“…The research area mainly has metallurgical industry, building materials industry, ceramic industry and so on [ 34 , 35 ]. These industries can produce large quantities of pollutants containing Cd, Cr, Pb and Mn in the process of production [ 36 , 37 , 38 ]; thus, factor 2 represented industrial sources. Factor 3 accounted for 25% of the total heavy metals and was mainly composed of Ti, Al and Ni, while Mg also showed some loadings on this factor.…”
Analysis of sediment grain sizes and heavy metal correlations in the western part of Lake Taihu shows that the grain size of the sediment is stable as a whole. With increasing depth, the grain size tends to decrease. Heavy metals such as Cr, Cd, Pd and Sr are strongly correlated and influence each other. Based on the positive matrix factorization (PMF) model, this study classified the origin of heavy metals in the sediments of western Lake Taihu into three major categories: Agricultural, industrial and geogenic. The contributions of the three heavy metal sources in each sample were analyzed and calculated. Overall, prior to the Chinese economic reform, the study area mainly practiced agriculture. The sources of heavy metals in the sediments were mostly of agricultural and geogenic origin, and remained relatively stable with contribution rates of 44.07 ± 11.84% (n = 30) and 35.67 ± 11.70% (n = 30), respectively. After the reform and opening up of China, as the economy experienced rapid development, industry and agriculture became the main sources of heavy metals in sediments, accounting for 56.99 ± 15.73% (n = 15) and 31.22 ± 14.31% (n = 15), respectively. The PMF model is convenient and efficient, and a good method to determine the origin of heavy metals in sediments.
“…The research area mainly has metallurgical industry, building materials industry, ceramic industry and so on [ 34 , 35 ]. These industries can produce large quantities of pollutants containing Cd, Cr, Pb and Mn in the process of production [ 36 , 37 , 38 ]; thus, factor 2 represented industrial sources. Factor 3 accounted for 25% of the total heavy metals and was mainly composed of Ti, Al and Ni, while Mg also showed some loadings on this factor.…”
Analysis of sediment grain sizes and heavy metal correlations in the western part of Lake Taihu shows that the grain size of the sediment is stable as a whole. With increasing depth, the grain size tends to decrease. Heavy metals such as Cr, Cd, Pd and Sr are strongly correlated and influence each other. Based on the positive matrix factorization (PMF) model, this study classified the origin of heavy metals in the sediments of western Lake Taihu into three major categories: Agricultural, industrial and geogenic. The contributions of the three heavy metal sources in each sample were analyzed and calculated. Overall, prior to the Chinese economic reform, the study area mainly practiced agriculture. The sources of heavy metals in the sediments were mostly of agricultural and geogenic origin, and remained relatively stable with contribution rates of 44.07 ± 11.84% (n = 30) and 35.67 ± 11.70% (n = 30), respectively. After the reform and opening up of China, as the economy experienced rapid development, industry and agriculture became the main sources of heavy metals in sediments, accounting for 56.99 ± 15.73% (n = 15) and 31.22 ± 14.31% (n = 15), respectively. The PMF model is convenient and efficient, and a good method to determine the origin of heavy metals in sediments.
“… Figure 2 Summary of multi-proxy records from Changdang Lake. Abundance of Emergent macrophyte ( a ), Submerged macrophyte ( b ), and Floating-leaved macrophyte ( c ); Middle-chain ( d ) and short chain ( e ) of n-alkane abundance, representing aquatic macrophyte and plankton, respectively 48 ; PCA1 of Diatom assemblages ( f ) and Cledocera assemblages ( g ); Magnetic susceptibility ( h ); Grain size ( i ); Total Nitrogen ( j ); Total organic carbon abundance ( k ); Enrichment factors of major trace metals ( l ). …”
Global lake systems have undergone rapid degradation over the past century. Scientists and managers are struggling to manage the highly degraded lake systems to cope with escalating anthropogenic pressures. Improved knowledge of how lakes and social systems co-evolved up to the present is vital for understanding, modeling, and anticipating the current and future ecological status of lakes. Here, by integrating paleoenvironmental, instrumental and historical documentary resources at multi-decadal scales, we demonstrate how a typical shallow lake system evolved over the last century in the Yangtze River Basin, an urbanized region containing thousands of shallow lakes. We find abrupt ecological shift happened in the lake ecosystem around the 1970s, with the significant reorganization of macrophyte, diatom and cladocera communities. The lake social-ecological system went through three stages as the local society transformed from a traditional agricultural before 1950s to an urbanized and industrialized society during the recent thirty years. The timing and interaction between social, economic and ecological feedbacks govern the transient and long-term dynamics of the freshwater ecosystem. Our results highlight the importance of accounting for the long-term dynamics and feedbacks between ecological, social and economic changes when defining safe operating spaces for sustainable freshwater ecosystem management.
“…In the context of global warming, the increase in microbial respiration and the mineralization rate of organic matter in water bodies and sediments may lead to a decline in the rate of organic carbon burial, and sediments may change from "carbon sink" to "carbon source" [13]. Many studies have shown that, with the increasing intensity of human activities, lake environments and ecosystems have experienced significant changes [14][15][16], and in-depth study of the temporal and spatial changes of organic carbon burial in lake sediments and their relationship with lake ecology, climate environment, and human activities will not only help to understand the evolution of the lake ecological environment more deeply but also make it possible to more scientifically assess the role of lake organic carbon burial in the global carbon cycle.…”
The burial of organic carbon in lake sediments plays an important role in the terrestrial carbon cycle. Clarifying the current status of carbon burial in the lakes of Central Asia is of great significance for the application of carbon balance assessments. With the analysis of the total organic carbon and nitrogen and the carbon isotope and organic carbon burial rate in the core sediment of the North Aral Sea, the status and influencing factors of organic carbon burial over the past 70 years can be revealed. The results showed that the main source of organic carbon was predominantly from lacustrine aquatic plants. However, the contribution of terrigenous organic carbon increased from the 1950s to the 1960s. The burial rate of organic carbon in North Aral Sea sediments was consistent with the overall change in the regional temperature. The burial rate of organic carbon showed an upward trend as a whole with an average of 28.78 g·m−2·a−1. Since 2010, the burial rate of organic carbon has stood at the highest level in nearly 70 years, with an average of 55.66 g·m−2·a−1. The protection of a lake by human beings can not only significantly improve the lake’s aquatic ecosystem but also help to increase the burial rate of the lake’s organic carbon.
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