Migration and transformation of fluoride through fluoride-containing water for the irrigation of a soil–plant system

The fluoride (F) content of groundwater is high in Kuitun, Xinjiang, China, and the amount of F in soil and plants severely exceeds the limit after irrigation. This study designed a potted plant experiment at different concentrations of irrigation water to investigate the migration and transformation pattern of a water–soil–plant system. Three kinds of green vegetables with high metabolism were selected. Different concentrations of NaF solutions were also prepared to simulate the irrigation of farmland in Kuitun. After the plants were irrigated with different NaF concentrations, the contents of water-soluble state fluorine (Ws-F) and the exchange state fluorine (Ex-F) increased. The F content in plants did not increase as the F concentration in irrigation water increased. The F concentration in different plant organs showed the following trend: root > stem > leaf. Bioconcentration factor (BCF) and transfer factor (TF) of plants initially increased and then decreased, indicating that plants exhibit a self-protection ability at high F concentration.     

西藏生态环境的氟水平

使用F离子选择电极法 ,对西藏不同地貌、生态特征的藏族人群居住区进行了水、土壤、燃料、粮食、食品、蔬菜、茶的F含量测定 .西藏的水F含量均数为 0 .0 6mg·L-1,土壤可溶性F 0 .45mg·kg-1,主要燃料F含量0 .10mg·kg-1,主要粮食、食品以及蔬菜的F含量 0 .0 6～ 0 .33mg·kg-1,用砖茶调制的酥油茶和糌粑F含量达3 .0 9mg·L-1和 3 .6 1mg·kg-1,产自四川、云南的砖茶水溶性F含量达到 5 33 .89～ 6 17.32mg·kg-1,可以认为 ,西藏有可能是砖茶型F中毒的流行区 .     

环境氟迁移与茶叶氟富集的关系

选择３种类型茶场进行大气氟污染与茶叶氟富集的现场监测与研究,对苏南茶区１１个茶场的土壤总氟、水溶性氟和茶叶氟富集量进行了测定。结果表明：茶叶氟富集量与来自砖瓦窑厂的大气氟污染浓度呈现高度的正相关,与土壤含氟量不呈现相关;茶树是高富集氟的植物,富集能力远高于一般植物,氟富集量可达每千克数十至数百毫克。茶叶的氟富集与氟污染应引起重视     

Groundwater contamination with cadmium concentrations in some West U.P. Regions,India

Water is considered a vital resource because it is necessary for all aspects of human and ecosystem survival. However, due to natural processes and anthropogenic activities, various pollutants have been added to the ground water system. Among these, heavy metals are some of the most serious pollutants. Cd, a toxic heavy metal used in Ni-Cd batteries, the colouration of plastic and various discarded electronic products released into the water system causes serious health issues. The chronic exposure to Cd produces a wide variety of acute and chronic effects in humans. Cd accumulates in the human body, especially in the kidneys, resulting in kidney damage (renal tubular damage), which is a critical health effect. Other effects of Cd exposure are disturbances in calcium metabolism, hypercalciuria and the formation of kidney stones. High exposure to Cd can lead to lung cancer and prostate cancer; hence, poor quality water that may result in Cd toxicity has become a global concern. Thus, the aim of this study is to determine the concentration of Cd in underground water sources in western U.P. regions. Water samples were acidified to 1% with nitric acid and then stored in double-capped polyethylene bottles for further analysis by an atomic absorption spectrophotometer. After comparing the data to the WHO (2011) permissible limit, the study revealed that the concentration of Cd was higher than the regulatory threshold; therefore, the underground water system is seriously affected by Cd toxicity.     

我国重点氟污染行业排放清单与土壤氟浓度估算

工业生产排放和土壤氟高背景值导致我国部分地区氟污染严重,给生态安全和人类健康造成严重威胁.本文基于我国氟排放重点行业的生产产能,估算重点行业生产过程中氟排放量,构建我国重点行业氟排放清单,基于数据集成和融合,分析我国土壤氟背景值、氟地球化学分布和土壤氟浓度分布,并对氟污染典型区域氟污染成因及控制进行系统分析.分析发现,我国氟排放的重点行业有钢铁、磷肥和电解铝.磷肥施用的氟排放量最大,但施用面积大,浓度贡献小;电解铝行业的氟排放强度大;钢铁行业的氟排放总量大,但排放强度较小.我国大部分地区土壤氟背景值不高,环境容量大.但部分地区氟污染严重,主要是由工业氟排放和土壤氟高背景值造成,这些地区应采取相应的防控措施.     

