Rainwater Chemistry at Mt. Etna (Italy): Natural and Anthropogenic Sources of Major Ions

Major ion content of 37 wet-only rainwater samples collected on the southern flank of Mount Etna volcano was investigated. Measured pH values range from 3.80 to 7.22 and display a positive correlation with Ca²⁺ and an inverse correlation with NO₃ ^–, suggesting that anthropogenic NO_x are the most effective acidifying agents while Ca, likely as solid CaCO₃, is the prevailing proton acceptor. Na/Cl ratios indicate a dominant marine origin for both species, while K, mg and Ca contents point to additional sources (soil dust, fertilisers etc.). Nitrate and sulphate concentrations display a nearly constant ratio indicating a common anthropogenic origin, and only a few samples are characterised by sulphate excess. The analysis of time series reveals a good correlation between the excess sulphate in rainwater and SO₂ fluxes from the summit craters plume. Non sea salt chloride contents show also a significant correlation with volcanic activity indicating a magmatic sulphur and chloride contribution to rainwater. Meteoric flux estimations point to a prevailing magmatic origin for sulphur in the collected rainwaters while sea spray is the main source of chlorine.     

云下雨滴蒸发产生硫酸盐气溶胶速率的研究

云下雨滴蒸发是雨滴下降过程中重要的物理过程，特别是当云下相对湿度较低时更为明显。本文建立了考虑雨滴蒸发的云下雨水酸化的物理化学模式，用以研究云下雨滴蒸发作用对各种大小雨滴及雨水酸化的影响，并估算了由于小雨滴的完全蒸发进入到大气中的硫酸盐气溶胶的生成速率。计算结果表明:这种小雨滴的完全蒸发使雨滴内化学反应生成的硫酸盐结晶进入大气，在降水初期云下相对湿度较小时，形成硫酸盐气溶胶的速率可达1% h-1，与气粒转化速率相当。     

Ecosystem shift resulting from loss of eelgrass and other submerged aquatic vegetation in two estuarine lagoons, Lake Nakaumi and Lake Shinji, Japan

Zostera marina L. was intensively harvested until the early 1950s in Lake Nakaumi, a eutrophic estuarine lagoon. We have estimated the amount of nitrogen (N) and phosphorus (P) removed from the lagoon through Z. marina harvesting. Lake Nakaumi lies in Tottori and Shimane prefectures, and the annual harvest of Z. marina in the late 1940s in Tottori was recorded as at least 56,250 t wet weight. The nutrient content of 56,250 t of Z. marina was calculated to be 61.9 t of N and 12.9 t of P, which is equivalent to 5.3% and 11%, respectively, of present annual nutrient loads to the lake. The nutrients formerly used by Z. marina were likely used by phytoplankton after the Z. marina started to decline in the mid-1950s at Lake Nakaumi. This shift in the chief primary producer, from benthic macrophytes to phytoplankton, caused a subsequent shift in secondary producers. Benthic fish and crustacean populations decreased and the non-commercial filter-feeding bivalve, Musculus senhausia, increased in Lake Nakaumi after the decline of seagrass beds. This affected the local economy, inducing not only eutrophication but also the collapse of local fisheries. On the other hand, at adjacent Lake Shinji, loss of submerged aquatic vegetation induced an increase of the commercial filter-feeding bivalve, Corbicula japonica, which doubled the fishery yield in the lake.     

屋面雨水回灌裂隙岩溶水水岩作用实验研究

在济南大学西校中采集奥陶系灰岩岩样,并设置不同的地下水、雨水混合比例进行室内溶蚀模拟实验。通过pH、电导率及几种常规离子的测定,并利用水文地球化学模拟软件PHREEQC等方法,分析雨水回灌含水层后与原有的地下水以及含水层介质之间的水—岩相互作用。结果表明:(1)地下水、雨水混合后,随振荡的持续进行,以及温度升高和脱碳酸作用的影响,水中CO2分压不断下降;(2)Ca2+浓度在混合比例为9∶1、7∶3和5∶5时略有下降,其它离子浓度无明显变化;(3)随雨水和岩溶系统作用时间的增加,方解石、白云石和石膏的饱和指数均不断减小,且随着雨水回灌量的增加,方解石、白云石饱和指数减小明显,从混合比例9∶1时的0.23~-0.39和0.05~-0.97到1∶9时的-0.34~-0.62和-1.59~-2.57,表明雨水能增强对方解石、白云石乃至整个含水层的溶蚀,且雨水回灌量越大,溶蚀作用越强烈,影响越明显;(4)雨水回灌所形成的溶蚀量比较有限,不会对回灌井周围含水层稳定产生严重影响。      

Oxygen and carbon isotopic characteristics of rainwater, drip water and present speleothems in a cave in Guilin area, and their environmental meanings

The studies of the oxgen and carbon isotopes of the rainwater in Guilin area, the drip water and the present carbonate deposit in Panlong cave of Guilin show that: (i) as to the general characteristics of the oxygen isotopes of the rainwater within a year and between years, the δ18O values decrease with an increase of air temperature and the rainfall, and the correlation between δ18O values and the mean monthly air temperature is much better than that between δ18O values and the rainfall, and the δ18O values of the rainwater during the summer monsoon are much smaller than those during winter monsoon; (ii) δ18O values of the drip water have a quite good correlation with the δ18O values of the rainwater in the same period; (iii) when the conditions are appropriate, δ13C can be used as an environmental proxy, that is, the smaller δ13C of speleothems is, the larger the proportion of C3 plants is and the more plentiful the rainfall is. On the contrary, C4 plants may be prevailing or the environment may be a stony desert caused by climate changes or human activity.     

