Reacidification Effects on Water Chemistry and Plankton in a Limed Lake in Sweden

Water chemistry and plankton has been monitored in three Lakes in Tyresta National park SE of Stockholm since 1977. Liming operations started in Lake Långsjön and Lake Trehörningen in 1978 and were repeated every 3–5 years, while Lake Årsjön is an unlimed reference Lake. During 1991–1999, the annual pH median in Lake Långsjön and Lake Årsjön ranged between 6.6–7.1 and 5.2–5.8, respectively, and the composition of phyto- and zooplankton in these lakes did not change markedly. After a final treatment in 1991, the liming of Lake Trehörningen was terminated intentionally. As a result, pH decreased from an annual median 7.1 in 1991, to 6.1 in 1999 (5.8 in 1998). Total organic carbon (TOC) did not change markedly during this period, while the levels of calcium decreased. Metals, known to be influenced by acidification, especially cadmium, manganese and aluminium (Al), increased. The labile-inorganic forms of Al also reached higher levels, especially in 1998. Following the decreasing pH, the total number of phytoplankton taxa decreased by ca 40%. Among zooplankton, the cladocerans Holopedium gibberum, Diaphanosoma brachyurum and Daphnia longispina, common during the limed period, became rare.     

Long-Term Ecological Effects of Liming — The Iselaw Programme

The Swedish liming programme was initiated in 1977 to counteract the effects of anthropogenic acidification on aquatic ecosystems until the acid deposition has been reduced. Ecosystem development in limed waters has been followed since 1989 in a programme for integrated studies of the effects of liming acidified waters (ISELAW). The main objectives are to assess a) the long-term ecological effects of liming, b) to what extent ecosystems recover to a pre-acidification state, and c) to elucidate possible detrimental effects of lime treatment. The programme comprises monitoring of water chemistry, phyto- and zooplankton, vegetation, benthic invertebrates and fish in 13 limed and 5 non-limed lakes, and 12 limed and 10 non-limed streams. Paleolimnological studies are performed to reveal pre-acidification lake history. The results show that lime treatment detoxifies the water, although chemical and biological development varies among and within sites. In general the long-term changes are small compared to the initial changes associated with first treatment. Water chemical changes over time are reflected as reduced sulfur concentrations and increased nitrogen concentrations. Treated ecosystems seem not to recover fully to the situation before acidification, and due to re-colonization failure, several species are lacking in the limed waters.     

Zooplankton communities and acidification processes (a review)

A review of the literature which deals the with zooplankton of acid-stressed ecosystems revealed several strong patterns, weaker patterns, areas of controversy or inconsistency, and poorly understood but potentially important factors. Those patterns which are strong, but not necessarily universal, include a general response to short term pH shocks suggesting that daphnids are least tolerant followed by other cladocerans, copepods, and chaoborids. In addition, the numbers of both crustacean and rotifer species are decreased, and the importance of daphnids is reduced in acidic lakes, while limnetic hemipterans are greatly increased in acidic fishless lakes. Weaker patterns include reduced zooplankton biomass, reduced importance of cyclopoids, and increased representation of generalist species in acidic lakes, and intraspecies differences in pH tolerance indicating that populations of acid-stressed ecosystems are more tolerant. But, zooplankton biomass is apparently a result of system productivity as opposed to pH per se. Inconsistencies within the literature exist as to whether chaoborids are more abundant in acidic fishless lakes, the influence of physiological stress contra predation in determining community structure, the immediate response of the zooplankton to lake neutralization, and the toxicity of Al. The importance of metals, humic substances, and the fauna in determining community dynamics is poorly understood. Although both phyto- and zooplankton communities can be severely simplified in acidic lakes, the influence of the phytoplankton on the zooplankton, beyond the relation edible biomass vs zooplankton standing stock, in these ecosystems is unclear. From the literature it is apparent that direct physiological influences of acid-stress are important, but that indirect (biotic) influences and variables which correlate with pH are often as important if not more so to the zooplankton.     