Sources of dissolved methane in Lake Biwa

The spatial distribution and seasonal variation in the concentration and carbon isotopic composition of dissolved methane in a river–lake ecosystem were studied in Lake Biwa, Japan, and its tributary rivers. Methane concentrations in all subsystems examined were supersaturated with respect to the atmosphere. The epilimnion showed higher concentrations of dissolved methane than the hypolimnion in the pelagic zone. Peak methane concentrations were observed at the thermocline. The largest amount of methane in the pelagic water column was recorded at the end of a stagnant period, at which the bottom water of the sublittoral zone (30m in depth) exhibited increased methane concentration. Transect observation of dissolved methane revealed three methane peaks at different water depths in the lake, and river water and the sediments in littoral and sublittoral zones were suggested to be the corresponding sources. Water at the river mouth was replete with dissolved oxygen but also contained a high concentration of methane. The present results suggest that river water and littoral sediment are potential sources of dissolved methane in Lake Biwa, and other sources, such as internal waves, are responsible for increased methane in the pelagic zone at the end of stagnant periods. Carbon stable isotope analysis indicated that there were different sources of dissolved methane, although it was difficult to identify the origins due to high variation of the isotopic composition of methane from different sources.     

宽甸县水中硼的背景浓度及污染现状分析

采集辽宁宽甸县各种水样51个,用ICP—MS分析硼含量。结果表明,宽甸县水中硼含量的背景值与世界水平相当,污染地区地表水和地下水硼含量的平均值分别是背景点的23．1和495．6倍。硼的开采和加工对水体产生了较严重的硼污染。     

Human Health Risk of Metals in Drinking-Water Source Areas from a Forest Zone after Long-Term Excessive Deforestation

The concentrations of 10 metals (As, Cd, Cr, Cu, Fe, Hg, Mn, Pb, Se, Zn) were determined in drinking water in Khingan, China, a forest zone after long-term excessive deforestation. These metals’ concentrations in water exceeded background values of metals in some other regions of the world, indicating that there were other metal sources contributing to such high levels of metals in Khingan. Arsenic was the only metal whose concentration exceeded the maximum levels allowed in drinking water. Principal component analysis showed that As, Cd, Cu, and Se originated from anthropogenic sources and exhibited significantly high concentrations in north Khingan, while Fe and Mn derived from natural formation and showed significantly high concentrations in central Khingan. Health risks from metals were evaluated by a model recommended by the U.S. Environmental Protection Agency. Ingestion was the predominant pathway of exposure to metals in water for local residents. Arsenic was also the only metal causing both noncarcinogenic hazard and carcinogenic risk in Khingan. The high risks occurred mainly in north Khingan and are associated with coal combustion. This study indicates that long-term excessive deforestation may increase As concentration considerably in drinking water and then pose health risks to local residents.     

Water source utilization and foliar nutrient status differs between upland and flooded plant communities in wetland tree islands

Tree islands in the Everglades wetlands are centers of biodiversity and targets of restoration, yet little is known about the pattern of water source utilization by the constituent woody plant communities: upland hammocks and flooded swamp forests. Two potential water sources exist: (1) entrapped rainwater in the vadose zone of the organic soil (referred to as upland soil water), that becomes enriched in phosphorus, and (2) phosphorus-poor groundwater/surface water (referred to as regional water). Using natural stable isotope abundance as a tracer, we observed that hammock plants used upland soil water in the wet season and shifted to regional water uptake in the dry season, while swamp forest plants used regional water throughout the year. Consistent with the previously observed phosphorus concentrations of the two water sources, hammock plants had a greater annual mean foliar phosphorus concentration over swamp forest plants, thereby supporting the idea that tree island hammocks are islands of high phosphorus concentrations in the oligotrophic Everglades. Foliar nitrogen levels in swamp forest plants were higher than those of hammock plants. Linking water sources with foliar nutrient concentrations can indicate nutrient sources and periods of nutrient uptake, thereby linking hydrology with the nutrient regimes of different plant communities in wetland ecosystems. Our results are consistent with the hypotheses that (1) over long periods, upland tree island communities incrementally increase their nutrient concentration by incorporating marsh nutrients through transpiration seasonally, and (2) small differences in micro-topography in a wetland ecosystem can lead to large differences in water and nutrient cycles.     

