In carbonate massifs, flow patterns are conditioned by karstification processes which develop a conduit network and preserve low permeability microfractured blocks. The Sierra de las Nieves karst massif (southern Spain) is subjected to a given climatic and geological context, and thus it is possible to analyse the spatial and temporal variability of the water temperature and electrical conductivity at its main karst outlets, which display different responses to rainfall episodes. In this experimental field area, conduit flow and diffuse flow drainage patterns have been distinguished by combining groundwater temperature and electrical conductivity data. Both parameters show large variations in water coming from conduit flow systems and low variations in water drained by springs draining diffuse flow systems. However, groundwater temperature displays the smallest variations, which seems to indicate that this parameter is less sensitive as regards characterising the degree of karstification, which is a key question in characterising the aquifer functioning.

Neste estudo analisaram-se os efeitos da fertirrigação com água residuária da suinocultura filtrada (ARSF) no solo e nas variáveis fisiológicas, sanitárias e de produção de tomate, em condições de lisímetros de drenagem sob ambiente protegido. O experimento foi conduzido na estação lisimétrica da Área Experimental de Hidráulica, Irrigação e Drenagem, no campus da Universidade Federal de Viçosa, MG. Os tratamentos constituíram-se de testemunha (T1 - irrigação e adubação recomendada para o tomateiro) e fertirrigação com ARSF fornecendo 100, 150 e 200% da dose de nitrogênio recomendada para o tomateiro sem complementação da adubação (T2, T3 e T4) e com complementação da adubação (T5, T6 e T7), respectivamente. As lâminas de ARSF foram calculadas conforme sugerido pela EPA (Environment Protection Department), considerando-se os riscos de contaminação de água subterrânea com nitrato. Foram analisadas variáveis físicas e químicas do solo, fisiológicas e de produção do tomateiro, bem como de qualidade e sanidade dos frutos de tomate. Diante dos resultados obtidos concluiu- se que: a adubação química foi mais efetiva na ionização da solução do solo do que a ARSF, apresentando maiores valores de CEes e ISNa; a aplicação de ARSF resultou em incrementos nas concentrações de potássio, cálcio e magnésio trocáveis, CTC efetiva, fósforo disponível, nitrogênio total e redução no valor do pH; as variações na porosidade total, microporosidade, massa específica e condutividade hidráulica do solo foram decorrentes da reestruturação e acomodação do solo nos lisimetros; as fertirrigações com ARSF não alteraram significativamente o tempo de florescimento, diâmetro do caule, número de folhas expandidas, potencial de água na folha, taxa fotossintética, condutância estomática e respiração do tomateiro, mas proporcionaram aumento na área foliar e suprimento das necessidades nutricionais, resultando em frutos saborosos e saudáveis do ponto de vista sanitário; considerando-se aspectos ambientais e de custo de produção, o tratamento 4 mostrou ser a melhor alternativa de manejo da cultura, entretanto, a aplicação de 150% das necessidades de nitrogênio da cultura usando ARSF passa a ser uma recomendação técnica e ambientalmente mais adequada. | In this study was analyzed the effects of fertirrigation with filtrated wastewater from swine (FWS) on soil and the physiological, sanitary variables and of tomato production, in drainage lysimeters under protected environment. The experiment was carried out in the lysimeter station at the Hydraulic, Irrigation and Drainage Experimental Area, in campus of the Universidade Federal de Viçosa, Minas Gerais State. The treatments were constituted of witness (T1 - irrigation and fertilization recommended for tomato) and fertirrigation with FWS supplying 100, 150 and 200% of the nitrogen doses recommended for tomato without fertilization complementation (T2, T3 and T4) and with application of fertilizer complementation (T5, T6 and T7), respectively. The FWS doses were calculated as suggested by EPA (Environment Protection Department), considering the contamination risks of subterranean water with nitrate. Were analyzed physical and chemical variables of the soil, physiological and of tomato production, as well as of tomato fruits quality and sanity. The results showed: the chemical application of fertilizer was more effective in the soil solution ionization than FWS, presenting CEes' larger values and ISNa; FWS application resulted in increments in the potassium concentrations, calcium and exchangeability magnesium, effective CTC, available phosphorus and total nitrogen, and reduction in pH value; the variations in the total porosity, microporosity, specific mass and hydraulic conductivity were current of the soil restructuring and accommodation in lysimeters; fertirrigations with FWS did not change significantly time of bloom, stem diameter, number of expanded, predawn leaf- water potential, photosynthesis, stomatic conductance and tomato breathing, but provided increase in the leaf area and needs nutritional supply, resulting in flavored and healthy fruits of the sanitary point of view; considering environmental aspects and of production cost, the treatment 4 stands out as the best culture management option, however, the application of 150% of the needs to culture nitrogen with FWS application proceeds being a technical recommendation and environmentally more adequate. | Coordenação de Aperfeiçoamento de Pessoal de Nível Superior

