Leaching evaluation of cement stabilisation / solidification treated kaolin clay

Sustainable land management often requires redevelopment of existing and often contaminated Brownfield sites over use of Greenfield or agricultural land. Stabilisation / solidification (S/S) offer a viable remediation option with particular suitability in treating heavy metal contaminants. However, uncertainties over long-term durability and previously cheap landfill disposal costs resulted in limited use in many countries. There is a need to characterise treated material and assess components containment and release, to improve S/S confidence and inform remedial design, using the evaluation of the leaching controlling mechanisms. To improve understanding of key features that will enable improvements to such designs, this paper presents an evaluation of leaching for CEM II stabilised kaolin, using the leaching behaviour of 4 main components—aluminium, silicon, calcium and sulphur. Results show no detrimental implications on chemical durability due to kaolin degradation with hydration under induced alkalinity, with increased formation of stable cementitious minerals. Availabilities for components show that aluminium and silicon had minimal leachability compared to total content, whilst calcium and sulphur show almost total leaching availability. Decreasing calcium and silicon leachability under natural chemical conditions with increased hydration duration supports the increased formation of stable cementitious products with time, using the products of kaolin dissociation.     

The Braunschweig meteorite − a recent L6 chondrite fall in Germany

On April 23rd 2013 at 2:07 a.m., a 1.3 kg meteorite fell in the Braunschweig suburb Melverode (52° 13′ 32.19″ N. 10° 31′ 11.60″ E). Its estimated velocity was 250 km/h and it formed an impact pit in the concrete fall site with a diameter of 7 cm and a depth of 3 cm. Radial dust striae are present around the impact pit. As a result of the impact, the meteorite disintegrated into several hundred fragments with masses up to 214 g. The meteorite is a typical L6 chondrite, moderately shocked (S4) – but with a remarkably high porosity (up to 20 vol%). The meteorite was ejected from its parent body as an object with a radius of about 10–15 cm (15–50 kg). The U,Th-He gas retention age of ∼550 Ma overlaps with the main impact event on the L-chondrite parent body ∼470 Ma ago that is recorded by many shocked L chondrites. The preferred cosmic-ray exposure age derived from production of radionuclides and noble gas isotopes is (6.0 ± 1.3) Ma.     

Research progress on the soil vapor extraction

Soil vapor extraction (SVE), the most common, efficient and economical means of remediation, is an in-situ remediation technique for removing volatile pollutants from unsaturated soil. The paper briefly introduced the technological rationale and cha?racteristics, summarized the theories and application research for SVE at home and abroad, and made the expectations and suggestions for the research on SVE. The international scholars have systematically researched the influence factors, remediation mechanism and numerical simulation of SVE. At present, SVE has been mostly integrated with other techniques to form enhanced SVE techniques, such as thermally enhanced SVE and AS-SVE (Air sparging-SVE), to be used for the field remediation widely. Compared with foreign countries, researches of Chinese scholars mainly focus on the laboratory research, especially on the influence factors, but rarely study the SVE model and the mass transfer mechanism of pollutant in SVE process. The SVE pilot studies are rare in China, and the field application has not been reported. In view of this situation, Chinese scholars in the future research can focus on the following aspects: (1) strengthening the research and systematized summary of SVE technical parameters and related knowledge; (2) strengthening the research on the mechanism and model of gas-phase mass transfer of pollutants in soil during SVE process; (3) strengthening the research on the enhanced SVE techniques and its application to actual site remediation.     

具产电性能光合细菌DH-3的分离及其对多种底物污水处理能力的评价

本文通过传统微生物分离培养方法从富营养化环境中分离培养出可高效处理多种底物的污水并具备胞外电子传递能力和产电潜力的兼性厌氧光合细菌。在光照培养条件下,利用改良的能够将光合细菌富集/分离的培养基分离培养光合细菌,从形态学和16S rDNA的分子生物学角度鉴定菌株。运用多个指标检测光合细菌处理不同底物的污水培养基的能力,如化学需氧量（chemical oxygen demand,COD）、总氮（total nitrogen,TN）、总磷（total phosphate,TP）,并在电化学工作站检测光合细菌的产电能力。结果表明,获取的光合细菌菌株DH-3与光合细菌类球红细菌（Rhodobacter sphaeroides）有97%的相似性。该菌株拥有在多种底物的污水培养基中生长的能力,其中在以乙酸为底物的培养基中生长最好。通过检测发现该菌株对污水的COD、TN和TP均具有较高的去除率。电化学工作站检测结果表明,菌株DH-3的最大产电流量能达到7.5mA/m²,最大功率密度达到0.056W/m²。由此可见,光合细菌DH-3在污水处理及资源再循环利用等方面具有十分重要的应用潜力。     

The geochemical characteristics and factors controlling the organic matter accumulation of the Late Ordovician-Early Silurian black shale in the Upper Yangtze Basin,South China

