Aerobic methane synthesis and dynamics in a river water environment.

Reports of aerobic biogenic methane (CH4) have generated new views about CH4 sources in nature. We examine this phenomenon in the free-flowing Yellowstone river wherein CH4 concentrations were tracked as a function of environmental conditions, phototrophic microorganisms (using chlorophyll a, Chl a, as proxy), as well as targeted methylated amines known to be associated with this process. CH4 was positively correlated with temperature and Chl a, although diurnal measurements showed CH4 concentrations were greatest during the night and lowest during maximal solar irradiation. CH4 efflux from the river surface was greater in quiescent edge waters (71-94 µmol m-2 d) than from open flowing current (~ 57 µmol m-2 d). Attempts to increase flux by disturbing the benthic environment in the quiescent water directly below (~ 1.0 m deep) or at varying distances (0-5 m) upstream of the flux chamber failed to increase surface flux. Glycine betaine (GB), dimethylamine and methylamine (MMA) were observed throughout the summer-long study, increasing during a period coinciding with a marked decline in Chl a, suggesting a lytic event led to their release; however, this did not correspond to increased CH4 concentrations. Spiking river water with GB or MMA yielded significantly greater CH4 than nonspiked controls, illustrating the metabolic potential of the river microbiome. In summary, this study provides evidence that: (1) phototrophic microorganisms are involved in CH4 synthesis in a river environment; (2) the river microbiome possesses the metabolic potential to convert methylated amines to CH4; and (3) river CH4 concentrations are dynamic diurnally as well as during the summer active months.

The effect of various washing methods on pesticide residues, toxic and essential elements removal in rice.

This study examined the effects of various treatments on removing pesticide residues and toxic elements in rice. In parallel, nutritional elements, magnesium (Mg), potassium (K), and phosphorous (P), were measured to investigate the effect of these washing treatments on the nutritional value of rice. A naturally contaminated rice sample containing five widespread used pesticides (azoxystrobin, buprofezin, carbendazim, and propiconazole) and toxic elements, arsenic (As), cadmium (Cd), and essential elements, was washed using several washing agents, including boiling water, 5% sodium bicarbonate (baking soda), 5% acetic acid (vinegar), 5% citric acid, and 5% sodium chloride (salt). The washing method was chosen based on its availability and widespread usage; soaking for 10 min was assumed to be reasonable. Our results showed that using 5% acetic acid significantly reduced azoxystrobin by 63%, buprofezin by 70%, carbendazim by 75%, and propiconazole by 61%. However, As and Cd were significantly reduced in sodium chloride by 57% and 32%, respectively. Furthermore, a significant reduction in essential nutrient elements was found in Mg (42%), K (37%), and P (23%) when rice was treated with 5% citric acid. Overall, washing agents reduced analytes in the following manners pesticides, toxic elements, and essential elements when using acetic acid, sodium chloride, and citric acid separately.

Characterisation of engineered titanium dioxide nanoparticles in selected food.

Titanium dioxide (TiO2), an E171 manufacturer-made food additive, is extensively utilised as a colourant in drug and a food products. Some studies showed that most of confectionary and food items contain inexplicable particles. The aim of this article is to determine the size and structure of TiO2 nanoparticles in different food products. Ten food samples, including coffee cream, white chocolate concentrate, frosting, gum, yoghurt candy, hard candies and chewy candies, were investigated for this purpose. The crystalline structure and particle size of TiO2 were determined by Powder X-ray Diffraction (PXRD) and Transmission Electron Microscopy (TEM). TEM images revealed that a few of the extracted nanoparticles had a rod-like shape, but most were spherical. Also, the size of the TiO2 particle had a wide distribution between 12 and 450 nm. Thus, to avoid human health risk, crucial factors such as size, and shape should be considered and regulated by food authorities.

Arsenic and Mercury Distribution in an Aquatic Food Chain: Importance of Femtoplankton and Picoplankton Filtration Fractions.

Arsenic (As) and mercury (Hg) were examined in the Yellowstone Lake food chain, focusing on two lake locations separated by approximately 20 km and differing in lake floor hydrothermal vent activity. Sampling spanned from femtoplankton to the main fish species, Yellowstone cutthroat trout and the apex predator lake trout. Mercury bioaccumulated in muscle and liver of both trout species, biomagnifying with age, whereas As decreased in older fish, which indicates differential exposure routes for these metal(loid)s. Mercury and As concentrations were higher in all food chain filter fractions (0.1-, 0.8-, and 3.0-µm filters) at the vent-associated Inflated Plain site, illustrating the impact of localized hydrothermal inputs. Femtoplankton and picoplankton size biomass (0.1- and 0.8-µm filters) accounted for 30%-70% of total Hg or As at both locations. By contrast, only approximately 4% of As and <1% of Hg were found in the 0.1-µm filtrate, indicating that comparatively little As or Hg actually exists as an ionic form or intercalated with humic compounds, a frequent assumption in freshwaters and marine waters. Ribosomal RNA (18S) gene sequencing of DNA derived from the 0.1-, 0.8-, and 3.0-µm filters showed significant eukaryote biomass in these fractions, providing a novel view of the femtoplankton and picoplankton size biomass, which assists in explaining why these fractions may contain such significant Hg and As. These results infer that femtoplankton and picoplankton metal(loid) loads represent aquatic food chain entry points that need to be accounted for and that are important for better understanding Hg and As biochemistry in aquatic systems. Environ Toxicol Chem 2023;42:225-241. © 2022 SETAC.

