Two constructed wetlands within a Mediterranean natural park immersed in an agrolandscape reduce most heavy metal water concentrations and dampen the majority of pesticide presence

Environmental Science and Pollution Research https://doi.org/10.1007/s11356-022-21365-w RESEARCH ARTICLE Two constructed wetlands within a Mediterranean natural park immersed in an agrolandscape reduce most heavy metal water concentrations and dampen the majority of pesticide presence Maria A. Rodrigo1 Fernando Juan4 · Eric Puche1 · Nuria Carabal1 · Sergio Armenta2 · Francesc A. Esteve‑Turrillas2 · Javier Jiménez3 · Received: 1 April 2022 / Accepted: 5 June 2022 © The Author(s) 2022 Abstract The water concentrations of 12 heavy and other metals/metalloids were analyzed seasonally along two horizontal-flow constructed wetlands (CWs) (Tancat Mília—TM and Tancat l’Illa—TLI) located within the Mediterranean Albufera de València Natural Park during 2020–2021. A wide-scope screening of pesticides present in waters was also performed. The two CWs were created to improve water quality and increase biodiversity. They currently receive effluent waters from two different tertiary-treatment wastewater plants, and the water flows along the CWs before being discharged into the main lagoon and a smaller lagoon in TM and TLI, respectively. TLI manages to reduce (Mn) or maintain the concentration of most of the studied elements (Zn, Ni, Hg, Cr, Fe Cd, Cu) at the same level as outside (67%). Only Al, Pb, B, and As remain at a higher concentration. TM also reduces Zn and Cu and keeps the concentration of Cr, Cd, and Hg (representing 42%). Al, Pb, B, and As remain at higher concentrations, as in TLI, but Ni, Fe, and Mn are also at higher concentrations. Although both CWs vary in their ability to remove elements, no risks to human health or the environment have been detected due to the low metal concentration in their outlets, all of them (except Hg) below the legal limits for environmental quality in the European Union. With the detection of 71 compounds in water in each CW area (26 herbicides, 26 insecticides, and 19 fungicides in TLI, and 29 herbicides, 23 insecticides, and 19 fungicides in TM), we also provide evidence of the impact of pesticides, which depends on the application method (helicopter, tractor), originated from areas with high agricultural pressure (chiefly rice crops) on systems (mainly TM) created to preserve biodiversity. Nevertheless, both systems provide crucial environmental services in water quality in this agrolandscape. Keywords Domestic wastewater · Tertiary treatment · Metals/Metalloids · Herbicides · Fungicides · Insecticides · Rice agriculture Introduction Responsible Editor: Alexandros Stefanakis * Maria A. Rodrigo 1 Integrative Ecology Group, Cavanilles Institute of Biodiversity and Evolutionary Biology, University of València, Catedrático José Beltrán 2, 46980 Paterna, Spain 2 Department of Analytical Chemistry, University of Valencia, Dr Moliner 50, 46100 Burjassot, Spain 3 Hidraqua Gestión Integral de Aguas de Levante, S.A. Carrer de Sant Sebastià, 12 Alfafar, 46910 Valencia, Spain 4 Aguas de Las Cuencas Mediterráneas, S.A. (ACUAMED), Pasaje Doctor Serra 2, 3º planta, 46004 Valencia, Spain Constructed wetlands (CWs) as ecological and alternative solutions for wastewater treatment have proven effective worldwide, particularly for nutrient reduction (Kadlec and Wallace 2008). However, the studies on CWs being used to reduce other kinds of pollution, such as priority hazardous substances, from municipal wastewater treatment plants before being discharged into natural and protected areas are scarce (Arroyo et al. 2010; Pedescoll et al. 2015). Wastewater, even treated, may contain undesirable chemical constituents such as heavy metals and pesticides, particularly in highly populated areas with intensive agricultural activities, such as coastal areas in the Mediterranean. The presence of both kinds of substances can be related, since, 13 Vol.:(0123456789) Environmental Science and Pollution Research for example, fertilizers are usually not sufficiently purified during the manufacturing processes, for economic reasons, and usually contain several impurities, including heavy metals. Moreover, heavy metals often form a part of the active compounds of pesticides (Gimeno-García et al. 1996). Many other human activities introduce metals into the environment (e.g., mining, traffic, industries, wastewater treatment plants, waste landfills, etc.) (Hernández-Crespo and Martín, 2015). Moreover, tertiary treatments in wastewater treatment plants using chemical reagents (coagulants, flocculants, etc.), to increase the removal efficiency of phosphorus and other nutrients (Iborra-Clar et al. 2011), may represent a source of certain elements being discharged into sensitive ecosystems such as wetlands within natural parks. The global term “heavy metals” sometimes includes other elements belonging to the periodical system, which are in fact not metals (e.g., boron), nor are they “heavy” (e.g., aluminum, manganese, iron), but they can become a serious environmental problem (e.g., acute and chronic toxicity to aquatic organisms, accumulation in the ecosystem, and losses of habitats and biodiversity; Directive 2006/11/EC; Yu et al. 2021). Within the term pesticide, a broader spectrum of substances is included, such as herbicides, insecticides, fungicides, but also repellents, growth regulators, etc. (European Commission 2020). Pesticides are considered as pollutants by the Water Framework Directive (WFD, Directive 2000/60/EEC), and are considered priority substances by Directive 2013/39/EU, being categorized as dangerous substances by Directive 2006/11/EC. In fact, monitoring studies have reported the presence of a large number of these types of contaminants in water bodies across Europe (Houtman 2010; Hedge et al. 2014; Rico et al. 2016, 2019). Furthermore, this chemical pollution is highly related and affects some other water quality parameters, depicting a complex amalgam of factors which have to be taken into consideration (Rico et al. 2016). The Albufera de València Natural Park is one of the most important wetlands in the Iberian Peninsula and the Mediterranean zone: it has been protected by the Ramsar Convention on Wetlands since 1990; mentioned as a special protection area (SPA) by the Birds Directive (Directive 2009/147/EC) since 1991; included in the Natura 2000 network (MITECO 2021) as well as being classified as a Site of Community Importance (SCI) by the Habitat Directive (Council Directive 92/43/EEC) in 2006. However, currently, the area is still subjected to degradation, which started at the beginning of the 1970s (Dafauce 1975). Intensive agriculture, urbanization, and industrial activities are the main causes of said deterioration (Soria 2006). For example, metals such as iron, zinc, and copper have been applied to rice-growing soils in the form of pesticides at levels of 1–15 kg/ha per year, whereas cadmium has been applied in fertilizers at amounts of 150–450 mg/ha per year (Boluda et al. 1993). 13 Among the several initiatives implemented (...truncated)