OCEAN AND COASTAL REVIEW http://dx.doi.org/10.1590/S2675-28242020068313 RESEARCH Contamination and toxicity in a subtropical Estuarine Protected Area influenced by former mining activities Fernando Cesar Perina1,2* , Denis Moledo de Souza Abessa2 1 Universidade de São Paulo, Programa de Pós-Graduação em Oceanografia. Instituto Oceanográfico da Universidade de São Paulo (Praça do Oceanográfico - 191 - Butantã - 05508120 - São Paulo - SP - Brazil) 2 Universidade Estadual Paulista, Campus do Litoral Paulista - UNESP-CLP - São Vicente (Praça Infante Dom Henrique s/nº - Parque Bitaru - 11.330-900 - São Vicente - SP - Brazil) *Corresponding author: [email protected] ABSTRACT The present paper reviews information about sources, fate, concentrations and toxicity of the metals found in the Cananéia-Iguape Estuarine Complex (CIEC), which is within a Ramsar site, the Cananéia-Iguape-Peruíbe Environmental Protected Area (CIP-PA). The main sources of metals to CIEC are the former mining sites located upstream, on the Ribeira de Iguape River basin. Pb is reported as the element of primary concern, but Cu, Zn, Cr and As have been detected in sediments and biota. In general, higher levels of metals are associated with muddy sediments, in depositional portions of the estuary. Metals appear to be bioavailable, as sediment toxicity has been reported, together with bioaccumulation and sub-chronic effects in fish and invertebrates. Areas with higher concentrations of metals and more severe sediment toxicity are not necessarily the closest to the sources. The worse conditions occur in depositional sites, which depend on rainfall in catchment basin and hydrological processes in the estuary. In fact, during the flooding season the deposition of particles seems to move southward, carrying metals to the southern portion of the CIEC. The results suggest that the protection objectives are not being fully achieved, demanding actions to ensure control of both internal and external sources of contaminants for the CIEC. Additionally, new enforcements and actions are required to control the contamination sources of mining residues located upstream. The current review highlights that estuarine and marine protected areas may be impacted by contaminants released from distant sources, and this situation should be properly addressed in management plans. Descriptors: Sediment, Metals, Pollution Sources, Bioaccumulation, Ecotoxicology. INTRODUCTION these transitional environments, even in relatively short spatial and temporal scales (Elliott and McLusky, Estuaries are coastal transition zones between 2002). The hydrodynamics of estuaries favor the re- fresh-water and seawater that present substantial tention of nutrients and consequently the primary gradients of abiotic parameters and which are most production, thus placing these environments among highly affected by freshwater inflows and tidal re- the most biologically productive coastal ecosystems gimes. Therefore, large variations in salinity, pH, tem- on the planet (Miranda et al., 2002; McLusky and perature and geochemical conditions may occur in Elliott, 2004). Estuaries also exhibit geomorphological and Submitted on: 01/March/2020 physical-chemical characteristics that favor material Approved on: 08/May/2020 deposition such as organic material and man-made Editor: Rubens M. Lopes contaminants (Du Laing et al., 2009). Estuarine ar- © 2020 The authors. This is an open access article distributed under eas normally present low energy from waves and the terms of the Creative Commons license. Ocean and Coastal Research 2020, v68:e20313 1 Perina and Abessa et al.: Environmental impacts history in Cananéia estuary currents making it difficult for the chemicals to dis- (Power and Chapman, 1992). Chemical analyses may perse, frequently resulting in accumulation of organ- provide information on specific levels of contami- ic and inorganic substances in the sediments. Once nants, which, if bioavailable, may lead to toxicity in the sediment, contaminants may directly affect the and bioaccumulation (USEPA, 2004). Nevertheless, benthic biota, but they may also return to the wa- different types of associations between sediments ter column through various physical, chemical and and contaminants may reduce their bioavailability biological processes, thus resulting in even greater (Simpson et al., 2016). Thus, chemical analyses indi- ecological effects (Chapman and Wang, 2001). These cate the nature of the contaminants present in the characteristics make estuaries very sensitive; and one environment and quantify their concentrations; but of the most significantly affected ecosystems by hu- they do not provide information on the possible ef- man activity (Lewis et al., 2011). fects on aquatic organisms. Therefore, a