Phosphorus mobility in sediments of acid mining lakes, Lusatia, Germany

Ecological Engineering 24 (2005) 89–100

Phosphorus mobility in sediments of acidmining lakes, Lusatia, Germany

Andreas Kleeberga, ∗, Bjorn Grunebergb

a Leibniz—Institute of Freshwater Ecology and Inland Fisheries, M¨uggelseedamm 301, D-12587 Berlin, Germanyb Brandenburg Technical University of Cottbus, Seestraße 45, Bad Saarow D-5526, Germany

Abstract

Changes in benthic retention and mobility of P were studied in a chronosequential approach in acid (pH 2.5–3.5) to moderatelyacid (pH 5.6–6.8) mining lakes (MLs) with respect to the threat of eutrophication during maturation. Although various MLsexhibit a high pelagic P availability there is currently no distinct threat of an enhanced eutrophication due to a C limitation anda high benthic P immobilization potential. The sequential P extraction applied revealed an increase in sedimentary total P withincreasing pH due to the additional uptake of P by Al- and Fe-hydroxides, but no increase in mobile P forms. Currently, theexcess in reactive Fe at a high Fe:P ratio in surface sediment at pH∼3 favours an efficient P precipitation of Fe-oxi-hydroxideswith a high specific surface area for P adsorption. However, an enhanced future P mobility of ML sediments and a threat ofeutrophication results from: (1) a distinct reduction of the import of Fe and Al from the catchment over time, resulting in a lowersupply towards the sediments, and (2) a reduction in the sedimentary Fe mineral surface area due to the future rise in pH.© 2004 Elsevier B.V. All rights reserved.

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eywords:pH; Phosphorus fractionation; Phosphorus mobility; Iron; Aluminium; Eutrophication

. Introduction

For about 100 years the Lusatia region has experi-nced extensive open-cast lignite mining activities. Atresent the pits are flooded with ground or river wa-

er. The lakes formed are generally deep (20–40 m),imictic, acidic (pH 2.5–3.5), and/or metal-laden due

o such geochemical processes as pyrite (FeS2) oxida-ion (e.g.Nixdorf et al., 2003). Since these conditionsan persist for many decades or longer (Yokom et al.,

∗ Corresponding author. Tel.: +49 (030) 64 181 741;ax: +49 (030) 64 181 682.E-mail address:kleeberg@igb-berlin.de (A. Kleeberg).

1997), current remediation strategies are aimed aremoval of acidity (neutralization) through the procof biogenic alkalinity formation. Under anaerobic cditions, sulfate is reduced to sulfide (desulfuricatiresulting in production of alkalinity. If hydrogen sufide reacts with ferrous iron to form FeS or FeS2, whichis buried permanently in the sediment, a net alkaity gain results (e.g.Peine and Peiffer, 1996; Frieet al., 1998). However, in most of the mining lak(MLs) the current net primary production betweenand 100 g C m−2 a−1 cannot produce sufficient surporganic C for the desulfurication, and the hypolimnwaters are usually not anoxic during stratificationriods (Nixdorf and Uhlmann, 2002). The intensity o

90 A. Kleeberg, B. Gr¨uneberg / Ecological Engineering 24 (2005) 89–100

Fig. 1. Location of study area Lusatia and the mining lakes (MLs) studied in the chronosequence approach.

plankton production itself depends on the availabilityof C and P (e.g.Nixdorf et al., 1998; Woelfl et al.,2000). Hence, biogenic alkalinity formation needs a‘controlled eutrophication’ by the addition of C and/orP sources, e.g. phosphate fertilizer treatments (Davisonet al., 1995; George and Davison, 2000), controlled sur-face water filling (Hupfer et al., 1998), the addition ofcow manure (Brugam and Stahl, 2000) or of natural or-ganic matter (Brugam et al., 1995; Fyson et al., 1998).The corresponding threat of eutrophication, however, isdifficult to predict, and remains a controversial question(Kleeberg, 1998; Nixdorf and Uhlmann, 2002; Yokomet al., 1997).

Although the predictions of ML water quality dateback at least to the 1960s (Morth et al., 1972), the long-term eutrophication models for pit MLs encounteredapplication problems, including waste load character-istics, dissolved oxygen depletion, sedimentation, andsediment P release (Yokom et al., 1997). The latter isgenerally regarded to be very low due to the surplus inmetals which guarantee a high P binding capacity. Todate there have been only a few studies investigatingthis issue (Saballus, 2000; Duffek and Langner, 2002;

Langner, 2001; Hupfer et al., 1998). Although a largebody of knowledge exists on bulk analysis of ML sed-iments (e.g.Brugam et al., 1988; Friese et al., 2000;Kapfer et al., 2000) detailed information on the P dia-genesis in the neutralization process of acidic MLs isnot available. Understanding the P diagenesis is a pre-requisite for predicting the fate of these lakes (Yokomet al., 1997; Fyson et al., 1998) as well as for modelingthe effect on the exchange and resupply of P to the over-lying water whose behavior is linked to the sedimentaryFe transformations. At a later stage of MLs, provideda sufficient C supply, sulfate reduction and FeS/FeS2formation could lead to a lack of binding partners forP, and consequently to an increase in P mobility as inneutral glacial lakes (e.g.Caraco et al., 1993; Rodenand Edmonds, 1997).

We report here on the actual state of the pelagicand benthic P mobility of extremely to moderatelyacidic post MLs. The goal was to delineate potentialchanges among different P pools over time. We ap-plied a sequential P fractionation to representative MLsediments of increasing age and pH representing dif-ferent stages of maturation to mimic the progressive

A. Kleeberg, B. Gr¨uneberg / Ecological Engineering 24 (2005) 89–100 91

neutralization process in a chronosequence (false-timeseries) attempt. The Lusatian mining district providesan ideal venue for this approach because of the succes-sive cessation of lignite extraction in the various mines(Nixdorf et al., 2003).

