Variations In Precipitation Chemistry Research Articles

Is atmospheric phosphorus pollution altering global alpine Lake stoichiometry?

AbstractAnthropogenic activities have significantly altered atmospheric chemistry and changed the global mobility of key macronutrients. Here we show that contemporary global patterns in nitrogen (N) and phosphorus (P) emissions drive large hemispheric variation in precipitation chemistry. These global patterns of nutrient emission and deposition (N:P) are in turn closely reflected in the water chemistry of naturally oligotrophic lakes (r2 = 0.81, p < 0.0001). Observed increases in anthropogenic N deposition play a role in nutrient concentrations (r2 = 0.20, p < 0.05); however, atmospheric deposition of P appears to be major contributor to this pattern (r2 = 0.65, p < 0.0001). Atmospheric simulations indicate a global increase in P deposition by 1.4 times the preindustrial rate largely due to increased dust and biomass burning emissions. Although changes in the mass flux of global P deposition are smaller than for N, the impacts on primary productivity may be greater because, on average, one unit of increased P deposition has 16 times the influence of one unit of N deposition. These stoichiometric considerations, combined with the evidence presented here, suggest that increases in P deposition may be a major driver of alpine Lake trophic status, particularly in the Southern Hemisphere. These results underscore the need for the broader scientific community to consider the impact of atmospheric phosphorus deposition on the water quality of naturally oligotrophic lakes.

Variation of the ratio of nitrate to non-seasalt sulfate in precipitation over East Asia with emissions from China

Changes in anthropogenic emissions in East Asia will cause substantial variations in the precipitation chemistry. In particular, the effects of changes in China, where NOx emissions have been rising continuously and SO2 emissions peaked in 2005–2006, are important. The absolute chemical concentration in precipitation is inherently linked to the amount of precipitation; therefore, in this work we used the ratio of nitrate (NO3−) to non-seasalt sulfate nss-SO42- concentration in precipitation on an equivalent basis (hereinafter, Ratio). Here, we extend the method in our previous study (Itahashi et al., 2014a) to Korea and China. We analyzed the long-term behavior of Ratio in precipitation during 2000–2011 and investigated the factors responsible for variations of Ratio in precipitation by using a model simulation with sensitivity analysis for emission changes in China. Ratio over Japan, Korea, and China decreased slightly or remained constant during 2000–2005 (first 6 years of 2000–2011) and subsequently increased during 2006–2011 (last 6 years of 2000–2011). Linear regression analysis of the observations showed significant increases in Ratio during 2006–2011: +3.4 ± 1.0%/year, +13.2 ± 4.1%/year, and +9.8 ± 2.5%/year for Japan, Korea, and China, respectively (each p < 0.05). These variations in Ratio corresponded closely to the changes in the NOx/SO2 emission ratio in China. This suggests that anthropogenic emissions from China were responsible for most of the variation in precipitation chemistry in East Asia. Model simulations for 2000–2011 and their reproducibility were validated by comparison with the observation dataset, and they captured the observed features well. Sensitivity analysis of emissions from China in the model simulation for 2009–2011 clarified that the increase in NOx emissions from China contributed to 55–60% of the increase in Ratio in China and around 50–55% in Korea and Japan; the contribution of the increase in NOx emissions was smaller in the region downwind of China. In contrast, the decline in SO2 emissions from China contributed below 40% in China and around 40–45% in Japan; the effect was larger in the region downwind of China.

Non-linear regression model for spatial variation in precipitation chemistry for South India

Chemical composition of rainwater changes from sea to inland under the influence of several major factors – topographic location of area, its distance from sea, annual rainfall. A model is developed here to quantify the variation in precipitation chemistry under the influence of inland distance and rainfall amount. Various sites in India categorized as ‘urban’, ‘suburban’ and ‘rural’ have been considered for model development. pH, HCO 3, NO 3 and Mg do not change much from coast to inland while, SO 4 and Ca change is subjected to local emissions. Cl and Na originate solely from sea salinity and are the chemistry parameters in the model. Non-linear multiple regressions performed for the various categories revealed that both rainfall amount and precipitation chemistry obeyed a power law reduction with distance from sea. Cl and Na decrease rapidly for the first 100 km distance from sea, then decrease marginally for the next 100 km, and later stabilize. Regression parameters estimated for different cases were found to be consistent ( R 2 ∼ 0.8). Variation in one of the parameters accounted for urbanization. Model was validated using data points from the southern peninsular region of the country. Estimates are found to be within 99.9% confidence interval. Finally, this relationship between the three parameters – rainfall amount, coastline distance, and concentration (in terms of Cl and Na) was validated with experiments conducted in a small experimental watershed in the south-west India. Chemistry estimated using the model was in good correlation with observed values with a relative error of ∼5%. Monthly variation in the chemistry is predicted from a downscaling model and then compared with the observed data. Hence, the model developed for rain chemistry is useful in estimating the concentrations at different spatio-temporal scales and is especially applicable for south-west region of India.

