The South African mineral and petroleum resources royalty act—Background and fundamental principles

After a prolonged drafting and consultation process, South Africa has introduced a new royalty charge to holders of mineral development rights. Deciding on an acceptable royalty is a complex process, especially when it targets deceptive economic rents. This is achieved with a variable royalty rate that slides in tandem with mine profitability. The base is sales revenue and to compensate for the need to charge for the mineral in its unprocessed form, refined production is charged at a lower rate. The aim of this paper is to discuss the Royalty Act in the context of its background, the underlying theory and fundamental principles. This paper argues that the fundamental principles on which the Act is based are sound, but raises a concern on potentially high compliance and reporting costs.     

External gamma-ray dose rate and radon concentration in indoor environments covered with Brazilian granites

Health hazard from natural radioactivity in Brazilian granites, covering the walls and floor in a typical dwelling room, was assessed by indirect methods to predict external gamma-ray dose rates and radon concentrations. The gamma-ray dose rate was estimated by a Monte Carlo simulation method and validated by in-situ measurements with a NaI spectrometer. Activity concentrations of ²³²Th, ²²⁶Ra, and ⁴⁰K in an extensive selection of Brazilian commercial granite samples measured by using gamma-ray spectrometry were found to be 4.5-450 Bq kg⁻¹, 4.9-160 Bq kg⁻¹ and 190-2029 Bq kg⁻¹, respectively. The maximum external gamma-ray dose rate from floor and walls covered with the Brazilian granites in the typical dwelling room (5.0 m × 4.0 m area, 2.8 m height) was found to be 120 nGy h⁻¹, which is comparable with the average worldwide exposure to external terrestrial radiation of 80 nGy h⁻¹ due to natural sources, proposed by United Nations Scientific Committee on the Effects of Atomic Radiation. Radon concentrations in the room were also estimated by a simple mass balance equation and exhalation rates calculated from the measured values of ²²⁶Ra concentrations and the material properties. The results showed that the radon concentration in the room ventilated adequately (0.5 h⁻¹) will be lower than 100 Bq m⁻³, value recommended as a reference level by the World Health Organization.     

氮磷钾和乙二胺四乙酸对镉污染三叶鬼针草的吸收特征研究

超富集植物的筛选是植物修复重金属污染土壤技术的核心内容.采用盆栽试验的方法,研究了Cd胁迫下添加营养元素N、P、K和螯合剂乙二胺四乙酸(EDTA)对三叶鬼针草(Bidens pilosa L.)的生长反应和生理生化特性以及对Cd的吸收积累特征.盆栽试验结果显示,在Cd为10 mg/kg时,添加营养元素N、P、K和EDT...     

北京城市水系水环境模拟及情景分析

城市水系是流域水环境管理中最为脆弱的控制点.针对城市水系水动力条件差、有机污染和富营养化严重的问题,应用QUAL2K模型模拟、预测城市水系水环境的时空变化,并在此基础上探讨北环水系水环境管理和污染防治的合理有效方案.结果显示,经过多次调整后的模型模拟的匹配度达到了0.9135,水温、溶解氧、COD、TN、TP和Chl-...     

施肥对桉树生长及植株营养效应的研究

本研究在雷州半岛贫瘠的砖红壤上进行．施用基肥可提高尾叶桉材积的生长量,直至4年时仍有极显著的效应．最佳施肥处理比不施肥材积肥材积增长315％基肥的施用以氮、磷、钾配施效果课最好．施PK、NK、NP的材积分别只有NPK全肥的67％、42％和28％。本试验不同处理中,最佳配比是每株N15g、P30g、K30g．施用一定量的N、P、K可改善植株的养分状况．过量施用反而不利N、P、K的正常吸收．破坏养分平衡．     

