Initial results of environmental monitoring in the Texas Rio Grande Valley

Persistent organic pollutants in eggs from south Texas Aplomado falcons

A program to reintroduce the Northern Aplomado falcon (Falco femoralis septentrionalis) in south Texas and the southwestern United States was initiated in the late 1970s. Fledgling Aplomado falcons were first released in the Laguna Atascosa National Wildlife Refuge in 1993 and the first nesting pair in the area was recorded by 1995. During 2004-2017 we collected addled eggs from nesting pairs in the Laguna Atascosa National Wildlife Refuge and Matagorda Island in south Texas, to determine if environmental contaminants in Aplomado falcon eggs had decreased over time and if eggshell thickness values were similar to those in the pre-DDT era. We analyzed organochlorine pesticides, PCBs, and PBDEs in 60 egg homogenates by gas chromatography-mass spectrometry. Eggshells were measured to determine thickness and to correlate with contaminant concentrations. Mean concentration in eggs were 244 ng/g ww for p,p'- DDE, 270 ng/g ww for PCBs and 10 ng/g ww for PBDEs. These values were lower than those reported in a previous study for eggs collected between 1999 and 2003, with a mean of 821 ng/g ww for p,p'-DDE and 1228 ng/g ww for total PCBs. Eggshell thickness ranged from 0.206 mm to 0.320 mm (n = 156). Overall, contaminant concentrations in eggs of Aplomado falcons were low, at levels not likely to impact the recovery of the species. Data from this and previous studies indicate that DDE has decreased significantly in eggs of Aplomado falcons over the last 25 years in south Texas. Breeding populations have been steady at over 30 breeding pairs in south Texas since 2011, although they decreased to 24 pairs in 2018 following Hurricane Harvey.

Prevalence of antibiotic resistant Salmonella spp. strains in shrimp farm source waters of Nagapattinam region in South India

The prevalence of antibiotic-resistant Salmonella spp. in the source waters of shrimp farms in the Nagapattinam region of South India was investigated. Water and sediment samples (188 Nos.) collected from 23 natural creeks during December 2018 to April 2019 were examined for Salmonella spp. by conventional and PCR methods. The study indicated 28.7% of water and 25.5% of sediment isolates as Salmonella spp., while PCR test gave positive for 7.44% and 5.15% of the isolates, respectively. The isolates were resistant to sulfonamide (SF), but sensitive to tetracycline (TC), chloramphenicol (CAP), and furazolidone (FZ). PCR amplification of mitochondrial 16S rRNA region identified the highly resistant Salmonella serovar as S. Montevideo, which is an emerging food-borne pathogen. The incidence of antibiotic-resistant S. Montevideo reported for the first time in the natural creeks that supply water for shrimp farms emphasizes the need for regulatory steps to control its prevalence.

Presence and Persistence of Salmonella in Water: The Impact on Microbial Quality of Water and Food Safety

Salmonella ranks high among the pathogens causing foodborne disease outbreaks. According to the Centers for Disease Control and Prevention, Salmonella contributed to about 53.4% of all foodborne disease outbreaks from 2006 to 2017, and approximately 32.7% of these foodborne Salmonella outbreaks were associated with consumption of produce. Trace-back investigations have suggested that irrigation water may be a source of Salmonella contamination of produce and a vehicle for transmission. Presence and persistence of Salmonella have been reported in surface waters such as rivers, lakes, and ponds, while ground water in general offers better microbial quality for irrigation. To date, culture methods are still the gold standard for detection, isolation and identification of Salmonella in foods and water. In addition to culture, other methods for the detection of Salmonella in water include most probable number, immunoassay, and PCR. The U.S. Food and Drug Administration (FDA) issued the Produce Safety Rule (PSR) in January 2013 based on the Food Safety Modernization Act (FSMA), which calls for more efforts toward enhancing and improving approaches for the prevention of foodborne outbreaks. In the PSR, agricultural water is defined as water used for in a way that is intended to, or likely to, contact covered produce, such as spray, wash, or irrigation. In summary, Salmonella is frequently present in surface water, an important source of water for irrigation. An increasing evidence indicates irrigation water as a source (or a vehicle) for transmission of Salmonella. This pathogen can survive in aquatic environments by a number of mechanisms, including entry into the viable but nonculturable (VBNC) state and/or residing within free-living protozoa. As such, assurance of microbial quality of irrigation water is critical to curtail the produce-related foodborne outbreaks and thus enhance the food safety. In this review, we will discuss the presence and persistence of Salmonella in water and the mechanisms Salmonella uses to persist in the aquatic environment, particularly irrigation water, to better understand the impact on the microbial quality of water and food safety due to the presence of Salmonella in the water environment.

