东海赤潮高发区春季溶解氧和pH分布特征及影响因素探讨

根据2002年4月27日—5月2日长江口邻近海域的大面调查,分析了东海溶解氧及pH值的分布特征,并对长江口外溶解氧低值区的成因及其与赤潮发生的关系进行了初步探讨。结果表明,调查海域pH值呈近岸低、外海高的分布趋势,溶解氧整体处于过饱和状态,呈近岸高、外海低的分布趋势。4月下旬在调查海区东南部底层已开始出现溶解氧低值区,面积约为15400km2,该水域表观耗氧量AOU一般在1.50mg/L以上,并伴随有氧的亏损发生,形成原因主要是水交换较弱和有机物分解耗氧。溶解氧低值区可能是有机碎屑的沉降汇集区,随着夏季温度的升高及长江丰水期的到来,有机碎屑有可能在台湾暖流的影响下产生西、北向的爬升而造成溶解氧低值区扩大和溶解氧含量的进一步降低。

X线数字断层融合技术在人工关节置换术后评估中的应用

目的分析人工关节置换术后应用X线数字断层融合技术的效果。方法回顾性分析2021年10月—2023年3月佛山市中医院收治的50例人工关节置换术患者的临床资料。根据检查方法不同分组,接受X线摄影技术检查为参照组,接受X线数字断层融合技术检查为研究组,比对两组图像质量、骨溶解区数量状况。结果研究组图像质量高于参照组,差异有统计学意义(P<0.05);研究组髋臼周围、股骨柄周围骨溶解区数量分别为(1.82±0.12)、(3.56±0.14)个,多于参照组,差异有统计学意义(t=14.618、21.828,P<0.05)。结论X线数字断层融合技术在人工关节置换术后评估中质量更高,识别骨溶解区数量高。

铸铁孕育处理时的石墨核心研究

将铁水用75FeSi孕育后液淬,终止其溶解过程,在溶解区中出现已经生长石墨相的非金属夹杂物,它们随后又溶回铁水中去.但已经复盖有石墨相的晶核能存在较长的时间孕育剂的作用是提供一个碳的过冷溶液。

竖流式一体化反应器处理乡镇污水的影响因素

设计了1种竖流式一体化反应器用于处理乡镇生活污水,该反应器将原本A2/O工艺中单独设置的厌氧区、缺氧区、好氧区和沉淀区整合为一体,实验考察了HRT和好氧区DO含量对处理效果的影响。结果表明,4组好氧区HRT分别为6、8、10、12 h时,COD、NH3-N、TN、TP的去除率分别为69%~81%、77%~87%、74%~81%、73%~82%;当好氧区DO的质量浓度分别为1.5、2.5、3.5 mg/L时,COD、NH3-N、TN、TP的去除率分别为69%~79%、76%~84%、72%~79%、74%~79%。综合考虑处理效果和成本,HRT为8 h、DO的质量浓度2.5 mg/L时较为适合,此时出水COD、NH3-N、TN、TP均可满足GB 18918-2002污水排放一级A标准。该竖流式一体化反应器具有结构紧凑、占地面积小等特点。

Solubility and metastable zone width measurement of 3,4-bis (3-nitrofurazan-4-yl) furoxan (DNTF) in ethanol + water

The solubility and supersolubility of 3,4-bis(3-nitrofurazan-4-yl)furoxan(DNTF) in ethanol + water at different operation were determined by laser monitoring system under atmospheric pressure to study the metastable zone width(MSZW). The modified Apelblat equation was adopted to correlate the experimental solubility data, and the correlation result showed perfect consistent with the experimental data. The standard dissolution enthalpy, standard dissolution entropy and Gibbs energy were calculated according to the experimental solubility data. The effect of the cooling rate, stirring rate, temperature and the concentration of ethanol + water on the MSZW was studied. It was found that the MSZW of DNTF increased with the increasing cooling rate, decreasing temperature, decreasing stirring rate and decreasing ratio of water. And the apparent nucleation order of DNTF in ethanol + water was calculated by the relationship between the cooling rate and the MSZW.

