Pharmaceuticals, herbicides, and disinfectants in agricultural water sources.

Agricultural water withdrawals account for the largest proportion of global freshwater use. Increasing municipal water demands and droughts are straining agricultural water supplies. Therefore, alternative solutions to agricultural water crises are urgently needed, including the use of nontraditional water sources such as advanced treated wastewater or reclaimed water, brackish water, return flows, and effluent from produce processing facilities. However, it is critical to ensure that such usage does not compromise soil, crop, and public health. Here, we characterized five different nontraditional water types (n = 357 samples) for the presence of pharmaceuticals, herbicides, and disinfectants using ultra-high-pressure liquid chromatography tandem mass spectrometry based method (UPLC-MS/MS). We then evaluated whether the levels of these contaminants were influenced by season. The highest level of herbicides (atrazine) was detected in untreated pond water (median concentration 135.9 ng/L). Reclaimed water had the highest levels of antibiotics and stimulants including azithromycin (215 ng/L), sulfamethoxazole (232.1 ng/L), and caffeine (89.4 ng/L). Produce processing plant water also tended to have high levels of atrazine (102.7 ng/L) and ciprofloxacin (80.1 ng/L). In addition, we observed seasonal variability across water types, with the highest atrazine concentrations observed during summer months, while the highest median azithromycin concentrations were observed in reclaimed water during the winter season. Further studies are needed to evaluate if economically feasible on-farm water treatment technologies can effectively remove such contaminants from nontraditional irrigation water sources.

Impact of high precipitation and temperature events on the distribution of emerging contaminants in surface water in the Mid-Atlantic, United States.

Extreme weather events induced by climate change have potential to impact water quality and have received increasing attention from surface water source management perspectives. However, it remains unclear how such phenomenon may influence concentration of emerging contaminants (ECs) in surface water that are vital source of irrigation. In the present study, we investigated the impact of high precipitation and ambient temperature on the distribution of ECs in surface water samples (N = 250) from Mid-Atlantic region, collected between 2016 and 2018. We analyzed the water samples using a liquid chromatography tandem mass spectrometry (LC-MS/MS) based method. We then investigated how the detection frequencies and concentrations of ten emerging contaminants were influenced by high precipitation and temperature events in the previous day or 7 days prior to the sampling events using a generalized additive model (GAM). We observed that heavy rainfalls occurring within 24 h before sampling increased the concentration/likelihood of detection of the ECs in surface waters, likely due to surface runoffs, remobilization from soil/sediment and sewage overflows. The impact of high precipitation during previous seven days varied across chemicals. Likewise, the detection frequency and concentration of most analytes increased with increasing temperature, in previous day of sampling event, likely due to enhanced solubility in water. Long-term high temperature events appeared to decrease the detection of the most tested ECs probably due to enhanced degradation. However, the potential risk of unknown degradation products cannot be ignored. Our results indicate potential decline of water quality after extreme weather events which may have implications for water source management under changing climate.

Antibiotic and herbicide concentrations in household greywater reuse systems and pond water used for food crop irrigation: West Bank, Palestinian Territories.

Greywater is increasingly treated and reused for agricultural irrigation in off-grid communities in the Middle East and other water scarce regions of the world. However, there is a dearth of data regarding levels of antibiotics and herbicides in off-grid greywater treatment systems. To address this knowledge gap, we evaluated levels of these contaminants in two types of greywater treatment systems on four farms in the West Bank, Palestinian Territories. Samples of household greywater (influent, n = 23), treated greywater effluent intended for agricultural irrigation (n = 23) and pumped groundwater held in irrigation water ponds (n = 12) were collected from October 2017 to June 2018. Samples were analyzed using high performance liquid chromatography tandem mass spectrometry (LC-MS/MS) for the following antibiotics and herbicides: alachlor, ampicillin, atrazine, azithromycin, ciprofloxacin, erythromycin, linezolid, oxacillin, oxolinic acid, penicillin G, pipemidic acid, sulfamethoxazole, triclocarban, tetracycline, triflualin, and vancomycin. All tested antibiotics and herbicides were detected in greywater influent samples at concentrations ranging from 1.3 to 1592.9 ng/L and 3.1-22.4 ng/L, respectively. When comparing influent to effluent concentrations, removal was observed for azithromycin, alachlor, linezolid, oxacillin, penicillin G, pipemidic acid, sulfamethoxazole, triclocarban, and vancomycin. Removal was not observed for atrazine, ciprofloxacin, erythromycin, oxolinic acid, tetracycline, and trifluralin. Pond water also contained the majority of tested contaminants, but at generally lower concentrations. To our knowledge, this is the first description of an extensive array of antibiotics and herbicides detected in household greywater from off-grid treatment systems.

Water ingestion during water recreation.

Quantitative risk assessments have estimated health risks of water recreation. One input to risk assessment models is the rate of water ingestion. One published study estimated rates of water ingestion during swimming, but estimates of water ingestion are not available for common limited contact water recreation activities such as canoeing, fishing, kayaking, motor boating, and rowing. In the summer of 2009 two related studies were conducted to estimate water ingestion during these activities. First, at Chicago area surface waters, survey research methods were utilized to characterize self-reported estimates of water ingestion during canoeing, kayaking, and fishing among 2705 people. Second, at outdoor swimming pools, survey research methods and the analysis of cyanuric acid, a tracer of swimming pool water, were used to characterize water ingestion among 662 people who engaged in a variety of full-contact and limited-contact recreational activities. Data from the swimming study was used to derive translation factors that quantify the volume of self-reported estimates. At surface waters, less than 2% of canoers and kayakers reported swallowing a teaspoon or more and 0.5% reported swallowing a mouthful or more. Swimmers in a pool were about 25-50 times more likely to report swallowing a teaspoon of water compared to those who participate in limited-contact recreational activities on surface waters. Mean and upper confidence estimates of water ingestion during limited-contact recreation on surface waters are about 3-4 mL and 10-15 mL, respectively. These estimates of water ingestion rates may be useful in modeling the health risks of water recreation.