移动通信基站电磁辐射时空分布及衰减特征

根据理论计算公式和实测数据,研究基站电磁辐射水平、垂直方向的衰减趋势,分析影响基站电磁辐射时空分布的各种因素,认为基站电磁辐射实际影响范围要远小于安全防护距离。     

The stable isotope signature of methane emitted from plant material under UV irradiation

Recent experiments have shown that dry and fresh leaves, other plant matter, as well as several structural plant components, emit methane upon irradiation with UV light. Here we present the source isotope signatures of the methane emitted from a range of dry natural plant leaves and structural compounds. UV-induced methane from organic matter is strongly depleted in both ¹³C and D compared to the bulk biomass. The isotopic content of plant methoxyl groups, which have been identified as important precursors of aerobic methane formation in plants, falls roughly halfway between the bulk and CH₄ isotopic composition. C3 and C4/CAM plants show the well-established isotope difference in bulk ¹³C content. Our results show that they also emit CH₄ with different δ¹³C value. Furthermore, δ¹³C of methoxyl groups in the plant material, and ester methoxyl groups only, show a similar difference between C3 and C4/CAM plants. The correlation between the δ¹³C of emitted CH₄ and methoxyl groups implies that methoxyl groups are not the only source substrate of CH₄.Interestingly, δD values of the emitted CH₄ are also found to be different for C3 and C4 plants, although there is no significant difference in the bulk material. Bulk δD analyses may be compromised by a large reservoir of exchangeable hydrogen, but no significant δD difference is found either for the methoxyl groups, which do not contain exchangeable hydrogen. The δD difference in CH₄ between C3 and C4 plants indicates that at least two different reservoirs are involved in CH₄ emission. One of them is the OCH₃ group, the other one must be significantly depleted, and contribute more to the emissions of C3 plants compared to C4 plants. In qualitative agreement with this hypothesis, CH₄ emission rates are higher for C3 plants than for C4 plants.     

Risk assessment and binding mechanisms of potentially toxic metals in sediments from different water levels in a coastal wetland

The excessive accumulation of potentially toxic metals (Pb and Cd) in coastal wetlands is among the main factors threatening wetland ecosystems. However, the effects of water table depth (WTD) on the risk and binding mechanisms of potentially toxic metals in sediments remain unclear. Here, sediments from different WTD obtained from a typical coastal wetland were evaluated using a newly developed strategy based on chemical extraction methods coupled with high-resolution spectroscopy. Our findings indicated that the WTD of the coastal wetland fluctuates frequently and the average enrichment factor for Pb was categorized as minor, whereas Cd enrichment was categorized as moderate. High-resolution spectroscopy techniques also demonstrated that organic functional groups and partly inorganic compounds (e.g., Fe-O/Si-O) played a vital role in the binding of Pb and Cd to surface sediments. Additionally, mineral components rather than organic groups were mainly bound to these metals in the bottom sediments. Collectively, our findings provide key insights into the potential health effects and binding characteristics of potentially toxic metals in sediments, as well as their dynamic behavior under varying sediment depths at a microscale.     

Synergistic effect of ozonation and ionizing radiation for PVA decomposition

Ozonation and ionizing radiation are both advanced oxidation processes (AOPs) without chemical addition and secondary pollution. Also, the two processes'' efficiency is determined by different pH conditions, which creates more possibilities for their combination. Importantly, the combined process of ozonation and ionizing radiation could be suitable for treating wastewaters with extreme pH values, i.e., textile wastewater. To find synergistic effects, the combined process of ozonation and ionizing radiation mineralization was investigated for degradation of polyvinyl alcohol (PVA) at different pH levels. A synergistic effect was found at initial pH in the range 3.0–9.4. When the initial pH was 3.0, the combined process of ozonation and ionizing radiation gave a PVA mineralization degree of 17%. This was 2.7 times the sum achieved by the two individual processes, and factors of 2.1 and 1.7 were achieved at initial pH of 7.0 and 9.4, respectively. The combined process of ozonation and ionizing radiation was demonstrated to be a feasible strategy for treatment of PVA-containing wastewater.     

