## 1 Introduction  
Organochlorine pesticides (OCPs) are a class of persistent organic pollutants (POPs) used extensively from the 1940s through the 1960s in agriculture and mosquito control. Although they have been prohibited for over 40 years, they and their metabolites still persist, propagate in food chains and have adverse effects on aquatic organisms and human beings [1; 2]. Hexachlorocyclohexanes (HCHs) and dichlororibhenyltrichloroethanes (DDTs) are two classic OCPs that are frequently used as insecticides. Although they were banned in 1983 for agricultural use in China, they still pose a serious threat to human health and aquatic environment because of their historical use and reemissions [3; 4; 5; 6]. Gamma-hexachlorocyclohexane (\(\gamma\)-HCH), also well known as lindane, is one typical isomer of HCHs. It has already been a global environmental problem because of historical use and strong persistence [7].  
\(p\),\(p\)'-dichlorophenylddichloroethylene (\(p\),\(p\)'-DDE), one of the main metabolites of DDT, can exist for decades in soils and aquatic sediments and have adverse effects on humans and the environment [8; 9; 10; 11].  
Sorption is an important mechanism for the interaction between OCPs and natural solids in aquatic environments [12], and it is closely related to the physicochemical properties of solids. Sediment is one of the common natural solids in aquatic environment that can sorb OCPs. The sorption of OCPs by the sediments has already caused great concern because of its importance in the migration and transformation of OCPs [13; 14; 15]. Although many factors affect the distribution and sorption of OCPs, total organic matter content is one of the most important in this regard in the sediments [16].  
Carbonaceous materials (CMs) are one of the main sources of total organic matter in aquatic sediments. Studies over the past two decades have shown that CMs have a key influence on the migration and transformation of organic pollutants in water [17; 18]. Black carbon (BC), usually defined as a CM formed during the incomplete combustion of biomass, is one of the CMs typically found in natural sediments [19]. The possible sources of BC in the sediments (SC) are the burning of nearby agricultural waste, vehicle exhaust emissions, and the burning of fossil fuel [1], which cause the BC to have a more complicated composition. Comparatively speaking, artificially prepared CMs, such as activated carbon (AC) and the BC produced by burning rice straw at 450 (BC450) and 850 \({}^{\circ}\)C (BC850) have relatively simple composition. The differences of physicochemical properties between the four CMs make their sorption characteristics more different. However, studies on the factors affecting the sorption of OCPs on CMs by comparing CMs in natural sediments with artificially prepared CMs are relatively scarce.  
The aims of this study were to investigate the effects of CMs on the sorption of lindane and \(p\),\(p\)'-DDE by the sediments. Lindane and \(p\),\(p\)'-DDE were selected as model OCPs; BC450, BC850, AC, and BC extracted from sediments were selected as model CMs. The physicochemical properties of CMs can have important effects on the sorption of sediments, therefore, these four CMs were compared to select the most suitable and typical one to investigate the effect of CMs on the sorption of lindane and \(p\),\(p\)'-DDE by the sediments.