Organic-rich black shale of the Upper Yangtze Basin from the Late Ordovician and Early Silurian is considered an excellent source rock in South China. The formation and preservation conditions of this resource are revealed by its geochemical characteristics in this study. Geochemical indices, including redox indices (V/(V + Ni), V/Cr, V/Sc, and Ni/Co) and primary productivity indices (P/Ti and Ba/Al), and paleoclimate, clastic flux and sedimentary rate analyses are presented to investigate the accumulation mechanism of organic matter. Redox indices suggest that a stagnant, anoxic environment predominated in the Upper Yangtze Basin during accumulation of Wufeng and Longmaxi formations. In contrast, ventilated and oxygenated marine conditions pervaded the Upper Yangtze Basin during deposition of Linxiang and Guanyinqiao formations. The concentrations of V and U demonstrate that accumulation of organic matter was mainly controlled by redox conditions. Besides, such factors as clastic fluxes, fresh water inflows or a mixed deposition with a rapid sedimentary rate cannot be ignored due to their influences on organic matter enrichment and preservation. However, weak co-variance relationship of TOC content and productivity proxies, including P/Ti and Ba/Al, demonstrates that the accumulation of organic matter was not controlled by primary productivity. Results of the present study suggest a depositional model that stresses the importance of tectonic movements and glacial events on the accumulation and preservation of organic matter. The model shows that the Upper Yangtze Basin was a semi-restricted basin system influenced by the isolation of Xuefeng, but also it implies that oxygen-depleted bottom water of the basin favored the accumulation and preservation of sedimentary organic matter, resulting in the formation of organic-rich black shale.     

Could the conventionally known Abu Roash “G” reservoir (upper Cenomanian) be a promising active hydrocarbon source in the extreme northwestern part of Egypt? Palynofacies,palaeoenvironmental, and organic geochemical answers

In different areas of the Western Desert of Egypt, the Abu Roash “G” Member exhibits either a reservoir or source affinity. Thus, thirteen cutting samples covering the Abu Roash “G” Member were selected from the Nest-1A well at Matruh Basin to investigate its hydrocarbon source potential. Palynological age dating of the section that is calibrated with foraminifera and ostracodes enabled a proper identification of the “G” Member. Detailed analysis of the vertical distribution of particulate organic matter of this member shows two palynofacies types. PF-1 reflects an outer middle shelf depositional environment of prevailed reducing (suboxic-anoxic) conditions for the organic-rich shales of the lower “G” Member (samples 1–8). While, PF-2 reflects a minor regression that resulted in deposition of another organic-rich shales of the upper “G” Member (samples 9–13) in an inner middle shelf setting under the same prevailing reducing (suboxic-anoxic) conditions.Organic geochemical analysis reveals good to very good potential of the “G” Member as a hydrocarbon source rock (1.8–2.41, avg. 2.15 total organic content wt %). It also shows good to very good petroleum potential (PP: 4.8–11 , avg. 8 mg HC/g rock). Pyrolsis and palynofacies analyses show kerogen type II for the lower “G” Member (samples 1–8), which is characterized by high Hydrogen index (HI: 396 and 329 mg HC/g TOC at depths 1500 and 1560 m) and very high dominance of oil-prone material (amorphous organic matter “AOM”, marine palynomorphs, and sporomorphs) and very rare occurrence of gas-prone material (brown phytoclasts). The upper “G” Member (samples 9–13) shows kerogen type II-III, which is characterized by a lower HI value of 213 mg HC/g TOC at depth 1340 m and it contains fewer amounts of gas-prone material and relatively lower AOM and marine palynomorphs in comparison to the upper “G” Member. Maturation parameters T_max (430–433 °C), production index (PI: 0.1 mg HC/g rock), and thermal alteration index (TAI: 2+) indicate the lower “G” Member has already entered the early oil-window kitchen, and it is expected to produce oil. The upper “G” Member is expected to produce only oil with no gas shows, because it is marginally mature (T_max 426 °C, PI 0.2, TAI 2). The source potential index (SPI: 5.3 t HC/m²) of the “G” Member shows it as currently generating moderate quantities of oil in the area of Nest-1A well.Consequently, the organic-rich shales of the “G” Member are suggested here as a promising, active oil source rock in that extreme northwestern part of the Western Desert of Egypt. However, for commercial oil recovery from the Abu Roash “G” Member, it is highly recommended to explore the depocentre of Matruh Basin at about 150 km east the Nest-1A well.     

