Sara Purca

Microplastics (MP) are an increasing environmental concern in aquatic ecosystems due to their widespread presence and adverse effects on organisms. The lower basin of the Lurín River is affected by wastewater discharges and solid waste pollution, making it vulnerable to MP contamination. This study assessed MP contamination in surface water and sediments of the Lurín River. Sampling was conducted at four sites from the lower basin to the river mouth during the dry and wet seasons. MP were detected in surface water, with a median of 0.24 items/m³ (range: 0–0.67), and in sediments, with a median of 20 items/kg (range: 0–80). White was the dominant MP color in surface water (64.3%) and sediments (42.9%). Fibers were the most prevalent morphology (>60%), followed by fragments in surface water (26.2%) and films in sediments (17.9%). A statistically significant difference in sediment MP abundance was observed between site P1 and P4 (H = 8.305; p = 0.040), with the highest abundance at P1, located near the river mouth. In surface water, MP abundance showed a significant negative correlation with precipitation (rs = −0.649; p = 0.004), indicating lower MP concentrations during periods of increased rainfall. No significant seasonal differences in MP abundance were detected between wet and dry seasons in surface water (p = 0.310) or sediments (p = 0.791). This pattern may be influenced by the 2023 El Niño event, which increased precipitation during the river’s dry season.

This research established robust approaches to understanding and monitoring sources, distribution, and fate of plastic waste generated on the Peruvian coast. Quantifying Lima and Callao inputs, and mapping behaviours to sources, impacts and interventions by the Regional Citizen Science Programme and Research Network of Marine-Coastal Stressors in Latin America and the Caribbean (REMARCO) over the last five years. In addition, the Instituto del Mar del Peru (IMARPE) showed the strengthened capacities for monitoring the presence of microplastics in sandy beaches, through the microplastics APEC course in 2014 and the inter-regional NUTEC plastics network coordination 2024-2028 period. The present study is the first attempt to investigate the occurrence and distribution pattern of macro, meso and microplastics (MPs) in the Costa Azul (CA) sandy beach of Peru. Fourier-transform infrared spectroscopy was used to identify the MP particle (> 300 µm). The mean abundance of macroplastics in this study site was 1.20 ± 0.80 particles m-2, the predominant types of plastics were fragments of plastic bags, hard plastics, and Styrofoam. The abundance of microplastics (5 -1 mm) was found in the following order: Hard plastics > Foams > fibres> beads > pellets. The greatest abundance of microplastics (5-1 mm) was concentrated in the supralittoral zone, with 3139.20 ± 2131.68 particles/m-2 in CA sandy beach. In addition, the most abundant polymer type was high-density polyethene (HDPE) (50%). The macro, meso and microplastics (MPs) monitoring by IMARPE characteristics are a.-The inter-regional harmonized protocols and standardized methods, increased collaboration between regions by NUTEC plastic, b.-The long-term monitoring supported by the Peruvian government, c.-The regional database platform to data sharing and open science practices.

Monitoring the movement of plastic into marine food webs is central to understanding and mitigating the plastic pollution crisis.

In northern Peru, the mangrove crab Ucides occidentalis is of great importance due to its ecological, economic, and social role. In this study, we reported for the first time the presence of microplastics in the gills and digestive tract of the mangrove crab U. occidentalis derived from local markets in Tumbes. Microplastics were identified in 100% of the crabs analyzed with a total of 921 items, 475 items (52.57%) found in the gills, and 446 (48.43%) found in the digestive tract. The size range was established in 2 to 250 µm, 250 to 500 µm, 500 to 1 mm, and 1 to 5 mm, microplastics with sizes between 2 and 250 µm were the most common with 53.79% in the digestive tract and 90% in the gills. A total of six different types of microplastic were recorded; The highest percentages for each tissue were fibers (59.64%–61.05%) and films (19.28%−36.63%), with clear fibers being the most prevalent microplastic type in both tissues. Microplastics with less than 250 µm size were found 90% in the gills and 53.79% in the crab digestive tract. Although the present study is a baseline for rapid identification of microplastics in mangrove crab, we suggested that these findings provided more information on the state of contamination as well as food security alert for local markets.

Este trabajo aborda la problemática representada por los micro y nanoplásticos (MP y NP, respectivamente) en las costas americanas del Océano Pacífico, desde la perspectiva de la Red Micro y Nano Allpa Pacha. Esta red está conformada por científicos de Chile, Perú, Costa Rica, Colombia, Ecuador, Panamá y México, quienes, preocupados por el impacto en el ambiente y su repercusión en la salud, decidieron establecer colaboraciones científicas internacionales para la geolocalización, monitoreo y caracterización de MP y NP presentes en las costas del Océano Pacífico en el continente americano. Se espera aportar datos basados en evidencias científicas y armonizados, que impacten en la enseñanza y en la planificación de medidas de control y regulación de estos contaminantes en nuestros países. En este trabajo se incluyen algunos aspectos de polímeros y plásticos, definiciones de MP’s y NP’s, y sus diversos impactos, la problemática de la toma de muestras, caracterización adecuada, entre otros. Unas de las conclusiones permitieron determinar que hay muchas características de los NP’s y MP’s sin investigar como la interacción con otros productos químicos, el impacto de la morfología en la biodisponibilidad, la formación de adherencias y liberación de las mismas durante su contacto con los compartimentos ambientales, la dependencia de su composición con su comportamiento y destino, entre otras. Asimismo, se determinó que todo aporte a la mitigación del problema de estos materiales debe incluir la concientización, la prevención y la reducción, mediante un enfoque integral de educación y capacitación, y considerando todos los actores de la sociedad, responsables de la problemática generada, bajo un enfoque de evidencia científica. Finalmente, se determinó que el tema aún está en su fase inicial, y la información es reiterativa y auto referenciada.

Over the last decades, the Humboldt Current upwelling ecosystem, particularly the northern component off the coast of Peru, has drawn the interest of the scientific community because of its unique characteristics: it is the upwelling system with the biggest catch productivity despite the fact it is embedded in a shallow and intense oxygen minimum zone (OMZ). It is also an area of intense nitrogen loss and anammox activity and experiences large interannual variability associated with the equatorial remote forcing. In this context, we examined the oceanographic and biogeochemical variability associated with the OMZ off central Peru from a monthly time series (1996–2011) recorded off the coast of Callao (12° 02′ S, 77° 29′ W). The data reveal a rich spectrum of variability in the OMZ that includes frequencies ranging from seasonal to interannual scales. Due to the efficient oceanic teleconnection off Peru, the observed variability is interpreted in the light of an estimate of the equatorial Kelvin wave contribution to sea level anomalies considering the peculiarities of its vertical structure (i.e., the first two baroclinic modes). The span of the data set allows us to contrast two OMZ regimes. The strong regime is associated with the strong 1997–1998 equatorial Pacific El Niño, during which the OMZ adjusted to Kelvin-wave-induced downwelling conditions that switched off the upwelling and drastically reduced nutrient availability. The weak regime corresponds to the post-2000 period associated with the occurrence of moderate central Pacific El Niño events and enhanced equatorial Kelvin wave activity, in which mean upwelling conditions are maintained. It is shown that the characteristics of the coupling between physics and biogeochemistry is distinct between the two regimes with the weak regime being associated with a larger explained variance in biogeochemical properties not linearly related to the ENSO oceanic teleconnection. The data also reveal a long-term trend from 1999 corresponding to a deepening of the oxygen-deficient waters and warming. The implications of our results for understanding the OMZ dynamics off Peru are discussed.