Calculation of the flow into a lake from underground springs using sedimentation rates

The scope of this work is to quantify the upflows through the underground sources in the bottom of Lake Banyoles (NE-Iberia). The method applied uses the mean settling rate and the fraction of solids per unit of volume of the suspensions at the underground sources, and also the horizontal areas covered by these suspensions. The results obtained reveal that about 90% of the total underground inflow enters the lake through one of the sources. This result agrees with the total underground inflow calculated from the difference of the surface in and outflow of the lake. The behaviour of the suspensions at the underground sources was in a accordance with the theory used to developed the measuring method. Finally, the degree of turbulence in the upper part of the suspension and the importance of the transmissivity of the limestone layer next to the lake are discussed and are found to be negligible.     

Low temperature reduction of hexavalent chromium by a microbial enrichment consortium and a novel strain of Arthrobacter aurescens

Background  

Chromium is a transition metal most commonly found in the environment in its trivalent [Cr(III)] and hexavalent [Cr(VI)] forms. The EPA maximum total chromium contaminant level for drinking water is 0.1 mg/l (0.1 ppm). Many water sources, especially underground sources, are at low temperatures (less than or equal to 15 Centigrade) year round. It is important to evaluate the possibility of microbial remediation of Cr(VI) contamination using microorganisms adapted to these low temperatures (psychrophiles).     

Micro-PIGE determination of fluorine distribution in developing hamster tooth germs

A micro-PIGE (Proton-Induced gamma-ray Emission) technique based on the delayed 5/2+----1/2+ nuclear transition of fluorine (E gamma = 197 keV, t1/2 = 87 ns) emitted after 19F(p,p', gamma)19F reaction was used to detect and study the distribution of fluorine in the developing enamel organ during pre-eruptive stages, i.e., the transitional to early maturation stages of enamel formation in neonatal hamsters administered a single IP dose of sodium fluoride (20 mg NaF/kg body weight). The aforementioned nuclear reaction is unique for fluorine, and therefore detection of gamma-rays emanating from this reaction in a biological specimen implies a positive identification of fluorine at that particular site. Calcium and phosphorus X-rays were also recorded and used as parameters for assessment of the relationship between the degree of mineralization and fluoride incorporation into the enamel organ. The highest fluorine concentration in the enamel organ was recorded in the dentin near the dentin-enamel junction (DEJ). In the enamel, the highest concentration of fluorine was found to be associated with the more mature areas of the enamel near the DEJ, but gradually decreased in the direction of the enamel surface. Fluorine was not detected in the control germs. These results suggest that administration of fluoride in high doses during the pre-eruptive stages of enamel formation leads to incorporation of the ion into the forming dentin and enamel mineral, and that the enamel matrix does not seem to bind fluoride avidly.     

The Influence of Fluorine on the Disturbances of Homeostasis in the Central Nervous System

