Heavy metal content of produce grown in San Juan County (New Mexico, USA).

The Animas River Watershed has long received discharges of naturally occurring acid rock drainage; however, on August 5, 2015, three million gallons flowed into the agricultural region of Farmington, New Mexico and the Navajo Nation. Consumers and growers in the region were fearful that produce might absorb heavy metals from contaminated irrigation water originating from these rivers. Samples were collected from the region including corn (n = 30), pumpkin (n = 10), squash (n = 10), and cucumber (n = 10) then processed and tested using inductively coupled plasma-optical emission spectrometry (ICP-OES) for concentrations of nine metals of interest. These include toxic metals: Al, As, and Pb, which were compared to the World Health Organization limits, 18.29 mg d-1, 0.192 mg d-1, and 0.05 mg kg-1, respectively and essential metals: Cr, Fe, Mn, Zn, Ca, and Cu whose levels were compared to the National Academies' dietary references for tolerable upper intake levels. Results indicate that produce grown in the region contained significantly less metal than the allowable limits, except for Pb in two corn samples. This research is the first attempt to monitor and analyze heavy metal absorption of produce in the area.

Genetic variation in metallothionein and metal-regulatory transcription factor 1 in relation to urinary cadmium, copper, and zinc.

BACKGROUND: Metallothionein (MT) proteins play critical roles in the physiological handling of both essential (Cu and Zn) and toxic (Cd) metals. MT expression is regulated by metal-regulatory transcription factor 1 (MTF1). Hence, genetic variation in the MT gene family and MTF1 might influence excretion of these metals. METHODS: 321 women were recruited in Seattle, WA and Las Cruces, NM and provided demographic information, urine samples for measurement of metal concentrations by mass spectrometry and creatinine, and blood or saliva for extraction of DNA. Forty-one single nucleotide polymorphisms (SNPs) within the MTF1 gene region and the region of chromosome 16 encoding the MT gene family were selected for genotyping in addition to an ancestry informative marker panel. Linear regression was used to estimate the association of SNPs with urinary Cd, Cu, and Zn, adjusted for age, urinary creatinine, smoking history, study site, and ancestry. RESULTS: Minor alleles of rs28366003 and rs10636 near the MT2A gene were associated with lower urinary Cd, Cu, and Zn. Minor alleles of rs8044719 and rs1599823, near MT1A and MT1B, were associated with lower urinary Cd and Zn, respectively. Minor alleles of rs4653329 in MTF1 were associated with lower urinary Cd. CONCLUSIONS: These results suggest that genetic variation in the MT gene region and MTF1 influences urinary Cd, Cu, and Zn excretion.

Agricultural soils of the Animas River watershed after the Gold King Mine spill: An elemental spatiotemporal analysis via portable X-ray fluorescence spectroscopy.

In August 2015, 11.3 million L of heavy metal-contaminated water spilled into the Animas River from the Gold King Mine (Colorado, USA). National attention focused on water quality and agricultural production in areas affected by the spill. In response to local concerns, surface soil elemental concentrations were analyzed in three New Mexico agricultural fields to determine potential threats to agronomic production. Irrigated fields in the Animas watershed were scanned using portable X-ray fluorescence (PXRF) spectrometry to monitor the spatiotemporal variability of Pb, As, Cu, and Cr. A total of 175 locations were scanned using PXRF before and after the growing season for 3 yr. The geostatistical model with the lowest RMSE was chosen as the optimal model. The lowest RMSE for the elements ranged from to 0.10 to 0.44 m for As, from 0.50 to 0.98 m for Cr, from 0.15 to 0.91 m for Cu, and from 0.14 to 0.44 m for Pb across the models selected. The spatial dependence between the measured values exhibited strong to moderate autocorrelation for all metals except for As, for which spatial dependence was strong to weak. Some areas in each field exceeded the New Mexico Environment Department soil screening limit of 7.07 mg As kg-1 . All sampling locations were below the screening limit at last sampling time in 2019. Mixed models used for temporal analysis showed a significant decrease only in As below the screening value at the end of the study. Results indicate that the agricultural soils were below the soil screening guideline values.

Urinary heavy metals in Hispanics 40-85 years old in Doña Ana County, New Mexico.

Exposure to As, Cd, Pb, and U among older Hispanic adults residing in underserved communities in southern New Mexico was investigated. Personal information was obtained by standardized interview from 188 adults aged 40-85 years. Urinary metal concentrations were measured and compared to results from the National Health and Nutritional Examination Survey (NHANES). Urinary As and U in study participants significantly (p < .05) exceeded NHANES reference values. Elevated urinary As concentration was significantly associated with older age, Latin American birthplace, clinic site, private-well drinking water, higher self-rated health, and diabetes. Higher urinary Cd was significantly associated with older age, clinic site, female sex, agricultural work, and current cigarette smoking. No personal characteristics were significantly associated with urinary Pb or U. Our results suggest elevated levels of As and U in this population.

Plant uptake of depleted uranium from manure-amended and citrate treated soil.

Six plant species were tested for their ability to accumulate depleted uranium in their above-ground biomass from deployed munitions contaminated soil in New Mexico. In greenhouse experiments, Kochia (Kochia scoparia L. Schrad.) and pigweed (Amaranthus retroflexus L) were grown with steer manure added at rates of 22.4, 44.8, and 89.6 Mg ha(-1). Citric acid and glyphosate (N-(phosphonomethyl) glycine) applied at the end of the growing season increased DU concentrations from 2.5 to 17 times. Leaf and stem DU concentrations in kochia increased from 17.0 to 41.9 mg kg(-1) and from 3.5 to 18.0 mg kg(-1), respectively. In pigweed, leaf and stem DU concentrations increased from 1.0 to 17.3 and from 1.0 to 4.7 mg kg(-1), respectively. Manure generally decreased or had no effect on DU uptake. The effect of citric acid and ammonium citrate on DU uptake by kochia, sunflower (Helianthus annuus L), and sweet corn (Zea mays L) was also studied. Ammonium citrate was just as effective in enhancing DU uptake as citric acid. This implies that the citrate ion is more important in DU uptake and translocation than the solubilization of DU through acidification. In both experiments, leaves had higher DU concentrations than stems.

Appropriate preservation of dairy wastewater samples for environmental analysis.

Thousands of gallons of water are used in dairies to wash cows before milking and for cleaning equipment. The wastewater generated contains elevated levels of organic matter and pollutants, including nitrogen that once converted, may contaminate groundwater with nitrate. This study was conducted to determine the amount of sulfuric acid needed to preserve wastewater samples from a New Mexico dairy in the southwestern U.S. Titrations of wastewater from a local dairy using full strength (18 M) sulfuric acid were performed to determine the amount of acid needed to bring the pH of the sample to below two, the recommended pH for sample preservation. An average of 0.33 mL of acid was required for every 100 mL of wastewater. Due to sample variability, we recommend that 0.4 mL sulfuric acid be added for every 100 mL dairy wastewater sample to ensure adequate acidification. This quantity is twice the amount currently recommended in U.S. Environmental Protection Agency guidelines.