2. Materials and methods

The area of our studies, Lusatia in the southeast ofthe federal state Brandenburg, is one of the larger lignitemining districts in Germany (Fig. 1). The area claimedby the former mining activities is 800 km2. Two hun-dred and fifty-nine lakes will develop in the post mininglandscape mainly due to rising ground water (Nixdorfet al., 2003). Morphometrical and limnological data ofthe MLs studied, are summarized inTable 1.

2.1. Sediment sampling and analysis

Intact sediment cores up to 20 cm long were takenin 2001 and 2002 with an Uwitec®-corer (flutter valve,acrylic glass tubes, i.d. = 57 mm) at the deepest lo-cation in the respective MLs (Table 1). From eachcore, the overlying water was siphoned off. After slic-ing the core (0–0.5, 0.5–1.0, 1–2, 2–4,. . ., 8–10 cm)aliquots were used for the determination of dry weight(d.w.; 48 h, 105◦C), organic matter as loss on igni-tion (OM; 3 h, 550◦C) and total inorganic carbon (TIC;3 h, 900◦C). Aliquots of d.w. were homogenized andanalysed for total P (TP) after wet digestion (K2S2O8,2 ye pec-t rds( smA( RP)a xest cord-iS mt ityo

ivelye Ta

ristic

oll−

l−1)

–200

97–2

–200

97–2

–200

h, 120◦C), and for total Fe (TFe) and Al (TAl) bnergy-dispersive X-ray fluorescence analysis (S

race 5000, Tracor) against pure elemental standaMicro matter®, Deer Park, WA, USA). The pH waeasured by a pH probe (pH 540 GLB, WTW®).fter centrifugation (5000×g, 10 min) and filtration

0.45�m) the concentration of soluble reactive P (Snd dissolved Fe were measured. Their diffusive flu

owards the sediment surface were calculated acng to Fick’s first law of diffusion (Berner, 1980; seeinke et al., 1990). The porosity was determined fro

he water loss at 105◦C, assuming a sediment densf 2.5 g cm−3.

.2. Phosphorus fractionation

Fresh sediment (0–0.5 to 8–10 cm) was successxtracted in duplicate, as summarized inTable 2. Two

Table 2Phosphorus fractionation scheme used according toPsenner et al. (1984), where only TP of each fraction was determined

Term Extractant Time (h) Expected form

NH4Cl-P 0.1 M NH4Cl 0.5 Pore-water P, loosely adsorbed onto surfaces (e.g. of Fe and CaCO3),immediately available P

BD-P 0.11 M bicarbonate/dithionite 1 Redox-sensitive P, mainly bound to Fe-hydroxides, Mn-compoundsNaOH-P 1 M NaOH 16 P bound to metal oxides, mainly of Al and Fe, which is exchange-

able against OH−; inorganic P compounds soluble in bases as well asorganic P

HCl-P 0.5 M HCl 16 P bound to carbonates and apatite-P, traces of hydrolysed organic PResidual P 0.5 M HCl, K2S2O8, 120◦C 2 Organic and other refractory P

modifications were made according toSaballus (2000).0.1 ml 1N HCl was used instead of H2SO4 for acidifi-cation of 20 ml BD extract prior TP digestion to reacha pH of 1. The pH of 20 ml NaOH extract was low-ered stepwise by first applying 2.3 ml 1N HCl to pH 5followed by 0.2 ml 4.2N H2SO4 to pH 1. SRP concen-tration was determined photometrically (Murphy andRiley, 1962). In the extractants the concentration of TFeand TAl was determined by flame AAS (Perkin Elmer3100®).

2.3. Diagenetically active iron

The diagenetically active Fe (FeHCl) was definedas the fraction of TFe removed by shaking ca. 0.2 gfresh sediment with 15 ml 0.5N HCl for 1 h at 22◦C(Moeslund et al., 1994). It represents exchangeable Fe,most Fe oxides, FeS and FeCO3, and probably someFe from silicates (Thamdrup et al., 1994). After filtra-tion (0.45�m) the Fe concentration was determinedphotometrically (Legler et al., 1986).

3. Results

Fig. 2 shows the relationship between the concen-tration of Chlorophyll a and TP of neutral glacial lakes(seeRucker et al., 2003) and of acid MLs. Becauseof the rapid transition between the Fe and Al buffer-ing system there are no weakly acidic (pH 4.3–6) MLs( nd5g po-st ofT erT hyll

a concentrations. This is attributed to the C limitationat low TIC concentrations of <1 mg l−1 (Nixdorf et al.,1998).

Fig. 3 shows a vertical profile of sediment param-eters of a Lusatian ML. Plessa 112 was chosen as arepresentative example for a young acid ML. In gen-eral, a fossil horizon with a higher d.w. compactionand lignite content (not shown), and a more recenthorizon (above 9 cm) can be distinguished. Ligniteparticles cause a higher proportion of organic mat-ter. Correspondingly, the TIC proportions are low atlower pH in the upper sediment layers. In concor-dance with the high TFe content and the intensive‘iron wheel’ at the sediment–water interface (see be-low), the concentration of Fe in the pore water is high;that of SRP is very low. The corresponding diffu-sive release rates are 0.92± 0.37 mg Fe m−2 d−1 and0.4± 0.3�g P m−2 d−1.

