Identifying the Causes of Sediment-Associated Toxicity in Urban Waterways of the Pearl River Delta, China

Abstract

Twenty-one sediments collected in urban waterways of the Pearl River Delta (PRD) in China were screened for acute toxicity using Chironomus dilutus in addition to being examined for potential contributors of sediment toxicity, including 19 organochlorine, five organophosphate, and nine pyrethroid insecticides, 28 polycyclic aromatic hydrocarbons, 27 polychlorinated biphenyls, 15 polybrominated diphenyl ethers, 12 metals, and ammonia. Fifteen of the 21 sediments exhibited acute toxicity to C. dilutus, with 33% of the samples exhibiting 100% mortality. This is one of the first studies in China which directly correlates a broad range of sediment-associated contaminants to ecological effects measured by bioassays. A toxic unit approach showed that pyrethroids contributed most to the observed toxicity; as cypermethrin alone was predicted to cause significant mortality in about half of the sites. Specific toxicity identification evaluation analysis confirmed pyrethroid toxicity. Other contaminants may also be supplemental contributors at a few sites. The current study suggests that pyrethroids are the principal cause of contamination and that future risk assessment and mitigation efforts in this area should focus primarily on pyrethroids but should not disregard other contaminants as potential risk is evident.

Distribution and toxicity of current-use insecticides in sediment of a lake receiving waters from areas in transition to urbanization

“…It suggested that the riverine input of Zhigao River is an important source of OPs, and it was consistent to a previous finding which reported elevated concentrations of dichlorodiphenyltrichloroethane and its metabolites in water adjacent to Zhigao River and claimed Zhigao River played a key role in insecticides' transport to Chaohu Lake . Generally higher OP concentrations were detected in sediment near the lake shore, and the lowest Holmes et al, 2008;Trimble et al, 2009), Illinois (Ding et al, 2010), and Texas (Hintzen et al, 2009) in USA, the Pearl River Delta Mehler et al, 2011), and Chaohu Lake (the current study) in China.…”

Inter-compartmental transport of organophosphate and pyrethroid pesticides in South China: Implications for a regional risk assessment

“…Current-use pesticides (CUPs), such as organophosphates and pyrethroids, have recently been detected in various environmental compartments worldwide (Gan et al, 2005;Hintzen et al, 2009;Li et al, 2013aLi et al, , 2014Mehler et al, 2011;Weston et al, 2005, however, little information is available on their transport within ecosystems. While transport of chlorpyrifos, an organophosphate, has been reported in an airewater system (Harman-Fetcho et al, 2000;Luo and Zhang, 2009;Zhong et al, 2012), studies detailing the transport of pyrethroids have been limited to surface runoff (Gan et al, 2005;.…”

Joint toxicity of a pyrethroid insecticide, cypermethrin, and a heavy metal, lead, to the benthic invertebrate Chironomus dilutus

“…As a result, detection frequency and concentrations of pyrethroid residues have become elevated in the environment [1][2][3][4]. Because of their hydrophobicity, pyrethroids tend to bind to sediment after entering aquatic systems and may contribute more to sediment-associated toxicity than legacy insecticides [5][6][7][8][9][10][11]. A recent study reported that pyrethroids were responsible for approximately 70% of the observed toxicity of sediments collected in urban waterways in the Pearl River Delta (PRD), China [11].…”

“…Because of their hydrophobicity, pyrethroids tend to bind to sediment after entering aquatic systems and may contribute more to sediment-associated toxicity than legacy insecticides [5][6][7][8][9][10][11]. A recent study reported that pyrethroids were responsible for approximately 70% of the observed toxicity of sediments collected in urban waterways in the Pearl River Delta (PRD), China [11]. Of the various pyrethroids that were analyzed, cypermethrin was the most commonly detected and attributed the most risk to benthic organisms in the PRD sediments [4,11].…”

“…A recent study reported that pyrethroids were responsible for approximately 70% of the observed toxicity of sediments collected in urban waterways in the Pearl River Delta (PRD), China [11]. Of the various pyrethroids that were analyzed, cypermethrin was the most commonly detected and attributed the most risk to benthic organisms in the PRD sediments [4,11]. Not surprisingly, recent work has also reported cypermethrin to be one of the two most frequently used pyrethroids in much of Asia [12].…”