Study on the coupling and coordination degree between urban tourism development and habitat environment in the Yangtze River Delta in China

By constructing the two evaluation systems of urban tourism development (TD) and habitat environment (HE), the dynamic response relationship between the two systems in the Yangtze River Delta urban agglomeration from 2001 to 2020 is explored by using panel vector autoregression (PVAR) model and coupled coordination degree model. The study unearthed four intriguing findings: (1) the level of TD in the study area has been continuously rising from 2001 to 2020, with an initial slow growth rate and then fast. The level of HE is increasing steadily at an average annual rate of 7.05%. There exists a reciprocal response relationship between the two systems, with a strong shock effect in the short term and a synergistic evolution in the long term. (2) The coupling degree between the urban TD and HE has an increasing trend, and the coupling coordination degree of the two systems has an average annual rate of 4.165%, implying the interaction and promotion effect between the two systems is improving. (3) Most of the cities in the Yangtze River Delta gradually realize the evolution from dysfunctional type to coordinated type, but the overall coordination intensity is low. (4) The barrier degrees of TD system indicators show a small annual increasing trend, while the barrier degrees of HE system indicators show a substantial and continuous decreasing trend. In terms of the barrier degree factors, some important factors that restrict the coupled and coordinated development of the two systems are also reported. This research can provide a useful reference for the synergistic improvement of urban tourism economy and habitat environment.

Coupling relation between urbanization and ecological risk of PAHs on coastal terrestrial ecosystem around the Bohai and Yellow Sea

Urbanization, the ecological risks of polycyclic aromatic hydrocarbons (PAHs) to terrestrial ecosystems, and the complex relationship between them have drawn globally attention. In this paper, a comprehensive indicator system was calculated to illustrate the levels of urbanization in 20 coastal cities around the Bohai and Yellow Sea. The top three cities with high levels of urbanization were Tianjin > Qingdao > Dalian. The ecological risk of phenanthrene (Phe) was 52.0%; while the risk of fluoranthene (Flt) was 25.8%, and that of pyrene (Pyr), benzo[a]anthracene (Bap), fluorene (Flu), and naphthalene (Nap) were below 20% throughout the entire region. Risks were high in Dandong, Tianjin, Tangshan, Nantong, and Lianyungang and low in Weihai, Dongying, and Rizhao. The degree of coupling between urbanization and ecological risk of PAHs was above high (0.6) and more than 50% of the coordination degrees were slight unbalance [0.3, 0.5). Furthermore, redundancy analysis showed that the indicator aspects of industry, transportation, and population made great contribution to PAHs risk. Industry correlated to Low Molecular Weight (LMW) PAHs, while transportation correlated to High Molecular Weight (HMW) PAHs. To minimize risk, urbanization scale should be under acceptable level, or the structure of industry and transportation should be optimized.