Hydrogeochemical Characteristics of Fluorine in Shallow Groundwater of Tongshan Area

Tongshan area,a part of the floodplain of the abandoned Huanghe River, is one of the popular endemic fluorosis areas in East China. One of the reasons is high concentration of fluorine in shallow groundwater. Test results of 36 groundwater samples show that fluorine concentration in shallow groundwater is 0.18–6.7 mg/L and 50 % of the samples exceed the Chinese drinking water quality standard. There exists a significant negative correlation in content between Ca2+ and F - . The correlations between fluorine concentration and other cations (for example Na+, K+, Mg2+) are not significant. The content of dissolved fluorine from the flooding sediments of the Huanghe River that varying from 5.6 mg/kg to 15.2 mg/kg plays an important role in forming the high fluorine groundwater. Usually, the dissolved fluorine content in silt is much higher than that in silty clay and clay. According to the geological investigation fluorine content in deep groundwater (over 60 m) is less than 1.0 mg/L and suitable for drinking, so it is an effective measure to prevent endemic fluorosis by extracting deep groundwater in disease areas.

THE STRENGTH OF THE DISSOLVED OXYGEN MAXIMUM IN THE VERTICAL DISTRIBUTION OF NANSHA ISLANDS WATERS

Observation data from a cruise in the Nansha Islands, in May to June 1990, December, 1993, September to October 1994, and July, 1999, respectively, were used to develop the method presented here to indicate the existing strength of the dissolved oxygen maximum in the vertical distribution of Nansha Islands waters. Its seasonal variation and regional distribution are discussed in this paper. Analysis results showed that the distribution of the strength of dissolved oxygen maximum (DO max -DO sur ) was closely related to the upper layer circulation and the bioactivity of Nansha Islands seawater.

Sources of dissolved inorganic carbon in rivers from the Changbaishan area, an active volcanic zone in North Eastern China

Major elements and carbon isotopes of dissolved inorganic carbon(DIC)have been measured in the waters of Changbaishan mountain,a volcanic area in northeastern China,between June and September 2016 to decipher the origin of the CO_2 involved in chemical weathering reactions.Spatial variations of major elements ratios measured in water samples can be explained by a change of the chemical composition of the volcanic rocks between the volcanic cone(trachytes)and the basaltic shield as evidenced by the variations in the composition of these rocks.Hence,DIC results from the neutralization of CO_2 by silicate rocks.DIC concentrations vary from 0.3 to 2.5 mmol/L and carbon isotopic compositions of DIC measured in rivers vary from-14.2‰to 3.5‰.At a first order,the DIC transported by rivers is derived from the chemical weathering’s consumption of CO_2 with a magmatic origin,enriched in^(13)C(-5%)and biogenic soil CO_2 with lower isotopic compositions.The highest δ^(13)C values likely result from C isotopes fractionation during CO_2 degassing in rivers.A mass balance based on carbon isotopes suggest that the contribution of magmatic CO_2 varied from less than 20%to more than 70%.Uncertainties in this calculation associated with CO_2 degassing in rivers are difficult to quantify,and the consequence of CO_2 degassing would be an overestimation of the contribution of DIC derived from the neutralization of magmatic CO_2 by silicate rocks.

Estimating the geographic range of a threatened shark in a data-poor region： Cetorhinus maximus in the South Atlantic Ocean

The distribution of the planktivorous basking shark Cetorhinus maximus is influenced by zooplankton abundance at small scales and temperature at medium scales in the North Atlantic. Here, we estimate the distribution of basking sharks on South Atlantic continental shelves, and the relative importance of chlorophyll concentration, as a proxy for zooplankton abun- dance, and temperature in determining habitat suitability for basking sharks at large scales. We used maximum entropy （MaxEnt） and maximum likelihood （MaxLike） species distribution modelling to test three hypotheses： the distribution of basking sharks is determined by （1） temperature, （2） chlorophyll concentration, or （3） both chlorophyll and temperature, while considering other factors, such as oxygen and salinity. Off South America, basking shark habitat included subtropical, temperate and cool-temperate waters between approximately 20°S and 55°S. Off Africa, basking shark habitat was limited to cool-temperate waters off Namibia and southern South Africa. MaxLike models bad a better fit than MaxEnt models. The best model included minimum chlorophyll concentration, dissolved oxygen concentration, and sea surface temperature range, supporting hypothesis 3. However, of all variables included in the best model, minimum chlorophyll concentration had the highest influence on basking shark distribution. Unlike the North Atlantic distribution, the South Atlantic distribution of basking sharks includes subtropical and cool-temperate waters. This difference is explained by high minimum chlorophyll concentration off southern Brazil as compared to North Atlantic subtropical areas. Observations in other regions of the world support this conclusion. The highest habitat suitability for basking sharks is located close to nearshore areas that experience high anthropogenic impact [Current Zoology 61 （5）： 811-826, 2015].