Sedimentary Evidence of Environmental Degradation in Sanliqi Lake, Daye City (A Typical Mining City, Central China)

Abstract

To reconstruct the history of environmental degradation in Sanliqi Lake (Daye City, central China), multiple proxies were analyzed in a sedimentary core which was dated using (137)Cs and spheroidal carbonaceous particles (SCPs). The results show that Sanliqi Lake has experienced serious degradation during the past 60 years, resulting from a large influx of metals and nutrients. Expansion of agricultural and industrial activities between 1945 and 1993 enhanced nutrient and metal enrichment, indicated by increases in metals, SCPs, magnetic susceptibility, total phosphorus, total nitrogen and total organic carbon. Further enrichment of Zn, Cd, Ni and Cr after 1993 was linked to a recent intensification of mining activities. Decreases in Cu and Pb after 2006 probably resulted from recent environmental remediation. This study verified the coupling between lake sediment pollution and human activities in Daye City during the past 60 years. The reconstructed history of lake pollution can provide reference information for continued restoration of Sanliqi Lake and other similar heavily polluted lakes in the developing regions.

Lithogenic and Anthropogenic Components in Surface Sediments from Lake Limboto as Shown by Magnetic Mineral Characteristics, Trace Metals, and REE Geochemistry

“…In the R area, the sources of magnetic minerals sometimes differed from those of trace metals, implying a complexity of anthropogenic sources [19,38]. The abundance of Mn as an indication of anthropogenic contributions (industrial and mining activities) to sediments has also been reported in Lake Sanliqi [11]. A high Mn content has also been reported as originating from agricultural waste, residential waste [39], electronic waste, fossil fuel emissions [40], industrial waste, and traffic emissions [41].…”

“…Anthropogenic contributions can also be identified by an increase in trace metal content. For instance, studies of sediments from Lake Champlain [9], East Lake [10], and Lake Sanliqi [11] have reported an increase in magnetic susceptibility followed by an increase in the trace metals Fe, Mn, Cu, Zn, Cr, Pb, and Cd from several forms of anthropogenic waste. Additionally, coarse grain magnetite (Fe 3 O 4 ) with PSD (pseudo-single domain)/MD (multi-domain) sizes were found in East Lake [10,12] and Lake Gonghai [13] that were contaminated not only from mining, industrial, agricultural, and residential wastes but also from vehicle emissions.…”

Spatial Variations in the Surface Water Chemistry of Subtropical Peatlands (Central China) Linked to Anthropogenic Pressures

“…All environmental factors (except pH) were log-transformed (log 10 (x + 1)) before statistical analysis. Cluster analysis for samples was performed using the Ward's minimum variance method based on Euclidean distance [23]. Since some environmental factors (e.g., ORP, DOC, NH 4 + , Ca, Mg, Mn, and Na) did not pass the test for normality, the significance level between clusters was determined using non-parametric statistical analysis [24].…”

“…The major cation levels of water samples showed marked differences among peatlands, lakes and rivers in the Yangtze basin. High concentrations of major cations in rivers and lakes in the Yangtze basin can be attributed to weathering processes of carbonate-rich bedrock in the upper reach [29], as well as a large influx of anthropogenic nutrients, such as agricultural and domestic sewage [23,30,31]. Compared with rivers and lakes in the Yangtze basin, peatlands are deficient in major cations, probably resulting from the less input of cation-enriched underground and surface runoff, as well as the cation exchange by Sphagnum plants [4,8].…”

“…Considering similar bedrock in the catchment and similar vegetation communities in the peatlands, the variations in water chemistry were probably linked to different anthropogenic disturbances. Samples from Group I were located near a road under construction and were thus likely influenced by metal pollutants in the dusts derived from road and gas combustion [17,19,23]. In addition, organic matter has a considerable adsorption capacity which can efficiently adsorb heavy metal ions [37].…”