Differences in the composition, source, and stability of suspended particulate matter and sediment organic matter in Hulun Lake, China

Abstract

Sediment (SOM) and suspended particulate (SPOM) organic matters are two important organic matters in water. Their occurrence, migration and transformation, and stability have important effects on the environmental behaviors of carbon, nitrogen, phosphorus, and other pollutants in a water environment. The content, composition, fluorescence characteristics, source, and stability of SOM and SPOM in Hulun Lake, a typical lake in cold and arid region of China, were compared by sequential extraction, three-dimensional fluorescence spectroscopy, parallel factor technique, carbon-nitrogen ratio, and stable carbon isotope. SOM and SPOM in north and west were higher than those in east and south. The average content of SPOM (24.70 ± 4.63 g/kg) was slightly higher than that of SOM (23.04 ± 10.27 g/kg), but the difference was not significant. Humin was the dominant component in SOM and SPOM, accounting for 73.7% and 61.2%, respectively. Humus was the main fluorescence component of water-extractable organic matter in SOM and SPOM, accounting for 79.9% and 70.4%, respectively, of the total fluorescence intensity. SOM and SPOM were derived from terrestrial sources with relative contribution rate of about 70%. SPOM was more influenced by autochthonous sources and had significantly lower humification degree and stability than SOM. Effects of climate changes on migration, transformation, stability, and bioavailability of organic matters and endogenous pollutants closely related to organic matters in lakes of cold and arid regions should be paid attention in the future.

The Source, Distribution, and Environmental Effects of Suspended Particulate Matter in the Yangtze River System

“…Autochthonous SPM production is imported from the resuspension of aquatic organisms (such as phytoplankton, zooplankton, and microorganisms) and sediments [58,59]. Moreover, SPM in the aqueous system is greatly affected by autochthonous production [60].…”

“…Schmitt et al (2014) found that in the past 15 years, algal blooms frequently occurred in summer in Taihu Lake, and the accumulation of algal blooms increased the concentration of SPM in the lake [74]. In summer, algae-derived SPM was also shown to dominate in Taihu Lake and Sanwan (Gongshan Bay, Meiliang Bay, and Zhushan Bay) [34], and the occurrence of phytoplankton and algae had a significant impact on the stability of SPM [60]. In addition, a gradual temperature increase can result in rapid phytoplankton growth and an increase in autochthonous SPM in the water column as algal biomass increases [58].…”