Trace metals and nutrients in lake sediments in the Province of Bali, Indonesia: a baseline assessment linking potential sources

Abstract

Bali, Indonesia, receives over 6 million tourists annually, placing demand on resources and infrastructure that competes with expectations of natural beauty. Strongly linked to tourism are highly productive small-scale crafts industries and intensive small-scale agriculture and aquaculture production. Concentrations of nutrients, trace metals and metalloids were determined in soils from various land uses and solid-waste containment areas associated with small-scale industries, along with sediments from Lake Beratan, Lake Tamblingan, Lake Buyan, Lake Batur and the Badung River estuary. Soil associated with laboratory waste storage, and some sediments, exceeded guideline values for mercury or copper. Concentrations of other metals in soils and sediments were consistently below guidelines values, except zinc in solid waste collected from batik production (i.e. fabric-dyeing operations). Waste from batik production contained elevated concentrations of trace metals and nutrients (phosphorus and potassium), but replicates were highly variable. Lake sediments were enriched with phosphorus and nitrogen, likely from agricultural runoff. This important baseline information highlights the value of lake-protection measures in place, identifies risks to environmental health and provides focus for improving the management of contaminant sources to prevent further impacts.