Selected current‐use and historic‐use pesticides in air and seawater of the Bohai and Yellow Seas, China

Abstract

Consumption of pesticides in China has increased rapidly in recent years; however, occurrence and fate of current-use pesticides (CUPs) in China coastal waters are poorly understood. Globally banned pesticides, so-called historic-use pesticides (HUPs), are still commonly observed in the environment. In this work, air and surface seawater samples taken from the Bohai and Yellow Seas in May 2012 were analyzed for CUPs including trifluralin, quintozene, chlorothalonil, dicofol, chlorpyrifos, and dacthal, as well as HUPs (hexachlorobenzene (HCB), hexachlorocyclohexanes (HCHs), and endosulfan). CUP profile in both air and seawater samples generally reflected their consumption patterns in China. HUPs in the air and seawater samples were in comparable levels as those of CUPs with high concentrations. α-Endosulfan, dicofol, and chlorothalonil showed strong net deposition likely resulting from their intensive use in recent years, while CUPs with low consumption amount (quintozene and dacthal) were close to equilibrium at most samplings sites. Another CUP with high usage amout (i.e., chlorpyrifos) underwent volatilization possibly due to its longer half-life in seawater than that in air. α-HCH and γ-HCH were close to equilibrium in the Bohai Sea, but mainly underwent net deposition in the Yellow Sea. The net deposition of α-HCH could be attributed to polluted air pulses from the East China identified by air mass back trajectories. β-HCH showed net volatilization in the Bohai Sea, which was driven by its relative enrichment in seawater. HCB either slightly favored net volatilization or was close to equilibrium in the Bohai and Yellow Seas.

Spatial distribution and seasonal variation of four current-use pesticides (CUPs) in air and surface water of the Bohai Sea, China

“…Spatial distribution and seasonal trends of most pesticides were observed in previous studies in air (Coscollà et al, 2014;Scheyer et al, 2007;Yao et al, 2008b;Yao et al, 2006) and seawater (Bigot et al, 2016;Mai et al, 2013). The same area was studied in May 2012 for trifluralin, chlorothalonil, chlorpyrifos, dicofol and 10 additional contaminants (Zhong et al, 2014). Our work further deepened the previous research and were filled the gap about seasonal variations in the Bohai Sea.…”

“…Glass microfiber filters (Whatman™, GF/F, diameter 150 mm) were used to collect particulate samples, followed by a glass column packed with PUF/Amberlite™ XAD-2 for gaseous samples in series (Zhong et al, 2014). Seawater samples were collected from the ship's seawater intake system, which was made of stainless steel and was located in the front of the vessel and 1 m below the waterline.…”

“…An estimated 3.74 million tons of technical pesticide products were produced in 2015, and 1.80 million tons were consumed in 2014 (www.stats.gov.cn). However, few data are available about the distribution and fates of CUPs in the marine environment (Zhong et al, 2014).…”

“…Previous studies have revealed that seawater acts as a major recipient of numerous pesticides through dry or wet atmospheric deposition, riverine discharge, and air-water exchange (Feng et al, 2011;Luek et al, 2017;Mai et al, 2016;Zhong et al, 2011). Riverine inputs could be important sources not only for CUPs with relatively high water solubility, but also for CUPs with low water solubility (Zhong et al, 2014). CUPs can be transported by currents into the offshore and deep ocean regions, and hence threaten coastal and pelagic ecosystems (Carratala et al, 2017;Li et al, 2015;Mai et al, 2013).…”

Exchange of polycyclic aromatic hydrocarbons across the air-water interface in the Bohai and Yellow Seas

“…Sample extraction was conducted strictly following standard analytical methods as reported in detail in the literature Zhong et al, 2014). Three field blanks were run for each sample type (gas phase, air particle phase, seawater dissolved phase and suspended particle phase).…”