Dissolved inorganic and organic iodine in the Chesapeake Bay and adjacent Atlantic waters: Speciation changes through an estuarine system

The distributions of iodate, iodide and dissolved organic iodine (DOI) were determined in two deep sub-basins in the Chesapeake Bay, the shallow waters at the mouth of the Bay and the adjacent North Atlantic between the late spring and the early fall along the net flow-path of the water entering and exiting the Chesapeake Bay by using an improved analytical scheme designed for the quantitative recovery of DOI. The concentration of R-DOI found in the surface mixed layer in the upper Bay was about twice of those found at the same location in previous studies. (R-X was the concentration of a dissolved iodine species X that had been normalized to a constant salinity of 35.) Thus, DOI in estuarine waters might have been underestimated significantly in the earlier studies. Following the water along its net flow-path, iodate initially constituted more than 60% of total iodine (TI) in the source water in the Middle Atlantic Bight off the Delmarva Peninsula. As this water entered the Chesapeake Bay through the northern part of its mouth, the concentration of R-iodate decreased while that of R-iodide increased progressively until the former became undetectable in the surface mixed layer while the latter reached a maximum of 0.42 μM in the deep water in the upper Bay. Then, the concentration of R-iodate rebounded while that of R-iodide decreased in the outflowing water that exited through the southern part of the mouth of the Bay and was later entrained by the Gulf Stream. The concentration of R-DOI in the surface waters followed the same pattern as R-iodide and reached a maximum of 0.20 μM in the upper Bay. However, R-DOI was depleted in the deep water in the sub-basins. Its concentration dropped to around the detection limit in the suboxic waters in the upper Bay. R-TI in the Bay far exceeded that in the incoming Middle Atlantic Bight water and reached 0.55 μM in the upper Bay. These distributions of the iodine species suggest that, as water from the Middle Atlantic Bight intruded into the Chesapeake Bay, in the well oxygenated surface mixed layer, iodate was reduced to iodide, and the inorganic iodine species could also be converted to DOI. In the deep water, iodate and DOI were converted to iodide. Superimposed on these inter-conversions among the iodine species, dissolved iodine, possibly in the form of iodide, was also added to the water column from the underlying sediments and the process was especially significant in the suboxic deep water in the upper Bay. Mixing between the surface mixed layer and the deep water could also have increased the concentrations of iodide and total iodine in the former.     

Sources, pathways and sinks of particulate organic matter in Hudson Bay: Evidence from lignin distributions

Hudson Bay is a large, estuarine, shelf-like sea at the southern margin of the Arctic, where changes in seasonal ice cover and river discharge appear already to be underway. Here we present lignin data for dated sediments from eleven box cores and evaluate sources of terrigenous carbon, transport pathways, and whether terrigenous organic matter has been influenced by recent environmental change. Lignin yields (0.04 to 1.46 mg/100 mg organic carbon) decreased from the margin to the interior and from south to north, broadly reflecting the distribution of river inputs. Lignin compositional patterns indicated distinct regional sources with boreal forest (woody gymnosperm) vegetation an important source in the south, vs. tundra (non-woody angiosperm) in the north. Lignin patterns suggest redistribution of a fine-grained, mineral-associated fraction of the southern-derived terrigenous carbon to the northeast part of the Bay and ultimately into west Hudson Strait with the Bay's cyclonic coastal circulation. A small component of the carbon makes it to the central basins of Hudson Bay but most of the terrigenous organic material in that area appears to derive from resuspension of older, isostatically-rebounding coastal and inner shelf deposits. Most modern plant debris appears to be retained near river mouths due to hydrodynamic sorting, with the exception of the southwest inner shelf, where these materials extend > 30 km from shore. Temporal changes in the composition of terrigenous organic carbon recorded in most of the southern Hudson Bay cores perhaps reflect increases in erosion and cross-shelf transport from coastal deposits, possibly mediated by change in ice climate. In contrast, temporal changes in the northwest may relate to changes in the supply of modern plant debris under recent warmer conditions. On the western shelf, changes may relate to ice climate and the distribution of northern coastal water and/or changes in the delivery of materials by the Churchill River due to water diversion. Although the cores show evidence of change related to the ice climate, there is little evidence that ice itself transports terrigenous organic carbon within the system.     

海洋溶解有机碳——从采样到分析

详细探讨了溶解有机碳(DOC)样品的采集与分析过程中的条件,以期发展DOC从采样到分析较为标准化(Robust)的方法步骤.影响DOC分析结果的关键有:采样过程中的样品瓶、垫片、滤膜、滤芯的选择及预处理,重力过滤,洁净台操作以及样品分析过程中仪器空白的确定.2001年5月和2002年11月两个航次在南海北部陆架上同一站位得到的DOC数据结果显示,夏季表层DOC浓度比冬季高10μmol/L,随深度增加DOC快速下降,50 m以下DOC下降较为缓慢,冬、夏两季DOC分布特征基本相同.同一水样用不同方法(GF/F过滤采样方法与走航式滤芯过滤采样方法)所得到的DOC浓度的几次比对结果如下:盐度1.14,走航采样方法为(493±14)μmol/L(n=3),GF/F方法为(478±7)μmol/L(n=3);盐度20,走航采样方法为(112±2)μmol/L(n=3),GF/F方法为(123±2.6)μmol/L(n=3);盐度33.9,走航采样方法为(102±0.7)μmol/L(n=3),GF/F方法为(93±1.5)μmol/L(n=3).结果表明,不论是在高盐度还是低盐度区域,两种方法结果基本相符,走航式采样过滤、方法可以应用于河口DOC的研究.