地下水污染健康风险模拟预测评估中参数的敏感度分析

随着地下水污染健康风险评估逐渐被重视,其风险的影响程度和发展趋势也越来越被关注,因此解析解模拟预测评估地下水污染健康风险也逐渐被应用。本文旨在研究解析解模型对污染物健康风险模拟的敏感度,为该方法更广泛的应用提供依据。选取解析解模型中的渗透系数(K)、纵向弥散度(αx)、污染物有机碳分配系数(Koc)和半衰期(t1/2)4个参数,在其他参数不变的情况下,依次改变各参数的值并进行解析解计算,记录对应的参数值与模拟结果,绘出模拟预测值与各个分析参数的变化曲线,分析解析解对各个参数的响应程度,从而为处理不确定因素提供依据。     

Multi-wheat-model ensemble responses to interannual climate variability

We compare 27 wheat models' yield responses to interannual climate variability, analyzed at locations in Argentina, Australia, India, and The Netherlands as part of the Agricultural Model Intercomparison and Improvement Project (AgMIP) Wheat Pilot. Each model simulated 1981–2010 grain yield, and we evaluate results against the interannual variability of growing season temperature, precipitation, and solar radiation. The amount of information used for calibration has only a minor effect on most models' climate response, and even small multi-model ensembles prove beneficial. Wheat model clusters reveal common characteristics of yield response to climate; however models rarely share the same cluster at all four sites indicating substantial independence. Only a weak relationship (R² ≤ 0.24) was found between the models' sensitivities to interannual temperature variability and their response to long-term warming, suggesting that additional processes differentiate climate change impacts from observed climate variability analogs and motivating continuing analysis and model development efforts.     

Cu-MOF assisted synthesis of CuS/CdS(H)/CdS(C): Enhanced photocatalytic hydrogen production under visible light

CuS/CdS(H)/CdS(C) photocatalysts were synthesized via the hydrothermal method by employing thiourea, Cd(CH₃COO)₂·3H₂O and copper 1,4-benzenedicarboxylate MOF (CuBDC). The photocatalysts were characterized by XRD, XPS, BET, TEM and UV–vis diffuse reflectance spectra. Interestingly, hexagonal CdS (CdS(H)) and cubic CdS (CdS(C)) were formed with phase junctions in one step when CuBDC was introduced in the synthesis process, in addition, CuS nanoparticles were deposited on CdS. However, only hexagonal CdS was obtained without CuBDC. It demonstrated that CuBDC was not only the precursor of CuS but also the structural modifier for CdS. With the reduction of re-combination of photo-induced electrons and holes caused by phase junctions and the enhancement of visible-light absorptions due to the loading of CuS, all CuS/CdS(H)/CdS(C) photocatalysts had higher photocurrent densities under visible-light irradiation, and consequently the higher rates of H₂ production than pure CdS(H). Typically, the catalyst with 2.89 wt% of Cu showed a highest rate of H₂ evolution at 2042 μmol/g/h.     

Novel direct Z-scheme AgI/N–TiO2 photocatalyst for removal of polluted tetracycline under visible irradiation

In the study, we doped N into TiO₂ lattice to narrow its band gap energy. Then, the synthesized N doped TiO₂ material was combined with AgI to form AgI/N–TiO₂ (ANT) direct Z scheme materials. The synthesized materials were utilized for photocatalytic removal of tetracycline (TC) using visible irradiation as an excitation source. We also conducted radical scavenging experiments to determine photocatalytic degradation mechanism. We investigated that these photo-excited electrons (e⁻) in N–TiO₂ conduction band tended to combine with the left holes (h⁺) in AgI valence band maintaining h⁺ in the valence band of the N–TiO₂ and e⁻ in the conduction band of the AgI. The remained e⁻ and h⁺ have high redox potential to initiate for photocatalytic decomposition of TC. Thus, the TC degradation by the ANT materials were significant greater than those by single components (AgI or N–TiO₂). We also investigated that the TC degradation by the ANT-30 material, which the AgI: N–TiO₂ molar ratio was 30%, exhibited that highest degradation efficiency. Finally, the ANT photocatalyst exhibited excellent stability during TC degradation processes supporting for its promising potential application in practical systems.     

