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首页> 外文期刊>Reviews of environmental contamination and toxicology >Pasture soils contaminated with fertilizer-derived cadmium and fluorine: livestock effects.
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Pasture soils contaminated with fertilizer-derived cadmium and fluorine: livestock effects.

机译：牧场土壤被肥料衍生的镉和氟污染：牲畜效应。

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摘要

Fertilizers are indispensable for ensuring sustainability of agricultural production, thereby achieving food and fiber security. Nitrogen, sulfur, and potassium fertilizers are relatively free of impurities, but phosphorus (P) fertilizers, the main fertilizer input for the economic production of legume-based pastures, contain several contaminants, of which F and Cd are considered to be of most concern because they have potentially harmful effects on soil quality, livestock health, and food safety. Incidences of fluorosis in grazing livestock, and accumulation of Cd in the edible offal products of livestock, above the maximum permissible concentration set by food authorities have been reported in many countries. The majority of Cd and F applied to pastures in many countries continues to accumulate in the biologically active topsoil due to strong adsorption to soil constituents. However, the rate of Cd accumulation in the last decade has slowed as a result of selective use of low-Cd fertilizers. Cd and Fadsorption in soils increase with increased contents of iron and aluminium oxides, layer silicates and allophane in soils, and increased soil pH. Cadmium adsorption also increases with increased Mn oxides and organic matter in soil. However, some Cd will be released during decomposition of plant and animal remains and organic matter. In most pastoral soils the majority of Cd and F added in fertilizers remains in the topsoil and little moves below 20-30 cm, and therefore these are unlikely to contaminate groundwater. However, F may pose a risk to shallow groundwater in very acidic low-P-fixing soils, and Cd may pose a risk in very acidic soils containing low organic matter and clay contents, or in soils with high chloride concentrations. Research is required both to test whether groundwater beneath farms with long histories of P fertilizer use is contaminated by these elements and also to examine their mechanisms of movement. Cd intake by grazing livestock occurs mostly by ingestion of pasture, and therefore measures to decrease plant availability of Cd in soils (e.g., maintaining high organic matter, reducing soil acidity and salinity, alleviating zinc deficiency, reducing weed) can reduce Cd accumulation in livestock. F intake by grazing livestock is mostly by soil ingestion; therefore, reducing soil ingestion by maintaining good pasture cover especially during winter periods can reduce F accumulation in livestock. In grazing livestock, Cd accumulates in kidney and liver, whereas F accumulates mainly in bones. Very little research has been carried out to study the effects of sustained but low levels of Cd and F additions on soil microbial activity, especially on the economically important N-fixers in symbiosis with pasture legumes and mycorrhizae. This subject also needs to be researched. The impact of F accumulation in bones of animals as influenced by the alternative low and high soil F intake between seasons and the effect of increasing age of animals needs further study to more accurately determine the potential risk of fluorosis and elucidate potential solutions to minimize F accumulation in bones and teeth of aged breeding stock. Computer-based models are required to identify farming systems that present a high risk of Cd concentrations in edible offal exceeding the MPC and livestock at risk of chronic fluorosis. A decision support model of this kind may be useful in developing management strategies capable of reducing Cd and F accumulation in animals. Preliminary empirical models have been developed for Cd (Loganathan et al. 1999) and F (Bretherton et al. 2002) accumulation in sheep grazing New Zealand pastures. Further development of these models is required for their wider applicability.
机译：为了确保农业生产的可持续性，从而实现粮食和纤维安全，肥料必不可少。氮，硫和钾肥料相对不含杂质，但是磷（P）肥料是豆类草场经济生产的主要肥料输入，其中包含多种污染物，其中F和Cd被认为是最令人关注的污染物。因为它们会对土壤质量，牲畜健康和食品安全产生潜在的有害影响。在许多国家，已经报道了放牧牲畜中氟中毒的发病率以及牲畜可食内脏产品中Cd的积累超过食品当局设定的最大允许浓度。在许多国家，由于对土壤成分的强烈吸附作用，大多数用于牧场的Cd和F仍在生物活性表土中累积。但是，由于有选择地使用了低镉肥料，近十年来镉的积累速度有所放缓。随着土壤中铁和铝氧化物，层状硅酸盐和金属铝的含量增加以及土壤pH值升高，土壤中的Cd和Fadsorption也会增加。镉的吸附也随着土壤中锰氧化物和有机物含量的增加而增加。但是，在动植物残体和有机物分解过程中会释放出一些镉。在大多数牧区土壤中，肥料中添加的大多数Cd和F都残留在表土中，并且在20-30 cm以下几乎没有移动，因此它们不太可能污染地下水。但是，F在酸性很强的低磷固着土壤中可能对浅层地下水构成风险，而Cd可能在有机物和粘土含量低的酸性很强的土壤中或氯化物浓度较高的土壤中构成风险。需要进行研究，既要检验长期使用磷肥的农场下方的地下水是否受到这些元素的污染，也要研究其运动机理。放牧牲畜摄入的Cd主要是通过牧场摄入来实现的，因此采取措施降低土壤中Cd的植物利用率（例如保持高有机质，降低土壤酸度和盐分，减轻锌缺乏，减少杂草）可以减少Cd在牲畜中的积累。放牧牲畜摄入的F主要是通过土壤摄入。因此，通过保持良好的牧场覆盖来减少土壤摄入，尤其是在冬季，可以减少家畜中的F积累。在放牧的牲畜中，Cd积累在肾脏和肝脏中，而F主要积累在骨骼中。很少进行研究来研究持续但少量添加Cd和F对土壤微生物活性的影响，特别是对与牧草和菌根共生的具有经济意义的N固定剂的影响。这个问题也需要研究。在季节之间，土壤中F的交替摄入量受交替的低和高F摄入量的影响以及动物年龄增长的影响，需要进一步研究以更准确地确定氟中毒的潜在风险并阐明可能的解决方案以最大程度地减少F积累。在老化的种畜的骨骼和牙齿中。需要使用基于计算机的模型来识别耕作系统，该系统对可食用内脏中的Cd浓度具有很高的风险，超过了MPC和面临慢性氟中毒风险的牲畜。这种决策支持模型可能有助于开发能够减少动物体内Cd和F积累的管理策略。已经开发了镉（Loganathan等，1999）和碳（Bretherton等，2002）在新西兰牧场放牧的绵羊中积累的初步经验模型。为了更广泛地应用它们，需要进一步开发这些模型。

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