Spatiotemporal distribution of organochlorine pesticides in the upper La Antigua watershed, Veracruz Mexico

Abstract

Even though the use of organochlorine pesticides has been prohibited since the last century their presence is still being recorded around the world. In the upper La Antigua watershed, Veracruz, Mexico we have reported concentrations of these contaminants in different compartments of the riverine ecosystems. This is of relevance due to their potential disruptive endocrine effect on the vertebrates drinking the water or feeding in the riverine area. In this study we evaluated concentrations of organochlorine pesticides (OCPs) in streams running throughout mountain cloud forest and two different types of land use, pasture lands and coffee plantations. Water and periphyton samples were collected during the wet and the dry seasons from streams located in independent micro-basins. Spatial explicit analyzes show that the concentrations measured are independent of the distribution of the streams in the geographical area sampled. However seasonal differences were found during the dry season in the water and during the rainy season in periphyton. While OCPs in water support the idea that micro-basins can be used as independent monitoring units, OCPs in periphyton can be indicators of the effect of different land use. Some concentrations of all the OCPs registered had values above the limits for tap water.

Keywords: La Antigua basin; Organochlorine pesticides; Periphyton; Spatial explicit models.

Fig. 1

Representation of the upper part of La Antigua basin, Veracruz, Mexico where the study was developed. Location (1–11) of the independent micro-basins where periphyton films and water running throughout the different land uses were collected. Upper left diagrams show the location of the high La Antigua basin in Mexico. This figure was created using satellite images in ArcGis 10.2 and classification of the vegetation and land use in Ecognition 8.3.

Fig. 2

OCPs concentrations (Concentrations ppm = µg L^− 1) measured in water from rivers of different land uses (Coffee plantations, Pasture Lands and Cloud Forest) during the dry and the wet season. BL: Cloud Forest Wet Season; BS: Cloud Forest Dry Season; CL: Coffee Plantation Wet Season; CS: Coffee Plantation Dry Season; PL: Pastureland Wet Season and PS: Pastureland Dry Season.

Fig. 3

Spatial explicit plot of OCPs concentrations in µg L^− 1 measured in the streams of the upper part of La Antigua basin, Veracruz, Mexico. Axes correspond to the normalized latitude and longitude of the geographic space where the basin is located. The rank-scale in the side of each graph represents concentrations measured in each site.

Fig. 4

OCPs concentrations (Concentrations ppm = µg (500 cm ^− 2)) measured in periphyton in the different land uses (Coffee plantations, Pasture Lands and Cloud Forest).