沱江流域磷矿开采和加工过程中放射性环境问题探讨   总被引：1，自引：0，他引：1  

施泽明  倪师军  张成江  葛良全  郑林  裴云倩 《地球科学进展》2012,27(10):1134-1139

大多数磷矿伴随着高含量的放射性元素U,通过对龙门山地区磷矿开采和加工过程中U,Th迁移的研究,初步查明了沱江流域放射性环境问题。研究结果显示,除含U磷块岩外,四川省磷肥及磷矿石中U含量水平相对偏高,磷矿开采加工是造成区域放射性元素含量偏高的主要原因;磷矿加工过程中放射性元素U,Th主要迁移到中间产物及最终产品中;磷石膏的堆放对周边土壤环境的放射性影响,水平方向上已超过2 km,垂向上近50 cm;磷矿的开采与加工已对流域产生了一定程度的放射性环境影响。  相似文献   

Adsorption of Phosphate by Biomass Char Deriving from Fast Pyrolysis of Biomass Waste     

Feng Peng  Pi‐Wen He  Yin Luo  Xiang Lu  Ying Liang  Jie Fu 《洁净——土壤、空气、水》2012,40(5):493-498

Biomass char (BC) deriving from fast pyrolysis of biomass was a potential adsorption material due to its relative high fixed‐carbon content and the inherent porous structures. Adsorption of phosphate from aqueous solution by BC was investigated in this paper. The results showed that the adsorption capacity of BC was dependent on pyrolysis conditions, such as temperature and holding time. The maximum adsorption capacity for phosphate was approximately 15.11 mg g^?1 at 298 K. The pseudo‐second order model of the adsorption kinetics indicated that the adsorption process was complex and several mechanisms were involved. Equilibrium isotherm was satisfactorily followed the Freundlich isotherm model. The K_F value in Freundlich equation gradually increased with elevating temperature. Moreover, the thermodynamic constants: ΔG⁰, ΔH⁰, and ΔS⁰ were evaluated as ?6.49 kJ mol^?1 (at 298 K), 13.41 kJ mol^?1, and 66.70 J mol^?1 K^?1, respectively. Phosphate adsorption onto BC was spontaneous and endothermic. As a waste, BC was a potentially attractive adsorbent for phosphate removal from aqueous solution with low cost and high capability.  相似文献   

Adsorption Characteristics of Phosphorus onto Soils from Water Level Fluctuation Zones of the Danjiangkou Reservoir          下载免费PDF全文

Chao Du  Xianyou Ren  Liang Zhang  Meng Xu  Xiaojun Wang  Yanhua Zhuang  Yun Du 《洁净——土壤、空气、水》2016,44(8):975-983

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Operational and Environmental Conditions for Efficient Biological Nutrient Removal in an Urban Wastewater Treatment Plant          下载免费PDF全文

Javier Bayo  Joaquín López‐Castellanos  Julio Puerta 《洁净——土壤、空气、水》2016,44(9):1123-1130

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The Potential for Environmentally Sound Development of Marine Deposits of Potassic and Phosphatic Minerals Offshore,Southern Africa     

S. K. P. Coles  C. I. Wright  D. A. Sinclair  P. Van den Bossche 《Marine Georesources & Geotechnology》2013,31(2):87-110

Extensive potassium and phosphorous-rich mineralization occurs on the outer continental shelf of the southern and west coasts of South Africa and Nambia. This article reviews the potential of exploiting these deposits in an environmentally sound manner for the manufacture of fertilizer. At present, reserves of potash and phosphate fertilizer are exploited from terresterial deposits, the majority being surface mined. The use of fertilizer in South Africa has shown no growth in the past 13 years, and, in some years, usage has even declined. On average, over the last decade, South Africa has consumed 2 million Mt of fertilizer (including nitrogen) per annum, the vast majority of phosphate fertilizer being produced by FOSKOR from the Phalaborwa Igneous Complex. Potash fertilizer is imported into South Africa. Although fertilizer consumption is expected to decrease in the short-term, there are good future prospects for the domestic and international fertilizer market. Considerable research into both glauconitic (containing K 2 O) and phosphatic deposits along the southern African continental shelf indicate that these sedimentary deposits have a complex genesis and mineralization. Of the total K 2 O reserves of 1300 million Mt on the southern African margin, 1000 million Mt is located off the southern African west coast, and the remainder situated on the Agulhas Bank. The largest glauconite concentration ( - 300 million Mt K 2 O) off southern Africa lies west of Saldanha Bay, South Africa. The distribution of P 2 O 5 off southern Africa is dominated by the vast deposit between Walvis Bay and Luderitz, Nambia. This reserve is estimated to contain 1000 million Mt of greater than 5% P 2 O 5 in a relatively small area of about 10000 km2. The phosphorite deposit south of Saldanha Bay constitutes a reserve of - 3500 million Mt of apatite and the deposit on the Agulhas Bank comprises 5500 million Mt. The phosphate deposit off Saldanha Bay occurs as an extensive, low to medium grade deposit. Although vast resources of potash and phosphatic minerals occur along the southern African outer continental shelf the expensive nature of marine exploitation may render most of these deposits, especially the phosphates, subeconomic. The low price of fertilizer andextensive natureontheonland deposits, although confined to asmallnumber of countries, mean that it will not be financially viable to extract these deposits. Assuming high grade glauconitic sand with the right composition can be located, the high market price indicates good future prospects for these potash deposits.  相似文献   