Fluorides occur naturally in the environment, the daily exposure of human organism to fluorine mainly depends on the intake of this element with drinking water and it is connected with the geographical region. In some countries, we can observe the endemic fluorosis—the damage of hard and soft tissues caused by the excessive intake of fluorine. Recent studies showed that fluorine is toxic to the central nervous system (CNS). There are several known mechanisms which lead to structural brain damage caused by the excessive intake of fluorine. This element is able to cross the blood-brain barrier, and it accumulates in neurons affecting cytological changes, cell activity and ion transport (e.g. chlorine transport). Additionally, fluorine changes the concentration of non-enzymatic advanced glycation end products (AGEs), the metabolism of neurotransmitters (influencing mainly glutamatergic neurotransmission) and the energy metabolism of neurons by the impaired glucose transporter—GLUT1. It can also change activity and lead to dysfunction of important proteins which are part of the respiratory chain. Fluorine also affects oxidative stress, glial activation and inflammation in the CNS which leads to neurodegeneration. All of those changes lead to abnormal cell differentiation and the activation of apoptosis through the changes in the expression of neural cell adhesion molecules (NCAM), glial fibrillary acidic protein (GFAP), brain-derived neurotrophic factor (BDNF) and MAP kinases. Excessive exposure to this element can cause harmful effects such as permanent damage of all brain structures, impaired learning ability, memory dysfunction and behavioural problems. This paper provides an overview of the fluoride neurotoxicity in juveniles and adults.     

Water circulation in the moraine ponds of northern Poland

The landscape of northern Poland is characterised by a very large number of ponds. Traditionally it has been assumed that their hydrology is determined by precipitation and evaporation, and that they are isolated from the adjacent river network. Recent studies, however, have shown that ponds contribute to river runoff for at least part of the year. Their existence is therefore additionally based on fluvial and underground water sources. In order to establish the principles of water circulation in typical ponds, we selected 14 ponds with seasonally intermittent streams. We measured water levels in these ponds and flows in the river segments that connect them. We also determined subsurface exchange fluxes from the water balance equation. Our results demonstrated that the hydrological functions of the ponds varied throughout the year and depended on the level of water storage in the pond’s catchment. When the level of retention in the pond’s catchment is low, the pond becomes a water body without surface outflow and a drainage base for groundwater. As the level of retention in the catchment rises, ponds develop surface outflows and reconnect with the river network. At this point, their main function becomes retention of water originating from subsurface and surface inflows. Any surplus water may be fed to underground or surface waters.     

A Literary Review on Bovine Fluorosis

The toxic action of ingested fluorine compounds was first observed among people living in places where the fluorine content of the water was high. The clinical picture was dominated by the easily detectable lesions in the enamel of the teeth. Later injury to domestic animals also was found. Bovines have been reported to be more sensitive than man, and they are the most susceptible among the domestic animals, the susceptibility decreasing in the order: Cattle, sheep, rabbits, swine, rats and poultry (Phillips et al. 1955).     

Origin of annual laminations in tufa deposits, southwest Japan

Laminated tufas and a tufa-depositing stream in SW Japan (Shirokawa, Ehime Prefecture) were studied monthly over a 3-yr period. A series of samples from the tufa clearly reveals the pattern of annual laminations. The annual layering pattern was primarily controlled by changes in the rate of calcite precipitation, as calculated from water chemistry. The concentration of dissolved CaCO₃, which correlates with the precipitation rate, was high in summer-autumn and low in winter-spring, owing to changes in the partial pressure of CO₂ in underground air. Regular seasonal changes in underground PCO₂ probably resulted from two temperature-dependent processes, the diffusion of soil CO₂ and the ventilation of underground air. These changes, in addition to water temperature changes, altered the precipitation rate, which has a clear seasonal pattern, especially in the lower stream. The seasonal precipitation rate was high in summer-autumn and low in winter-spring, which is consistent with the seasonal lamination pattern seen in the tufas. The textures of collected samples show that the laminations consist of densely calcified summer-autumn (June-October) laminae and lightly calcified winter-spring (November-May) laminae. We infer that the increased precipitation rate stimulated thick calcite encrustation on cyanobacterial filaments to produce the dense textures. This interpretation is supported by the lowered organic/inorganic carbon-production ratio in summer-autumn. Seasonal variations in cyanobacterial assemblages are present, but do not reflect the seasonal lamination pattern. Because the relevant processes are temperature dependent, the seasonal lamination pattern at Shirokawa is thought to generally apply to other laminated tufas deposited in temperate climates. However, a reversed pattern can result from local and climatic circumstances. Dense laminae were deposited in winter near the source of the spring at Shirokawa, because calcite precipitation was high owing to low underground PCO₂ in winter. Reversed patterns reported from northwestern Europe were probably influenced by seasonal rainfall, which is reflected in hydrological conditions.     

