chromatography with diode array detection was developed and validated for the simultaneous determination of terbuthylazine (TER) and its major degradation products, desethyl-terbuthylazine, desisopropy-atrazine, hydroxy-terbuthylazine, desethyl-hydroxy-atrazine, and desethyl-hydroxy-terbuthylazine. This method includes both a cleanup and a solid phase extraction step (using Florisil and MCX cartridges, respectively) with adequate overall recovery efficiency (71–96%). The statistical evaluation of the method reveals good linearity, accuracy, and precision for the compounds determined, with RSD values not exceeding 10.5%, while the limit of detection for all analytes was found to be 17 ng g−1. This method can be employed in phytoremediation studies of TER by Typha latifolia L. in constructed wetlands.

Development of a UAV system for VNIR-TIR acquisitions in precision agriculture

Adoption of precision agriculture techniques requires the development of specialized tools that provide spatially distributed information. Both flying platforms and airborne sensors are being continuously evolved to cover the needs of plant and soil sensing at affordable costs. Due to restrictions in payload, flying platforms are usually limited to carry a single sensor on board. The aim of this work is to present the development of a vertical take-off and landing autonomous unmanned aerial vehicle (VTOL UAV) system for the simultaneous acquisition of high resolution vertical images at the visible, near infrared (VNIR) and thermal infrared (TIR) wavelengths. A system was developed that has the ability to trigger two cameras simultaneously with a fully automated process and no pilot intervention. A commercial unmanned hexacopter UAV platform was optimized to increase reliability, ease of operation and automation. The designed systems communication platform is based on a reduced instruction set computing (RISC) processor running Linux OS with custom developed drivers in an efficient way, while keeping the cost and weight to a minimum. Special software was also developed for the automated image capture, data processing and on board data and metadata storage. The system was tested over a kiwifruit field in northern Greece, at flying heights of 70 and 100m above the ground. The acquired images were mosaicked and geo-corrected. Images from both flying heights were of good quality and revealed unprecedented detail within the field. The normalized difference vegetation index (NDVI) was calculated along with the thermal image in order to provide information on the accurate location of stressors and other parameters related to the crop productivity. Compared to other available sources of data, this system can provide low cost, high resolution and easily repeatable information to cover the requirements of precision agriculture.

Transport and dissipation study of the herbicide terbuthylazine and its major metabolites in wetland sediment substrates planted with Typha latifolia L

Abstract It is widely recognized that the organic micropollutants, coming from the intensive agricultural use of land, are the major thread against surface and ground water. However, they are an environmental engineering challenge in order to encounter the pollution by the use of constructed wetlands. The aim of this work is the study of the potential transport and dissipation of the herbicide terbuthylazine (TER) and its major hydroxy and dealkylated metabolites at the vertical profile of a constructed wetland sediment substrate, planted with Typha latifolia L., in order to determine the processes and study the possible remediation mechanisms for wetland ecosystems contaminated by the aforementioned substances. The results show that the dissipation of TER exhibits a gradient behavior through depth of the sediment substrate of wetlands and its major degradation products follow the effect of biotic and abiotic mechanisms of degradation in the bioreactor substrate. Moreover, the greater recovery of the herb...

Challenges in Recreational SCUBA Diving in the Mediterranean Sea: Posidonia oceanica Meadows

Posidonia oceanica is an endemic Mediterranean ecosystem which is widely distributed along the Greek coasts, and is considered a biotic index of good water quality. Apart from the ecological interest of Posidonia meadows, these habitats can be an attractive pole for recreational SCUBA diving activities. A total of 255 divers (210 males and 45 females) from diving resorts and diving clubs in Sani region (Chalkidiki, North Aegean Sea, Greece) filled in questionnaires. According to the results, only few divers prefer to dive in Posidonia oceanica beds, mainly due to the lack of knowledge. Posidonia diving appears to be a new challenging destination into the Mediterranean basin and this study examines the possibility to increase the value of Posidonia beds as a diving site. The benefits of this are numerous for both the enhancement of the diving industry and the conservation of natural resources. As a general conclusion, the necessity of an appropriate informing and training procedure, through the pre-dive briefing, is underlined.

Development of a Web-based GIS monitoring and environmental assessment system for the Black Sea: application in the Danube Delta area.

In this paper, the development of a Web-based GIS system for the monitoring and assessment of the Black Sea is presented. The integrated multilevel system is based on the combination of terrestrial and satellite Earth observation data through the technological assets provided by innovative information tools and facilities. The key component of the system is a unified, easy to update geodatabase including a wide range of appropriately selected environmental parameters. The collection procedure of current and historical data along with the methods employed for their processing in three test areas of the current study are extensively discussed, and special attention is given to the overall design and structure of the developed geodatabase. Furthermore, the information system includes a decision support component (DSC) which allows assessment and effective management of a wide range of heterogeneous data and environmental parameters within an appropriately designed and well-tested methodology. The DSC provides simplified and straightforward results based on a classification procedure, thus contributing to a monitoring system not only for experts but for auxiliary staff as well. The examples of the system’s functionality that are presented highlight its usability as well as the assistance that is provided to the decision maker. The given examples emphasize on the Danube Delta area; however, the information layers of the integrated system can be expanded in the future to cover other regions, thus contributing to the development of an environmental monitoring system for the entire Black Sea.