High work-hardening effect of the pure NiAl intermetallic compound fabricated by the combustion synthesis and hot pressing technique

The pure NiAl intermetallic compound was fabricated by the combustion synthesis and hot pressing technique. Microstructure examination showed that the NiAl intermetallic compound contained fine grains. Analysis of the X-ray diffraction and the HRTEM studies showed that the phase in the intermetallics was the only NiAl phase. The NiAl showed prominent compression properties. The true ultimate compression strength and the fracture strain of the NiAl are 1002_? 94^+ 72 MPa and 21.6_? 1.8^+ 1.8%, respectively. The work-hardening capacity (H_c) is 1.40_? 0.07^+ 0.09 and the Vickers micro-hardness is 360_? 19^+ 15 HV. The finer grains, the high density dislocation and the seriously distorted lattices in the matrix, and the intense interactions between dislocations contribute to the prominent compression properties.     

氮肥对地下水中氮迁转机理研究

为研究地下水中“三氮”迁移转化的主要影响因子,以江西省泰和县境内的千烟洲试验站为研究对象,根据研究需要进行了实验区域的划定,对研究区域的地下水位、“三氮”、铁、锰和pH值进行了长期的监测,通过数据整理、作图分析后,利用SPSS软件对“三氮”、总铁、可滤态锰和pH值的相关性进行分析。结果表明:研究区地下水已经受到了农业氮面源污染的影响;地下水中铁、锰具有显著的伴生性;铵态氮和亚硝酸盐态氮与铁、锰存在显著的正相关。总铁、可滤态锰、pH值、温度和降雨是地下水中“三氮”迁移转化的主要影响因子。通过“三氮”迁移转化影响因子的分析,可为农业氮面源污染的防治提供一定的理论基础。     

(Bio-)chemical and physical microsensor arrays using an identical transducer principle

A new concept based on an identical transducer principle and structure for both (bio-)chemical and physical sensors is presented. For all sensors, the field effect is used as transducer principle. In this approach, the same chemical sensor is employed also as a physical sensor. A novel design of a temperature sensor on the basis of a differential arrangement of two identical ISFETs operating in different working points is demonstrated. A multifunctionality of the sensor system is achieved by means of different sensor arrangements and/or operation modes. Thus, the number of the obtained (bio-)chemical and physical quantities, like ion concentration, temperature, flow rate can be higher than the number of the sensors applied. A hybrid sensor module, for the pH, penicillin and temperature determination is realised and its performance has been investigated.     

Mapping oil palm extent in Malaysia using ALOS-2 PALSAR-2 data

The extent of oil palm plantations has increased rapidly in Malaysia over the past few decades. To evaluate ecological effects and economic values, it is important to produce an accurate oil palm map for Malaysia. The Phased Array Type L-band Synthetic Aperture Radar (PALSAR) on the Advance Land Observing Satellite (ALOS) is useful in land-cover mapping in tropical regions under all-weather conditions. In this study, PALSAR-2 images from 2015 were used for oil palm mapping with maximum likelihood classifier (MLC)-based supervised classification. The processed PALSAR-2 data were resampled to multiple coarser resolutions (50, 100, 250, 500, and 1000 m), and then used to investigate the effect of speckle in oil palm mapping. Both independent testing samples and inventories from the Malaysia Palm Oil Board (MPOB) were used to evaluate the mapping accuracy. The oil palm mapping result indicates 50–500 m to be a good resolution for either retaining spatial details or reducing speckle noise of PALSAR-2 images. Among which, the best overall mapping accuracies and average oil palm accuracies reached 94.50% and 89.78%, respectively. Moreover, the oil palm area derived from the 100-m resolution map is 6.14 million hectares (Mha), which is the closest to the official MPOB inventories (~8.87% overestimation).     

Experimental investigation on rainfall infiltration and solute transport in layered porous and fractured media

Layered structures with upper porous and lower fractured media are widely distributed in the world. An experimental investigation on rainfall infiltration and solute transport in such layered structures can provide the necessary foundation for effectively preventing and forecasting water bursting in mines, controlling contamination of mine water, and accomplishing ecological restoration of mining areas. A typical physical model of the layered structures with porous and fractured media was created in this study. Then rainfall infiltration experiments were conducted after salt solution was sprayed on the surface of the layered structure. The volumetric water content and concentration of chlorine ions at different specified positions along the profile of the experiment system were measured in real-time. The experimental results showed that the lower fractured media, with a considerably higher permeability than that of the upper porous media, had significant effects on preventing water infiltration. Moreover, although the porous media were homogeneous statistically in the whole domain, spatial variations in the features of effluent concentrations with regards to time, or so called breakthrough curves, at various sampling points located at the horizontal plane in the porous media near the porous-fractured interface were observed, indicating the diversity of solute transport at small scales. Furthermore, the breakthrough curves of the outflow at the bottom, located beneath the underlying fractured rock, were able to capture and integrate features of the breakthrough curves of both the upper porous and fractured media, which exhibited multiple peaks, while the peak values were reduced one by one with time.