F (Chla ando e TPt ivelyr

Nixdorf et al., 1998). Whereas, pH values of 5.1 a.9 result from calculation of means (Table 1). In thelacial lakes Chlorophyll a increases with TP. Opite, at TP threshold values between 30 and 60�g l−1,he phytoplankton significantly react to a reductionP (Chorus, 1995). A few MLs are far above the uppP threshold value, but show much lower Chlorop

ig. 2. Relationship between the concentration of chlorophyll a) and total P (TP) of circum neutral glacial lakes in Brandenburgf acid mining lakes at pH <4 and >6. The vertical lines denote th

hreshold values at which the phytoplankton biomass is effecteduced (Chorus, 1995).

Fig. 3. Vertical profile of the mean value± S.D. (n= 2–3) of dry weight (d.w.), organic matter (OM), total inorganic carbon (TIC), pH, total Feand soluble reactive P (SRP) in the pore water at the deepest location of ML Plessa 112 in November 2001.

Fig. 4shows the vertical distribution of P fractionsof ML Plessa 112. Most P is found in the metal-boundform. The BD-P fraction represents mainly Fe-boundP. The NaOH fraction also contains Fe- as well as Al-bound P (see alsoFig. 5) and organic P. Only minoramounts of P can be found in the NH4Cl fraction, whichrepresents the immediately available (loosely sorbed) P.The low amounts of HCl-P (carbonate-bound P) are inconcordance with the low TIC content of this sediment(Fig. 3). The residual P is most probably P enclosed inlignite.

Fig. 5 shows the percentage of the P fractions onTP, and the percentage of dissolved Fe and Al on TFeand TAl for ML Plessa 112. The vertical distribution

Fig. 4. Mean value± S.D. (n= 3) of P fractions (Psenner et al., 1984)at the deepest location of ML Plessa 112 in November 2001.

of Fe and Al in the corresponding extractant confirmsthe dominance of metal-bound P. It is obvious that forthe BD-fraction, Fe is the predominant sorption part-ner which becomes obvious in the significant relationsbetween P and Fe extracted in that fraction:

BD-P (% TP)= 0.677Feextracted(% TFe)− 5.12;

R2 = 0.81, P = 0.05, n = 7 (1)

Fig. 5. Vertical profile of the percentage of the P fractions in total P(TP), and the percentage of dissolved Fe and Al (determined in thecorresponding extractant) in total Fe (TFe) and Al (TAl) as well itsvertical course in ML Plessa 112 (November 2001). NH4Cl-P standsfor immediately available (loosely sorbed) P, BD-P for reductant-soluble (mostly FeOOH) P, NaOH-P for Fe- and Al-bound P, HCl-Pfor Ca-bound P, and residual P for refractary P.

Whereas, Al causes high concentrations of NaOH-P asreflected in the significant correlation between P andAl as extracted in NaOH:

NaOH-P (% TP)= 0.945Alextracted(% TAl) + 14.68;

R2 = 0.94, P = 0.05, n = 7 (2)

The on average high but variable Al:P ratios (up-per 10 cm,n= 7) for Lusatian MLs varied between69.4± 33.4 (ML Dreiweibern) and 183.6± 153.6 (MLPlessa 112). The slightly higher proportions of resid-ual P in the deepest sediment layer (8–10 cm) obviouslyoriginate from the lignite, while the increase towardsthe sediment surface results from the accumulation oforganic matter.

Fig. 6shows the benthic P for each fraction as per-centage of TP versus the benthic pH for mining andglacial lakes (upper 10 cm). Most MLs of different ageand increasing pH should represent a different stageof maturation in the progressive neutralization pro-cess. The following major trends become distinct. TPincreases slowly due to a P-accumulation over time(Fig. 6a):

TP (mg g d.w.−1) = 0.510pH− 1.211;

R2 = 0.77, P = 0.05, n = 12 (3)

During the maturation, with the neutralization ofMLs, the percentage of loosely adsorbed, available P(i ing.T OH-P ndf

D in-c ion ofi idualP blyf mu-l ial.

m lixp

Fig. 6. Mean value± S.D. (n= 4–7) of the percentage of sediment(0–10 cm) P fractions (a) in total P (TP) vs. the benthic pH for min-ing and neutral lakes, where (b) NH4Cl-P = immediately available(loosely sorbed) P, (c) BD-P = reductant-soluble (mostly FeOOH)P, (d) NaOH-P = Fe- and Al-bound P, (e) HCl-P = Ca-bound P, and(f) residual P = refractary P according toPsenner et al. (1984). Addi-tional ML data were drawn fromDuffek and Langner (2002), Hupferet al. (1998), andKapfer et al. (2000). The broken line (no statisticalproven correlation) represents the major trend for the MLs.

The 35 years younger ML 112 has a much lower pelagicpH of 2.9 and a distinctly higher pelagic TFe concentra-tion of 33 mg l−1. As a result, the ML 112 sediment hasa 10-fold higher TFe concentration. The mean (n= 14)percentage of FeHCl is, with 23.6± 6.8% TFe in MLFelix, significantly higher than in ML 112 (6.0± 1.3%TFe). For both MLs, the remarkable Fe accumulationup-core is attributed to a continuous Fe supply via sed-imentation due to an efficient precipitation at a pH ofaround 3, a reductive dissolution of Fe(III) in deepersediment layers and a diffusion of Fe(II) into overlyingwater where it can be oxidized or hydrolysed to pre-cipitate again. The higher the amount of TFe as well asFeHCl, the higher the amount of P in the BD fraction

NH4Cl-P) remains low in most cases (Fig. 6b), indicat-ng a constant surplus of metals for efficient P bindhis is evidenced by an increase of the BD- and Na. A statistically significant relationship could be fou

or BD-P (Fig. 6c):

D-P (mg g d.w.−1) = 2.731pH+ 2.016;

R2 = 0.51, P = 0.05, n = 12 (4)

uring neutralization, the Ca-bound P (HCl-P)reases noticeably due to a progressive accumulat

norganic C in the sediment. The percentage of resforms (refractory P) which originate most proba

rom the lignite decreases with an increasing accuation of authochthonous, more organic rich mater

Fig. 7 shows the vertical profile of FeHCl ing g d.w.−1and as a percentage of TFe. In ML Feelagic pH reaches 3.9 and TFe 0.51 mg l−1 (Table 1).