FeSO_4-K_2SO_4-H_2O体系中Fe/K摩尔比对生物成因羟基硫酸铁矿物质量的影响及环境意义

在FeSO4-K2SO4-H2O的嗜酸性氧化亚铁硫杆菌催化氧化体系中,当起始Fe2+浓度分别为20、40、80和160mmol.L-1时,通过设定系列Fe/K摩尔比(3~200)来调控溶液的K+含量,合成得到次生羟基硫酸铁矿物,主要包括施威特曼石、黄钾铁矾以及两者的混合物.结果表明,当起始Fe2+浓度较低,如20mmol.L-1和40mmol.L-1时,72h反应后,不同Fe/K摩尔比处理所得矿物质量很少,最大只有0.38g.而随着Fe2+浓度增大,Fe/K摩尔比例的减小,矿物质量明显增加,例如在Fe2+=160mmo.lL-1、Fe/K=3时,250mL体系中矿物质量达到了4.48g,同时矿物相由结晶度差的施威特曼石逐渐过渡到结晶度好的黄钾铁矾.笔者发现矿物质量与矿物相有非常密切的关系,当产物为晶型黄钾铁矾时,其对应的矿物质量也更多.因此,微生物成因羟基硫酸铁矿物质量在很大程度上取决于起始Fe2+浓度和Fe/K摩尔比,该现象对去除酸性矿山废水中可溶性Fe和SO24-有潜在意义.     

酸沉降下红壤对K+吸附特征及反应动力学

研究酸沉降下K+在红壤表面的化学吸附行为,结果表明,K+的等温吸附可用Langmuir方程较好地描述;在K+的平衡吸附过程中,土壤表面有H+的释放;加入pH3.5酸溶液后,存在H+的消耗过程,其机理与SO42-的专性吸附释放OH-以中和溶液中H+有关.利用设计的动力学装置能很好地研究K+的吸附动力学,比较K+吸附的动力学模型,以一级动力学方程和Elovich方程为最佳模型;运用数据平滑工具求算吸附速率与吸附量的关系,进一步求得一级动力学方程的表观平衡吸附量和表观吸附速率常数.联合一级动力学方程的微分式和Elovich方程也可求得反应速率与时间的关系.     

四钛酸钾晶须对亚甲基蓝吸附性能研究

利用四钛酸钾晶须作为吸附剂,研究了亚甲基蓝在其上的吸附行为,考察了吸附体系pH值、吸附剂用量、吸附时间对其吸附效果的影响.实验结果表明,四钛酸钾晶须对亚甲基蓝有较强的吸附力,得到的吸附等温线能较好的符合Freundlich方程,其R2都能达到0.991以上,吸附动力学可以用拟二级动力学模型描述.在碱性范围内四钛酸钾晶须...     

城市污泥在矿区废弃地复垦中应用的可行性研究

通过对城市污泥和矿区土壤成分分析,研究了施用城市污泥对矿区土壤环境的影响。结果表明,利用污泥中大量的N、P、K和有机质以及污泥较强的粘性、持水性和保水性等理化性质不仅可以提高矿区土壤的肥力、迅速恢复植被,而且可以改善土壤的结构,从而达到复恳的目的。     

高铁酸钾法去除水中1,1-DCE

选取水中常见的1,1-DCE为目标污染物,通过间歇实验探讨了目标化合物在以高铁酸钾为氧化剂的情况下,不同反应条件下的去除效果、反应动力学以及反应机理。实验结果表明,不同pH值对高铁酸钾去除1,1-DCE的反应速率影响很大,在pH=3时去除效果最好;反应符合一级动力学方程,去除速率随温度升高而增大,且活化能Ea为28.52 kJ/mol,表明温度对高铁酸钾的氧化性有很大影响;反应的ΔH*>0,ΔS*G*>0;以NaNO3调节反应体系的离子强度,当离子强度为0~0.2 mol/L时,高铁酸钾去除1,1-DCE的反应速率随离子强度的增大而减小。通过对实验机理的分析看出,高铁酸钾法去除卤代烃机理为氧化及吸附共存。