Contaminants and heavy metals along the mangrove area of Dongzhai Harbor, China: distribution and assessment

Jing Liu,Thiri Myat

doi:10.1007/s42452-021-04802-2

Abstract

In recent decades, higher-place shrimp ponds are prevalent in coastal areas of developing countries. However, shrimp aquaculture has a growing negative impact on mangrove wetland ecosystems. Mangroves located in Dongzhai harbor are under threat continuously of this commercialization. Therefore, a comprehensive analysis of contaminants and heavy metals is necessary for Dongzhai harbor, considering the mangrove area was declined and ecological services offered to the coastal communities with an insight for future restoration activities. In this study, pond effluents (Total Nitrogen (TN), Ammonia Nitrogen (AN), Total phosphorus (TP), Chemical Oxygen Demond (COD)) and heavy metals (Cd, Cu, Pb, Zn) were monitored in Dongzhai harbor yearly between 2013 and 2017. The results showed that the contents of Cd, Cu, Pb, and Zn were far lower than the standards. However, the main contaminants were organic matter and nitrogen. Maximum values of COD and TN were 26.10 mg·L−1 and 1.34 mg·L−1, respectively in 2017. Single factor index, Nemerow's pollution index, and Trophic level index revealed that the heavily polluted areas were Tashi and Sanjiang town.

Highlights

Mangroves are tropical and subtropical highly productive coastal ecosystems, which are found within the intertidal areas [1, 2]
Mangrove ecosystems are more resilient to natural disturbances than to human-induced disturbances
The higher-place shrimp ponds needed a large amount of artificial feed for highdensity aquaculture, but the amount of nutrients added to the pond was only a few could translate into the biomass of shrimp, most nutrients flow into the surrounding mangrove wetlands along with the discharge of aquaculture wastewater [30]

Summary

Introduction

Mangroves are tropical and subtropical highly productive coastal ecosystems, which are found within the intertidal areas [1, 2]. Mangroves can provide numerous food, wood, medicine, fuel and other goods or services, which is absolutely important to human and society [3, 4]. In addition to providing numerous avian and aquatic species with suitable habitats, mangrove wetland ecosystems can protect coastal areas from tsunamis, hurricanes, tropical cyclones, and other natural disasters [3, 5]. Salt production, and agriculture are the man-made causes of mangrove loss [7, 8]. Global warming, tropical cyclones, tsunamis, and other natural disturbances have contributed to mangrove loss [9, 10]. Mangrove ecosystems are more resilient to natural disturbances than to human-induced disturbances

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Results

Discussion

Conclusion