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.

Effect of Vegetation Restoration on Soil Humus and Aggregate Stability within the Karst Region of Southwest China

“…In this study, the PAD attained a significant positive correlation with the HMr content in the aggregates of each particle size and attained the highest correlation with the HMr content in >2 mm aggregates, which indicates that the increase in HMr plays a vital role in microaggregate content enhancement. In this study, the MWD achieved a significant positive correlation with the HMr content in large aggregates and a very significant positive correlation with the HMc content in the aggregates of the various particle sizes, indicating that an increase in the contents of these two humus components could enhance the stability of large aggregates, especially the HMc content in large aggregates (>1 mm); moreover, an increase in the HMr content in microaggregates (<0.25 mm) could significantly promote the aggregation and stability of soil particles, which is consistent with the research conclusions of Wang et al [61]. There was no significant correlation between the HMi content in the aggregates of the different particle sizes and stability indicators.…”

“…This conclusion is consistent with the research results of Jovanović et al [35]. The HA content in the undisturbed soil and >2 mm and <0.25 mm aggregates was significantly positively correlated with the content of WSAs and negatively correlated with the RSI and RMI, but the correlation was not significant, indicating that HA accumulation in large aggregates could significantly improve the water stability of aggregates and reduce the sensitivity of aggregates to dissipation to a certain extent, which is consistent with the research results of Wang et al [61]. An increase in the FA content could significantly improve the aggregation degree of soil microaggregates and the content of >0.25 mm water-stable aggregates, reduce the destruction rate of large aggregates, and inhibit the destruction of aggregates via rainwater dissipation.…”