An Integration of Water Physicochemistry,Algal Bioassays,Phytoplankton, and Zooplankton for Ecotoxicological Assessment in a Highly Polluted Lowland River

Results of different approaches potentially useful for the evaluation of water ambient quality were analysed and compared in a small temperate lowland river with mixed diffuse and multiple-point source pollution. The Reconquista River (Buenos Aires Province, Argentina), one of the most polluted watercourses of Latin America, receives agrochemicals as well as domestic and industrial (mostly untreated) effluents. Physical and chemical water variables were determined; unispecies algal bioassays (with Chlorella pyrenoidosa and Scenedesmus acutus) were carried out in laboratory; and density and structure of phyto- and zooplankton were analysed at three sites in four dates (representing a range of likely conditions in the river). A general scheme of association among plankton, bioassays and physical/chemical variables was elaborated, that helped to infer possible control factors in this multi-stressed system. Some empirical methods, but mainly mathematical ones including multivariate techniques (as PCA, cluster analysis), were applied for evaluation of samples. A preliminary selection of indices and attributes as potential indicators of the water river quality was made, and then applied for assay a tentative integrative ordination of samples. The relative best water quality was recorded when-where dissolved oxygen concentration, algal diversity and planktonic crustacean density were higher. The worst water quality corresponded to the lack of cladocerans and lowest crustacean density, and higher: organic and industrial pollution, major nutrients (ammonium and orthophosphates), BOD, hardness, conductivity, algal biomass in bioassays, phytoplankton density (>10 000 ind. mL^-1), dominance of a single algal species (>90%), and rotifer proportion in zooplankton (>85%).     

Development of zooplankton in relation to lime treatment in two acidified lakes

Zooplankton has been studied in Lakes Östra Nedsjön and Ömmern (1974–94), two acidified lakes in South-Western Sweden. The former lake was first limed in 1971–73, and secondly in 1982. The first liming increased the pH-level from ca. 5.3 to 6, and the second one from ca. 5.8 to 7–7.5. The pH-value in Lake Ömmern was about 6.1 in 1973, but decreased to 5.3 in 1981, when liming raised the value to 6.5–7. After the first liming in Lake Ö. Nedsjön, the rotatorians represented in average 1% of the total volume of zooplankton. Among the copepods, which made up ca. 22% of the volume, Cyclops was frequent, and both Eudiaptomus gracilis and Heterocope appendiculata were recorded. After the second liming on the other hand the rotatorians increased to in average 28% of the total volume, while the volume of copepods was only ca. 6%. Heterocope disappeared, and Eudiaptomus and Cyclops, usually favoured by liming, were rare. Consequently the supply of larger forms of crustaceans, suitable as fish food was severely reduced. In Lake Ömmern the effects of acidification within the zooplankton were moderate. The species richness was about the same as in unacidified lakes. After liming the development of zooplankton was similar to that in most other limed lakes, i. e. increased frequency of rotatorians, cladocerans and Cyclops spp. In Lake Ö. Nedsjön, however, the small zooplankton volumes and the elimination of copepods was in contrast to the zooplankton development in other limed lakes and in unacidified ones.     

Biomass,Mineral Accumulation,and Calcium Crystals in Trema micrantha (L.) Blume as a Function of Calcium Carbonate Addition

Trema micrantha (L.) Blume is a neotropical multipurpose tree species, which could be used in forest restoration and agroforestry. Several cultures, however, require liming to satisfactory yields in acid soils. Therefore, it is important to determine the effect of liming to this native species, in order to include it in agroforestry associations. The aim of this work was to evaluate the morphological changes of T. micrantha, including the calcium oxalate (druses) and cystolith density, as caused by the calcium carbonate (CaCO₃) addition. The assay included three treatments: control, pH 5.3; treatment 1, pH 5.5; treatment 2, pH 6.0. The liming reduced the root biomass and increased the shoot biomass. The leaf specific mass and nutrients concentration were not changed. The leaves presented higher density of druses in treatment 2. The cystolith density was not modified, but the cystolith size was increased by the liming. The results indicate liming tolerance in this species.     

Changes of planktivore fauna and development of zooplankton after liming of the acidified Lake Gårdsjön

The quantitative dynamics of the zooplankton community was studied during a period of 13 years in the manipulated Lake Gårdsjön and an acidified reference lake. Lake Gårdsjön was acid during the first 3 years, limed and fishless the following 4 years and stocked with brown trout for a period of 6 years. During the final 2 years rainbow trout was added. Changes in water chemistry and phytoplankton standing stock are associated with the manipulations. Liming had a positive effect on the overall species richness and diversity among rotifers and cladocerans. Changes in the zooplankton community during the different phases of the lake restoration are discussed in relation to the development of the planktivorous fauna of the lake, phantom midge larvae, aquatic hemipterans and fish. It can be concluded that liming creates a potential for the restoration of the zooplankton diversity, but the actual structure of the zooplankton community in limed lakes is strongly influenced by predatory and competitive interactions.     