sediment Changes in salinity, temperature, pH and oxida- quality assessment performed exclusively through tion/reduction potential regulate the retention, and chemical analyses is insufficient for estimating dam- release of metals associated with the finest sediment ages to biota. Hence, an ecotoxicological approach is fraction, organic material, iron oxides and sulfides required for evaluating sediment quality, since it pro- (Caporale and Violante, 2016). The resuspension of vides information on the biological effects caused by contaminated sediments can occur naturally, as is ob- contaminants (Chapman, 2016). served in the turbidity maximum zone (TMZ). These In order to evaluate the presence of metals in an zones mainly occur in estuaries in which salinity is important subtropical estuarine protected area, this partially stratified. The turbulent movement induced paper reviews a series of studies on the contamina- by currents close to the bottom causes sediment re- tion and toxicity of the sediments in Cananéia-Iguape suspension and increases the levels of suspended Estuarine Complex (CIEC). The CIEC is located on the sediments; up to 100 times higher than those found southern coast of Sao Paulo State, Brazil, and it is in- upstream and downstream (Postma, 1967). Besides, fluenced by former mining activities along the Ribeira the TMZ is displaced following the tidal cycles and de Iguape River catchment basin. Thus, the current the rainfall precipitation regime, being subject to information on the extent of metal contamination in daily and seasonal variations. the Ribeira de Iguape River was also analyzed, since it Metals in estuaries may come from natural sourc- is the most important freshwater and fine sediment es involving both local geological composition and contributor to the CIEC (Barcellos et al., 2009). the leaching of soils and rocks present in the drain- age basin. However, for the most of the toxic metals, METHODS the greatest contribution comes from human sourc- This literature review considered studies on con- es, such as domestic and industrial effluents, agricul- tamination carried out in the CIEC and in the Ribeira tural pesticides (Ebrahimpour and Mushrifah, 2008), de Iguape River catchment basin (also known as the atmospheric deposition (Pereira et al., 2006) and min- Ribeira Valley), which has a history of contamination ing activities. It is important to note that, even when by metals (Eysink et al., 1988; Guimarães and Sígolo, pollution sources are located at substantial distance 2008a; Abessa et al., 2014). The criterion for inclusion away from estuaries, the contaminants may reach the of a paper into this review was that the study had estuarine ecosystems. Studies reported that mining to have analyzed field-collected samples to mea- activities located hundreds of kilometers upstream sure metal in sediments or biological effects of con- were responsible for the contamination of estua- taminants. To obtain articles that fit these criterion, rine zones worldwide, largely due to the transport of we conducted sequential searches in the relevant residues and sediments containing absorbed metals databases (Scopus, Web of Knowledge and SciElo) (Johnson et al., 2005; Price et al., 2005; Masson et al., by crossing the terms *contamin-*, or *pollut-*, or 2006; Osher et al., 2006). *toxic-*, or *bioacum-*, or biomarker against the Sediments are important indicators of environ- terms “Cananeia Iguape Peruibe protected area”, or mental quality and can be considered one of the “Cananeia”, or “Ribeira de Iguape”. We searched for most complex matrices to exist in aquatic ecosystems additional studies by examining monitoring reports Ocean and Coastal Research 2020, v68:e20313 2 Perina and Abessa et al.: Environmental impacts history in Cananéia estuary available on databases of environmental agencies presents an extensive network of PAs, which forms as well as academic thesis and dissertations that are a large ecological corridor, encompassing terrestrial, available on digital libraries. We recognize that some marine and estuarine areas. The Cananéia-Iguape- of the information about metal contamination in the Peruíbe Protected Area (CIP-PA) is inserted in this net- CIEC is unpublished (academic documents not avail- work; this PA was created in 1984 through Brazilian able on the web) or part of monitoring reports. Law No. 90.347; it covers the cities of Cananéia, This review selected only papers that have ad- Iguape, Peruíbe, Itariri, Pedro de Toledo, and Miracatu opted analytical procedures widely accepted around (IBAMA/SMA-SP, 1996). This protected area is part of the world and quality control procedures (quality as- the “Atlantic Forest Biosphere Reserve”, recognized as surance/quality control - QA/QC).