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Knowledge of phosphorus (P) components in water is vital to understanding the biogeochemistry of the P cycle, but little information is available about P, especially organic P components in water. We used solution 31 P nuclear magnetic resonance technology ( 31 P NMR) to characterize the classes of dissolved and particulate P compounds, as well as their spatial variation, in eutrophic Lake Taihu, Eastern China. Results showed that orthophosphate and monoesters were the dominant components in dissolved and particulate P. The main difference between the classes of dissolved and particulate P compounds was that phosphonate was detected in dissolved P, whereas pyrophosphate was mainly found in particulate P. The proportions of various classes of P compounds in particulate total P were relatively stable, which may be partly attributed to phytoplankton. In dissolved total P (DTP), the proportions of orthophosphate and monoester varied substantially and were significantly correlated with DTP concentration. According to the source of P and the ratios of dominant classes of P compounds in dissolved and particulate P, the dissolved orthophosphate may be substantially influenced by pollution sources, and other P compounds are mainly controlled by biological transformation processes.

Landscape pattern changes caused by human activities are among the most important driving factors affecting ecosystem spatial structure and components, and significantly impact ecosystem services. Understanding the relationship between landscape patterns and ecosystem services is important for improving regional conservation and establishing ecosystem management strategies. Taking the Huaihe River Basin as an example, this study used land-use data, meteorological data, and topographic data to analyze the spatial and temporal changes in landscape patterns via landscape transfer matrix and landscape indices, and measured four ecosystem services (water retention, soil retention, carbon storage, and biodiversity conservation) with the InVEST models. Furthermore, correlation analysis and global spatial autocorrelation coefficient were used to analyze the impact of landscape pattern changes on ecosystem services. The results showed grassland and farmland areas had continuously decreased, while built-up land and affected water had significantly increased. Landscape fragmentation was reduced, the connectivity between patches was weakened, landscape heterogeneity, evenness, and patch irregularity were increased. Changes in landscape composition and configuration have affected the ecosystem services of the Huaihe River Basin. The reduction in grassland areas and the increase in built-up land areas have significantly reduced the capacity for soil retention, carbon storage, and biodiversity conservation. Spatially, regions with low landscape fragmentation and high patch connectivity had a higher water retention capacity and biodiversity conservation, while soil retention and carbon storage were opposite. Temporally, reduction of landscape fragmentation and increase of patch shape irregularity had a negative effect on water retention, carbon storage, and biodiversity conservation, while soil retention was not sensitive to these changes. The findings in this paper promote an understanding of the relationship between landscape patterns and ecosystem services on a large scale and provide theoretical guidance for ecosystem management and protection planning in the Huaihe River Basin, China.

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