Impact of Nitrate Addition on Phosphorus Availability in Sediment and Water Column and on Plankton Biomass-Experimental Field Study in the Shallow Brackish Schlei Fjord (Western Baltic, Germany)

The Schlei is a hypertrophic brackish fjord of the Baltic. In order to assess the optimal method for restorative sediment treatment, an in-situ-experiment was carried out to oxidize the uppermost sediment strata by direct nitrate injection. An area of 3,5 ha, covered with sapropelic sediment, was treated with 50 t of commercial calcium-salpetre. Half of this area was treated once with a dose of 140 g NO3-N m-2, whereas the other half was treated twice receiving a dose of 280 g NO3-N m-2. Two enclosures were installed on these treated areas. The reaction in the interstitial water of the sediment (nitrate, phosphate, sulphate, iron) and in the water bulk (tot-N, tot-P) are documented and compared with an untreated reference area. Moreover, the impact of the sediment treatment on the phyto- and zooplankton biomass is discussed.     

Liming the acid lake Hovvatn,Norway: A whole-ecosystem study

Hovvatn, a 1-km² chronically-acidified lake in southernmost Norway, was treated with 200 tonne of powdered limestone in March 1981. An additional 40 tonne were added to a 0.046 km² pond (Pollen) draining into Hovvatn. The lakes were stocked with brown trout in June 1981 and in each subsequent year. At ice-out pH rose from 4.4 to 6.3 (Hovvatn) and 7.5 (Pollen), Ca and alkalinity increased, and total Al decreased by 120 μg L^?1. None of the other major ions exhibited significant changes in concentration. Total organic Cand Pincreased after liming. The phytoplankton community was dominated by chrysophytes and did not change significantly following liming. The zooplankton community was typical of acid lakes prior to liming. There was a clear succession in species dominance following treatment, although no new species immigrated to the lakes. Zoobenthos changed from a community characterized by low abundance and reduced number of species to increased abundances of oligochaetes, mayflies and chironomids. Hovvatn and Pollen were barren of fish prior to stocking. The stocked fish showed remarkably high growth rate during the first years. Liming apparently improved conditions for zoobenthos, enhancing the processing of fine detritus which in turn resulted in elevated levels of TOC and P in the lakewaters during the first year after liming. The “oligotrophication” process typical of acid lakes was temporarily reversed by liming. The interactions between groups of organisms in Hovvatn and Pollen indicates that many years are required before a new steady-state can be attained following liming.     

Liming of acidified lakes: Induced long-term changes

This study presents data concerning long-term trends after neutralization of four acidified lakes in two regions on the Swedish west coast. Neutralization was achieved by a di-Ca-silicate with 52% CaO and about 11.5% MgO. Between 61 and 74% of the spread lime product dissolved during a 5 to 7 yr period. The liming increased pH, from a range of 4.5 to 5.2 to near neutral and restored alkalinity in the range of 0.2 to 0.3 meq l^?1 and the Ca-content became 3 to 4 times higher than before liming. In two lakes transparency decreased significantly presumably due to changed phytoplankton composition. These changes successively declined due to dilution and continuous acid loading. The changes in water chemistry and development of stocked brown trout (Salmo trutta) populations initiated biotic changes. Phyto- and zooplankton communities reacted both instantly and later with successions in species composition. Changes of benthic macroinvertebrate species occured over several years, but some pelagic species, e.g. corixids were rapidly reduced due to predation of fish. Observed changes were predominantly due to expanding populations of species present at very low abundances even during acid state of the lakes. Some organisms found during preacid state of the lakes did not establish new populations and this process may need a prolonged time with favorable conditions. Reacidification towards the end of the study period significantly stressed the brown trout population and also favored expansion of the filamentous algaMougeotia sp. andSphagnum sp. that almost vanished during the first year after liming. Decreasing concentration of total P was not influenced by neutralization and may be mostly dependent on negative changes in the soils surrounding the lakes. If generally valid, this process may be an important factor for the oligotrophication of lakes in areas where acid deposition is high.     