Fig. 7. Vertical profile of diagenetically active Fe (FeHCl) and its percentage in total Fe (TFe) in the sediment of two mining lakes (MLs) ofdifferent ages after termination of lignite extraction (in brackets).

(Figs. 4 and 5):

BD-P (mg g d.w.−1) = 0.506TFe (mg g d.w.−1)

− 37.52; R2 = 0.78,

P = 0.05, n = 7 (5)

BD-P (mg g d.w.−1) = 6.522FeHCl (mg g d.w.−1)

−15.42; R2 = 0.56,

P = 0.05, n = 7 (6)

Fig. 8shows specific surface areas of Fe-oxi-hydroxideminerals identified in ML sediments. Their stabilitydepends on the prevailing milieu conditions, e.g. to alarge extent on pH. So in sulfate-rich waters (∼3 g l−1),

and at a pH of 2.8–4.5 schwertmannite with traces ofgoethite is formed. Between pH 4.5 and 6.5, mixturesof ferrihydrite and schwertmannite are likely to form,whereas at a pH of 6.5, ferrihydrite or ferrihydrite in amixture with goethite is formed preferentially (Bighamet al., 1996). Jarosite is assumed to be unstable at pH>3 (Bigham et al., 1996). However, critical for spe-cific adsorption of phosphate onto Fe-oxi-hydroxidesare the progressive decrease of the mineral-specific sur-face area via dissolution with increasing pH and mi-crobial Fe reduction (Schinzel et al., 1993). Specificsurface area may decrease from 67.0 m2 g−1 (goethite)to 6.04 m2 g−1 (magnetite) or 4.33 m2 g−1 (hematite).

Fig. 9 shows the atomic Fe:P ratio versus the pHof water (upper panel) and surface sediment (lower

Fig. 8. Specific surface areas of Fe-oxi-hydroxide minerals and their stability within a certain range of pH. Data were drawn fromZinder (1985),P sprung

Fig. 9. Mean values of the atomic Fe:P ratio of upper sediment layers (0–10 cm,n= 4–7) vs. the pH of water (upper panel) and the pH ofsediment (lower panel), and their corresponding relationship. For the Fe:P ratio and the pH of sediment of MLs, a significant correlation couldbe found (case A), whereas there seems to be the opposite trend for the Fe:P ratios which were grouped according to the pH byBorovec andHejzlar (2001)(case B). But using all available data over the full pH range the overall trend is a decrease with rising pH (case C). Additionaldata are drawn fromBrugam et al. (1988)andFriese et al. (1998).

panel, case A) of MLs as well as of lakes influencedby mining activities. This ratio is regarded as a sim-ple indicator of P mobility, at least for the redox-sensitive P compounds (e.g.Jensen et al., 1992). Al-though there is a large scattering among the MLs witha pelagic pH around 3 (upper panel), the significantcorrelation indicates a decrease of benthic P bindingpotential with increasing pH. Considering only the dataof approximately neutral lakes (Borovec and Hejzlar,2001), an opposite trend of an increasing Fe:P ratiowith pH is observed (case B). However, using all avail-able data of lakes over the full pH range, the overalltrend is a decrease of the Fe:P ratio with rising pH(case C).

Fig. 10shows annual losses of the important P bind-ing partners Fe and Al from pine and oak forests of dif-ferent age located within the post mining landscape inLusatia (Knoche et al., 2000). For all chronosequencesites the significant correlations shown clearly indicatea decreasing export of dissolved Fe and Al speciesthrough the soil solution over time. This is reflectedin their decreasing concentration with the rise in pHfor all MLs studied (Table 1) and in particular for theMLs Felix and Grunewalder Lauch (Table 3).

Fig. 10. Annual losses of Fe and Al from soil solution of differentold sites dominated either by pine (Pinusspec.) or by oak (Quercusspec.) in the post mining landscape in Lusatia. Data were drawn fromKnoche et al. (2000).

4. Discussion

4.1. Threat of eutrophication

Most of the Lusatian MLs are idiotrophic waters dueto their exceptional morphometry and extreme chem-istry (Table 1), and still exhibit a restricted tendencyto an enhanced eutrophication. The reasons are mani-

Table 3Mean value± S.D. of pelagic Fe and Al concentration in two Lusa-tian mining lakes between 1995 and 2003

Lake Felix Lake Grunewalde

1995/1996 2000/2001 1997/1998 2002/2003

Fe (mg l−1) 0.6± 0.2 0.4± 0.2 19.8± 4.2 11.3± 2.1n 9 4 8 13

Al (mg l−1) 2.5± 0.7 1.7± 0.1 1.7± 0.3 1.1± 0.3n 14 4 7 13

pH 3.8± 0.1 3.9± 0.1 2.9± 0.1 3.1± 0.2n 14 4 10 24

fold. The current external diffusive P loading from thecatchment can be neglected. Our findings pertainingto the sedimentary P distribution of a ML around pH 3(Figs. 3–5) support the hypothesis that the P imported isconstantly removed from the water column by efficientco-precipitation with Fe and Al (Duffek and Langner,2002). These metals in surplus of the required ratio forP sorption (Fig. 5) favour a high benthic P retentionand a low P mobility (Figs. 3 and 4). The P release ratecalculated (where NH4Cl < 1% TP,Fig. 5), indicates norelevant internal P supply. In contrast,Langner (2001)calculated P release rates in mesoscosms with maxi-mal 6.2 mg m−2 d−1 at pH 3, and 0.62 mg m−2 d−1 atneutral conditions. But, the neutralization of MLs as C-limited waters can be retarded by a diffusion of Fe(II)into oxic waters and the consecutive acidity genera-tion through the complete reoxidation in the absenceof sulfide balanced the alkalinity gain from Fe reduc-tion (Blodau and Peiffer, 2003; Peine et al., 2000).

