Studies identified mutton as a core food staple, comprising 6% of the total energy and 10% of the total protein consumed in the Diné diet. The current study participants reported that 35% of their total protein meat intake is comprised by local O. aries.In the study community, the typical serving size per foodstuff is reported to be 76.54 g of sheep muscle protein, roasted or boiled whole liver 377.5 g, roasted one whole kidney 76 g, and roasted or boiled lung 111.5 g. Using the typical serving size for each food stuff, we used the maximum HM concentration for each food item to calculate the weekly intake of HM from the current diet of the study population. The calculations for Mo and Se are based on the information provided by harvesters and are reflective of the sheep meat average consumption of one day per week. The Recommended Dietary Allowance for Mo was exceeded by more than a factor of 2 but, but the tolerable upper intake limit was not exceeded. The liver alone exceeded the Mo RDA by a factor of 1.8. By our estimates, an individual would have to consume half of the typical serving size to meet the RDA. The Mo levels in all sheep food products consumed comprised of 4.6% of the UL. The Se Reference Dietary Intake for adult males and females is 55 µg per day,big pot for flowers and the Tolerable Upper Intake level is set at 400 µg/day.
For all sheep products, the harvesters exceeded the Se RDI by more than a factor of seven and were slightly below the tolerable upper intake level of 400 µg/day. The liver protein intake alone comprised 80% of the tolerable upper limit of Se. Hypothetically, if one consumes liver protein more than once a week in the current scenario, the Se UL will be exceeded. The reported values only take into account the levels representative of sheep protein intake evaluated in this study and exclude non-subsistence and other dietary sources. In summary, in this U mining impacted area, our calculations indicate that the Se levels found in locally harvested sheep exceeded the RDI significantly but were marginally below the established daily tolerable upper intake level. Similarly, the RDA for Mo was exceeded, while the Mo UL was not exceeded. Consuming liver once a week has exhibited exceedances in Se RDI and Mo RDA, and it is anticipated that eating more than one serving size of liver per week would cause one to exceed the Se UL. Dietary sheep intake should be adjusted to avoid exceeding the Cd PTWI and Se UL. Diversification of the overall dietary intake or minimizing the intake of high HM content foods are recommended until further research can be done. Our study was comprised of adults only; therefore, our calculations are based exclusively on adult food intake. Recommendations based on tailored research are needed for those that are more sensitive to HM exposure such as children, the elderly, pregnant women, or those with at risk health conditions. There is no dietary intake guideline for the remaining HM examined in this study.
Tropical regions are experiencing wide-spread and rapid conversion of native vegetation to agricultural land uses, often resulting in severe soil degradation . Several studies document rapid degradation of selected soil properties, with a focus on processes affecting carbon cycling, soil fertility, and soil physical properties . However, few studies report on land-use changes to soil colloidal properties, such as miner alogical and surface charge characteristics. The few existing studies showed either no differences in clay mineralogy or minimal clay mineral degradation with strong acidification resulting from long-term ammonium fertilizer application . In contrast to soil organic carbon and fertility characteristics, the soil colloidal fraction is generally more resilient to changes in land use and therefore any changes are difficult to detect in short-term studies. As a result, there is a distinct paucity of information regarding changes in soil mineralogical characteristic in response to land use change, especially for tropical Andosols that represent >50% of global Andosol land area . Indonesia has 127 active volcanoes resulting in wide distribution of Andosols.These Andosols support high agricultural productivity with some of the world’s highest human-carrying capacity being found on volcanic soils in Indonesia . Andosols have several unique physical and chemical properties owing to a dominance of ‘active’ iron, aluminum and aluminosilicate materials in their colloidal fraction. While volcanic soils have been extensively studied, there are relatively few studies examining the active Fe/Al fraction of tropical Andosols and their resilience to ecosystem perturbations, such as land-use change. It is expected that the active Fe/ Al fraction will be more kinetically and thermodynamically susceptible to alteration from land-use conversion than crystal line clay minerals . As the active Fe/Al fraction imparts soil and ecosystem resiliency, it is important to document long-term changes in the soil colloidalfraction in response to land-use change as this fraction has a strong effect on carbon cycling, soil fertility and nutrient leaching.
