Distribution and ecological risk assessment of heavy metals in sediments of Dajiuhu Lake Wetland in Shennongjia, China.

The rapid development of modern society has resulted in discharge of large, heavy metal quantities into wetlands that have been continuously accumulating, causing severe pollution. Dajiuhu, located in the Shennongjia Forest District of Hubei Province in China, is a wetland of significant value internationally, serving as a model wetland ecosystem with heightened scientific research value. In this study, 27 surface sediment samples from nine sub-lakes in Dajiuhu were collected in August 2020. The concentrations of Cd, Cr, Cu, Ni, Pb, and Zn in the sediments were determined. The heavy metal occurrence and speciation characteristics were analyzed by an improved BCR (European Community Bureau of Reference) extraction method. Four methods were used to evaluate heavy metals' pollution degree and ecological risk. The possible source of heavy metals was inferred using correlation analysis and principal component analysis. The heavy metal content in the lake sediments of Dajiuhu wetland was from the highest to the lowest concentration as follows: Zn [Formula: see text] Cr [Formula: see text] Ni [Formula: see text] Pb [Formula: see text] Cu [Formula: see text] Cd. The average Cd content exceeded the national nature reserve threshold values, while the other heavy metals measured were below their respective threshold values. However, due to the occurrence of Pb and Cd in different forms, they still pose certain pollution and ecological risk to the lake wetlands. On the other hand, Zn, Cr, Ni, and Cu do not pose an ecological risk in the lakes of the Dajiuhu wetland. The spatial distribution of heavy metal content in the nine sub-lakes did vary significantly. Regarding the heavy metal sources in the lake sediments, Ni, Cr, and Cu originate from natural factors, and Cd and Pb have mainly anthropogenic origins. In contrast, Zn has both natural and anthropogenic origins. This study provides further insights into the study of heavy metal pollution in lake wetlands. It provides a framework and a direction for managing heavy metal pollution in the Dajiuhu wetland.

Wang J ，Ge J ，Yang X ，Cheng D ，Yuan C ，Liu Z ，Yang S ，Guo Y ，Gu Y ... -  《-》

Spatial Distribution, Ecological Risk Assessment and Source Analysis of Heavy Metals Pollution in Urban Lake Sediments of Huaihe River Basin.

Wu D ，Liu H ，Wu J ，Gao X ... -  《-》

Assessment of heavy metals in surface water, sediment and macrozoobenthos in inland rivers: a case study of the Heihe River, Northwest China.

Long-term retention and accumulation of heavy metals in surface water and sediment pose a great threat to the sustainable development of aquatic ecosystems and human health. In this research, macrozoobenthos, and surface water and sediment heavy metal (Mn, Cr, Cu, Ni, Pb, Zn, Cd, and As) samples were collected from 23 sites in the upper and middle reaches of the Heihe River in the summers of 2019-2020. The interrelationships between heavy metals and macrozoobenthos were analyzed by Pearson correlation analysis and redundancy analysis (RDA), and the contamination level and potential ecological risk of the heavy metals in surface water and sediments were assessed by comprehensive pollution index (WQI), single potential ecological risk index ([Formula: see text]), and sediment quality guideline-quotient (SQG-Q), respectively. The results showed that the level of heavy metal pollution in the surface water of the Heihe River was extremely low, but the contents of Mn and Pb exceeded the third class of surface water environmental quality standards (GB 3838-2002). The spatial distribution of heavy metals in surface sediments were significantly different, and the average concentration of 8 heavy metals exceeded the background values of Gansu Province. Meanwhile, the pollution level of heavy metals in surface sediments was high pollution, and the ecological risk level was moderate risk. Combining [Formula: see text] and SQG-Q evaluations showed that Cd, Ni, and Cr were the main ecological risk factors. In addition, the distribution coefficients of Cr and Cd were low, indicating that Cr and Cd were easily released from the surface sediments, causing secondary pollution. In terms of the source of the heavy metals, Cu, As, Zn, Cr, and Ni mainly came from industrial and agricultural wastewaters, Pb was from the mining industry and natural sources, and Mn and Cd mainly came from tailings and their landfill leachate. Basommatophora and Araneae can be used as potential indicator organisms for heavy metal pollution in surface water, and Basommatophora, Coleoptera, Hemiptera, and Araneae can be used as indicator species for heavy metal pollution in surface sediments. The study showed that macroinvertebrate community characteristics had a sensitive response to heavy metals in the surface waters and sediments of the Heihe River, which can be used to evaluate the pollution status of heavy metals in inland rivers.

Wang Y ，Li BL ，Zhu JL ，Feng Q ，Liu W ，He YH ，Wang X ... -  《-》

Ecological risk assessment of metals in sediments and selective plants of Uchalli Wetland Complex (UWC)-a Ramsar site.

Bhatti SG ，Tabinda AB ，Yasin F ，Mehmood A ，Salman M ，Yasar A ，Rasheed R ，Wajahat R ... -  《-》

Distribution, ecological risk assessment and source identification of pollutants in soils of different land-use types in degraded wetlands.

Urbanization and global warming are generating ecological degradation and land pattern alteration problems in natural wetlands. These changes are greatly affecting the ecological services of wetlands. Therefore, there is an urgent need to explore the relationship between pollutants and land-use type for wetland restoration purposes. Zaozhadian Lake is a freshwater wetland in the North China Plain, which is facing degradation and land-use types changes. An experiment for analyzing soil pollutants was conducted in three land-use types of farmland, lake, and ditch in the Zaozhadian Lake. The aims of this study were to identify the distribution, pollution degree, and sources of pollutants in different land-use types, and to explore the influence of land-use type changes on contamination. In this study, surface sediments (0-10 cm) of three land types (farmland, lake, and ditch) in Zaozhadian Lake were collected, and heavy metals (Cu, Ni, Zn, Pb, Cd, Cr, Hg), As, total nitrogen (TN), total phosphorus (TP) and organic matter (OM) were determined. Kriging interpolation was used to visualize the pollutants distribution. The pollution degree of TN and TP was evaluated by the Nemerow pollution index. The pollution of heavy metals and As was evaluated by the geological accumulation index (Igeo ) and the potential ecological risk index (RI). Then, dual hierarchical clustering analysis and the principal component analysis were performed to further analyze the impact of land type changes on pollutants. The heavy metal contents in the farmland were higher than other areas, while the TN (3.71 ± 1.03 g kg-1) and OM (57.17 ± 15.16 g kg-1) in lake sediments were higher than that in other regions. Farmland, lake, and ditches had low ecological risks, with RI values of 84.21, 71.34, and 50.78, respectively. The primary heavy metal pollutants are Pb, Cu, and Ni. Furthermore, Cu, As, Ni, Pb, and Zn were primarily derived from agriculture pollution, the source of Cd was the industrial pollution, and Cr mainly originated from natural sources. Nutrients primarily came from the decomposition of aquatic animals, plants, and human-related activities. When the lake area was converted into farmland, the heavy metal concentrations in the soils increased and the TN and OM decreased. Based on the results, this study put forward key strategies including the adjustment of the land-use type and restriction of the entry of pollutants into the wetland ecosystems in the Zaozhadian Lake. More attention should be paid to the impact of land-use type change on pollutants in wetlands.

Han Y ，Wang H ，Zhang G ，Zhang S ，Liu X ，Liu L ... -  《-》