Arsenic mobility and groundwater extraction in Bangladesh

High levels of arsenic in well water are causing widespread poisoning in Bangladesh. In a typical aquifer in southern Bangladesh, chemical data imply that arsenic mobilization is associated with recent inflow of carbon. High concentrations of radiocarbon-young methane indicate that young carbon has driven recent biogeochemical processes, and irrigation pumping is sufficient to have drawn water to the depth where dissolved arsenic is at a maximum. The results of field injection of molasses, nitrate, and low-arsenic water show that organic carbon or its degradation products may quickly mobilize arsenic, oxidants may lower arsenic concentrations, and sorption of arsenic is limited by saturation of aquifer materials.     

Competition in desert rodents: an experiment with semipermeable exclosures

Larger species of seed-eating desert rodents were excluded from experimental plots while smaller, potentially competing species were allowed to enter. Density of small granivores on these plots increased to nearly 3.5 times that on control plots but only after 8 months. These results indicate that interspecific competition affects the abundance of desert rodents; they also support indirect evidence that competition for seeds influences the organization of desert rodent communities.     

三江平原地下水资源管理问题研究

在水文理论的基础上建立三江平原地下水流动的微分方程数学模型,并采用解析有限元法将微分方程线性化为大型线性方程组,把线性方程组作为优化模型的一部分约束条件,将地下水流动状态方程与优化模型进行耦合,并用Lingo软件求解。结果表明,该地区浅层地下水资源丰富,具有较大的开发潜力,但由于近年来水资源配置不合理,地下水开采量过大,使区域水通量呈下降趋势。     

Uranium disequilibrium in groundwater: an isotope dilution approach in hydrologic investigations

The distribution and environmental disequilibrium patterns of naturally occurring uranium isotopes (U(234) and U(238)) in waters of the Floridan aquifer suggest that variations in the ratios of isotopic activity and concentrations can be used quantitatively to evaluate mixing proportions of waters from differing sources. Uranium is probably unique in its potential for this approach, which seems to have general usefulness in hydrologic investigations.     

Atmospheric water uptake by an atacama desert shrub

Nolana mollis, a succulent-leaved shrub of the extreme coastal desert of Chile, has the capacity to condense water on its leaves out of unsaturated atmospheres, Metabolic energy would have to be expended to move this water either from the leaf surface directly to the mesophyll or, when dripped to the soil, from there into the roots. Because of the unusual aridity of its habitat and of the utilization of water-use-efficient metabolism by Nolana, at least during certain periods, such an energy expenditure could be effective.     

微波萃取-原子荧光光谱法测定稻米中砷化学形态

采用微波萃取、高效液相色谱-氢化物发生-原子荧光光谱法联用技术建立了稻米中了三价砷As(Ⅲ)、五价砷As(V)、一甲基砷酸(MMA)、二甲基砷酸(DMA)等4种形态砷的分析方法。结果表明,稻米中4种形态砷的加标回收率为80%～110%,批内及批间相对标准偏差为0.3%～4.8%,方法检出限为1.6~4.0μg/kg。将该方法应用于实际样品的测定,分析结果显示,稻米样品中含有一定量的三价砷As(Ⅲ)和少量的二甲基砷酸(DMA),其形态之和已接近我国国标中关于稻米产品中砷限量标准的规定。     

荒漠生态补偿利益主体行为的演化博弈分析

建立与完善生态补偿机制是荒漠生态环境保护的重点内容.为了研究荒漠地区生态保护利益相关者的补偿机理,通过建立演化博弈分析的复制动态模型,对各利益相关主体的行为及其相互影响进行研究,分析各策略的动态演变过程,讨论演化结果的稳定性.结果表明:各博弈方策略的演化方向受对方策略初始状态的影响,并与博弈双方支付矩阵的参数有关,但政府及管理部门是更为重要的主导者,他们的行为与意愿直接决定了均衡解;生态补偿在保证农牧民采取稳定的“保护”策略中起着至关重要的作用;合理确定沙区的生态补偿金额、降低沙区的生态保护成本、在监管过程引入奖惩机制和增大监管力度,有助于实现荒漠生态保护的可持续发展.     

村镇垃圾治理典型案例及问题分析

垃圾治理是农村人居环境整治的重要组成部分。当前各地农村围绕垃圾分类、收运及处理处置开展了众多实践尝试。为及时、深入地了解村镇垃圾的治理现状,本文基于2021年村镇垃圾治理实用技术与实践案例征集活动的结果,对比分析了应征案例的指标达成状况,系统梳理了村镇垃圾的分类收运、资源化利用及热处理三类典型案例的特点和存在的问题,旨在为我国村镇垃圾治理工作的高效推进提供参考。就分类收运而言,“五网协同”、“一户一码”、第三方运营等管理机制方面的创新对村镇垃圾治理的高效推进具有重要作用,同时也存在目标效果缺乏数据支撑、案例覆盖人口数量少及案例可推广性有待验证等问题。资源化处理方面,升级版的阳光房堆肥技术及模式运行成本较低,操作相对简便,可推广性强;虽然厨余（易腐）垃圾机械制肥推广应用较多,具有一定的适用性,但其运行成本高,且部分运行时间较短的工艺无法满足产物腐熟的要求。易腐垃圾昆虫生物转化技术的减量化和资源化水平较高,有较好的规模化推广应用前景。此外,大部分村镇生活垃圾热处理案例存在运行不稳定及污染物排放不达标等问题,因此应加强原料控制、热解（焚烧）过程优化等方面的科学研究和实践应用。     

Taboo search: an approach to the multiple minima problem

Described here is a method, based on Glover's taboo search for discrete functions, of solving the multiple minima problem for continuous functions. As demonstrated by model calculations, the algorithm avoids entrapment in local minima and continues the search to give a near-optimal final solution. Unlike other methods of global optimization, this procedure is generally applicable, easy to implement, derivative-free, and conceptually simple.     