Comparison of mussels and crustacean plankton to monitor heavy metal pollution

The ability of freshwater organisms (mussels — Unio pictorum L. and crustacean plankton —Cladocera and Copepoda species) to monitor heavy metal pollution was compared under field conditions, near the effluent discharge of a sewage water treatment plant at Lake Balaton (Hungary). The mussels were transferred from their less polluted habitat to the study area. The crustacean plankton was collected at this site The concentrations of Hg Cd Cr Cut Pb, Zn, and Fe were measured m the gills of the transplanted mussels as well as the natural zooplankton in the summer period, using the AAS method. Both mussel gills and the zooplankton showed periodically high Fe-, Zn-, and Cu-concentrations. An elevated level of Hg was only observed in mussels, while high Pb- and Cr-concentrations were found only in crustacean plankton. Accordingly the zooplankton seems a more suitable model for monitoring heavy metal pollution under these field conditions.     

EFFECTS OF WATERSHED LIMING ON PICEA RUBENS SEEDLING BIOMASS AND NUTRIENT ELEMENT CONCENTRATION

Effects of watershed liming on the biomass and tissue chemistry of planted Picea rubens Sarg. (red spruce) seedlings were investigated for two growing seasons after two subcatchments in a forested Adirondack, New York (U.S.A.) watershed were limed aerially with 6.89 t ha^-1 of calcitic limestone (CaCO₃). Picea rubens has been the focus of numerous atmospheric deposition research studies, but less well investigated for responses to amelioration. Picea rubens seedlings were planted in limed and reference subcatchments and harvested the first and second growing season after liming to measure total, foliar, and stem (i.e., branch) biomass, and concentrations of Ca, Mg, K, Al, Na, and P in the annual growth increment of foliage and branches. In the second year after liming, both foliage and stem biomass of seedlings from reference plots were at least 50% greater than seedling biomass from limed plots. Seedlings in limed areas had significantly greater foliar concentrations of Mg and P in the first year after liming, but not in the second year. Foliar Ca was not significantly different in limed than reference seedlings. Foliar Al concentrations were greater in reference than limed seedlings, but still below documented toxicity levels. Stem concentrations of Mg, K, and P in seedlings from limed areas decreased significantly between the first and second growing season after liming, while reference seedling stem concentrations either increased or declined only slightly. Correlations among foliar nutrients and foliar biomass from limed plots were negative and suggest an inverse dilution effect. Foliar Al concentrations were negatively correlated with Ca, Mg, K, and P in seedlings from reference plots, but positively correlated in limed plots. The adverse response of P. rubens seedlings to lime may reflect changes in nutrient availability associated with changes in soil pH.     

Chemical,biological and socio-economic approaches to the liming of Lake Alinenjärvi in southern Finland

The aim of this comprehensive study is to estimate the effects and usefulness of liming Lake Alinenjärvi based on chemical, biological and socio-economic studies. Methodological standpoints concerning the limestone dissolution rate, acidic surges and reacidification are also discussed. L. Alinenjärvi (0.4S km²) is located near the city of Nokia with a surrounding population of over 5 000 (< 2 km). Before liming, the lake had only a sparse crayfish (Astacus astacus L.) population left, because reproduction had been failing since the early 1980s. The most important effect of liming is that it should connect with the potential production of crayfish. The roach (Rutilus rutilus L.) population was also affected. The liming improved the chemical quality of the water, and decreased also the Al and Mn concentrations. The number of phytoplankton species increased, and the species composition of periphyton changed after liming. The a-chlorophyll concentration in water remained low. Furthermore, crustacean zooplankton and benthic animals increased in abundance in the first late summer after liming. The diet analysis of perch (Perca fluviatilis L.) gave comparable results suggesting a possible positive effect of liming on their food resources. The improved water quality seems to make the reproduction of the crayfish possible again, but recovery would take several years. To guarantee a recovery, the introduction of new crayfish individuals and supplementary neutralizing methods would be needed. The results of a mailed survey showed that L, Alinenjärvi is a valuable water source for the local people. The most usual forms of leisure around the lake and shores are, however, outdoor recreation and swimming, with only minor usage for fishing. Despite that, though the immediate benefits would be negligible, a majority of local residents supported the continuation of liming even though they would have to carry the costs in the future.     