Field experiments on remediation of coastal sediments using granulated coal ash     

Kyunghoi Kim  Tadashi Hibino  Tamiji Yamamoto  Shinjiro Hayakawa  Yugo Mito  Kenji Nakamoto  In-Cheol Lee 《Marine pollution bulletin》2014

Field experiments were carried out to evaluate the effect of Granulated Coal Ash (GCA) on remediation of coastal sediments in terms of removing phosphates and hydrogen sulfide. Phosphate concentrations in the sediment were kept below 0.2 mg/l after the application of GCA, whereas those in the control sites increased up to 1.0 mg/l. The concentration of hydrogen sulfide in the sediment was maintained at almost zero in the experimental sites (GCA application sites) for over one year, whereas it ranged 0.1–2.4 mg S L⁻¹ in control sites. Meanwhile, individual number of benthos increased in the experimental sites by several orders of magnitude compared to the control sites. The major process involved in hydrogen sulfide removal by GCA was thought to be the increase in pH, which suppresses hydrogen sulfide formation. From our findings, we concluded that GCA is an effective material for remediating organically enriched coastal sediment.  相似文献   

Phosphatic series under Plio-Quaternary cover of Tadla Plain,Morocco: Gravity and seismic data     

《Comptes Rendus Geoscience》2019,351(6):420-429

The Ouled Abdoun sedimentary basin in Morocco contains the largest phosphate reserves in the world. To the Northwest of the basin, the phosphate layers crop out or are at a shallow depth and are exploited in open pit mines. By contrast, towards the central and southwestern parts of the basin, the phosphate layers lay below the Plio-Quaternary sediments of the Tadla Plain. This study aims to characterize the distribution and structure of the phosphatic series at depth under this cover, in particular to guide the future exploration and exploitation of the phosphate deposits. The work is based on gravimetric and seismic data acquired in a previous oil exploration study, calibrated by borehole data. The analysis of the gravity data controlled by boreholes first reveals the existence of large regional faults in the basin, forming pronounced gradients in the gravity data. The faults are also seen in the seismic profiles. In the Southeast of the basin, the phosphatic series exhibit a stairway structure controlled by some of these regional faults.The drilling data and the isochron maps established from the seismic profiles show that the base of the phosphatic series is more than 500 m deep in the southeastern area of the basin. As the phosphatic layers get buried deeper, they also become thicker. The phosphate reserves thus increase towards the southeast, and our analysis identifies the areas where this reserve is larger. Our results eventually suggest that the mining methods currently adopted in the Khouribga mining district will need to be modified and adapted to the more complex situation of the phosphatic series deeply buried in the basin.  相似文献   

Trace Metals in Phosphate Fertilizers Used in Eastern Mediterranean Countries     

《洁净——土壤、空气、水》2017,45(1)

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pH-Dependent iron oxide precipitation in a subterranean estuary     

C. Spiteri  P. Regnier  C.P. Slomp  M.A. Charette 《Journal of Geochemical Exploration》2006,88(1-3):399

Iron-oxide-coated sediment particles in subterranean estuaries can act as a geochemical barrier (“iron curtain”) for various chemical species in groundwater (e.g. phosphate), thus limiting their discharge to coastal waters. Little is known about the factors controlling this Fe-oxide precipitation. Here, we implement a simple reaction network in a 1D reactive transport model (RTM), to investigate the effect of O₂ and pH gradients along a flow-line in the subterranean estuary of Waquoit Bay (Cape Cod, Massachusetts) on oxidative precipitation of Fe(II) and subsequent PO₄ sorption. Results show that the observed O₂ gradient is not the main factor controlling precipitation and that it is the pH gradient at the mixing zone of freshwater (pH 5.5) and seawater (pH 7.9) near the beach face that causes a  7-fold increase in the rate of oxidative precipitation of Fe(II) at  15 m. Thus, the pH gradient determines the location and magnitude of the observed iron oxide accumulation and the subsequent removal of PO₄ in this subterranean estuary.  相似文献   

海水中超低含量活性磷酸盐的Mg(OH)₂共沉淀法测定研究   总被引：1，自引：0，他引：1       下载免费PDF全文

朱赖民  李犇 《海洋学报》2008,30(3):148-152

活性磷(正磷酸盐)是海洋浮游植物生长所必需的物质基础[1-8],磷的生物可利用性直接影响全球的初级生产力水平.磷在特定的海洋环境中还可能限制固氮作用,成为限制海洋初级生产力的重要因素[1,3,6].海水中磷酸盐含量的测定也是海洋污染调查的重要指标之一[4,9].农业和工业废水中磷的过度排放导致河口和近岸海水富营养化,引起浮游植物异常繁殖,造成“赤潮”现象[4].因此,海水中磷的准确测定对深入理解生物地球化学过程及海洋环境保护具有重要理论和实际意义[4-6,9].磷钼蓝分光光度法是海水中活性磷的经典测定方法,检测限为324 nmo1/dm3[5],但在一些寡营养盐海域,例如在南海、地中海  相似文献