ABSTRACT
Microplastics (MPs), as a new type of environmental pollutant, have attracted extensive attention in recent years. However, there has been relatively little research specifically focusing on MPs in the Yellow River Basin, China, particularly regarding MP migration patterns. Based on surface water and sediment samples from 19 sampling sites in the Wuding River (WDR), the abundances and characteristic distributions of MPs were analyzed, and the environmental factors affecting their distribution and potential ecological risks were evaluated. The results showed that the MP abundances in surface water and sediments of the WDR were significantly different (P <0.05), with mean values of 2.98 ± 0.69 items/L and 419.47 ± 75.61 items/kg, respectively. In terms of MP characteristics, the most common size class was 0.1-0.5 mm in surface water. Polyethylene (PE, 32.50%) and polypropylene (PP, 27.50%) were the main polymer types of MPs in surface water. Although similar MP characteristics were observed in sediments, there were significantly more particles in the <0.1 mm particle size (P <0.05), which was 15.0% higher than in surface water. Also, more high-density MP fragments were observed in sediment samples. The retention of MPs in sediments was influenced by the MP characteristics (density, shape, particle size) and sediment particle size. In contrast, the MP abundance in surface water was more closely related to the presence of other environmental pollutants, such as total phosphorus (WTP) and ammonia nitrogen (WAN). Temperature (T), agricultural land (AGR), and residential land (RES) only had significant effects on the distribution of MPs in surface water (P <0.05). Potential ecological risk assessments revealed that MP pollution in sediments was more serious than in surface water, especially in the middle and lower reaches. The results of this study are important for understanding MP transport in a sandy river and for eliminating potential sources of MPs.
ABSTRACT
Prioritizing threatened species protection has been proposed as an efficient response to the global biodiversity crisis. We used in-situ conservation data to predict the potential habitat area of four flagship species: the giant panda (Ailuropoda melanoleuca), golden monkey (Rhinopithecus roxella quinlingensis), takin (Budorcas taxicolor bedfordi), and crested ibis (Nipponia nippon). We then designed systematic conservation planning schemes for various scenarios given species habitat preferences and anthropogenic activities and conducted a cost-effectiveness assessment. Broadly, the geographical distributions of suitable habitats for giant pandas, golden monkeys, and takins exhibited high spatial congruence (correlation coefficients of 0.59-0.90), and areas of high congruence were concentrated in the northern portion of the Qinling Mountains at high elevation (>1500 m). By contrast, the crested ibis was negatively correlated in space with its sympatric species (-0.47 to -0.29). Crested ibis habitats were clustered in the southern portion of the region at low elevation (<1500 m). A hypothetical conservation priority area (CPA) based on the giant panda, golden monkey, and takin included 39.64% of the Qinling Mountains and 100%, 99.99%, 99.59%, and 7.84% of the suitable habitats for giant pandas, golden monkeys, takins, and crested ibises, respectively. The same area included 99.07%, 70.87%, and 39.96% of the highly important areas for the ecosystem services of biodiversity conservation, water supply, and soil retention, respectively, and only 4.62%, 16.83%, and 13.4% of the area were associated with high-density residential area, impervious surfaces, and cropland, respectively. Therefore, we conclude that a CPA approach based on the specialist species could result in effective, low-cost biodiversity conservation in the Qinling Mountains. However, we note that existing protected areas account for only 26.52% of the CPA. We recommend that the main area of the proposed Qinling National Park should be based on the CPA developed here.