Underground system of Mandevilla atroviolacea (Stadelm.) Woodson (Apocynaceae,Apocynoideae) from the Brazilian high-altitude grassland

The underground systems of plants show the most varied structures adapted to survival in unfavorable environmental conditions. For instance, long-term droughts may induce the development of either water and reserve substances or vegetative propagation structures. Since Mandevilla atroviolacea is a species found at high altitudes on rocky outcrops, this study aimed to provide information on the morpho-anatomy of the underground system of this species that may assist in understanding the adaptive strategies at play. Samples from the underground system of three young and two mature plants collected in the field were sectioned and processed according to standard plant anatomical techniques. The upper area of the underground system corresponds to a xylopodium, while the lower is a tuberous stem organ. Tuberous roots account for the majority of the underground system. The increase in tuberous root diameter results from the action of a typical cambium. The high shoot-forming potential and storage of water and reserve substances observed in the underground system of this species are important strategies for it to survive in this habitat.     

茅尾海营养状况及其来源研究

根据2008年茅尾海海域水质调查结果,采用营养指数法、营养状态质量指数法、有机污染指数法对海湾营养状况进行了评价,并结合2007年入海污染源调查结果,探讨了茅尾海的营养盐来源。结果表明:茅尾海受无机氮污染较重,海域处于呈富营养状态,有机污染程度属2级,表明开始受到有机污染。营养盐高值区集中在北部海域和东部海域。钦江、茅岭江等入海河流携带入海的营养盐是海域营养的主要来源,占入海污染物总量的79%以上,其次来自钦州湾外海的混合排污口。2001~2007年茅尾海DIN、DIP年均浓度分别与入海河流氮、磷营养盐入海负荷呈显著正相关,两者的相关系数分别为0.873和0.824。     

基于SWAT的西北干旱区县域水文模拟——以临泽县为例

以西北干旱区的临泽县为例,利用1980—2012年的气象数据、土地利用数据、土壤数据、数字高程数据驱动SWAT模型,对县域水文过程进行了模拟并对行政区内的水资源状况进行了时空特征分析。研究表明临泽县1980—2012年均实际蒸发量、下渗量、壤中流补给量、地下水补给量、产流量、可用地表水资源量和产流系数分别为130.53、49.78、68.95、48.00、53.47 mm、(13.17±0.60)×108m3和0.16;生态用水量大(3.56±0.12)×1011m3),且呈现出增加趋势。由于黑河分水措施的影响,各水量要素的突变年份出现在2000年之后的5年内。从空间分布上看,地下水补给量和产流系数都呈现“南高北低”的趋势。研究结果也表明临泽县1980—2012年的产流量由地下水补给量控制,壤中流和地下径流的贡献分别为43%和57%;而可利用水资源量主要依赖上游的来水,上游来水量的贡献率达到83%。此外,我们的研究也发现临泽县2007—2012的实际蒸发持续增加,从而导致“蒸发悖论”现象的存在。     

Pyrosequencing Analysis of the Bacterial Community in Drinking Water Wells

Wells used for drinking water often have a large biomass and a high bacterial diversity. Current technologies are not always able to reduce the bacterial population, and the threat of pathogen proliferation in drinking water sources is omnipresent. The environmental conditions that shape the microbial communities in drinking water sources have to be elucidated, so that pathogen proliferation can be foreseen. In this work, the bacterial community in nine water wells of a groundwater aquifer in Northern Mexico were characterized and correlated to environmental characteristics that might control them. Although a large variation was observed between the water samples, temperature and iron concentration were the characteristics that affected the bacterial community structure and composition in groundwater wells. Small increases in the concentration of iron in water modified the bacterial communities and promoted the growth of the iron-oxidizing bacteria Acidovorax. The abundance of the genera Flavobacterium and Duganella was correlated positively with temperature and the Acidobacteria Gp4 and Gp1, and the genus Acidovorax with iron concentrations in the well water. Large percentages of Flavobacterium and Pseudomonas bacteria were found, and this is of special concern as bacteria belonging to both genera are often biofilm developers, where pathogens survival increases.