Liming of wetlands in the Røynelandsvatn catchment — Effects on soil chemistry and neutralisation properties in the soil profile

In 1990, wetlands in the Røynelandsvatn catchment in Southern Norway were limed with finely ground limestone powder at a rate of 20 t ha^–1 to remediate acid discharge. JORDFORSK has investigated changes in the chemical properties of soil over a three year period in a selected limed fen. Calcium (Ca) contents above natural background levels were found in the uppermost 20 cm of the peatsoil. The major part of Ca introduced by liming was in the uppermost 3 cm of the peatsoil. Remaining Ca from liming is roughly estimated to be 2,5–3 t ha^–1. Similarly, pH of the uppermost cm of the peatsoil of the limed fen was around 7. Deeper peatsoils (> 20 cm) had pH-values around 3,8–4,9. After liming the dominance of hydrogen (H) — and aluminium (Al) ions in the exchangeable cation pool was replaced by Ca in the uppermost cm of the fensoil. In deeper peatlayers (> 20 cm) the exchangeable cations were still dominated by H⁺ and Al-ions. A smaller part of organically bound Al in the lime-influenced mire topsoil than in other peatsoil may indicate that Al has changed from an organically bound to a mineral (amorphous) phase. The liming has changed chemical properties of the uppermost part of the soil. This will counteract acidic and Al-rich input The results underline the origin of acid-neutralising effects and stress the importance of hydrology and patterns of water flow in the surface layers of mires.     

Integrated studies of the effects of liming acidified waters (ISELAW-programme)

To assess the long-term (>15 years) effects of liming, an integrated programme for studies of the effects of liming in acidified waters (ISELAW) was initiated in 1989. At present, 14 lakes and 14 streams are included in the programme. Although on average of 14 years have passed since the first lime treatment, and the chemical goal of liming have been achieved in all lakes, i.e. to raise pH over 6.0 and alkalinity over 0.1 meq 1–1, changes in biota could still be observed in several of the lakes. Species richness and species diversity was in general not different in the limed lakes as compared to circumneutral reference lakes, although the composition of the fauna did not resembled that of neutral lakes. Among zooplankton, rotifers were still more abundant than expected in limed lakes. The fish communities appeared unstable and the species proportions as well as population structures are changing, partly as a result of re-colonisation of acid-sensitive species after liming. The results indicate that the long-term changes may persist for more than 15 years after liming and emphasise the importance of comparable time series in non-limed lakes.     

The effect of earthworms and liming on soil microbial communities

The effect of liming and earthworms on the composition and function of soil microbial communities was investigated in an upland soil from the UK in order to understand interactions between the biotic and abiotic components of soil systems. A factorial experiment was established using soils from the Sourhope Farm, near Kelso, with lime or no lime added, with or without earthworms added and a combined treatment of both lime and earthworm additions. The soils were incubated and destructively sampled after 180 days. Measurements of soil microbial biomass, dehydrogenase activity, phenotypic structure (by phospholipid fatty acid analysis (PLFA) and responses to four carbon substrates (d-glucose, l-arginine, α-ketoglutaric acid, α-cyclodextrin) were determined. Statistically significant results were limited to the litter layers, with no significant observations in either the H or Ah horizons. There were significant decreases in the soil microbial biomass and microbial activity in the litter layers caused by the addition of earthworms; liming reduced microbial biomass only. The addition of earthworms caused a significant difference in the PLFA principle component analysis (PCA) profile, as did liming. For the PLFA PCA profile, earthworm plus lime treatment was indistinguishable from the liming result. Addition of earthworms significantly suppressed the response to glucose; this effect was removed by liming. This indicates that liming may significantly alter the ecological interactions between earthworms and the microbial community.     

Effect of liming on some chemical,biochemical, and microbiological properties of acid soils under spruce (Picea abies L.)