Groundwater Storage through Rain Water Harvesting (RWH)

Groundwater extraction is rampant in many developing countries and urban areas whereas the natural recharge is decreasing due to covering of Earth's surface for various developmental activities. This leads to declining levels of groundwater and deterioration in groundwater quality. Artificial recharge with rain water harvesting techniques offers an excellent scope to arrest this degradation. This paper presents a study that analyzes the influence of rain water harvesting (RWH) on groundwater storage and quality. Chennai City, India is selected as study area, as major RWH implementation has taken place during 2002–2003 due to Government legislation. Preliminary analysis of groundwater levels were done spatially and temporally. Groundwater table contours were drawn using the GIS software for pre‐ (1999–2000) and post‐RWH (2009–2010) periods. The groundwater levels follow a decreasing trend before implementation of RWH where as a positive increasing trend takes place after construction of RWH structures. “Groundwater Estimation Committee (GEC)” norms of Government of India were used to estimate the change in storage during pre‐ and post‐RWH periods, which are found to be 1.76 × 10⁶ and 32.77 × 10⁶ m³, respectively. The results show that the implementation of RWH has increased the groundwater storage considerably. Also, the influence of RWH on groundwater quality is found to be encouraging in some parts of the studied area.     

Soil erosion and overland flow in forested areas with pine plantations at coastal mountain range,central chile

The effects of timber-cutting on sediment concentrations, soil loss and overland flow in an insigne pine (Pinus radiata) plantation were studied in a mountain watershed of the Cordillera de la Costa, central Chile. Soil formation rates for the lithological conditions of the watershed were estimated. Soil loss measurements on the plantation were taken in 100 m² plots, equipped with Coshocton samplers, during the years 1991 and 1992. Treatments were: clear-cutting no residues/burned, clear-cutting with residues and undisturbed controls. First-year soil losses were greater from the no residues/burned (2128 kg ha^?1) than from the residues (1219 kg ha^?1) or undisturbed (48 kg ha^?1) plots. During the second post-treatment year, soil loss was greater from the burned plots (1349 kg ha^?1) than from the residues (243 kg ha^?1) or the undisturbed (72 kg ha^?1) plots. Sediment concentrations for the three treatments were 561, 340 and 59 mgl-¹ during the first year, and 400, 150 and 83 mgl^?1 in the second year. Runoff from the no residues/burned plots was greater than from residues or undisturbed plots during the two post-treatment years. Long-term soil losses were projected to average 240 kg ha^?1 yr^?1 from areas without residues/burned and 120 kg ha^?1 yr^?1 in areas with residues treatment, over a 25 year rotation period, whereas control areas were projected to average 60 kg ha^?1 yr^?1.     

Spatial, Temporal and Interannual Variability of Methanesulfonate and Non-Sea-Salt Sulfate in Rainwater in the Southern Indian Ocean (Amsterdam, Crozet and Kerguelen Islands)

Methanesulfonate (MS^–) and non-sea-salt sulfate (nss-SO ₄ ^2– ), two of the major oxidation products of atmospheric dimethylsulfide (DMS), have been continuously measured in rainwater at three remote islands in the Southern Indian Ocean: Amsterdam since 1991, Crozet since 1992, and Kerguelen since 1993. The annual volume weighted mean (VWM) concentrations of nss-SO ₄ ^2– in rainwater were 3.19, 3.04 and 4.57 eq l^–1 at Amsterdam, Crozet, and Kerguelen, respectively while the VWM of MS^– were 0.24, 0.15 and 0.30 eq l^–1, respectively. At all three islands, MS^– presented a well-distinguished seasonal variation with a maximum during summer whereas the seasonal variation of nss-SO ₄ ^2– was less pronounced, possibly due to the increased anthropogenic influence during the winter period. Furthermore, MS^– presented significant interannual variations, in particular at Amsterdam and Crozet, which is closely related to the sea-surface temperature (SST) anomalies). Finally, the nss-SO ₄ ^2– deposition at Crozet Island presented a decreasing interannual trend, reflecting probably reductions in sulfur emissions from Southern Africa. On the contrary no interannual tendency was observed in the nss-SO ₄ ^2– concentrations at Amsterdam Island, indicating that the biogeochemical sulfur cycle at this area is mainly influenced by biogenic emissions.     

水资源合理调控利用发展农业节水灌溉

南皮县淡水资源短缺,咸水广布,制约农业生产的可持续发展.解决途径是合理调控利用当地水资源,开发利用浅层地下水包括微咸水和半咸水抗旱灌溉,调蓄雨季降雨径流及汛后河流来水作为补源,地下水地上水联合运用,发展农业节水灌溉,调整农业种植结构,提高水的利用效率.实现水资源可持续利用,农业生产可持续发展,生态环境良性循环,人与自然和谐相处.