However, at the same time there are various indi-cations for a threat of eutrophication. Concentrationsof TP > 60�g l−1 would theoretically guarantee a eu-trophic level (Fig. 2). The availability of C and P, ratherthan extreme acidic conditions, are the limiting factorsin phytoplankton growth (Nixdorf et al., 1998; Woelflet al., 2000). MLs have an enormous potential for pri-mary production and algal growth, which in turn cansupply C towards the sediments and deteriorate the wa-ter quality. Due to the dissolution of P-rich phospho-rite at appropriate TIC concentrations in an acid ML( n-tF c-t )wa eso-

cosm studies with sediments from an extremely acidML resulted in the sharp rising of the pH gradient fromnear the sediment surface, and an overall increase indissolved Fe, P and C in the system (Fyson et al., 1998).

The transition from very acid to neutral conditions issharp (no MLs between pH 4 and 6 inFigs. 2 and 9), andenhances the TIC solubility. Moreover, the continuousnatural input of organic matter from a revegetated land-scape, flooding by sestonic-rich river water and, moresignificantly, the intentional addition of C sources willnot only stimulate the algae growth but will also haveconsequences for the future benthic P mobilization.

4.2. Changes in benthic phosphorus retention andmobility

Since only 12 cases are included in the chronose-quence (false-time series) approach of the different Ppools from older to younger MLs (Fig. 6), only somepreliminary major trends become visible in their mat-uration. Sedimentary TP increased along with an in-creasing pH (Eq.(3), Fig. 6a), but no change in thepore water P (NH4Cl-P) had become distinct until now(Fig. 6b). Both trends are attributed to more P in themetal-bound P fractions (Figs. 4 and 5). Due to the ac-tual high metal supply to the sediment (Table 1, Fig. 7),most P is currently associated with an excess of Al inthe NaOH fraction (Eq.(2), Fig. 4), and with an excessof Fe in the BD fraction (Eqs.(1) and (4)) as reflectedin the percent Fe distribution (Fig. 5). Hence, both frac-taf nd2 t toca in-i ,t ianM

andA e( plyt ratep c-t , atam ch-m

pH = 2.5), an algal bloom with Chlorophyll a concerations of 2656�g l−1 developed (Woelfl et al., 2000).ollowing 14C additions, even higher primary produ

ion rates, between 1.5 and 14.4 mg C (mg Chl a h−1,ere measured at pH 2.7–2.8 (Nixdorf et al., 1998). Inddition, organic C amendments (potatoes) in m

ions are able to take up additional amounts of P (Fig. 6cnd d). Al salts (Al2(SO4)3, Na3[Al(OH)6]) are used

or P inactivation. Atomic Al:P ratios between 4.6 a7.5 (n= 21 lakes) are documented to be sufficienontrol benthic P release (Welch and Cooke, 1999),nd an Al:P ratio of 100:1 is optimal when determ

ng dosage requirements (James et al., 2000). Hencehe 2- to 14-fold higher mean Al:P ratios for LusatLs indicate an efficient P immobilization.However, the import of the P binding partners Fe

l from the catchment area will slow down with timFig. 10). Consequently, metal availability and supowards the sediment surface from acidic to modeH decreases (Table 1, Fig. 7), leading to a slow redu

ion of the benthic P retention capacity. In additionn actual very low P import of 0.001 g m−2 a−1, thisight coincide with a larger loss of P from the catent due to a more intensive use in future.

Decisive are also changes in the Fe availability overtime (Fig. 7). The portion of FeHCl on TFe clearly de-creases with depth (Fig. 7), and consequently the Fe-mediated binding capacity for P over time. Phosphatecan specifically sorb onto Fe-hydroxide and therebychange its surface properties. But the progressive re-duction of the Fe(III)oxi-hydrates by inorganic andorganic compounds plays only a subordinate role incomparison to the microbial-mediated Fe reduction(Schinzel et al., 1993). First, the larger the specificsurface of the Fe(III)oxi-hydrates (Fig. 8), the fasterthe micobial reduction of the minerals starts with thesubsequent microbial SO42− reduction (Schinzel et al.,1993). Second, with rising pH, other more crystallineminerals will be formed which are as e.g. goethitenot very prone to microbial-mediated Fe(III) reduc-tion (Langner, 2001). This progressive reduction of thespecific surface (Fig. 8) additionally reduces P sorp-tion capacity. At pH∼3, the predominance of Fe re-duction over SO42− reduction can be further stabilizedby the transformation of schwertmannite to goethitewhich releases acidity (Blodau and Peiffer, 2003; Peineet al., 2000). However, due to the presence of Fe inthe HCl fraction (Fig. 5), the formation of FeS cannotbe excluded since HCl also extracts sulfidic-bound Fe(Thamdrup et al., 1994).

