Sedimentary records of chironomids and pigments from Poyang Lake (middle Yangtze floodplain, China)

The sedimentary chironomids and pigments in two Yangtze floodplain (China) lake sediment cores since 1800s CE. The sediment cores were dated using lead-210 with the constant rate of supply (CRS) model. Chironomids were ananlyzed following standard procedures. About 10 g wet samples were firstly deflocculated using 10% potassium hydroxide (KOH) in a 75 °C water bath for about 15 minutes. Then, sediments were gently washed through 212 μm and 90 μm sieves with water after which the residues on the sieves were backwashed into a sorting tray. Chironomid head capsules were picked out individually using fine forceps under a dissecting microscope. The chironomid head capsules were identified using a microscope at ×100/×400 magnification. At least 50 head capsules were picked out from each sample to make the results and interpretations statistically robust.