Occurrence and distribution of OCPs and PAHs in water, soil and sediment of Daye lake

To elucidate the concentrations, spatial distribution, sources, and risk of sixteen polycyclic aromatic hydrocarbons (PAHs) and twenty-four organochlorine pesticides (OCPs), thirteen sites were chosen for collecting water, sediment, and soil samples from Daye lake in April 2019. All pollutants were frequently observed in three media of Daye lake. Higher concentrations of OCPs were determined in the soil whereas PAHs were dominant among sediment samples. However, the water of Daye lake is contaminated with both of the pollutants. In water, sigma DRINs, sigma DDTs, sigma HCHs and LMW PAHs accounted for 22.1%, 19.6%, 17.9% and 85.5%, respectively. Among sediments, OCPs and PAHs were ranged from 1.53-51.38 ng.g- 1 and 14.38-4659.66 ng.g- 1, respectively. While soil accounted for a larger percentage of heptachlorepoxide i.e. 96.5% and HMW PAHs i.e. 82.7%. Furthermore, the low alpha-to gamma-HCH ratio suggested fresh input of HCH and the higher ratio of (DDE + DDD)/DDT determined the historical use of DDT. Additionally, diagnostic molecular ratio along with principal component analysis evaluated that PAHs mainly came from fossil fuel, biomass, and coal combustion. Moreover, ecological risk assessment of Daye lake indicated that the carcinogenic PAHs in water and soil can pose 10% risk to the environment also OCPs in sediments has a visible effect on ecology. According to incremental lifetime cancer risks (ILCRs) evaluation, OCPs have negligible to low cancer risk among all sites for water, soil, and sediments while PAHs value fluctuate in the midst of 10-6 to 10-2 which shows the potential risk of cancer on children as well as adults. Therefore, measures should be taken to control them in time.

Automated summary

The study revealed the presence of various organic pollutants in the water, sediment, and soil of Daye lake, with OCPs and PAHs being the main contaminants. Furthermore, the study found that these pollutants mainly originate from fossil fuels, biomass, and coal combustion. Ecological risk assessment of Daye lake indicated that carcinogenic PAHs in water and soil pose a 10% risk to the environment, while OCPs in sediments have a visible impact on ecology.