Recipient Organization
CONNECTICUT AGRICULTURAL EXPERIMENT STATION
PO BOX 1106
NEW HAVEN,CT 06504
Performing Department
Environmental Sciences
Non Technical Summary
Water scarcity is a problem throughout the modern world and is expected to increase as human population expands and climate change intensifies. Wastewater reuse for agricultural irrigation is an important strategy to reduce demand from surface and ground water sources and is gaining momentum as obtaining freshwater from other sources becomes more difficult. While an important strategy for combating water scarcity, wastewater reuse for agriculture is not without risks. Wastewater can contain higher levels of bacteria, heavy metals, salts, and other contaminants than conventional water sources. Specifically, there is increasing concern over organic microcontaminants (OMCs) such as pharmaceuticals, pesticides, and endocrine disrupting compounds that may be taken up into irrigated crop plants. Designing methods to detect new and emerging OMCs will be increasingly important as water recycling continues to expand.High Resolution Mass Spectrometry (HRMS), often coupled with liquid chromatography (LC), is a new technology that can be used to detect OMCs in water, soil, and food crops. HRMS data can be used for suspect screening, which searches databases of past measurements to find matches for chemicals present in new samples, and for non-targeted analysis (NTA) which identifies features in the data without necessarily matching them to known chemicals. The USFDA and USEPA do not yet have standardized methods for suspect screening and NTA, but use of these types of data analysis could greatly improve recognition of new and unexpected OMCs in food and in the environment.This project will focus on developing suspect screening and NTA methods for use at the Connecticut Agricultural Experiment Station (CAES) and analyzing crops irrigated with recycled water. The first portion of the project will focus on substantial method development and validation experiments with LC-HRMS, and the second portion will be a greenhouse experiment where we grow and compare tomatoes, celery, and lettuce irrigated with fresh water and recycled wastewater. We will measure OMC and heavy metal accumulation in the plants and also assess plant health. At CAES, we have the knowledge and resources available to develop and implement these methods, and to grow crops and assess plant health effects. Our project will result in knowledge and publications about new analytical methods, as well as the effects of water reuse for agricultural irrigation.
Animal Health Component
10%
Research Effort Categories
Basic
30%
Applied
10%
Developmental
60%
Goals / Objectives
This project will focus on developing liquid chromatography - high resolution mass spectrometry based suspect screening and non-targeted analysismethods for use at the Connecticut Agricultural Experiment Station and analyzing the effects of irrigation with recycled water on crop plants. Our project will result in knowledge and publications about new analytical methods, as well as the effects of water reuse for agricultural irrigation.Objective 1: Developand evaluatesuspect screening and non-targeted analysis methods for crop plants, soils, and recycled water.Objective 2: Investigate organic microcontaminant and heavy metal accumulation by crop plants irrigated with recycled water and relate the results to effects on plant health.
Project Methods
Objective 1:We will develop computational, analytical, and sample preparation methods for conducting suspect screening and non-targeted analysis (NTA) at the Connecticut Agricultural Experiment Station (CAES), and provide a validation framework for similar methods in other labs.The first step will be to ensure we have the computational abilities to conduct suspect screening and NTA. We will conduct three types of computational analysis: internal suspect screening, external suspect screening, and true NTA. Computational method development will require minimal collection of new data. CAES has collected data for many projects already using the orbitrap mass spectrometers, but only targeted data analysis has been done. Non-targeted analysis can be conducted on the same data. We will test our new computational methods by reanalyzing the files to see if our results are comparable. For example, we should be able to use the new suspect screening methods to identify pesticides that were previously spiked into a vegetable sample for targeted, quantitative method development. We will also use our new computational methods to search for additional information about previous samples. For example, we will look for evidence for the presence of pesticides that were not on the analyte lists for previous studies.We will also develop analytical and sample preparation methods for use in this project. We will use the Q-Exactive LC-MS in the CAES Analytical Chemistry department for all data collection and base our instrument methods on those that are commonly used here already. We will create a standard mixture of approximately 50 organic micro contaminants (OMCs) that are commonly found in reclaimed wastewater (including pharmaceuticals, personal care product ingredients, pesticides, disinfection byproducts, and food additives), and ensure that as many as possible can be successfully measured using our instrument method(s). We will develop sample preparation methods for plants, soil, and water, that are as universal as possible, sensitive, and similar to each other. We will conduct tests where our 50 compound mixture is spiked into to water at 10 µg·L-1 and to plant tissue and soil at 10 ng·g-1, and assess our ability to extract and measure the spiked compounds.As a complete method development test, we will have a CAES technician create an "unknown" spiking solution using a subset of compounds in the method development mixture, as well as some that were not included. Plant, soil, and water samples will be fortified with the mixture, then extracted and analyzed using the developed methods. We will then use our internal and external suspect screening methods to determine the compounds included in the spike solution. We will report information about which compounds we can detect, as well as those we cannot and those that we identify as false positives.No extraction and analysis method is truly universal, and we expect there will be compounds on our list of 50 that we are unable to detect. However, knowledge about the limitations of the methods used can help with the suspect screening and NTA process. Some candidate structures matched to detected masses can be eliminated based on knowledge about the detection methods used. Thus, the positive and negative data obtained will be useful as we move forward to studies using the methods developed.Objective 2:We will conduct a greenhouse experiment where we grow and compare tomatoes, celery, and lettuce irrigated with fresh water and recycled wastewater. We will obtain a supply of secondary treated wastewater from the Greater New Haven Area Water Pollution Control Authority. Our irrigation protocol will follow the policies established for recycled water use in California. Plants will be watered with their designated irrigation treatment starting when seeds are first germinated. No-plant controls will also be included for each irrigation treatment. Plants will be grown in field soil obtained from the CAES farm.Plants will be harvested after they produce viable fruit (tomato) or when they reach a standard harvest size for human consumption (celery and lettuce). We will use the methods developed in Objective 1 to analyze for OMCs in the irrigation water, harvested plants (roots, stems, fruit, and leaves), and irrigated soil. We will compare which OMCs are detected in water, soil, and the different plant species via suspect screening, and use NTA to compare the full analyte profile of the different types of samples. Many of the compounds that we detect in plants using our NTA and suspect screening methods will not be OMCs; it is likely we will find many chemicals related to plant health such as hormones and metabolites. Therefore, we will also investigate whether irrigation water affects the levels of any of these detected chemicals using a metabolomics type approach. The metabolomics analysis should provide us with some information about recycled water effects on plant health. We will also use more conventional methods for assessing plant health such as germination rate, emergence time, time to flower/fruit production, plant mass, length, and height, major elemental content, chlorophyll content, oxidative stress, and metabolic enzyme activity. We will also conduct heavy metal analysis on water, plants, and soil using ICP-MS.