The conjunction of a new ultrasonic-assisted dispersive solid-phase extraction method with HPLC-DAD for the trace determination of diazinon in biological and water media

Herein, a new ultrasonic-assisted dispersive solid-phase extraction method was successfully developed for the trace detection of diazinon.

Biochemical and histological changes in the liver tissue of rainbow trout (Oncorhynchus mykiss) exposed to sub-lethal concentrations of diazinon

The organophosphate insecticide diazinon is widely used to control pest in Iran. The purpose of the present study was to investigate the antioxidant and histopathological changes in the liver tissue of rainbow trout (Oncorhynchus mykiss) exposed to 0.1 and 0.2 mg/L of a commercial formula of diazinon for a period of 28 days. Antioxidant enzyme activities--catalase, superoxide dismutase, glutathione peroxidase and glutathione reductase--were determined after 7, 14 and 28 days of exposure. Histopathological analyses were performed at the 28th day. All antioxidant enzymes were induced after 7 days of diazinon treatment in both concentrations of diazinon. Catalase and superoxide dismutase maintained elevated activities during all the treatment period. Glutathione peroxidase activity returned to the control values at the 14th day, decreasing to values below control at the 28th day in both diazinon concentrations. Glutathione reductase maintained increased activities at the 14th day in the 0.1 mg/L diazinon, decreasing to control values at the 28th day. In the 0.2 mg/L group, the activity returned to control values at the 14th and decreased below the control at the 28th day. Total antioxidant capacity of hepatocytes significantly decreased in fishes exposed to diazinon during all experimental periods. Hypertrophy of hepatocytes, vacuolization of cell cytoplasm and hepatocyte cloudy swelling were observed in the liver tissue of fish exposed to both concentrations of diazinon. The results showed that diazinon altered the activity of antioxidant enzymes and the cellular total antioxidant capacity inducing oxidative stress and cellular damage in hepatocytes evidenced by histopathological analysis.

Assessment of organochlorine pesticide levels in Manadas Creek, an urban tributary of the Rio Grande in Laredo, Texas

The Rio Grande is the natural boundary between the United States and Mexico from El Paso, Texas, to Brownsville, Texas. It supports about 12 million people on both sides of the border for municipal, agricultural, industrial, and recreational uses. The rapid population and economic growth along the border region has led to increased pollution in the Rio Grande, which has been linked to several border health issues associated with pesticide contamination. This project was initiated to assess the organochlorine pesticide levels in the water and sediments in Manadas Creek, an urban tributary of the Rio Grande located in north Laredo, Texas. Water and sediment samples were collected monthly during a 6-month period from July to December of 2006 and analyzed using gas chromatography with an electron capture detector after extraction via a solid-phase microextraction technique. Among the water and sediment samples collected, several organochlorine pesticides including alpha-, beta-, and gamma-hexachlorocyclohexane (HCH), heptachlor epoxide, endrin, and 4,4'-DDT were found in either the creek water or sediments. Analysis of variance results indicated that only gamma-HCH had significant variation in the creek water among the sampling periods. Comparison of results with previous findings showed the presence of higher levels of HCH isomers and much lower DDT concentrations in the present study.

Preliminary environmental monitoring of water quality in the Rio Grande in the Laredo-Nuevo Laredo Region

The international border region of the Rio Grande faces severe environmental and economic challenges. Contamination and degradation of its fragile lotic environments are mainly due to stresses from rapid population growth and unchecked industrial development. This study evaluates the water quality of the Rio Grande in the area of Nuevo Laredo, Mexico and Laredo, Texas, USA, in terms of physical, chemical and bacteriological parameters, as well as total metals, organochlorine pesticides, volatile organic compounds (VOC), semi-volatile organic compounds (SVOC) and radioactivity. Surface water samples were collected at 3 sites along the river. Two additional non-river sites (potable water and residual water) were studied for a better assessment of water quality in the region. Three series of samples were taken every other day during one week (November 3 to November 8, 2005) from the five sampling sites. Levels of oil and grease in all the river samples exceeded the limits established by Mexican regulations. Concentrations of aluminum above the permissible limits for source of drinking water and for quality for protection of freshwater biota were also found in all of the river sites. A number of unregulated elements (Cd, Sr, Mg, Na, Fe, Si, Li and K) appeared in the river samples. The average concentrations of Ba and Na in the potable water samples were below the permissible limits. Ca, Sr, Mg and Si were also found but are not regulated. The majority of the organic compounds studied in both the river and in residual water samples was below detection limits. In all the potable water samples, bromodichloromethane and dibromochloromethane were found above their limit of quantitation (LOQ), but these compounds are not regulated. This preliminary study suggests the need for consistent periodic monitoring to track the environmental status of the Rio Grande.

