Dichloroacetamide safeners (e.g., AD-67, benoxacor, dichlormid, and furilazole) are co-applied with chloroacetanilide herbicides to protect crops from herbicide toxicity. While such safeners have been used since the early 1970s, there are minimal data about safener usage, occurrence in streams, or potential ecological effects. This study focused on one of these research gaps, occurrence in streams. Seven Midwestern U.S. streams (five in Iowa and two in Illinois), with extensive row-crop agriculture, were sampled at varying frequencies from spring 2016 through summer 2017. All four safeners were detected at least once; furilazole was the most frequently detected (31%), followed by benoxacor (29%), dichlormid (15%), and AD-67 (2%). The maximum concentrations ranged from 42 to 190 ng/L. Stream detections and concentrations of safeners appear to be driven by a combination of timing of application (spring following herbicide application) and precipitation events. Detected concentrations were below known toxicity levels for aquatic organisms.
With rising demands on water supplies necessitating water reuse, wastewater treatment plant (WWTP) effluent is often used to irrigate agricultural lands. Emerging contaminants, like pharmaceuticals and personal care products (PPCPs), are frequently found in effluent due to limited removal during WWTP processes. Concern has arisen about the environmental fate of PPCPs, especially regarding plant uptake. The aim of this study was to analyze uptake of sulfamethoxazole, trimethoprim, ofloxacin, and carbamazepine in wheat (Triticum aestivum L.) plants that were spray-irrigated with WWTP effluent. Wheat was collected before and during harvest, and plants were divided into grain and straw. Subsamples were rinsed with methanol to remove compounds adhering to surfaces. All plant tissues underwent liquid-solid extraction, solid-phase extraction cleanup, and liquid chromatography-tandem mass spectrometry analysis. Residues of each compound were present on most plant surfaces. Ofloxacin was found throughout the plant, with higher concentrations in the straw (10.2 ± 7.05 ng g ). Trimethoprim was found only on grain or straw surfaces, whereas carbamazepine and sulfamethoxazole were concentrated within the grain (1.88 ± 2.11 and 0.64 ± 0.37 ng g −1 , respectively). These findings demonstrate that PPCPs can be taken up into wheat plants and adhere to plant surfaces when WWTP effluent is spray-irrigated. The presence of PPCPs within and on the surfaces of plants used as food sources raises the question of potential health risks for humans and animals.
Agricultural
production and associated applications of nitrogen
(N) fertilizers have increased dramatically in the last century, and
current projections to 2050 show that demands will continue to increase
as the human population grows. Applied in both organic and inorganic
fertilizer forms, N is an essential nutrient in crop productivity.
Increased fertilizer applications, however, create the potential for
more N loss before plant uptake. One strategy for minimizing N loss
is the use of enhanced efficiency fertilizers, fortified with a nitrification
inhibitor, such as nitrapyrin. In soils and water, nitrapyrin inhibits
the activity of ammonia monooxygenase, a microbial enzyme that catalyzes
the first step of nitrification from ammonium to nitrite. Potential
benefits of using nitrification inhibitors range from reduced nitrate
leaching and nitrous oxide emissions to increased crop yield. The
extent of these benefits, however, depends on environmental conditions
and management practices. Thus, such benefits are not always realized.
Additionally, nitrapyrin has been shown to transport off-field, and
it is unknown what effects environmental nitrapyrin could have on
nontarget organisms and the ecological nitrogen cycle. Here, we review
the agronomic and environmental benefits and costs of nitrapyrin use
and present a series of research questions and considerations to be
addressed with future nitrification inhibitor research.
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