Seasonal content of heavy metals in the "soil–feed–milk–manure" system in horse husbandry in Kazakhstan

Abstract

Background and Aim: The quality of food, especially animal-based food, is crucial for human health. However, the quality of milk and other animal products has become an acute cause for concern in Kazakhstan . Technogenic dispersion of heavy metals (HMs) causes adverse effects on living organisms and creates unfavorable conditions for the existence of humans, animals, and plants. The purpose of this study was to analyze the content of several HMs in samples of soil, horse feed (hay, mixed feed, and bran), mare's milk, and manure to assess bioaccumulation and possible adverse effects on the bodies of horses. An additional purpose was to identify areas with acceptable conditions for obtaining environmentally safe horse breeding products in the agricultural zones of the Almaty region, Kazakhstan. Materials and Methods: Samples were obtained from two farms in the Almaty region in 2020 (spring, summer, and autumn). In total, 72 soil samples were analyzed, which were taken from the upper humus horizon to the depth of the arable layer. Eighty-six samples were taken from the feed of horses. Green feed was represented by perennial and annual grasses (alsike clover, Medicago sativa, sweet yellow clover, as well as pea and oat mix). Barley and wheat bran stored in the warehouses of the farm were sampled for the research as feed supplements. The mixed feed comprised components such as maize and sunflower. In addition, 46 samples of mare's milk and 28 samples of horse manure were collected. The HM analysis was performed in the laboratory of the Kazakh-Japanese Innovation Center. The residual amounts of HMs were determined using an absorption spectrometer with a voltammetric analyzer. The content of cadmium (Cd), lead (Pb), mercury (Hg), and arsenic (As) in all the studied samples of soil, feed, mare's milk, and manure did not exceed the threshold limit values (TLVs), suggesting that the intake of these toxic elements into the human body with food was low. Results: The average Cd concentration was in the range of 0.29-0.31 mg/kg in soil samples and in the range of 0.20-0.27 mg/kg in feed samples. In milk, the Cd concentration varied from 0.01 to 0.02 mg/L and was lower in summer and higher in fall. The total average Cd content in horse manure was 0.1844 mg/kg. The concentration of Pb in soil samples ranged from 1.09 to 1.30 mg/kg with the lowest value in spring and the highest in fall. In the feed, the concentration of Pb varied from 0.14 to 0.76 mg/kg and in milk from 0.03 to 0.15 mg/L. The average concentrations of Hg and As in soil samples averaged 0.022 and 0.019 mg/kg, respectively, and were within the TLVs. Conclusion: In the study areas, the calculated transition rates in the soil–feed–milk–manure system revealed that the greatest transition of HMs was observed for Pb and Cd, and a smaller migration was observed for Hg and As. The tendency of accumulation of trace elements continued in the feed.

Lead, Cadmium, and Arsenic in Raw Milk Produced in the Vicinity of a Mini Mineral Concentrator in the Central Andes and Health Risk

“…The concentration of Cd in the study milk was lower than the values reported in Kazakhstan by Kozhanova et al [ 60 ], from 0.01 to 0.02 mg/L, in summer and autumn, respectively, but it was higher than that reported in Iran by Shahbazi et al [ 69 ]; [ 71 ] which was 0.0011 mg/kg and would be because the farm in our study adjoins a mini mineral concentrator plant.…”

“…In this study, the As content in the soil represented 47% of the ML, and in the case of pastures, it represented 2.7% of MPL. The As content in soil was well above those reported in other latitudes; thus, Kozhanova et al [ 60 ] in different seasons reported the As concentrations of 0.022 and 0.019 mg/kg with a range of 0.20–0.27 mg/kg, the lowest in spring and highest in autumn. Martin et al [ 25 ] in New Zealand soils report average contents of 3.5 mg/kg, with a range of 0.4 and 10.9 mg/kg, related to the structure and type of soil that sequesters As, with variations in As levels in soils and pastures.…”

“…The Cd content in the study soils was 2.5 times higher than the MPL, in the forages represented 25% of the MPL, the potential sources of Cd being the use of synthetic fertilizers, the presence of mining-metallurgical liquid waste dumped into the Mantaro River and mainly the proximity to the mini mineral concentrator whose discharges adjoin the grazing area and its dust contaminates the soil. In various regions of the world, where there is better control of industrial emissions, lower or similar Cd contents are reported; thus, Tepanosyan et al [ 12 ], Zhou et al [ 5 ], and Kozhanova et al [ 60 ] report Cd concentrations in the soil between 0.2 and 2.0 mg/kg. Martin et al [ 25 ] report that in New Zealand, they have suggested a national average baseline of 0.16 mg/kg and 0.35 mg/kg on all agricultural land.…”

“…It is important to consider that heavy metals can be deposited in agricultural soils through manure [ 60 ], pesticides, phosphorus fertilizers, and fertilizers [ 62 ], which affect the productive quality of the soil. In Peru, there are big deposits of phosphoric rock that for decades have been used directly as fertilizer or raw material for the manufacture of commercial phosphorus products that also contain residues of Cd, Cr, Zn, As, and other heavy metals.…”

HEAVY METALS LEVELS IN RAW COW’S MILK AND HEALTH RISK IMPLICATION FROM THERMAL POWER PLANTS EMISSION IN OBILIC, KOSOVA

“…Regarding the toxic heavy metals, there was no significant seasonal variations in cadmium content, compared to reports by Kozhanova et al (2021) where was detected significant seasonal variations in cadmium content in animal milk. In all three seasons the maximum level and mean value of cadmium and lead exceeds the values recommended in these reports and indicate a concentration in toxic values (IDF Standard, 1979, Codex Alimentarius Commission, 2007.…”