Photocatalytic degradation of agricultural N-heterocyclic organic pollutants using immobilized nanoparticles of titania

Degradation and mineralization of two agricultural organic pollutants (Diazinon and Imidacloprid as N-heterocyclic aromatics) in aqueous solution by nanophotocatalysis using immobilized titania nanoparticles were investigated. Insecticides, Diazinon and Imidacloprid, are persistent pollutants in agricultural soil and watercourses. A simple and effective method was developed to immobilization of titania nanoparticles. UV-vis, ion chromatography (IC) and chemical oxygen demand (COD) analyses were employed. The effects of operational parameters such as H(2)O(2) and inorganic anions (NO(3)(-), Cl(-) and SO(4)(2-)) were investigated. The mineralization of Diazinon and Imidacloprid was evaluated by monitoring of the formed inorganic anions. The selected pollutants are effectively degraded following first order kinetics model. Results show that the nanophotocatalysis using immobilized titania nanoparticle is an effective method for treatment Diazinon and Imidacloprid from contaminated water.

Determination of endocrine disruptors in Kafue lechwe (Kobus leche kafuensis) samples from the Lochinvar National Park of Zambia

Analysis of serum, whole blood and liver tissue samples from Kafue lechwe in the Lochinvar National Park of Zambia for suspected endocrine disrupting compounds revealed high concentrations for some of the compounds. 45 samples of serum, whole blood and liver tissue were extracted by liquid-liquid extraction followed by an analysis using Gas Chromatography-Electron Capture Detection (GC-ECD). The following endocrine disruptors were analyzed: deltamethrin, aldrin, endosulfan, dieldrin, pp-DDD, heptachlor, d-t-allethrin, pp-DDE, endrin and pp-DDT. For all the samples, dieldrin showed the highest concentration ranging from 1.7 to 44.4 microg/ml in serum and whole blood sample extracts and 0.10-5.1 microg/g wet weight in liver sample extracts. The most frequently detected was deltamethrin in 62% of the samples. Percent recoveries in spiked laboratory blanks ranged between 60% and 100% while calculated detection limits ranged from 0.004 to 0.21 microg/ml for all the endocrine disruptors evaluated. Where endocrine disruptors were detected, the concentrations of most of them far exceeded the maximum residue limits (MRLs) and the extraneous maximum residue limits (EMRLs) set by the Codex Alimentarius of the United Nations (UN), Food and Agricultural Organization (FAO).

Analysis of chemical contamination within a canal in a Mexican border colonia

This study examines urban pollution within Derechos Humanos, a colonia popular in Matamoros, Tamaulipas, Mexico. General water quality indicators (coliform bacteria, total dissolved solids, ecologically relevant cations and anions), heavy metals (copper, lead, nickel, zinc, iron and cadmium), and volatile organic compounds (benzene, toluene, ethylbenzene, styrene, and dichlorobenzene and xylene isomers) were quantified within a wastewater canal running adjacent to the community. Water samples were collected at multiple sites along the banks of the canal and evidence of anthropogenic emissions existed at each sampling location. Sample site 2, approximately 10 m upstream of the colonia, contained both the widest range of hazardous pollutants and the greatest number exceeding US Environmental Protection Agency surface water standards. At each sampling location, high concentrations of total coliform (> 10(4) colonies/100 mL sample), lead (ranging from 0.05 to 0.40 mg/L), nickel (levels from 0.21 to 1.45 mg/L), and benzene (up to 9.80 mg/L) were noted.

Identification of photocatalytic degradation products of diazinon in TiO2 aqueous suspensions using GC/MS/MS and LC/MS with quadrupole time-of-flight mass spectrometry

The photocatalytic degradation of the organophosphorus insecticide diazinon in aqueous suspensions has been studied by using titanium dioxide as a photocatalyst. The degradation of the insecticide was a fast process and included the formation of several intermediates that were identified using GC/ion-trap mass spectrometry with EI or CI in positive and negative ionization mode and HPLC/electrospray-QqTOF mass spectrometry. Since primarily hydroxy derivatives were identified in these aqueous suspensions, the mechanism of degradation was probably based on hydroxyl radical attack. The initial oxidative pathways of the degradation of diazinon involved the substitution of sulfur by oxygen on the Pz.dbnd6;S bond, cleavage of the pyrimidine ester bond, and oxidation of the isopropyl group. Exact mass measurements of the derivatives allowed the elemental formula of the molecules to be determined confidently. Similarities to the metabolic pathways occurring in living organisms were observed.