The high amount of Fe(III) compounds can immo-bilize P effectively (Fe:P > 100,Fig. 9) and SO4

2− re-duction and sulfide formation is obviously not Fe lim-ited (S:Fe < 40), but limited by organic C (Kleeberg,1 latet ,l isso-l( nac -t sul-fi ersf ility( 97

ox-s entlyi iths Pd oses (pH8 also

be permanently immobilized by vivianite under strongreducing conditions (Hupfer et al., 1998). In case ofML Niemegk (pH 3.0) a rise in the NaOH-P fractionwith sediment depth was attributed to the dissolution ofschwertmannite to goethite whereby P was temporarilydesorbed, but afterwards consumed in vivianite forma-tion (Langner, 2001).

Only traces of carbonate-bound P were found in theHCl-P fraction (Fig. 5), however there may be a slowincrease in the carbonate-bound P during the neutral-ization process of MLs (Fig. 6) related to a C accumu-lation in the sediments. The reasons for the decreaseof the residual P (Fig. 6) are twofold. First, it mightbe an artefact of the chemical fractionation (Table 2).Second, the decrease in that fraction is an indication ofthe lower input of lignite. The majority of the residualP (Figs. 4 and 6) originates from the lignite, but is mostprobably not relevant for a benthic P release.

4.3. Implications of benthic phosphorus mobilityfor mining lake succession

In addition to laborious P fractionations, the atomicFe:P ratio in surface sediments of MLs is a useful toolwhich can indicate the potential P mobility and mayhelp to characterize the stage of succession, at certainpelagic TP thresholds (Fig. 2), particularly at pH >6(Fig. 9). The higher the benthic Fe:P ratio, the betterthe P retention capacity and the lower the P mobilityare. Hence, the major decrease in the Fe:P ratio witht ent( hisi ter-s i-t edlyea uldb .

ianM elyt ten-d hicc er,t mo-b var-i

998). Hence, the addition of organic C can stimuhe dissolution of lime added and the SO4

2− reductioneading to an increase in pH, and consequently dute Fe(III) minerals, e.g. jarosite KFe3(SO4)2(OH)6Herzsprung et al., 2002). In a later stage of maturatiot a higher organic C availability, the still high SO4

2−oncentration (Table 1, Kleeberg, 1998) enables an inense SO42− reduction. As a consequence, the ironde formation could lead to a lack in binding partnor P, and consequently to an increase in P mobe.g.Caraco et al., 1993; Roden and Edmonds, 19).

Under reducing conditions, in contrast to redensitive Fe-bound P, Al-bound P can be permanmmobilized. The increased portion of NaOH-P wediment depth (Fig. 5) suggests that BD extractableissolved during diagenesis is transformed into thpecies. It could be demonstrated for ML Golpa.4) by thermodynamic calculations that P could

he progressive neutralization of water and sedimFig. 9) also implies a slow increase in P mobility. Ts related to a diminishing Fe import from the wahed with time (Table 1, Fig. 10). Since organic C addions lead to an overall amelioration and undoubtnhance the in-lake neutralization via SO4

2− reductionnd iron sulfide formation, the benthic Fe:P ratio shoe considered first if C amendments are intended

. Summary and conclusions

Although the large variability among the LusatLs in the chronosequence approach from extrem

o moderately acid delineates clearly the futureency of ML development. The current idiotroponditions limit the threat of eutrophication. Howevhe actual stage of pelagic availability and benthicility of P and their potential future changes reveal

ous counteracting processes.

Processes delaying benthic P mobility—bindingand mobility of P is influenced by a high input anda surplus of Al and Fe as reflected in the dominance ofmetal-bound P, only traces of mobile P forms, and anincrease in sedimentary TP with rising pH. The excessin reactive Fe at a high Fe:P ratio favours an efficient Pbinding. A currently low pH favours the precipitation ofFe-oxi-hydroxides with a high specific surface area forP adsorption. The future Fe-mediated P binding is noteasy to predict. First, the wide range of TFe and FeHClmakes an estimation of the availability and reactivitydifficult. Second, the future extent of acidification isoften unknown or at least partial long-lasting and stabi-lized through reoxidation of microbially formed Fe(II)and the transformation of schwertmannite to goethite.

Processes accelerating benthic P mobility—besidesan appropriate P concentration in various MLs to reacha high(er) productivity, there is a diminishing importof Al and Fe from the watershed and a lowering in Femineral surfaces at rising pH which also reduces the Pretention. Further information is needed on the role ofAl compounds on permanent P binding in relation tothe future supply of both, Fe and P, from the catchment.The velocity and the supply of C will determine thefuture benthic P remobilization and the extent of redox-controlled P release.

At the end of succession of the maturation of sulfate-rich MLs, as in neutral glacial lakes an enhanced ironsulfide formation might lead to a lack of Fe as a Pbinding partner and an enhanced P mobility. Hence,b andg he Pb uet ses,t cultt atedb

Pe-t ion)f wella ot-t wl-e TUC Re-

search Centre 565, and was supported by the DeutscheForschungsgemeinschaft (DFG, Bonn).

References

Berner, R.A., 1980. Early Diagenesis. A Theoretical Approach.Princeton University Press, New York, 241 pp.

Bigham, J.M., Carlson, L., Murad, E., 1994. Schwertmannite, a newiron oxyhydroxysulphate from Pyhasalmi, Finland, and other lo-calities. Miner. Mag. 58, 641–648.

Bigham, J.M., Schwertmann, U., Traina, S.J., Winland, R.L., Wolf,M., 1996. Schwertmannite and the geochemical modeling ofiron in acid sulfate waters. Geochim. Cosmochim. Acta 60,2111–2121.

