This paper proposes a distributed energy-efficient algorithm for environmental event detection and monitoring using a mobile wireless sensor network. The mobile sensors could be sensors mounted on vehicles that move in the monitored environment and the mounted sensors collect environmental data. The proposed technique collects the data from the mobile sensors using a mobile sink (e.g. drone). The mobile sink processes the collected to detect and monitor environmental events such as air pollution. The path of the mobile sink affects the accuracy and speed of detecting environmental events. To efficiently detect events, the mobile sink path is shortened and yet all sensed data by the mobile sensors are collected by mobile sink. Therefore, mobile sensors group themselves and then each group selects a group head (GH). The mobile sensors send the sensed data to the their GH, which aggregates the data. To shorten the path of the mobile sink, the proposed method creates a path that passes through the GHs’ locations only. The proposed method uses a space-filling curve to determine the order of GHs along the path of the mobile sink. The mobile sink collects the group’s aggregated data from these GHs. Then, the mobile sink process the collected data to detect the environmental events.