Pyrrolizidine Alkaloid Extraction and Analysis: Recent Updates.

Pyrrolizidine alkaloids are natural secondary metabolites that are mainly produced in plants, bacteria, and fungi as a part of an organism's defense machinery. These compounds constitute the largest class of alkaloids and are produced in nearly 3% of flowering plants, most of which belong to the Asteraceae and Boraginaceae families. Chemically, pyrrolizidine alkaloids are esters of the amino alcohol necine (which consists of two fused five-membered rings including a nitrogen atom) and one or more units of necic acids. Pyrrolizidine alkaloids are toxic to humans and mammals; thus, the ability to detect these alkaloids in food and nutrients is a matter of food security. The latest advances in the extraction and analysis of this class of alkaloids are summarized in this review, with special emphasis on chromatographic-based analysis and determinations in food.

Analyzing pesticides and metal(loid)s in imported tobacco to Saudi Arabia and risk assessment of inhalation exposure to certain metals.

Exposure to toxic chemicals through smoked tobacco is a significant global public health issue due to their genotoxic and carcinogenic properties. The study aims to (1) measure Arsenic (As), Cadmium (Cd), Cobalt (Co), Chromium (Cr), Mercury (Hg), Nickle (Ni), lead (Pb), and 407 pesticides in tobacco commercialized in Saudi Arabia; and (2) evaluate human health risks associated with smoking tobacco. Thus, we analyzed 60 tobacco samples per brand from eight of the most popular tobacco brands in the Saudi market. The analyzed tobacco contained significant concentrations of toxic metal (loid)s and banned pesticides. Twenty-three out of 407 pesticide residues were found, with an average concentration of 0.004-1.155 µg/g. Average concentrations of As, Cd, Co, Cr, Hg, Ni, and Pb for all brands were 0.16, 0.57, 0.75, 1.36, 1.94, 0.01, and 0.37 µg/g, respectively. The risk assessment indicated that high cancer risks are associated with exposure to As, Cd, Cr, and Ni, while lower risks are associated with Pb. Additionally, the potential cancer risk estimated for Cr was higher than other toxic elements. The cumulative cancer risks (95%) under three different cases for all brands were greater than the permissible limits (=10-4). The chances of getting cancer through inhalation of particulate As, Cd, Cr, Ni, and Pb was 4 in 10 000 cases in the best case scenario (1 cigarette per day). Therefore, metal content in cigarette tobacco should be reduced to improve public health.HIGHLIGHTSAll tested brands contained banned pesticide residues except for brand C.Tobacco samples contained significant concentrations of toxic metal(loid)s.A high risk of developing cancer is associated with exposure to As, Cd, Cr, and Ni, while a lower risk is associated with exposure to Pb.

Determination of inorganic arsenic, heavy metals, pesticides and mycotoxins in Indian rice (Oryza sativa) and a probabilistic dietary risk assessment for the population of Saudi Arabia.

In this study, total arsenic (As), inorganic arsenic (iAs), cadmium (Cd), lead (Pb), mercury (Hg), pesticides, and aflatoxins (B1, B2, G1, G2) in Indian rice (Oryza sativa) and their dietary exposure risks for the general Saudi population were evaluated. A total of 483 samples were acquired from various ports and supermarkets throughout the country. Average elemental concentrations were found to be in the following order: As (0.1 ± 0.024)>iAs (0.038 ± 0.015)>Pb (0.023 ± 0.008)>Cd (0.019 ± 0.005)>Hg (0.002 ± 0.0004), and results did not exceed maximum residue limits (MRLs). Out of the 294 analyzed pesticides, 15 were detected in rice, of which six were fungicides, and nine were insecticides with a detection frequency of 22% and 26%, respectively. Eight of the detected pesticides were non-approved by the European Union (EU) commission, but their detection frequencies were low. Surprisingly, rice samples analyzed for aflatoxins were below the limit of quantification (LOQ). Risk assessment coupled with Monte Carlo simulation based on the hazard quotient (HQ) and incremental lifetime cancer risk (ILCR) approaches revealed that exposure to metal(loid)s and pesticides in rice were below levels that might pose a health risk.

LC-MS/MS and GC-MS/MS analysis of pesticide residues in Ecuadorian and Filipino Cavendish bananas imported into Saudi Arabia.

The occurrence of pesticide residues in bananas imported from Ecuador and the Philippines into Saudi Arabia was investigated. Eighty-seven banana samples were purchased from various supermarkets around the country. The conventional QuEChERS method was used to extract 294 pesticides in whole bananas and the analysis was carried out using LC-MS/MS and GC-MS/MS. In total, nine pesticides were detected of which azoxystrobin, carbendazim, chlorpyrifos, imazalil, and thiabendazole were the most frequently found in bananas from both countries. The levels of these pesticides were complaint according to the Saudi Food & Drug Authority's (SFDA) maximum residue levels (MRLs), therefore they cannot be considered a public health problem. Detectable residues of these agrochemicals show that they are used extensively in banana cultivation. The Ecuadorian Agency for Agricultural Quality Assurance (Agrocalidad) and the Saudi Ministry of Environment, Water and Agriculture (MEWA) prohibit the use of carbendazim in agriculture, while the Filipino Fertiliser and Pesticide Authority (FPA) allows its use. A legislative comparison of pesticide approval status revealed a lack of consensus between banana exporting and importing countries that could affect food safety and trade.