Blodau, C., Peiffer, S., 2003. Thermodynamics and organic matter:constraints on neutralization processes in sediments of highlyacidic waters. Appl. Geochem. 18, 25–36.

Borovec, J., Hejzlar, J., 2001. Phosphorus fractions and phospho-rus sorption characteristics of freshwater sediments and theirrelationships to sediment composition. Arch. Hydrobiol. 151,687–703.

Brugam, R.B., Gastineau, J., Ratcliff, E., 1995. The neutralizationof acidic coal mine lakes by addition of natural organic matter:a mesocosm test. Hydrobiologia 316, 153–159.

Brugam, R.B., Stahl, J.B., 2000. The potential of organic matter ad-ditions for neutralizing surface mine lakes. Trans. Illinois Acad.Sci. 93, 127–144.

Brugam, R.B., Chakraverty, S., Lamkin, J., 1988. Sediment chem-istry of lakes formed by surface-mining for coal in the midwesternUSA. Hydrobiologia 164, 221–233.

Caraco, N.F., Cole, J.J., Likens, G.E., 1993. Sulfate-control of phos-phorus availability in lakes. Hydrobiologia 253, 275–280.

Chorus, I., 1995. Mussen in der Seesanierung Gesamtphosphat-Schwellenwerte unterschritten werden, bevor das Phytoplank-

D d re-izer.

D lakeein.

F isticsLig-s.),er,

F A.,sul-any.

F thewither Air

esides the detailed knowledge of geohydrauliceochemical boundary conditions, the status of tinding conditions must always be known. Finally, d

o the differing extent of the counteracting proceshe velocity of an accelerated eutrophication is diffio predict and can only be time-dependently estimy an additional iron and acidity balance.

cknowledgements

We thank A. Riße, J. Koebcke, R. Ender, and S.ersohn (BTU Cottbus, Chair of Water Conservator sediment sampling and laboratory assistance ass E. Tatan and W. Wiehe for metal analysis (BTU C

bus, Central Analytical Laboratory). We also acknodge the language revision by Benjamin Barnes (Bottbus). This study was part of the Collaborative

ton eine Reaktion zeigt. In: Jaeger, D., Koschel, R. (Eds.),fahren zur Sanierung und Restaurierung stehender Gewasser, vol8. Limnologie Aktuell, pp. 21–28.

avison, W., George, D.G., Edwards, N.J.A., 1995. Controlleversal of lake acidification by treatment with phosphate fertilNature 377, 504–507.

uffek, A., Langner, C., 2002. P retention in an acidic miningunder the influence of flooding with river water. Verh. Int. VerLimnol. 28, 1717–1720.

riese, K., Hupfer, M., Schultze, M., 2000. Chemical characterof water and sediment in acid mining lakes of the Lusatiannite district. In: Geller, W., Klapper, H., Salomons, W. (EdAcidic Mining Lakes—Limnology and Reclamation. SpringHeidelberg, pp. 25–45.

riese, K., Wendt-Potthoff, K., Zachmann, D.W., Fauville,Mayer, B., Veizer, J., 1998. Biogeochemistry of iron andfur in sediments of an acidic mining lake in Lusatia, GermWater Air Soil Pollut. 108, 231–247.

yson, A., Nixdorf, B., Steinberg, C.E.W., 1998. Manipulation ofsediment–water interface of extremely acidic mining lakespotatoes: laboratory studies with intact sediment cores. WatSoil Pollut. 108, 353–363.

George, D.G., Davison, W., 2000. Managing the pH of an acid lakeby adding phosphate fertilizer. In: Geller, W., Klapper, H., Sa-lomons, W. (Eds.), Acidic Mining Lakes—Limnology and Recla-mation. Springer, Heidelberg, pp. 365–384.

Herzsprung, P., Friese, K., Frommichen, R., Gottlicher, J., Koschor-reck, M., von Tumpling, W., Wendt-Potthoff, K., 2002. Chemicalchanges in sediment pore-waters of an acidic mining lake afteraddition of organic substrate and lime for stimulating lake reme-diation. Water Air Soil Pollut.: Focus 2, 123–140.

Hupfer, M., Fischer, P., Friese, K., 1998. Phosphorus retention mech-anisms in the sediment of a eutrophic mining lake. Water Air SoilPollut. 108, 341–352.

James, W.F., Barko, J.W., Eakin, H.L., Helsel, D.R., 2000. Distribu-tion of sediment phosphorus pools and fluxes in relation to alumtreatment. J. Am. Water Res. Assoc. 36, 647–656.

Jensen, H.S., Kristensen, P., Jeppesen, E., Skytthe, A., 1992.Iron–phosphorus ratio in surface sediment as an indicator ofphosphate release from aerobic sediments in shallow lakes. Hy-drobiologia 235/236, 731–743.

Kapfer, M., Fyson, A., Ender, R., Nixdorf, B., 2000. Biogeochemis-che Stoffumsetzungen an der Sediment-Wasser-Grenzflache inTagebauseen. In: Huttl, R.F., Weber, E., Klem, D. (Eds.),Okologisches Entwicklungspotential der Bergbaufolgeland-schaften im Niederlausitzer Braunkohlenrevier. B.G. TeubnerVerlag Stuttgart, Leipzig, pp. 157–178.

Kleeberg, A., 1998. The quantification of sulfate reduction in sulfate-rich freshwater lakes—a means for predicting the eutrophica-tion process of acidic mining lakes. Water Air Soil Pollut. 108,365–374.