Seasonal and regional variations in precipitation chemistry in the Lake Taihu Basin, China

To evaluate seasonal and regional variations in precipitation chemistry in Lake Taihu Basin, 5 cities around the lake were selected for monthly collection of rainfall samples from July 2002 to June 2003. The analytical parameters included pH, cations (K +, Na +, Ca 2+, Mg 2+, NH 4 + ), anions (F −, Cl −, SO 4 2 - , NO 3 - ), total nitrogen (TN) and total phosphorus (TP). In descending order, concentrations (in meq L −1) of the ions in wet deposition can be ordered as SO 4 2 - > Ca 2 + > NH 4 + > NO 3 - >Cl −>Na +>Mg 2+>K +>F − with concentratin percentages of 48.7%, 19.1%, 11.6%, 8.1%, 5.6%, 2.6%, 1.7%, 1.6% and 1%, respectively. Rainfall was seasonally variable, with high rates in spring and summer but low rates in autumn and winter, while ion concentrations followed the reverse seasonal cycle. To evaluate deposition rates (DR) of different elements, average DR of each ion was calculated from a simple model. Most of the highest DRs of these substances occurred in Suzhou and Wuxi, located east and north of Lake Taihu, which shows there was considerable variation over the 5 stations. This regional pattern reflects local emissions from industry and agriculture, and suggests that steps need to be taken by local governments for particle emission reductions. The estimated annual inputs of TN and TP over the lake are 4722 and 75 t, respectively, which accounts for around 16.5% and 7.3% of the annual total external inputs of these nutrients. Primary productivity in Lake Taihu associated solely with wet deposition of nitrogen to the lake was estimated to be 7.03×10 6 mol C day −1. These results suggest that wet deposition can have significant impacts on the trophic status of Lake Taihu and that attention to nutrients in precipitation should be included in the management of external nutrient loads to the lake.

Characterizinig Precipitation Chemistry in Changhua, Central Taiwan Using Weather Conditions And Multivariate Analysis

Few studies of atmospheric deposition come from the fast growing region of Southeast Asia. Precipitation in Changhua City in central Taiwan was collected to examine its chemical composition and relationship with meteorological patterns. Fifty percent of the precipitation measurements had pH<5.0. Deposition fluxes of most ions were comparable to that reported for heavily industrialized temperate regions. Storms associated with air masses which originated in China had higher ion concentrations than other storms, suggesting substantial contribution of long-range transport. Two factors, a sea salt factor and an anthropogenic factor, explained more than 70% of the variation in precipitation chemistry. A third factor had a high loading only on H+, suggesting that pH of precipitation in Changhua City was not dominated only by acidic or basic ions alone. Instead it is determined by all components. The influences of soil and dust, as indicated by high loading on Ca2+ and K+, cannot be recognized without sea salt correction.

Temporal variation in precipitation chemistry on the shore of the Chesapeake Bay

We studied precipitation chemistry at the Rhode River on the western shore of the Chesapeake Bay. We sampled on an event basis, beginning in 1973 for some constituents in bulk precipitation. Beginning in 1981, we also sampled wet precipitation separately from bulk precipitation. In this report, we examine temporal variability of precipitation chemistry at different time scales. Several constituents showed long-term trends. In bulk precipitation, hydronium concentration increased by 27% of its mean concentration per decade, calcium by 67%, ammonium by 28%, and nitrate by 25%, while organic nitrogen decreased by 41%, organic phosphorus by 31%, and organic carbon by 16%. In wet precipitation, ammonium increased by 33% and calcium by 100%, while magnesium decreased by 78% per decade. Concentrations differed greatly among precipitation events, increasing as the volume of precipitation decreased and as the interval since the previous event increased. Most constituents also showed marked seasonal variation. We used a regression model to predict concentrations for each event from month, precipitation volume, and the time since the previous event. We evaluated how much of the interannual variability could be explained by these factors. The event-scale model accounted for almost half of the variability among annual means for ammonium, sodium, and magnesium in bulk precipitation, and for potassium in wet precipitation. This suggests that much of the interannual variability of concentrations may result from interannual variation in the temporal distribution of precipitation.

The influence of riming and frontal dynamics on winter precipitation chemistry in level terrain

The relative influences of accretional ice crystal growth (riming) and frontal passages on winter precipitation chemistry were evaluated in level terrain in east central Illinois during the winter of 1992. Six precipitation events were analyzed during the period January to March, 1992. Five events were characterized by the passage of cold Arctic fronts and no riming was observed. Precipitation chemistry was observed to change substantially during frontal passage, reflecting the different pollutant loadings in pre- and post-frontal air masses. Precipitation that fell on March 11, 1992, associated with a warm or occluded frontal system, was moderately rimed. Application of a linear multiple regression model revealed that most of the temporal variations in precipitation chemistry during this event could be explained by changes in the degree of riming and changes in the identity of the air mass producing precipitation above the site. Accreted ice crystal mass was dominated by cloud drops with diameters between 20 and 40 μm, indicating that the composition of drops in this size range exert the most influence on precipitation chemistry.

