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Effect of hydrogeological and anthropogenic factors on the spatial and temporal distribution of CVOCs in the karst system of northern Puerto Rico.

ABSTRACT: This study evaluates factors affecting the spatial and temporal distribution of chlorinated volatile organic contaminants (CVOCs) in the highly productive aquifers of the karst region in northern Puerto Rico (KR-NPR). Historical records from 1982 to 2016 are analyzed using spatial and statistical methods to evaluate hydrogeological and anthropogenic factors affecting the presence and concentrations of multiple CVOCs in the KR-NPR. Results show extensive spatial and temporal distributions of CVOCs, as single entities and as mixtures. It is found that at least one type of CVOC is present above detection limits in 64% of the samples and 77% of the sampling sites during the study period. CVOC distribution in the KR-NPR is contaminant-dependent, with some species being strongly influenced by the source of contamination and hydrogeological characteristics of the system. Persistent presence of CVOCs in the KR-NPR system, even after contaminated sites have been subjected to active remediation, reflect the high capacity of the system to store and slowly release contaminants over long periods of time. This study shows that karst aquifers are highly vulnerable to contamination and can serve as a long-term route of contaminants to potential points of exposure.

SUBMITTER: Torres NI

PROVIDER: S-EPMC6953914 | biostudies-literature | 2019 Oct

REPOSITORIES: biostudies-literature

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Effect of hydrogeological and anthropogenic factors on the spatial and temporal distribution of CVOCs in the karst system of northern Puerto Rico.

Torres Norma I NI Rivera Vilda L VL Padilla Ingrid Y IY Macchiavelli Raul E RE Kaeli David D Alshawabkeh Akram N AN

Environmental earth sciences 20191004 20

This study evaluates factors affecting the spatial and temporal distribution of chlorinated volatile organic contaminants (CVOCs) in the highly productive aquifers of the karst region in northern Puerto Rico (KR-NPR). Historical records from 1982 to 2016 are analyzed using spatial and statistical methods to evaluate hydrogeological and anthropogenic factors affecting the presence and concentrations of multiple CVOCs in the KR-NPR. Results show extensive spatial and temporal distributions of CVOC ...[more]

PMID: 31929835

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Project description:BackgroundIn previous studies, exposures to heavy metals such as Pb and Cd have been associated with adverse birth outcomes; however, knowledge on effects at low levels of exposure and of other elements remain limited.MethodWe examined individual and mixture effects of metals and metalloids on birth outcomes among 812 pregnant women in the Puerto Rico Testsite for Exploring Contamination Threats (PROTECT) cohort. We measured 16 essential and non-essential metal(loid)s in maternal blood collected at 16-20 and 24-28 weeks gestation. We used linear and logistic regression to independently examine associations between geometric mean (GM) concentrations of each metal across visits and gestational age, birthweight z-scores, preterm birth, small for gestational age (SGA), and large for gestational age (LGA). We evaluated effect modification with infant sex*metal interaction terms. To identify critical windows of susceptibility, birth outcomes were regressed on visit-specific metal concentrations. Furthermore, average metal concentrations were divided into tertiles to examine the potential for non-linear relationships. We used elastic net (ENET) regularization to construct Environmental Risk Score (ERS) as a metal risk score and Bayesian Kernel Machine Regression (BKMR) to identify individual metals most critical to each outcome, accounting for correlated exposures.ResultsIn adjusted models, an interquartile range (IQR) increase in GM lead (Pb) was associated with 1.63 higher odds of preterm birth (95%CI = 1.17, 2.28) and 2 days shorter gestational age (95% CI = -3.1, -0.5). Manganese (Mn) and zinc (Zn) were also associated with higher odds of preterm birth and shorter gestational age; the associations were strongest among the highest tertile for Mn and among females for Zn. Mercury (Hg) was associated with higher risk of preterm birth at the later window of pregnancy. Ni measured later in pregnancy was associated with lower odds of SGA. ENET and BKMR models selected similar metals as "important" predictors of birth outcomes. The association between ERS and preterm birth was assessed and the third tertile of ERS was significantly associated with an elevated odds ratio of 2.13 (95% CI = 1.12, 5.49) for preterm birth compared to the first tertile.ConclusionAs the PROTECT cohort has lower Pb concentrations (GM = 0.33 μg/dL) compared to the mainland US, our findings suggest that low-level prenatal lead exposure, as well as elevated Mn and Zn exposure, may adversely affect birth outcomes. Improved understanding on environmental factors contributing to preterm birth, together with sustainable technologies to remove contamination, will have a direct impact in Puerto Rico and elsewhere.

Dataset Information

Effect of hydrogeological and anthropogenic factors on the spatial and temporal distribution of CVOCs in the karst system of northern Puerto Rico.

Publications

Effect of hydrogeological and anthropogenic factors on the spatial and temporal distribution of CVOCs in the karst system of northern Puerto Rico.

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