GSM移动通信基站电磁辐射环境影响分析

本文阐述了电磁辐射的相关理论、电磁辐射环境的评价标准以及基站的工作原理,对电磁环境进行了理论预测,对不同的天线增益下的电磁辐射功率密度值进行了计算,得到了在天线增益15dBi、17dBi和18dBi三种情况下与天线不同直线距离的预测点的功率密度预测值,并对功率密度预测值进行了分析。     

Effect of Tinospora cordifolia on the reduction of ultraviolet radiation‐induced cytotoxicity and DNA damage in PC12 cells

The safety of Tinospora cordifolia and its potential to protect against ultraviolet radiation‐induced cytotoxicity and DNA damage in PC12 cells were investigated. To evaluate the safety of T. cordifolia, cell viability and agarose gel electrophoresis were carried out using PC12 cells treated with 0 to 100 μg mL^?1 of methanol extract of T. cordifolia. T. cordifolia extracts did not show cytotoxicity ranging 0 to 100 μg mL^?1. In addition, T. cordifolia extracts significantly increased cell viability at 1 ng, 10 ng and 1 μg mL^?1 concentrations in serum‐deprived medium compared to control. To confirm the protective role against UV‐induced damage, PC12 cells alone or in the presence of 10 ng, 100 ng, or 1 μg mL^?1 of T. cordifolia extract were exposed to 250, 270 and 290 nm of UV radiation, which corresponded to doses of 120, 150 and 300 mJ cm^?2, respectively. Treatment with T. cordifolia extracts significantly increased the cell survival rate irradiated at 290 nm. In addition, T. cordifolia extracts significantly reduced cyclobutane pyrimidine dimer formation induced by UV irradiation at all wavelengths. In conclusion, T. cordifolia is not toxic and safe for cells. Our findings can support its application as phototherapy in the medical sector.     

紫外辐射对小球藻混凝效果作用途径探讨

针对藻类在常规水处理过程中难以被有效去除的现状,采用紫外辐射对藻类混凝过程进行强化处理.结果表明,随着紫外照射时间的增加,混凝后对藻细胞和浊度的去除均呈先上升后下降的趋势,并在照射50 min时达到最大值.PAC(聚合氯化铝)投加量为5 mg·L~(-1)时,照射样的除藻率和去浊率达到最大,分别比空白样高20.1%和18%左右.pH值在6~9范围内,紫外辐射强化混凝效果的变化较小.溶液pH=8、紫外照射50 min,混凝后的除藻率和去浊率分别达到了93.5%和90.6%.此时,藻细胞Zeta电位最大,同时释放出藻黏液,有利于混凝沉降.而当紫外照射超过60 min后,出现细胞膜破裂,胞内有机物渗出,使得溶液中的有机物浓度急剧上升,Zeta电位开始下降,不利于后续混凝的进行.     

基于GOCI数据的霾天气气溶胶辐射强迫的日内变化——以长江三角洲为例

以长江三角洲（以下简称长三角）为研究区,基于2017年10~12月内共16d 94景的晴空静止卫星GOCI L1B图像和6S模型,采用深蓝算法反演长三角地区气溶胶光学厚度（AOD）,并利用2个实测站数据进行验证.再通过反演得到的AOD结果进一步模拟计算该区域地表和大气层顶的气溶胶直接辐射效应（ADRE）,并结合典型的雾霾天气进行分析.结果表明：利用GOCI数据反演的AOD具有较高拟合精度,北辰楼站点拟合相关性R²为0.68,太湖站点为0.67.空间上,由于气溶胶存在制冷效应,AOD和地表面、大气层顶气溶胶直接辐射强度均呈现出显著的线性关系.时间上,由于气溶胶扩散和风向等因素,早上和下午辐射效应强度较高,中午较低.其中10：00和11：00影像可以较好地模拟日均ADRE的特征,利用ADRE日内变化成功捕捉到一次雾霾爆发并消失的现象,对气象部门监测近地表气温和分析灰霾的形成等具有重要意义.     

废彩色阴极射线管玻璃的X和γ射线屏蔽特性

废电视机和计算机监视器产生了数量庞大的废阴极射线管（CRTs）,已成为全球面临的环境风险,迫切需要找出新的处置方法和再利用途径来化解风险。用Χ和γ射线标准剂量测定装置(QH16),XRF,ICP,XRD和灰熔点炉等试验手段测试了废彩色CRTs玻璃的铅当量、化学组成和烧结等特性,并与钢、铁矿石、重晶石等进行对比;讨论了废彩色CRTs玻璃的X和γ射线质量衰减系数,能量吸收特性和辐射屏蔽能力。结果表明,废彩色CRTs玻璃所含的Pb、Ba、Sr、Sb、Ce、Zn等金属元素具有优良的Χ和γ射线屏蔽性能,将其通过烧结法制备成射线屏蔽材料是控制污染和再利用的有效途径。     

肿瘤病房医用直线加速器对周围环境电离辐射的调查分析

通过对医院肿瘤病房医用直线加速器机房周围环境的电离辐射监测调查 ,并计算分析各相关人群的年有效剂量当量 ,结果低于《辐射防护规定》(GB870 3- 88)中的标准限值。表明医用直线加速器机房的辐射防护设施设计是安全合理的 ,具有重要的现实意义 ,该辐射防护设施具有推广价值。