Summary Soil pH, total organic C, total N, exchangeable Al, available P, CO₂ evolution, microbial biomass C and N, phosphatase and dehydrogenase activities were determined in acid soils sampled under spruce subjected to acid deposition, before and after liming. A slight decrease in pH values was observed from the edge of a tree canopy to the base of the trunk in acid soils. Liming drastically reduced exchangeable Al and increased CO₂ evolution, microbial biomass, and the metabolic quotient. The microbial biomass C to total organic C ratio increased after liming but did not reach 2%, the average value considered valid in soils where the C content is in equilibrium, that is when C inputs are equal to C outputs. The microbial biomass C:N ratio decreased after liming, thus indicating that bacteria became predominant over fungi when soil acidity decreased. Dehydrogenase activity but not phosphatase activity was increased by liming. The decrease in phosphatase activity was not completely related to the increase in available P, but was also dependent on microbial growth and the decrease in acid phosphatase, the predominant component of acid soils.     

Population dynamics of brook trout (Salvelinus fontinalis) during maintenance liming of an acidic lake

Maintenance liming of an acidic lake in the Adirondack Mountains of New York state (Woods Lake) was conducted three times over a 5 yr period in an attempt to establish a self maintaining brook trout population. Various strains and age classes of marked brook trout were stocked annually and the population was inventoried semi annually to evaluate survival, growth, and reproductive success. The Woods Lake brook trout population was dominated by young, stocked fish throughout the maintenance liming period of 1985-89. Based on spring emergent fry trap catches and fall trap net catches of unmarked fish, only one naturally produced year class (1986) was successfully recruited to the Woods Lake brook trout population. Low annual survival rates (G 20%) of juvenile trout were observed throughout the study period. Although initial growth rates and condition of young trout were satisfactory, increased intraspecific competition for food resulted in declining growth rates and condition of older age classes. Fall standing crops of brook trout remained at relatively low levels of 6 to 10 kg ha^?1 and both production per unit biomass and growth efficiency decreased over the 5-yr. Repeated whole lake liming and limited spawning habitat improvement were not sufficient to sustain brook trout natural reproduction in Woods Lake. Low productivity, marginal spawning habitat quality, and low survival rates of stocked trout in Woods Lake resulted in the failure to establish a self maintaining, productive brook trout population in Woods Lake.     

Phosphorus Availability in Lolium perenne L. in Acidic and Limed Soils

Soil liming may increase phosphorus (P) availability, but this increase may also be achieved with generous P applications. However, it is not well known which practice has longer-term effects. Thus, in a pot experiment, an acidic soil (pH 4.57), limed to pH 6.5, was added with P and sown with Lolium perenne L. We conducted three cuttings (on Days 40, 80, and 120) in order to evaluate P dynamics in each of the treatments. As expected, biomass increased significantly with liming. We also found that plant P concentration increased in the liming treatment, but not in the P-added treatment, although the difference was reduced on Day 120. This shows that in severely acidic soils, liming should be preferred over P addition, although the beneficial effects may not last for a very long time, since in this experiment, they only lasted for 4 months. Similar conclusions were drawn from soil P extraction results.     

Long‐term effects of liming on microbial biomass and activity and soil organic matter quality (13C CPMAS NMR) in organic horizons of Norway spruce forests in Southern Germany

Long‐term effects of liming on microbial biomass and activity and soil organic matter (SOM) were investigated in samples from organic horizons (Of/Oh) in spruce forests at Adenau, Höglwald, Idar‐Oberstein, and Schluchsee (Southern Germany) where plots have been manually treated 7 to 13 years ago with dolomitic limestone. At all sites, pH values were markedly increased after liming. The contents of C and N in the organic horizons of the limed plots appeared to be lower with the greatest decrease at Höglwald (Dystric Luvisol) where liming has affected the soil properties for the longest time of all sites. Catalase activity was promoted after liming at Adenau (Cambic Podzol). This was also the case for the Dystric Luvisol where liming resulted also in higher basal respiration. Biomass‐C was higher in samples from the limed plot at Idar‐Oberstein (Dystric Cambisol). The ¹³C CPMAS NMR spectra of organic horizons from the control plots indicate no differences in the gross carbon composition of SOM. Furthermore, spectra from the limed Cambic Podzol, Dystric Cambisol, and Haplic Podzol (Schluchsee) were remarkably similar. However, for the Dystric Luvisol, the lime‐induced promotion of microbial activity resulted in lower O‐alkyl‐C intensity. The observed patterns of microbial biomass and activity were site‐dependent rather than a result of liming. Obviously liming had only small long‐term effects on the humus quality in the organic horizons, as far as detectable by CPMAS NMR spectroscopy. More sensitive techniques like pyrolysis‐GC/MS should be applied to analyze differences in C composition.