土壤砷污染及其对作物的毒害研究进展

综述了土壤中砷的形态、毒性、转化、污染等研究现状和土壤砷有效性的影，响因素，以及砷对作物形态、生理、产量等的影响，总结了作物砷毒害的生理机制，分析了作物砷毒害研究中存在的问题，提出了今后的研究方向和建议。     

Arsenic in detergents: possible danger and pollution hazard

Arsenic at a concentration of 10 to 70 parts per million has been detected in several common presoaks and household detergents. Arsenic values of 2 to 8 parts per billion have been measured in the Kansas River. These concentrations are close to the amount (10 parts per billion) recommended by the United States Public Health Service as a drinking-water standard.     

荒漠绿洲区干旱遥感监测指数的对比分析

绿洲农业在南疆经济社会发展进程中意义非凡,及时获取荒漠绿洲区土壤相对湿度数据,对有限水资源合理分配、促进绿洲农业和生态环境的健康持续发展至关重要,选择适宜的干旱遥感监测指数是干旱监测面临的问题。基于Landsat 8和实测土壤相对湿度数据,对比分析NDWI、VSWI、TVDI、MEI在荒漠绿洲区的有效性。结果表明,受人类活动等各种因素影响,4种指数在农田区域（棉田、枣地）效果不理想;4种指数均能反映研究区荒漠土壤相对湿度的空间特征,最佳监测深度为0～10 cm;从相关系数分析,NDWI、MEI监测效果优于VSWI和TVDI。受水资源分布和人类活动影响,塔里木河两岸及农田周边荒漠土壤相对湿度较高。     

Oceili: a celestial compass in the desert ant cataglyphis

In addition to multifaceted lateral compound eyes, most insects possess three frontal eyes called ocelli. Each ocellus has a single lens, as does the vertebrate eye. The ocelli of some flying insects, locusts and dragonflies, have been shown to function as horizon detectors involved in the visual stabilization of course. In a walking insect, the desert ant Cataglyphis, it is now shown that the ocelli can read compass information from the blue sky. When the ant's compound eyes are occluded and both sun and landmarks are obscured, the ocelli, using the pattern of polarized light in the sky as a compass cue, help in guiding the ant back home.     

Climate and groundwater recharge during the last glaciation in an ice-covered region

A multitracer study of a small aquifer in northern Switzerland indicates that the atmosphere in central Europe cooled by at least 5 degreesC during the last glacial period. The relation between oxygen isotope ratios (delta18O) and recharge temperatures reconstructed for this period is similar to the present-day one if a shift in the delta18O value of the oceans during the ice age is taken into account. This similarity suggests that the present-day delta18O-temperature relation can be used to reconstruct paleoclimate conditions in northern Switzerland. A gap in calculated groundwater age between about 17,000 and 25,000 years before the present indicates that during the last glacial maximum, local groundwater recharge was prevented by overlying glaciers.     

佳木斯市城区地下水动态特征分析

采用佳木斯市区2001～2005年的地下水观测资料,对城区地下水的动态变化、影响因素及降落漏斗的现状与发展进行分析。结果表明,"十五"期间,佳木斯市城区地下水位埋深范围为6.64～10.85m,水位标高范围为70.92～74.66m。由于大气降水具有迟后补给作用,2001年降水量最小,为350.5mm,造成2002年地下水位最低;2003年降水量最大,为564.4mm,使得2004年水位最高。地下水的常年大量开采,使城区已形成约60km2的降落漏斗,并向南侧和东北侧略有扩展。     

Arbuscular mycorrhiza fungi as an ecology indicator for evaluating desert soil conditions

Arbuscular mycorrhiza (AM) fungi are the most common underground symbiosis. They can form vesicles and arbuscules in the roots of about 80% of plant species. In this paper, using the arbuscular mycorrhiza’s colonization as an evaluating indicator in combination with other experimental indicators, we composed a system of evaluating various indices to analyze desert soil conditions. A fuzzy optimization system model was introduced to analyze the experimental results. The results showed that the soil quality was Yulin > Ecology Station > Yanchi > Shapotou > Dingbian. ‘μ _i ’, an indicator of soil quality, was the greatest in the topmost layer of soil, in the 0–10 cm soil, at the sampling sites Yulin, Ecology Station, Yanchi and Dingbian. However, at Shapotou the maximum value of μ _i was found in the 10–20 cm soil layer. The weight value of the AM fungal index ranged from 37% to 95% at different sites.