Lake water, river water, and groundwater from the Lake Qinghai catchment in the northeastern Tibetan Plateau, China have been analyzed and the results demonstrate that the chemical components and ⁸⁷Sr/⁸⁶Sr ratios of the waters are strictly constrained by the age and rock types of the tributaries, especially for groundwater. Dissolved ions in the Lake Qinghai catchment are derived from carbonate weathering and part from silicate sources. The chemistry of Buha River water, the largest tributary within the catchment, underlain by the late Paleozoic marine limestone and sandstones, constrains carbonate-dominated compositions of the lake water, being buffered by the waters from the other tributaries and probably by groundwater. The variation of ⁸⁷Sr/⁸⁶Sr ratios with cation concentrations places constraint on the Sr-isotopic compositions of the main subcatchments surrounding Lake Qinghai. The relative significance of river-water sources from different tributaries (possibly groundwater as well) in controlling the Sr distribution in Lake Qinghai provides the potential to link the influence of hydrological processes to past biological and physical parameters in the lake. The potential role of groundwater input in the water budget and chemistry of the lake emphasizes the need to further understand hydrogeological processes within the Lake Qinghai system.

Goodenough Spring (Texas, USA) is a large spring near the border of the American state of Texas and the Mexican state of Coahuila, discharging into the international Amistad Reservoir on the river Rio Grande (Rio Bravo). Discharge was routinely measured from 1928 until 1968 to partition the flow of the river between the two countries in accordance with water-use treaties. Samples were analyzed for water-quality parameters in 1967–1968 prior to inundation under 45 m of Amistad Reservoir in 1968. Subsequently, discharge has been estimated indirectly by the International Boundary and Water Commission (IBWC). For the first direct measurements of the spring in 37 years, velocity and cross-sectional measurements were made and water samples collected in the summer of 2005 using advanced self-contained underwater breathing apparatus (SCUBA) techniques. Spring discharge was calculated at 2.03 m³ s–¹, approximately one-half of the historical mean of 3.94 m³ s–¹. In situ and laboratory analyses of samples for temperature, pH, dissolved oxygen, specific conductance, alkalinity, nitrate-nitrogen, dissolved solids, chloride, sulfate, fluoride, phosphorus, calcium, sodium, potassium, magnesium, and iron showed the water quality to be very good for human consumption and crop irrigation. Measurement values are relatively unchanged from those reported 37 years prior.

³H, δ¹³C and hydrochemical data were used to estimate the corrected groundwater age derived from conventional ¹⁴C age of dissolved inorganic carbon (DIC). The Middle-Upper Devonian aquifer system from the Baltic upland recharge area in eastern Lithuania towards the discharge area on the Baltic Sea coast in the west was considered. The concentration of total dissolved solids (TDS) in groundwater changes from 300 to 24,000 mg/L and increases downgradient towards the coast. The other major constituents have the same trend as the TDS. The hydrochemical facies of groundwater vary from an alkali-earth carbonates facies at the eastern upland area to an alkali-earth carbonate-sulfate and chloride facies at transit and discharge areas. Meteoric water percolating through the Quaternary and Devonian aquifers regulate the initial ¹⁴C activities of groundwater involving two main members of DIC: soil CO₂ with modern ¹⁴C activity uptake and dissolution of ¹⁴C-free aquifer carbonates. Other sources of DIC are less common. ¹⁴C activity of DIC in the groundwater ranged from 60 to 108 pMC at the shallow depths. With an increase of the aquifers depth the dolomitization of aqueous solution and leakage of the “old” groundwater from lower aquifers take place, traced by lower activities (7–30 pMC).

Over the past few years groundwater has been recognized as an important contributor of freshwater to Lake St Lucia, South Africa during periods of prolonged drought. This has led to a management strategy aiming at increasing the groundwater recharge and minimizing groundwater use through active manipulation of the vegetation. For the Eastern Shores on the edge of Lake St Lucia, the replacement of vast areas of pine (Pinus elliottii) plantations with grassland over the past decade, combined with a strict burning regime, has led to a general rise of the water table, which has increased the groundwater seepage to Lake St Lucia. A numerical groundwater model has been applied to assess the effects of local management strategies on the mass balance of a shallow aquifer and these are compared to the effects of predicted climate and sea-level change for this area. The simulations indicate that local management actions that are being applied to the Eastern Shores have positive effects on the groundwater flux into Lake St Lucia and that they outweigh potential negative effects of future climate and sea-level change predicted for this area.

