Under the rapid development of the global economy, environmental pollution has intensified significantly. The evolving external environment presents both opportunities and challenges to traditional supply chains. As an innovative management philosophy and practical approach, the green supply chain has rapidly become an integral component of corporate sustainable development strategies. However, the transition from traditional supply chain to green supply chain necessitates effective collaboration and coordination among supply chain members. Contractual coordination has therefore emerged as an effective methodology to enhance operational efficiency and profitability across supply chain participants. To investigate the impact of various coordination mechanisms on the optimal decision-making of green supply chains, we construct a Stackelberg game model involving bilateral green investments by both manufacturer and retailer within a two-echelon green supply chain system. Considering the bilateral green efforts from both manufacturer and retailer, we comparatively analyze game equilibrium solutions under three scenarios: non-coordination, cost-sharing contract coordination, and two-part contract coordination. Specifically，we examine how these coordination mechanisms influence pricing strategies, green investment levels, and profit distributions within the supply chain network. Finally, the results are validated and illustrated using numerical simulation. It is discovered that 1) the cost-sharing contract cannot simultaneously increase the Pareto improvement of producers' and retailers' revenues; 2) the cost-sharing contract cannot increase the social utility and additive greenness of products; however, it can improve the marketing effort; and 3) When retailers maintain an optimistic stance toward manufacturers' green initiatives, the two-part tariff contract enables concurrent Pareto improvements in both parties' profits while simultaneously enhancing product greenness, marketing efforts, and social welfare, thereby achieving efficient supply chain coordination.

The management of recycling and remanufacturing supply chains, which can help enterprises achieve low pollution, low energy consumption and sustainable development, has become a new strategy of modern enterprises. The factors of supply chain and government mechanisms will have an impact on enterprise decisions for recycling, remanufacturing and social welfare. In order to promote the sustainable operation of the supply chain, considering the coordination role of government mechanisms and supply chain, a recycling and remanufacturing supply chain model composed of a manufacturer, retailer and recycler is constructed. This paper discusses the pricing decision of new/remanufactured products, supply chain performance level, such as remanufacturing effort, publicity service efforts and profit, and social welfare in five models of three situations: centralized situation, including non-government mechanisms and non-supply chain coordination; manufacturer-led situation, including non-government mechanisms and non-supply chain coordination, government mechanisms and non-supply chain coordination, government mechanisms and supply chain coordination; government-led situation, including government mechanisms and non-supply chain coordination. It is found that under manufacturer-led situations, the government subsidy and bonus-penalty mechanisms can encourage manufacturer and retailer to actively participate in the recycling and remanufacturing activities. The supply chain coordination contract can further enhance the role of the consumer market and promote the implementation of government mechanisms. Manufacturer adopts a cost-sharing contract to encourage recyclers to carry out recycling activities. Under certain conditions, the contract can effectively improve the benefits and social welfare. The research conclusions have important theoretical and practical application value for the coordination and cooperation among enterprises in the supply chain and the formulation of government mechanisms.