In Indonesia, land use/land cover of Andosols is primarily native rainforest, tea plantation, horticultural crops, paddy fields and other food crops. Land-use conversion from native rainforest to agriculture has taken place over long periods of time making assessments of long-term alteration to soil properties possible. Our previous assessment of changes in soil properties following conversion from rainforest to agronomic land use in Indonesia demonstrated strong resilience of soil physical properties, carbon stocks and fertility factors . For example,grow table soils showed increased bulk density and meso/micropores that contributed to increased plant-available water retention capacity; increased soil carbon and nitrogen stocks with a redistribution of organic matter from topsoil to subsoil horizons; and lower carbon mineralization and microbial biomass, especially in topsoil horizons. This study expands upon our previous work to examine changes in the mineralogical and surface charge characteristics of the soil colloidal fraction following conversion of native rainforest to tea plantation and horticultural crops. Results of this study inform strategic policy and management practices involving tropical forest conservation/reforestation and sustainable agricultural production in tropical Andosols.Under the perudic/isothermic soil climatic regime in West Java, Indonesia, chemical weathering rates are expected to be very high. Weathering rates are further accelerated by several characteristics of the basaltic-andesite tephra, such as large surface area , high permeability and a glass fraction dominated by highly weatherable colored glass. Shoji et al. measured rates of aluminum release from colored glass being 1.5 times greater than noncolored glass and weathering rates increased ~1.5 times for each 10 °C increase in temperature between 0 and 30 °C. Thus, it is not unexpected that the volcanic glass fraction was largely depleted within the ~8,700 and ~14,500 years since deposition. In particular, substantial desilication has occurred as indicated by the decrease in the Si:Al molar ratio from ~2.9 in a typical basaltic-andesite material to the range of 0.94 to 1.36 in the investigated soils. As the silica content of the soil becomes depleted, the clay-size mineralogy transforms from those mate rials requiring high silica activities to those stable at lower silica activities . Without periodic tephra deposition to rejuvenate the weathering sequence, the intensity of the isothermic/ perudic weathering environment would lead to severe desilication and occurrence of Ultisols/Oxisols dominated by low activity clays in the humid tropics. In terms of the land-use treatments, markedly higher weathering rates were suggested under PF1 and TP1 based on their higher total Ti and Zr concentrations that accumulate during chemical weathering/leaching . For soil profiles developed from uniform parent materials, Ti and Zr concentrations decrease with increasing soil depth . However, in this study, Ti and Zr concentrations increased with increasing soil depth reflecting the older, more highly weathered soil materials at depth. Higher weathering rates in the PF1 and TP1 pedons are further supported by the higher Fed:Fet indicating a greater release of iron by chemical weathering.
We posit that higher apparent weathering rates may result from the lower pH and higher DOC concentrations found in the PF1 and TP1 pedons . We acknowledge that subtle differences in the chemical composition of the tephra depos its may contribute to differences among pedons. Therefore, it is difficult to assess whether the apparent differences in chemical weathering can be solely attributed to changes in land use over the ~100-yr period.The dominance of poorly crystalline materials is likely associated with rapid weathering of the volcanic glass fraction. Rapid chemical weathering results in supersaturation of the soil solution, which kinetically favors formation of metastable nanocrystalline and paracrystalline precipitation products . Further, the lack of a distinct dry season hinders the crystallization process as Ostwald ripening and dehydration are energetically and kinetically favored by prolonged periods of high temperature and desic cation . These findings are similar to the weathering of tephra deposits in mesic/udic climatic regimes, such as in northern Japan and New Zealand, which yields a prevalence of poorly crystalline materials with few crystalline minerals at a similar stage of weathering . Allophanic materials are the favored weathering product in humid, temperate climates under conditions of low organic matter concentrations and pHH2O > 4.9 . Soil genesis associated with the native pine forest, which was the dominant land use for the majority of time during soil formation at all sites, resulted in high organic matter and low pH values that might be expected to favor formation of Al-humus complexes as opposed to allophanic materials, thereby leading to formation of non-allophanic Andosols. However, another important factor controlling the fate of Al3+ in non-allophanic Andosols of northern Japan is eolian inputs of 2:1 layer silicates from Asia, which incorporate Al3+ in their interlayer position rendering it unavailable for allophane formation . Eolian inputs of 2:1 layer silicates in Indonesia are expected to be minor compared to northern Japan. Therefore, the release of Al3+ by chemical weathering appears to exceed the incorporation of Al3+ into organic com plexes and 2:1 layer silicates leading to abundant formation of allophanic materials in this study. In terms of land use, the TP1 topsoil displayed a distinctly lower allophanic content in the upper two horizons than the other land-use types. The lower allophane concentrations may be due to dissolution of allophanic materials by soil acidification associated with high rates of ammonia- fertilizer applica tion to tea plantations . Dahlgren and Saigusa demon strated rapid dissolution of allophanic materials under acidic conditions and dissolution rates showed a strong H+ – dependence. This interpretation is consistent with Takahashi et al. who documented a decrease in allophanic materials with a concomitant increase in Al–humus complexes asso ciated with strong acidification of tea plantations. Notably, the lower allophanic material concentrations in the upper two horizons of the TP1 pedon correspond to the highest Al humus complex concentrations found in this study. While the PF1 profile also displayed strong acidification, its allophanic content was consistently high throughout the pedon com pared to the other land-use types. We posit that biogenic cycling of silica by forest vegetation coupled with higher evapotranspiration in the native forest, which lowers the leaching potential, may compensate for the strong natural acidity by maintaining higher silica activities to support the stability of allophanic materials. The overall high Feo/Fed ratio across all soil profiles indicates the dominance of nanocrystalline iron oxides, such as ferrihydrite, whose formation is favored by high organic matter concentrations and high Al3+/silica activities that are posited to inhibit crystallization . Additionally, the perudic moisture regime prevents soil profile desiccation limiting Ostwald ripening and dehydration that promote crystallization. The 2Bw3 horizon of the HF1 profile was a notable exception to the overall iron oxide pattern having a very high Fed content and lower Feo:Fed . This horizon occurs at a tephra-unit discontinuity and may represent a redox fea ture associated with imperfect vertical drainage . We posit that redox cycling driven by alternating anaerobic/aerobic cycles leads to ferrolysis that contributes to intense proton generation and localized weathering leading to Fe oxides and gibbsite enrichment . Higher Feo concentrations in the PF1 and TP1 profiles may be associated with the appreciably lower pH values compared to the HF1/IH1 profiles .