Knoche, D., Embacher, A., Katzur, J., 2000. Wasser- undStoffhaushaltsdynamik einer Eichenchronosequenz auf starkkohle-und schwefelhaltigen Kippsubstraten des Braunkohle-bergbaus der Niederlausitz. In: Huttl, R.F., Weber, E., Klem, D.(Eds.),Okologisches Entwicklungspotential der Bergbaufolge-landschaften im Niederlausitzer Braunkohlenrevier. B.G. Teub-

L nteneispielh.D.

L us-Gus-

M ironsonal

M s: aental

M forActa

N ncein

Nixdorf, B., Uhlmann, W., 2002.Okotechnologische Steuerung derGewassergute in sauren Tagebauseen. Teil 1. Desulfurikation undMorphometrie. Wass. Boden 54, 16–21.

Nixdorf, B., Mischke, U., Leßmann, D., 1998. Chrysophytes andchlamydomonads: pioneer colonists in extremely acidic mininglakes (pH < 3) in Lusatia (Germany). Hydrobiologia 369/370,315–327.

Peine, A., 1998. Saure Restreen des Braunkohletagetaus-Charakterisierurg und Quantifiziorung biogeochemisoherProzesse und Abschatzung ihrer Bedeutung fur die secinterne.Neutralisierung. Ph.D. Thesis. Bayrenther forumokologie 62,1–132.

Peine, A., Peiffer, S., 1996. Neutralization processes in acid minelake sediments. Arch. Hydrobiol. Spec. Issues Adv. Limnol. 48,261–267.

Peine, A., Tritschler, A., Kusel, K., Peiffer, S., 2000. Electron flowin an iron-rich acidic sediment—evidence for an acidity-driveniron cycle. Limnol. Oceanogr. 45, 1077–1087.

Psenner, R., Pucsko, R., Sager, M., 1984. Die Fraktionierung organis-cher und anorganischer Phosphorverbindungen von Sedimenten.Arch. Hydrobiol. Suppl. 70, 111–155.

Roden, E.E., Edmonds, J.W., 1997. Phosphate mobilization in iron-rich anaerobic sediments: microbial Fe(III) oxide reduction ver-sus iron-sulfide formation. Arch. Hydrobiol. 139, 347–378.

Rucker, J., Nixdorf, B., Deneke, R., Kleeberg, A., Mischke, U.,2003. Reaktionen von Seen im Scharmutzelseegebiet auf die Re-duzierung der externen Belastung. Wass. Boden 55, 4–10.

Saballus, M., 2000. Bewertung eines Sanierungskonzeptes fureinen Bergbaurestsee bezuglich des P-Eutrophierungspotentials.Diploma Thesis. Fachhochschule Magdeburg, FachbereichWasserwirtschaft, 69 pp.

Schinzel, U., Dahmke, A., Schulz, H.-D., 1993. Reaktion vonEisen(III)-Oxihydraten wahrend der Fruhdiagenese in marinenSedimenten: Experimentelle Untersuchungen. Z. dt. Geol. Ges.144, 224–247.

S F.R.,em-e eu-l. 23,

T , iron,ark.

W hos-–27.

W nceand

Y ofodel

Z der-

ner Verlag Stuttgart, Leipzig, pp. 55–72.angner, C., 2001. Fruhdiagenetische Prozesse in jungen Sedime

von entsehenden Seen des Braunkohletagebaus am Bder Flutung des Goitschekomplexes in Mitteldeutschland. PThesis. Universitat Bremen, Fachbereich 5, 138 pp.

egler, Ch., Breitig, G., Steppuhn, G., Vobach, V., 1986. Agewahlte Methoden der Wasseruntersuchung, vol. I, 2nd ed.tav Fischer Verlag Jena, 517 pp.

oeslund, L., Thamdrub, B., Jorgensen, B.B., 1994. Sulfur andcycling in a coastal sediment: radiotracer studies and seadynamics. Biogeochemistry 27, 129–152.

orth, A.H., Smith, E.E., Shumate, K.S., 1972. Pyrite systemmathematical model. Contract Report for the U.S. EnvironmProtection Agency, EPA-R2-72-002.

urphy, J., Riley, J.P., 1962. A modified single solution methoddetermination of phosphate in natural waters. Anal. Chim.27, 31–36.

ixdorf, B., Leßmann, D., Steinberg, C.E.W., 2003. The importaof chemical buffering for pelagic and benthic colonizationacidic waters. Water Air Soil Pollut. 3, 27–46.

inke, A.J.C., Cornelese, A.A., Keizer, P., van Tongeren, O.Cappenberg, T.E., 1990. Mineralization, pore water chistry and phosphorus release from peaty sediments in thtrophic Loosdrecht lakes, The Netherlands. Freshwater Bio587–599.

hamdrup, B., Fossing, H., Jorgensen, B.B., 1994. Manganeseand sulfur cycling in a coastal sediment, Aarhus Bay, DenmGeochim. Cosmochim. Acta 58, 5115–5129.

elch, E.B., Cooke, G.D., 1999. Effectiveness and longevity of pphorus inactivation with alum. J. Lake Reserv. Manage. 15, 5

oelfl, S., Tittel, J., Zippel, B., Kringel, R., 2000. Occurreof an algal mass development in an acidic (pH 2.5), ironaluminium-rich coal mining pond. Acta Hydrochim. Hydrob28, 305–309.

okom, S., Axler, R., McDonald, M., Wilcox, D., 1997. Recoverya mine pit lake from aquacultural phosphorus enrichment: mpredictions and mechanisms. Ecol. Eng. 8, 195–218.

inder, B., 1985. Phosphatrucklosung aus Sedimenten als FolgeReduktion von Eisenoxiden. Ph.D. Thesis. Eidgenossische Technische Hochschule Zurich, 117 pp.

Phosphorus mobility in sediments of acid mining lakes, Lusatia, Germany

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