On the interpretation of event and sub-event rainfall chemistry

Variations in precipitation chemistry between and within rain events have been examined in order to identify possible relationships with synoptic, mesoscale and micrometeorological processes. A microprocessor-based acid rain monitor was used to provide high resolution meteorological and rain chemistry data from which two case study events have been selected to illustrate event and sub-event rainfall chemistry characteristics. Event rainfall chemistry is strongly influenced by the history of the prevailing air mass and the synoptic situation. From back trajectories calculated at the 950 mbar level it is clear that air mass history can change markedly within a few hours. These observations emphasise the value of high resolution rainfall chemistry measurements. Pollutant concentrations in rainwater have been shown to fluctuate markedly within the course of individual events as a result of both advective and scavenging processes. Advective effects may result from: (a) air mass discontinuities at frontal zones; and/or (b) variable rainfall interception of the air mass prior to arrival at the site. A simple mathematical model has been developed to describe the scavenging mechanisms and it shows good agreement with field observations. Theoretical considerations suggest that in-cloud processes give rise to most of the observed decline in concentrations.

Red pine growth and chemical composition of foliage and forest floors across a precipitation-chemistry gradient in Wisconsin

Three red pine (Pinusresinosa Ait.) plantations were located at each of five sites across the precipitation-chemistry gradient in Wisconsin (loadings of H ion, SO42−, and NO3− generally decrease from southeast to northwest). The plantations were selected to be as similar as possible in stand characteristics, including age, initial stocking, number of thinnings, site index, and basal area, and in soils (mixed frigid Typic Udipsamments or Entic Haplorthods). Despite the care exercised in selecting the plantations, analysis of variance incorporating a nested design showed that for the growth parameters, within-site variation generally was greater than among-site variation. The large within-site variation may have masked any differences attributable to variations in precipitation chemistry across the gradient. Site-related differences in radial increment (1982–1986 period) were attributed to time since thinning. There were significant site-related differences in mass, concentrations, and contents (mg/50 fascicles) of N, P, Ca, and S in current needles and in mass, concentrations, and contents (kg•ha−1) of N, P, and S in the forest floor. Differences in mass and chemical composition of needles among sites may be due to slight differences in soils. We attribute the differences in mass and chemical composition of the forest floor among sites to differences in preplanting site conditions and stand treatment.

The chemistry of bulk precipitation at a site in southeast england—I. Small-scale spatial variation, frequency distributions and variation with time

This paper contains a statistical analysis of bulk precipitation chemistry data from rain falling on the Tillingbourne Catchment, Surrey, SE England, in the years 1978–1981. Measurements of weekly average pH, organic content, sulphate, nitrate, ammonium and chloride were made. There was some evidence for small-scale spatial variation in precipitation chemistry, particularly for the organics. Frequency distributions were mostly log-normal but for ammonium and total sulphate there were more high values and for H + fewer high values, than expected on a log-normal basis. There was a Spring peak in the concentration of most ions, but Cl t- had a Winter peak. These seasonal variations are probably determined by meteorological factors.

Geomedicine in Norway

The scope of geomedicine is briefly discussed. An interest in geomedical problems has existed in Norway since the last century, involving goitre in dry inland regions ( I deficiency), and osteomalaci in cattle (P deficiency). Geographical variations in precipitation chemistry (including Mg, Na, Cl, Br, I and Se) are summarized. Deficiencies can be remedied by changes in fertilization and foddering. Areas with strong naturally poisoned soils and plants occur (involving Pb, Cu, Ni, Zn and Cd). Cases of industrial pollution are known at Odda (Zn, Pb, Cd, Hg, Cu, As, Se and F), Røros (Cu), Kongsberg (Hg), Evje (Ni), Modum (As), and aluminium factories (F). Regional geochemical maps based on systematic sampling of forest soils are being produced (Oppland, Buskerud, Nord-Trøndelag), plus stream sediment geochemical prospecting maps which will also be valuable in geomedicine. A large project on the effects of acid precipitation is nearly completed. Norwegian research councils and a cancer organisation have started geomedical projects (e.g. analysis of human blood serum; the relationship between soil conditions and the chemical composition of small-grain and other plant foods). Cooperation between the Scandinavian countries in geomedicine has already begun. World-wide contacts between scientists are desirable in such a multi-disciplinary subject.

Design and operation of a simple, sequential precipitation sampler with some preliminary results

An inexpensive mechanical sampler has been designed to take sequential samples of precipitation. Its principal features are: non-electrical or motor-driven operation, sampling rate dependent on quantity not time, time of sampling recorded by a clock chart. Advantages of this design are: low materials cost, resistance to damp, minimal attention required in dry periods, permits detailed study of variations in precipitation chemistry and is easily adapted for other sampling purposes. Results of analyses for common ions in precipitation from two events are presented to illustrate the operation and research potential of the sampler.