An integrated method for the control factor identification of resources and environmental carrying capacity in coastal zones: A case study in Qingdao, China

- Index system of offshore environmental quality was established.
- An integrated method was established to identify the control factors.
- A series of remediation measures were proposed in Qingdao and its coastal area.

Large amounts of pollution in coastal waters have placed marine ecosystems under stress. In relation to this, socio-economic development can only be considered sustainable when the ecosystem is under normal carrying capacity. However, accurately evaluating the environmental carrying capacity and efficiently remediating related problems are difficult to carry out in the absence of systematic methods to identify the influencing factors. Hence, this study established an integrated identification method, including the selection and horizontal independence test of potential factors as well as the identification of control factors and water quality effects. We identified the control factors and proposed a series of remediation measures based on the survey and statistical data from 1982 to 2015 in Qingdao and its coastal area. Results indicated 21 control factors, five of which were high-level control factors in Qingdao offshore, namely, wastewater discharge, livestock production, ammonia nitrogen emission, river runoff, sewage treatment. In addition, reclamation area was identified as significant pollution contributors in the Jiaozhou Bay. These control factors showed that the carrying capacity for land-based pollutant emissions and shoreline destruction in the Qingdao offshore is generally overloaded, especially in Jiaozhou Bay. The reduction of land-based pollutants and watershed restoration projects, such as the removal of artificial dikes and the rehabilitation of its natural shoreline, are thus needed to resolve this problem in Jiaozhou Bay. Meanwhile, only differential reduction approaches on land-based pollutants are needed for other coastal waters in Qingdao, such as adjusting the industrial structure, enhancing investments in sewage treatment facilities.