Shallow groundwater is the main source for drinking water in Kabul, Afghanistan. It comes from a multitude of shallow hand-pumped wells spread over the whole city area. The groundwater is characterised by slightly oxic redox conditions. Interactions with aquifer carbonates lead to near-neutral pH and high degrees of hardness. The mostly negative water budget of the Kabul Basin is the result of strong evaporation which leads to an increase in salt and also of some undesirable constituents, e.g. borate. Several years of drought have aggravated this problem. The shallow groundwater in the city has received tremendous amounts of pollution due to a lack of proper waste disposal and sewage treatment. Common indicators are elevated concentrations of nutrients such as nitrate and faecal bacteria. The high infant mortality can at least partially be attributed to the insufficient water hygiene. Acid generated during the mineralisation of the wastewater is hidden due to the strong pH buffering capacity of the groundwater system. Redox and pH conditions preclude significant mobilisation of trace metals and metalloids.

The microbial degradation of pharmaceuticals found in surface water used for artificial recharge is strongly dependent on redox conditions of the subsurface. Furthermore the durability of production wells may decrease considerably with the presence of oxygen and ferrous iron due to the precipitation of trivalent iron oxides and subsequent clogging. Field measurements are presented for oxygen at a bank filtration site in Berlin, Germany, along with simplified calculations of different oxygen pathways into the groundwater. For a two-dimensional vertical cross-section, oxygen input has been calculated for six scenarios related to different water management strategies. Calculations were carried out in order to assess the amount of oxygen input due to (1) the infiltration of oxic lake water, (2) air entrapment as a result of water table oscillations, (3) diffusive oxygen flux from soil air and (4) infiltrating rainwater. The results show that air entrapment and infiltrating lake water during winter constitute by far the most important mechanism of oxygen input. Oxygen input by percolating rainwater and by diffusive delivery of oxygen in the gas phase is negligible. The results exemplify the importance of well management as a determining factor for water oscillations and redox conditions during artificial recharge.

Algal blooms and fish kills were reported on a river in coastal Georgia (USA) downstream of a poultry-processing plant, prompting officials to conclude the problems resulted from overland flow associated with over-application of wastewater at the plant’s land application system (LAS). An investigation was undertaken to test the hypothesis that contaminated groundwater was also playing a significant role. Weekly samples were collected over a 12-month period along an 18 km reach of the river and key tributaries. Results showed elevated nitrogen concentrations in tributaries draining the plant and a tenfold increase in nitrate in the river between the tributary inputs. Because ammonia concentrations were low in this reach, it was concluded that nitrate was entering via groundwater discharge. Data from detailed river sampling and direct groundwater samples from springs and boreholes were used to isolate the entry point of the contaminant plume. Analysis showed two separate plumes, one associated with the plant’s unlined wastewater lagoon and another with its LAS spray fields. The continuous discharge of contaminated groundwater during summer low-flow conditions was found to have a more profound impact on river-water quality than periodic inputs by overland flow and tributary runoff.

Groundwater recharge was investigated in the most extensive sand and gravel aquifer (area of approximately 200 km²) in the Republic of Ireland as part of a wider study seeking to derive recharge estimates using aquifer vulnerability mapping. The proportion of effective rainfall (total rainfall minus actual evapotranspiration) that leads to recharge is known as the recharge coefficient. The recharge investigation involved a variety of approaches, including soil moisture budgeting, well hydrograph analysis, numerical modelling and a catchment water balance. The adoption of multiple techniques provided insights on recharge and also on aquifer properties. Comparison of two soil moisture budgeting approaches (FAO Penman-Monteith with Penman-Grindley) showed how variations in the effective rainfall values from these methods influence groundwater levels simulated in a numerical groundwater model. The catchment water balance estimated the recharge coefficient to be between 81 and 85%, which is considered a reasonable range for this aquifer, where overland flow is rarely observed. The well hydrograph analysis, using a previous estimate of specific yield (0.13), gave recharge coefficients in the range of 40–80%, considered low for this aquifer: a revised specific yield of 0.19 resulted in a more reasonable range of recharge coefficients of between 70 and 100%.